A Technical Assessment of E10 and E20 Petrol Ethanol Blends

A Technical Assessment of E10 and E20 Petrol Ethanol Blends
A Technical Assessment of
E10 and E20 Petrol Ethanol Blends Applied to
Non-Automotive Engines.
Failure Mode and Effects Analysis
of Engine Function and Component Design for
Mercury Marine 15hp Outboard
and Stihl FS45 Line-Trimmer Engines.
Report to Environment Australia
Nov. 2002
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Table of Contents
1
2
Overview
A description of the FMEA
4
6
2.1
What is a FMEA?
2.1.1
The FMEA team selection.
2.1.2
The FMEA format.
2.2
FMEA columns descriptions
3
2.2.1
2.2.2
2.2.3
2.2.4
2.2.5
2.2.6
2.2.7
Item and Function
Potential failure mode
Potential effect of failure
Severity
Potential cause/mechanism of failure
Occurrence
Current Design Controls
2.2.8
Detection
2.2.9
Risk Priority Number
Functional FMEA
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10
3.11
4
6
6
6
7
7
7
7
7
8
8
9
9
9
10
Engine Groups
Engine Functions
Potential Failure Modes
Potential Effect of Failure
Severity Rating
Potential Cause(s)/ Mechanism(s) of Failure
Occurrence Rating
Current Design Controls
Detection Rating
Risk Priority Number
Summary of Function FMEA
10
10
11
11
12
12
12
13
14
15
16
Design FMEA - 15hp Mercury Marine Outboard
4.1
Item/ Function
4.2
Potential Failure Modes
4.3
Potential Effect(s) of Failure
4.4
Severity Rating
4.5
Potential Cause/ Mechanism of Failure
4.5.1
Material Degradation
4.5.2
Gumming
4.5.3
Lubrication Deficiency
4.5.4
Altered Combustion
4.5.5
Fuel Properties
4.6
Occurrence
4.7
Current Design Controls
4.8
Detection Rating
4.9
Risk Priority Number
4.10 Summary of Design FMEA 15hp Mercury Marine Outboard
5
Design FMEA - Stihl FS45 Line-trimmer
5.1
5.2
5.3
5.4
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20
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20
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25
Item/ Function
Potential Failure Modes
Potential Effect(s) of Failure
Severity Rating
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5.5
5.6
5.7
5.8
5.9
5.10
Potential Cause/ Mechanism of Failure
Occurrence
Current Design Controls
Detection Rating
Risk Priority Number
Summary of Design FMEA FS45 Stihl Line-trimmer
6 References
7 Appendix A
8 Appendix B
9 Appendix C
10 ..Appendix D
11 ..Appendix E
12 ..Appendix F
13 ..Appendix G
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1 Overview
The purpose of this report is to identify potential sources of system function failure
of typical non-automotive engine applications, when used with ethanol-blended
E20 fuel. The report also identifies possible sources of component failure,
through the use of ethanol-blended E20 fuel, on two engine applications. The
selected applications for investigation were a 15hp Outboard marine engine and a
Line-trimmer engine.
A technique termed Failure Mode and Effect Analysis (FMEA) was used to
perform the functional and design FMEAs detailed in this report. This technique
is used throughout industry to enable objective assessment of designs,
processes, systems and functions.
A functional FMEA was used to investigate the effect of ethanol-blended E20 fuel
on various engine functions (eg cold start, idle). The FMEA technique was
repeated on four engine groups defined by typical applications. The groups were:
Aircraft; Utility; Marine and Vehicle engines.
The FMEA identified that
investigation is required to determine the effects of E20 fuel on numerous engine
functions.
The results of the functional FMEA tend to be biased as the data reflects test
programs that are in place to evaluate engine operation on E10 and E20 fuels.
This is illustrated in Figure 5, where aircraft and vehicle engine groups exhibit the
highest risk priority number (RPN) since these engine groups show the highest
detection rating (no control in place to detect failure). It must be noted that the
RPN for the aircraft group is higher than the vehicle group due to the severity
rating shown in Figure 1.
Of particular concern is the use of E10 and E20 fuel for aircraft applications. Due
to associated risks of engine failure, the use of E10 and E20 fuel use for this
application is not recommended without successful completion of a
comprehensive testing program approved by the appropriate aviation authorities.
A design FMEA was used to investigate the effect of ethanol-blended E10 and
E20 fuel on the components of a 15hp Outboard marine engine and a Linetrimmer engine. The design FMEA for both engines highlighted the possibility of
engine failure through: material compatibility with E10 and E20 fuel; enleanment;
and gumming. Material compatibility was found to potentially cause engine
damage through corrosion of critical bearing surfaces and external fuel leaks.
Enleanment occurs as a result of the E10 and E20 fuel properties and leads to
knock and pre-ignition in engines intended for use with regular gasoline. This
effect was found to be potentially the main source of base engine component
failure. Gumming was highlighted as a potential failure mode, due to the potential
risk of fuel residues depositing on critical surfaces or causing blockages within
components.
The FMEAs performed have investigated the effect of the use of E10 and E20
fuel on engine function. The analyses have highlighted potential failure modes
and mechanisms of failure.
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The FMEA technique is a valuable tool to identify potential component/ system
design or functional issues, however rigorous verification techniques are required
to fully ascertain functionality compliance. The outcome of an FMEA is a list of
functions and components with an assigned objective risk priority number (RPN).
The RPN is typically used to identify and rank the priority of components and
functions that require verification. In conjunction with other inputs such as:
warranty data; design studies; competitive analysis; etc, the FMEA is used to
generate a verification plan that details the necessary analysis and testing
required for validating component and/ or system function.
The potential failure modes as identified by the FMEAs presented in this report,
require appropriate testing to establish whether these are in fact issues affecting
the function of non-automotive engine applications, when used with ethanolblended E10 and E20 fuel.
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2 A description of the FMEA
2.1 What is a FMEA?
A FMEA is a systematic approach that utilises a tabular method to aid the thought
processes used by engineers to identify potential failure modes and their effects.
Its purpose is to identify potential failure modes, rate the severity of their effects
and rank in order the likelihood of their occurrence.
The contents of a FMEA may be based on a number of inputs or information
sources, for example;
• Design requirements
• Other studies
• Engineers previous knowledge
• Supporting documentation and reports
• Where possible information gathered from in-field performance for
example warranty return information.
As such the FMEA procedure outputs a document that indicates what may occur,
the associated causes and the means of addressing those occurrences.
2.1.1 The FMEA team selection.
The engineer responsible for the FMEA has chosen team members ensuring as
wide a ranging skill and experience base. The team then went about selecting
the format for the FMEA as well as identifying the approach for the FMEA.
2.1.2 The FMEA format.
The format selected by the FMEA team members was that of the design FMEA
as this format is suitable to carry out a FMEA for components and it is the logical
structure of the FMEA process that is to be utilised. The team adopted the
functional approach as most suitable.
The FMEA studies completed, follow the format described by the Ford Worldwide
FMEA document [21], it utilises a similar layout of the form shown in [21]. The
complete process of the design FMEA has not been followed here, as only the
potential failure modes and their effects inclusive of safety concerns are to be
documented. In fact the design FMEA should be completed before the product is
released to the market. The other outputs from the design FMEA, planning
product design verification test programs and establishing a priority for design
improvement actions, etc. are not pursued as it is outside the scope of this study
and are vehicle manufacturer related issues.
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2.2 FMEA columns descriptions
These following descriptions are provided to allow readers who are unfamiliar
with FMEA’s to understand the FMEA study without having to refer to the Ford
handbook [21]. The reader may like to view one of the FMEA studies in the
appendix section of this report while reading the following FMEA column
descriptions.
2.2.1 Item and Function
This column lists every component that may be affected either directly or
indirectly by the E20 ethanol blend fuel. There is also a description of the
function of the item as the team adopted the functional approach to the FMEA.
2.2.2 Potential failure mode
This column lists all the potential failure modes for each item. A failure mode is
considered to have occurred when the component ceases to operate in the
correct manner. For example, the fuel tank should neither corrode nor perish, if
either occurs then these are modes of failure induced by the potential cause or
mechanism of the failure. The hardware or component based approach has been
adopted as each part has been listed.
2.2.3 Potential effect of failure
This column lists all the possible effects of a failure mode. These effects are the
consequences of a failure mode in terms of their impact on other systems, the
vehicle and the customer or government regulations. For example when the fuel
tank perishes or corrodes the effect of this failure is a fuel leak.
2.2.4 Severity
This column contains a rating on a 1 to 10 scale of the seriousness of the
effect(s) of a potential failure mode. The rating table of severity is shown below.
Table 1 Severity rating table
Effect
Rating
No effect
1
No effect
Very slight effect
2
Customer not annoyed. Very slight effect on vehicle or system performance
Slight effect
3
Customer slightly annoyed. Slight effect on vehicle or system performance
Minor effect
4
Customer experiences minor annoyance. Minor effect on vehicle or system performance
Moderate effect
5
Significant effect
6
Major effect
7
Extreme effect
8
Serious effect
9
Hazardous effect
10
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Criteria
Customer experiences some dissatisfaction. Moderate effect on vehicle or system
performance
Customer experiences discomfort. Vehicle performance degraded but operable and
safe. Partial loss of system function but operable.
Customer dissatisfied. Vehicle performance severely affected but driveable and safe
system function impaired
Customer very dissatisfied. Vehicle inoperable but safe. System inoperable
Potential hazardous effect. Able to stop vehicle without mishap, gradual failure.
Compliance with government regulations in jeopardy
Hazardous effect. Safety related sudden failure non compliance with government
regulations
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2.2.5 Potential cause/mechanism of failure
This column lists the design deficiencies of a component that result in the failure
mode. For example if the fuel tank perishes or corrodes then the design
deficiency is that the tank was constructed from either the incorrect material or an
incorrect surface treatment for use with the E20 ethanol blend was utilized.
2.2.6 Occurrence
This column lists the estimated cumulative number of component failures (CNF)
that could occur for a given cause over the design life of the component. The
rating table of occurrence is shown below.
Table 2 Occurrence rating table
Occurrence
Rating
Almost impossible
1
Remote
2
Very slight
3
Slight
4
Low
5
Medium
6
Moderately high
7
High
8
Very high
9
Almost certain
10
CNF/1000
<0.00058
(1 in 1,500,000)
0.0068
(1 in 150,000)
0.063
(1 in 15,000)
0.46
(1 in 2000)
2.7
(1 in 400)
12.4
(1 in 80)
46
(1 in 20)
134
(1 in 8)
316
(1 in 3)
>316
(1 in 3)
Criteria
Failure unlikely
Rare number of failures likely
Very few failures likely
Few failures likely
Occasional number of failures likely
Medium number of failures likely
Moderately high number of failures likely
High number of failures likely
Very high number of failures likely
Failure almost certain to occur
In order to apply scaling to the occurrence ratings the FMEA team decided on the
following ratings.
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A rating of 10 will be applied to the following:
• All components specifically mentioned as having the potential for failure or
exhibiting problems by the reference material.
• All components or subcomponents specifically mentioned as requiring
replacement or redesign for use with the E20 ethanol petrol blend by
stakeholders.
For all other items, an estimated rating agreed on by the FMEA team is applied.
2.2.7 Current Design Controls
A design control is a method or test used to either detect a cause of a potential
failure mode or to detect a failure mode. Within the E20 program, engine
durability, emissions and components compatibility testing is targeted as the
design control methods available for detection.
2.2.8 Detection
The detection rating is scaled from 1 to 10 where 1 indicates an almost certain
likelihood that a design control method or test will detect a first level cause of a
potential failure mode and a 10 indicates that detection is almost impossible,
either because no design control method is available or none is planned. Table 3
shown below presents the ratings and how they relate to the design control
chosen.
Table 3 Detection rating table
Effect
Rating
Criteria: Design Control
Almost Certain
1
Has the highest effectiveness in each applicable category
Very high
2
Has very high effectiveness
High
3
Has high effectiveness
Moderately high
4
Has moderately high effectiveness
Medium
5
Has medium effectiveness
Low
6
Has low effectiveness
Slight
7
Has very low effectiveness
Very Slight
8
Has lowest effectiveness in each applicable category
Remote
9
Is unproven, unreliable or effectiveness unknown
Almost impossible
10
No Design Control method available or none planned
2.2.9 Risk Priority Number
Risk Priority Number (RPN) is the product of the occurrence, severity and
detection ratings. The RPN should only be used to rank the concerns, as the
ratings and final RPN numbers have no value or meaning in themselves.
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3 Functional FMEA
A functional FMEA was performed to determine the effect of E20 fuel on engine
functions for selected engine groups. Appendix A to Appendix D contains the
completed function FMEA tables.
3.1 Engine Groups
In an attempt to rationalise the extensive range of non-automotive engine
applications four engine groups were created. The groups were, aircraft, utility,
marine and vehicle. Table 4 below illustrates examples of engines in each group.
Table 4 Example of an engine application within nominated engine groups
Engine Group
Example
Aircraft
Ultra-light, hovercraft, light air craft
Utility
Line-trimmer,
compressors
Marine
Outboards, personal water craft
Vehicle
Snowmobile, motorcycle, all terrain vehicles
chainsaw,
lawn
mower,
generator,
3.2 Engine Functions
Functions that a typical non-automotive engine must be able to perform are
shown in Table 5. This information formed the basis for the functional FMEA on
the four engine groups.
Table 5 Engine functions and definitions
Item
Function Description
Cold Start
Commence engine operation
Hot Start
Recommence engine operation
Warm-up
Engine operation before reaching operating temperature
Idle
Operation at lowest power required to drive equipment
Part Load
Engine operating point between idle and full load
Full Load
Engine operating point full throttle
Speed Control
Engine operation for constant speed varying load
Load Control
Torque backup
Over-speed
Limit maximum engine speed
Over-run
When device drives engine
Shutdown
Cease engine operation
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3.3 Potential Failure Modes
Potential failure modes for the engine functions were found to be the same for all
engine groups. Table 6 illustrates potential failure modes for specified engine
functions.
Table 6 Potential failure modes for engine functions
Item
Potential Failure Mode
Function
Cold Starting
Engine fails to start
-To commence engine operation
Start time is excessive
Engine starts then stalls
Hot Starting
Engine fails to start
-To recommence engine operation
Start time is excessive
Engine starts then stalls
Warm-up
Engine stalls
- Engine operation when Not at Engine power output low
operating temperature
Engine Not efficient
Rough engine operation
Idle
Engine stalls
-Operation at lowest engine power Rough engine operation
while driving equipment
Inefficient operation
Part Load
Engine stalls
-Engine operating point between idle Engine seizure
and full load
Rough engine operation
Inefficient operation
Full Load
-Engine operating point full throttle
Engine stalls
Engine seizure
Rough engine operation
Inefficient operation
Lack of power
Speed Control
Engine damage
-Engine operation for constant speed Inefficient operation
varying load
Inaccurate control
Poor control to Nominal speed
Engine exceed maximum engine speed
Load Control
- Torque backup
Engine Stalls
Inaccurate control
Engine cannot maintain load
Engine damage
Over-speed
Engine failure
-Function to limit maximum engine Poor speed control
speed
Engine over-speed
Shutdown
-Cease engine operation
Ignition kill does Not stop engine
3.4 Potential Effect of Failure
For all engine groups, potential effects of failure were found to be similar, though
subtle differences did exist depending on the application. For example if an
aircraft engine stalls at altitude then it will lose altitude, whereas a vehicle remains
stationary. A consequence of the difference in effects of failure alters the severity
rating for each engine group.
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3.5 Severity Rating
Severity ratings were developed for the engine functions of each engine group.
Figure 1 illustrates the severity rating for each engine function and engine group.
The severity ratings are generally highest for aircraft applications since any failure
may cause personal injury. Failure to adequately limit over-speed and perform
shutdown were given a high rating for utility engine group due to the potential for
operator injury.
Aircraft Application
Utility Application
Marine Application
Vehicle Application
12
Severity Rating (/10)
10
8
6
4
2
Shutdown
Overrun
operation
Overspeed
Load Control
Speed Control
Full Load
Part Load
Idle
Warmup
Hot Starting
Cold Starting
0
Engine Function
Figure 1 Severity rating for each function and engine group
3.6 Potential Cause(s)/ Mechanism(s) of Failure
Potential causes of failure are generally the same for all engine groups. The
majority of the mechanisms for failure are related to fuel properties.
3.7 Occurrence Rating
No statistics were available to provide satisfactory reference for an occurrence
rating. A document survey (list appears in References) was conducted to
determine which mechanisms were likely to cause function failure. The results of
this appear in Figure 2. Using this information it was possible to develop
subjective occurrence ratings for the failure of a specific engine function. Figure 3
illustrates occurrence values assigned to engine functions.
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Aircraft Application
Utility Application
Marine Application
Vehicle Application
60%
Percentage of Documents (%)
50%
40%
30%
20%
10%
0%
Water and Phase
Separation
Corrosion and
Material Selection
Vapour Lock and
Formation
Deposits and
Gumming
Enleanment
Icing
Cause/Mechanism
Figure 2 Results of document search on failure mechanisms
Aircraft Application
Utility Application
Marine Application
Vehicle Application
12
Occurence Rating (/10)
10
8
6
4
2
Shutdown
Overrun
operation
Overspeed
Load Control
Speed Control
Full Load
Part Load
Idle
Warmup
Hot Starting
Cold Starting
0
Engine Function
Figure 3 Occurrence rating for engine function and engine groups
3.8 Current Design Controls
Current design controls are dependant on testing performed as part of the E10
and E20 Ethanol test program. Limited testing is being performed on only one
example from engine groups Marine and Utility. Table 7 lists the current design
controls for engine function for each engine group. Note that many items are
listed as “No controls in place” because testing is not being undertaken.
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Table 7 Current design controls for engine function for each engine group
Current Design Control
Item
Aircraft
Function
Cold Starting
No controls in place
-To commence engine operation
Utility
Marine
Vehicle
Engine Testing
Engine Testing
No controls in place
No controls in place
Engine Testing
Engine Testing
No controls in place
Warm-up
No controls in place
-Ensure engine operation when
Not at operating temperature
Engine Testing
Engine Testing
No controls in place
Idle
No controls in place
-Operation at lowest engine
power while driving equipment
Engine Testing
Engine Testing
No controls in place
Part Load
No controls in place
-Engine operating point between
idle and full load
Engine Testing
No controls in place
No controls in place
Full Load
-Engine operating
throttle
Engine Testing
Engine Testing
No controls in place
Hot Starting
-To
recommence
operation
engine
No controls in place
point
full
Speed Control
No controls in place
-Engine operation for constant
speed varying load
No
controls
place
in No controls in place
No controls in place
Load Control
- Torque backup
No controls in place
No
controls
place
in No controls in place
No controls in place
No controls in place
Engine Testing
No controls in place
No controls in place
in No controls in place
No controls in place
Over-speed
-Function to
engine speed
limit
maximum
Over-run operation
No controls in place
-Engine operation when device
drives engine
No
controls
place
Shutdown
-Cease engine operation
Engine Testing
No controls in place
Engine Testing
No controls in place
3.9 Detection Rating
Detection ratings assigned to failure of engine functions are shown in Figure 4.
Note that the majority of the detection ratings have a value of 10 since no control
is in place to establish failure of the specific function. This action results in a high
detection rating, hence biasing the RPN. Several functions within the marine and
utility engine groups were assigned detection values of 1 since it is expected that
testing to be performed as part of the E20 test program will detect failures of
these functions.
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Aircraft Application
Utility Application
Marine Application
Vehicle Application
12
Detection Rating (/10)
10
8
6
4
2
Shutdown
Overrun
operation
Overspeed
Load Control
Speed Control
Full Load
Part Load
Idle
Warmup
Hot Starting
Cold Starting
0
Engine Function
Figure 4 Detection Rating for engine functions and engine groups
3.10 Risk Priority Number
Risk priority number for each engine function is shown in Figure 5. The aircraft
and vehicle groups have the highest RPN values. The lower RPN values of the
utility and marine engine groups are a reflection of the test program being
performed on these engine groups.
Aircraft Application
Utility Application
Marine Application
Vehicle Application
1200
Risk Priority Number (/1000)
1000
800
600
400
200
Shutdown
Overrun
operation
Overspeed
Load Control
Speed Control
Full Load
Part Load
Idle
Warmup
Hot Starting
Cold Starting
0
Engine Function
Figure 5 Risk priority number for engine function and engine groups
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3.11 Summary of Function FMEA
A functional Failure Mode FMEA was used to investigate the effect of ethanolblended fuel E20 on various engine functions (eg cold start, idle). The FMEA
technique was repeated on four engine groups defined by typical applications.
The groups were: Aircraft, Utility, Marine and Vehicle engines.
The results of the functional FMEA tend to be biased as the RPN reflects test
programs that are in place to evaluate engine operation on E10 and E20 fuels.
This is illustrated in Figure 5, where aircraft and vehicle engine groups exhibit the
highest risk priority number (RPN) since these engine groups show the highest
detection rating (no control in place to detect failure). It must be noted that the
RPN for the aircraft group is higher than the vehicle group due to the severity
rating shown in Figure 1.
Of particular concern is the use of E20 fuel for aircraft applications. Due to
associated risks of engine failure, it is recommended that E20 use for this
application be deferred until comprehensive testing is completed and E20 use
approved by suitable aviation authorities.
The FMEA has identified that further investigation is required to determine the
effects of E10 and E20 fuel on a number of engine functions not addressed by the
test program being undertaken on the outboard and line-trimmer engines. Speed
control function is a particularly important function for the utility group when an
engine may be used to drive machinery at a constant speed with varying load (for
example a generator set, concrete mixer, mulcher). Load control (torque back
up) is an important function for all engine groups since this function is a
fundamental requirement for an engine driving rotating equipment. Over-speed
control is an important function since engine durability in all groups is dependant
on this function.
The current test program will provide good insight to most issues likely to occur
as a result of using ethanol-blended fuels. However, as discussed above, there
are specific functions that will not be addressed. Therefore any subsequent test
programs should consider including verification of: speed control, load control for
all engine groups; part load for utility group; and over-speed for marine and
vehicle groups.
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4 Design FMEA - 15hp Mercury Marine Outboard
A design FMEA was conducted on a 2002 model year 15hp two-stroke Mercury
Marine outboard engine. This engine was considered to be representative of
engines in the marine group. The FMEA exercise was limited to how component
function may be impaired by using ethanol-blended fuels. The FMEA table is
attached in Appendix E. A discussion of the FMEA analysis follows.
4.1 Item/ Function
The first step in conducting the FMEA was to list all engine components exposed
to fuel and the associated functions that may be affected by the fuel. For
example a fuel hose has two functions: transfer fuel and maintain connection with
fuel connector. The listing of components and associated functions is shown in
Appendix E. Figures of components and assemblies exposed to E20 fuel are
illustrated in Appendix F.
4.2 Potential Failure Modes
The potential failure modes identified for the 15hp outboard engine are listed in
detail in Appendix E. The failure modes relate to the failure of the component to
perform the intended function.
4.3 Potential Effect(s) of Failure
Potential effects of failure are shown in Appendix E. The analysis found that
many component function failures had the potential to create similar effects of
failure. Potential effects of failure include:
• Lack of power
• Fuel leaks
• Engine stopping
• Rough engine operation
• Engine seizure
• Engine not starting
• Poor starting
• Throttle sticking
Figure 6 illustrates a summary of potential effects of failure and provides a
percentage rating for each effect of failure. Lack of power and fuel leaks are the
most common effect of potential function failure, followed by engine stopping and
rough engine operation.
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1%
Effect of Function Failure
Throttle sticks
2%
Poor start
Engine will
not start
4%
5%
Engine seizure
Rough engine
operation
17%
18%
Engine stops
24%
Fuel leaks
29%
Lack of power
0%
5%
10%
15%
20%
25%
30%
35%
Percentage of Total Effects (%)
Figure 6 Effect of component function failure on engine
Figure 6 does not address the severity of the effect of function failure.
4.4 Severity Rating
Severity ratings were assigned based upon the effect of the failure mode. Figure
7 illustrates the severity ratings assigned for this FMEA
Poor start
Effect of failure
Rough engine
operation
Lack of power
Engine will
not start
Engine seizure
Engine stops
Fuel leaks
Throttle sticks
0
2
4
6
8
10
12
Severity rating (/10)
Figure 7 Severity rating of the effect of failure for components exposed to E20
Throttle sticking was assigned the maximum severity rating of 10 due to the
possibility of the throttle being stuck wide-open during engine operation, with an
associated operator safety risk.
Fuel leaks were assigned a value of 9, since their occurrence is potentially
hazardous.
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Failure effects that resulted in the engine being inoperable but safe were given a
rating of 8.
Failure effects that resulted in degraded engine performance were assigned a
severity rating of 6.
4.5 Potential Cause/ Mechanism of Failure
Potential causes of failure specific to E20 fuel, in order of significance, were found
to be the following:
• Material degradation
• Gumming
• Lubrication deficiency
• Altered combustion
• Fuel properties
To summarise the potential mechanisms of failure, Figure 8 displays the
proportion of mechanisms discussed in this analysis. This figure shows that
material degradation (corrosion or perishing) is potentially the most significant
function failure mechanism.
Mechanism of Failure
Fuel properties
3%
Altered
combustion
6%
Lubricant
deficiency
9%
Gumming
13%
Material
degradation
69%
0%
20%
40%
60%
80%
Percentage of Total Mechanisms of Failure (%)
Figure 8 Mechanism of failure vs. Percentage of total
4.5.1 Material Degradation
Questionable material compatibility with E20 fuel is potentially the most common
cause of function failure. This cause of failure potentially produces component
degradation (corrosion and perishing), fuel leaks and incorrect fuel metering.
Failure of fuel supply components (eg fuel tank, fuel tubing) has the potential to
allow water into the fuel. Water contaminated fuel may be the result of several
components not functioning correctly. Water contamination is a recognized
failure mode for ethanol-blended fuel since it leads to phase separation. Water
contamination in ethanol blend fuels also promotes aggressive corrosion of
materials. Water contamination is also associated with lubrication failure resulting
in high wear rates for components (including potential for engine seizure).
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4.5.2 Gumming
Gumming is due to deposits, which may form on components from compounds
within the fuel. Gumming may also be the result of the E20 fuel dissolving
gasoline fuel residue and depositing it elsewhere. Gumming has the potential to
block fuel metering or flow control devices (eg check valves and needle valves).
4.5.3 Lubrication Deficiency
Lubrication deficiency is a failure mechanism, which describes potential failures
attributed to lubricating oil. The term captures several modes of lubrication
failure, including; insufficient lubrication, unsuitable oil (for fuel used), lubrication
failure, unsuitable or insufficient detergents in oil.
4.5.4 Altered Combustion
Combustion may be altered by a phenomenon known as enleanment. E20 fuel
necessitates a richer air to fuel ratio for stoichiometric combustion than that
necessary for regular gasoline. When using ethanol-blended fuels in engines
designed for use of regular gasoline, the resulting air to fuel ratio is therefore
leaner Enleanment has the potential to cause severe damage to base engine
components through knock or pre-ignition. Enleanment may also occur through
blockages in the fuel system components or metering orifice in the carburettor,
due to material degradation or gumming.
4.5.5 Fuel Properties
Fuel properties will definitely have an effect on engine performance. For example
it was found through the FMEA exercise that the ability of the carburettor to mix
fuel and air might be inhibited by the fuels vaporisation properties. Another
potential failure mechanism of fuel properties (or composition) is due to carbon
deposits forming on the ports and piston ring grooves. Note that carbon deposit
formation in ports or ring grooves is also a function of lubricating oil detergents
and combustion temperatures.
4.6 Occurrence
No statistics were available to provide satisfactory reference for an occurrence
rating. The FMEA team was consulted to determine likely occurrence ratings,
based upon the potential cause of failure. Figure 9 illustrates occurrence ratings
assigned by the FMEA team.
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Mechanism of Failure
Fuel properties
Gumming
Lubricant
deficiency
Altered
combustion
Material
degradation
0
2
4
6
8
10
12
Occurrence Rating (/10)
Figure 9 Occurrence rating for the cause of components exposed to ethanol-blended fuels
Occurrence ratings of 10 were assigned to causes of failure due to altered
combustion. This cause is influenced by ethanol-blended fuels effect on
combustion temperatures and hence the likelihood of damage to base engine
components such as pistons, piston rings and sparkplugs. The FMEA team
decided that it was impossible to determine an occurrence rating for these items,
resulting in the assigned value of 10.
The occurrence values assigned to causes of failure due to material degradation
was determined to be a 10. The FMEA team decided that it was impossible to
determine an occurrence rating for these items, since little is known about the
material specifications, resulting in the assigned value of 10.
4.7 Current Design Controls
Current design controls in place for the 15hp Mercury Marine engine include
durability tank testing, emissions testing and materials compatibility testing.
4.8 Detection Rating
A detection rating of 1 (almost certain) was assigned to material compatibility
tests. Engine testing was assigned a 3 since testing should detect component
failures.
4.9 Risk Priority Number
Risk priority numbers ranged from 12 to 240. Risk priority numbers are illustrated
in Figure 10.
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250
200
150
100
50
0
Plastic Fuel Tank
Plastic Gauge and Cap
Fuel Pickup Screen
Fuel Pickup Tube
Top of Pickup
Connector - Fuel tank to fuel hose
Fuel Hose
Check valve assembly inlet and
Primer bulb
Tank fuel connector
Engine fuel connector
Fuel filter assembly
Fuel hose
Carburettor body
Throttle blade
Throttle shaft
Throttle blade screw
Mixture screw
Mixture screw O-ring
Top carburettor cover
Cover gasket
Fuel gallery plug
Main fuel nozzle
Main fuel jet
Float valve (needle and seat)
Float
Float pin
Float lever
Float screw
Float bowl gasket
Float bowl
Main jet screw
Main jet screw gasket
Pump body gasket
Diaphragm
Check valve retainer
Check valve
Fuel pump housing
Diaphragm return spring
Cover
Startup enrichment pump diaphragm
Enrichment pump gasket
Enrichment pump spring
Enrichment pump check valve
Carburettor gasket
Restrictor plate
Reed block
Reeds
Reed screws
Crankshaft
Connecting rods
Bearings
Crank seals
Piston
Piston Rings
Piston Pin Clip
Piston Pin
Cylinder block
Spark-plug
Risk Priority Number (/1000)
300
Item
Figure 10 Risk priority number for components exposed to E20
The components analysed were grouped based on RPN ranking. Table 8 lists
the components in RPN and group order. Components in Group A have the
highest priority for validation of function.
Group A contains base engine components (eg crankshaft, pistons and bearings).
An observation that can be made is the occurrence rating for these components
is 10. There is a high expectation that the failure will be detected during engine
testing (detection – 3). The potential failures are a result of the relatively
unknown effect of ethanol-blended fuels effect on combustion and corrosion of
critical bearing surfaces in an outboard marine engine.
Group B contains ancillary components that are critical to engine function. The
components potential failure typically produces rough engine running, lack of
power or poor engine starting (severity – 6). There is a high expectation that the
failure will be detected during engine testing (detection – 3). The failure
mechanisms are due to the relatively unknown effect of ethanol-blended fuels
effect on combustion and material degradation
Group C components are manufactured from a variety of materials. The potential
failure of the components is typically through material degradation. The failure
would typically produce a fuel leak or stop the engine running (severity – 9).
Material compatibility test should detect failure of these components (detection –
1)
Group D is the lowest risk category. Failure of group D components can have a
variety of effects, from engine stopping to fuel leaks, however the likely
occurrence of these failures ranks them low on the RPN scale.
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Table 8 Outboard components severity rating, occurrence rating, detection rating and risk
priority number
Item
GROUP A
Crankshaft
Connecting rods
Bearings
Piston
Piston Rings
Piston Pin
Cylinder block
GROUP B
Reed block
Reeds
Spark-plug
GROUP C
Plastic Fuel Tank
Top of Pickup
Connector - Fuel tank to fuel hose
Fuel Hose
Check valve assembly inlet and outlet
Primer bulb
Tank fuel connector
Engine fuel connector
Fuel filter assembly
Fuel hose
Carburettor body
Fuel gallery plug
Float valve (needle and seat)
Float
Float pin
Float lever
Float bowl
Main jet screw
Diaphragm
Fuel pump housing
Startup enrichment pump diaphragm
Plastic Gauge and Cap
Fuel Pickup Screen
Fuel Pickup Tube
Check valve
Diaphragm return spring
GROUP D
Throttle shaft
Mixture screw
Mixture screw O-ring
Main fuel nozzle
Main fuel jet
Enrichment pump spring
Enrichment pump check valve assembly
Crank seals
Piston Pin Clip
Cover gasket
Float bowl gasket
Main jet screw gasket
Pump body gasket
Enrichment pump gasket
Carburettor gasket
Reed screws
Throttle blade screw
Top carburettor cover
Float screw
Cover
Check valve retainer
Throttle blade
Restrictor plate
Orbital Engine Company
Severity
rating
Occurrence
rating
8
8
8
8
8
8
8
10
10
10
10
10
10
10
6
6
6
10
10
10
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
8
8
8
8
8
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
6
6
6
6
6
6
6
6
8
9
9
9
9
9
9
6
10
9
9
9
8
6
6
10
10
10
10
10
10
10
10
2
5
5
5
5
5
5
2
2
2
2
2
2
2
2
Detection
rating
Risk priority
number
RPN>180
3
3
3
3
3
3
3
240
240
240
240
240
240
240
3
3
3
180
180
180
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
80
80
80
80
80
1
1
1
1
1
1
1
1
3
1
1
1
1
1
1
3
1
1
1
1
1
1
1
60
60
60
60
60
60
60
60
48
45
45
45
45
45
45
36
20
18
18
18
16
12
12
RPN=<180
RPN=<120
RPN=<60
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4.10 Summary of Design FMEA 15hp Mercury Marine Outboard
The design FMEA conducted on the 15hp Mercury Marine Outboard (model year
2002) using ethanol-blended fuels was used to rank component function failures
in terms of risk priority.
The analysis found that base engine components with critical bearing surfaces
were most at risk. To detect failure of these components, testing on a number of
engines is recommended in order to ensure confidence in failure detection.
Components in the second highest risk category were ancillary components
fundamental to engine operation. The failure of those items does not result in a
severe failure, however failure will degrade engine performance. Detection of
failure of these components is also via engine testing.
Components in the third highest risk category are generally components which
may fail through material degradation. The potential failure of these components
may produce hazardous fuel leaks. Material compatibility tests are almost certain
to detect material compatibility failures.
The lowest risk category contains a variety of components. Components in this
group will be monitored during testing of higher risk components.
Engine components could potentially experience function failure through the use
of ethanol-blended fuel. The effects of function failure (in order of potential
incidence) include:
• Lack of power
• Fuel leaks
• Engine stopping
• Rough engine operation
• Engine seizure
• Engine not starting
• Poor starting
• Throttle sticking
Lack of power, fuel leaks, engine stopping and rough engine operation have the
potential to be the most common effects of component failure. The mechanisms
by which these failures potentially occur are material degradation and gumming.
Proposed durability, emissions and materials testing is considered to almost
certainly capture these highlighted potential failures.
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5 Design FMEA - Stihl FS45 Line-trimmer
A design FMEA was conducted on a two-stroke Stihl FS45 Line-trimmer engine.
This engine was considered to be representative of engines in the utility group.
The FMEA exercise was limited to how components function may be impaired by
using ethanol-blended fuels. The FMEA table is attached in Appendix G. A
discussion of the FMEA analysis follows.
5.1 Item/ Function
The first step in conducting the FMEA was to list all engine components exposed
to the E20 fuel and the components function. The list of components was
generated by disassembly of the engine to allow inspection and naming of all
components. The list of components and functions is shown in Appendix G.
5.2 Potential Failure Modes
Typical failure modes for the line-trimmer engine are listed in Appendix G. The
failure mode relates to the failure of the component to perform the intended
function.
5.3 Potential Effect(s) of Failure
Potential effects of failure are listed in Appendix G. The analysis found that many
component function failures had the potential to create similar effects of failure.
Potential effects of failure include:
• Lack of power
• Rough engine operation
• Fuel leaks
• Engine seizure
• Engine stopping
• Engine not starting
• Poor starting
• Throttle sticking
Figure 11 illustrates a summary of potential effects of failure and provides a
percentage rating for each effect of failure. Lack of power and rough engine
operation are the most common effect of potential function failure, followed by
fuel leaks and engine seizure.
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1%
Throttle sticks
2%
Effect of Function Failure
Poor start
Engine will
not start
4%
Engine seizure
13%
Rough engine
operation
19%
11%
Engine stops
17%
Fuel leaks
Lack of power
32%
0%
5%
10%
15%
20%
25%
30%
35%
Percentage of Total Effects (%)
Figure 11 Effect of component function failure on engine operation
Figure 11 does not address the severity of the effect of function failure.
5.4 Severity Rating
Occurrence ratings were assigned using information outlined in section 4.4.
5.5 Potential Cause/ Mechanism of Failure
Refer to section 4.5, which contains detailed information on potential mechanisms
of function failure for engines running ethanol-blended fuels.
To summarise the potential mechanisms of failure Figure 12 displays the
proportion of mechanisms discussed in this analysis. This figure shows that
material degradation (corrosion or perishing) is potentially the most significant
function failure mechanism.
Mechanism of Failure
Fuel properties
4%
Altered
combustion
8%
Lubricant
deficiency
11%
Gumming
15%
Material
degradation
62%
0%
10%
20%
30%
40%
50%
60%
70%
Percentage of Total Mechanisms of Failure (%)
Figure 12 Percentage of total mechanism of function failure
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5.6 Occurrence
Occurrence ratings were assigned using information outlined in section 4.6.
5.7 Current Design Controls
Current design controls in place for the TS45 Stihl Line-trimmer engine include
durability, emissions and material compatibility testing.
5.8 Detection Rating
A detection rating of 1 (almost certain) was assigned to all engine components
since component material compatibility tests and engine testing will detect
component failures.
5.9 Risk Priority Number
Risk priority numbers ranged from 10 to 240. Risk priority numbers are illustrated
in Figure 13.
250
200
150
100
50
0
Plastic Fuel Tank
Fuel Tank cap
Filler cap attachment assembly
Fuel Pickup Screen
Fuel Pickup Tube
Air cleaner
Air cleaner housing
Choke lever
Air cleaner housing gasket
Primer bulb
Primer housing
Primer housing gasket
Carburettor body
Throttle blade
Throttle shaft
Throttle blade screw
Regulator diaphragm
Needle valve
Needle control arm
Control arm pivot
Pivot retaining screw
Main fuel nozzle
Low speed mixture screw
Low speed mixture screw O-ring
High speed mixture screw
High speed mixture screw O-ring
Main fuel jet
Elbow fittings
Cover
Cover screw
Pump diaphragm and check valves
Cover gasket
Inlet insulating block
Inlet heat shield/Gasket
Piston
Piston Rings
Piston Pin Clip
Piston Pin
Bearings
Crankshaft
Crank seals
Connecting rod
Spark-plug
Barrel gasket
Barrel
Crankcase
Risk Priority Number (/1000)
300
Item
Figure 13 Risk Priority Number for components of FS45 Line-trimmer engine
The components analysed were grouped based on RPN ranking. Table 9 lists
the components in RPN order and group order. Components in Group A have
the highest priority for validation of function.
Group A contains base engine components (eg crankshaft, pistons and bearings).
An observation that can be made is the occurrence rating for these components
is 10. There is a high expectation that the failure will be detected during engine
testing (detection – 3). The potential failures are a result of the relatively
unknown effect of ethanol-blended fuels effect on combustion and corrosion of
critical bearing surfaces in a line-trimmer engine.
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Group B contains ancillary components that must be validated by engine testing
(detection – 3).
Group C components are also manufactured from a variety of materials. The
potential failure of the components is typically through material degradation. The
failure would typically produce a fuel leak or stop the engine running (severity –
9). Material compatibility test should detect failure of these components
(detection – 1)
Group D is the lowest risk category. Failure of group D components can have a
variety of effects, from engine stopping to fuel leaks, however the likely
occurrence of these failures ranks them low on the RPN scale.
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Table 9 Line-trimmer components severity rating, occurrence rating, detection rating and
risk priority number
Item
Severity
rating
GROUP A
Piston
Piston Rings
Piston Pin
Bearings
Crankshaft
Connecting rod
Barrel
Crankcase
Occurrence
Detection
rating
rating
RPN>180
8
8
8
8
8
8
8
8
10
10
10
10
10
10
10
10
6
9
10
5
9
9
9
9
9
9
9
9
9
9
9
9
8
8
8
8
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
6
6
6
6
6
6
6
6
8
9
9
9
8
10
9
9
9
9
7
1
10
10
10
10
10
10
10
10
2
5
5
5
5
2
2
2
2
2
2
10
GROUP B
Spark-plug
Barrel gasket
Orbital Engine Company
240
240
240
240
240
240
240
240
3
3
180
135
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
90
90
90
90
90
90
90
90
90
90
90
90
80
80
80
80
1
1
1
1
1
1
1
1
3
1
1
1
1
1
1
1
1
1
1
1
60
60
60
60
60
60
60
60
48
45
45
45
40
20
18
18
18
18
14
10
RPN=<120
GROUP D
Choke lever
Throttle shaft
Main fuel nozzle
Low speed mixture screw
Low speed mixture screw O-ring
High speed mixture screw
High speed mixture screw O-ring
Main fuel jet
Piston Pin Clip
Primer housing gasket
Cover gasket
Inlet heat shield/Gasket
Air cleaner housing gasket
Throttle blade screw
Control arm pivot
Pivot retaining screw
Cover
Cover screw
Throttle blade
Filler cap attachment assembly
3
3
3
3
3
3
3
3
RPN=<180
GROUP C
Plastic Fuel Tank
Fuel Pickup Tube
Primer bulb
Primer housing
Carburettor body
Regulator diaphragm
Needle valve
Needle control arm
Elbow fittings
Pump diaphragm and check valves
Inlet insulating block
Crank seals
Fuel Tank cap
Fuel Pickup Screen
Air cleaner
Air cleaner housing
Risk priority
number
RPN=<60
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5.10 Summary of Design FMEA FS45 Stihl Line-trimmer
The design FMEA conducted on the Stihl FS45 Line-trimmer engine indicates that
potential failure mechanisms are the same as those of the outboard engine as
discussed in section 4.10.
The analysis confirmed that base engine components with critical bearing
surfaces were most at risk of function failure. To detect failure of these
components, testing on a number of engines is recommended in order to ensure
confidence in failure detection
Components in the second highest risk category were components which must be
evaluated by engine testing.
Components in the third highest risk category are generally components which
may fail through material degradation. The potential failure of these components
may produce hazardous fuel leaks. Material compatibility tests are almost certain
to detect material compatibility failures.
Engine components could potentially experience function failure through the use
of ethanol-blended fuel. The effects of function failure (in order of potential
incidence) include:
• Lack of power
• Rough engine operation
• Fuel leaks
• Engine seizure
• Engine stopping
• Engine not starting
• Poor starting
• Throttle sticking
Lack of power, rough engine operation, fuel leaks and engine seizure have the
potential to be the most common effects of component failure. The mechanisms
by which these potentially occur are material degradation, gumming, lubricant
deficiency and altered combustion.
Proposed durability, emissions and materials testing is considered to almost
certainly capture these highlighted potential failures.
Orbital Engine Company
30 of 81
E20 FMEA technical assessment
6 References
1.
Alaska Mining and Diving Supply, AMDA Online,
www.akmining.com/boat/john01.html, 15/10/2002
2.
Australian Ultralight Federation, Fuel Quality,
www.auf/asn.au/airworthiness/fuelquality.html
3.
Australian Ultralight Federation, Possible MOGAS Fuel Contamination in
Victoria, 30/11/2000, www.auf/asn.au/airworthiness/fuelquality.html,
4.
Clean Snowmobile Facts – Solutions – Oxygenated Fuels
www.deq.state.mt.us/CleanSnowmobile/solutions/fuels/oxygenated.html
5.
Arapatsakos C.I., Air and Water Influence of Two Stroke Outboard Engine
Using Gasoline-Ethanol Mixtures, SAE 2000-01-2973
6.
Biofuels
Update,
Ethanol
Takes
Off,
www.ott.doe.gov/biofuels/pdfs/bu_v4-2.pdf
7.
Bresenham D. and Riesel J., The Effect of High Ethanol Blends on
Emissions from Small Utility Engines, JSAE 1999-01-3345
8.
California Environmental Protection Agency Air Resources
Evaporative Emissions from Off-road Equipment, 22/06/2001
9.
Canadian Renewable Fuels Association, Questions and Answers on
Ethanol, www.greenfuels.org/ethaques.html, 24/09/2002
10.
Canadian Renewable Fuels Association, Ethanol and Small Engines,
www.greenfuels.org/smallengines, 24/09/2002
11.
Canadian Renewable Fuels Association, What Fuel Alternatives are
Available, www.greenfuels.org/ethaalt, 24/09/2002
12.
Chevron, Use of Oxygenated Fuels in Non-automotive
www.chevron.com/prodserv/fuels/bulletin/owy-nona, 10/10/2001
13.
D’Ornellas C.V., The Effect of Ethanol on Gasoline Stability, SAE 2001-013582
14.
Downstream Alternatives, Fuel Recommendations Data Base NonAutomotive Gasoline Powered Equipment, 1999
www.ethanolrfa.org/pdf/non%20auto1999.pdf
15.
Downstream Alternatives, Lubricity of Reformulated and Oxygenated
Gasolines, March 1997, www.ethanolrfa.org/pdf/DAI970301lubricity.pdf
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Spring/Summer
1996
Board,
Engines,
E20 FMEA technical assessment
16.
Downstream Alternatives, Alternatives, The Use of Reformulated Gasoline
in Aircraft Certified to Operate on Automotive Gasoline, May 1997,
www.ethanolrfa.org/pdf/DAI970501Aviation.pdf
17.
Downstream Alternatives, The Compatibility of Reformulated Oxygenated
Gasoline
with
Fuel
System
Materials,
February
1997,
www.ethanolrfa.org/pdf/DAI970201.pdf
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E-10 Unleaded in Small Engines,
www.e10unleaded.com/smallengines.html, 25/09/2002
19.
Energy and Environmental Research Centre, FAA Funds Development of
Aviation Grade Ethanol Fuel at UND,
www.eerc.und.nodak.edu/news/news1.html, 4/10/2002
20.
Ethanol Use in Two Cycle and Four Cycle Small
www.stinker.com/Site/Stinker/ethanol/2cycle.html, 4/10/2002
21.
Ford Motor Company, Ford Worldwide Failure Mode and Effect Analysis
Handbook.
22.
Haines H, The Snowmobile Dilemma, or, Who Spilled What in the
Refrigerator vs. Who’s Going to Clean It Up?
www.deq.state.mt.us/ppa/p2/snowmobl/snowmobl.html, 27/09/2002
23.
Helder D., Behnken J. and Aulich T., Design of Ethanol Based Fuels for
Aviation, SAE 2000-01-1712
24.
HKS Company LTD, HKS700E Operations Manual, July 1999 Version 2.00
25.
Iowa Corn Growers
Recommendations on
15/10/2002
26.
Johnson G.W., Use of Alternate Fuels in Light Aircraft, SAE 2002-01-1539
27.
Kasperson A.D. and Reynolds R.E., Test Program Summary – Field
Evaluation of Small Engine Lawn and Garden Equipment Operating on
Gasoline Containing 10% Ethanol,
www.ilcorn.org/Ethanol/Ethan_Studies/Small_Engines/small_engines.html,
27/09/2002
28.
Mercury Marine, Technical Update #02-01, BP Market Trial of EthanolBlended Fuel,
29.
Mercruiser Stern drives and Inboards, Service Bulletin No 95-7 395,
Reformulated Gasoline (USA).
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Engines,
Association, Small Engine Manufacturers
Ethanol Use, www.iowacorn.org/semr.html,
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E20 FMEA technical assessment
30.
Energy and Environmental Research Centre, FAA Certifies Low-cost,
Environmentally Friendly, Ethanol-Based Fuel,
www.eerc.und.nodak.edu/features/EBAF.html, 4/10/2002
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Experimental
Aircraft
Association,
Automobile
www.eaa.org/education/fuel.html, 18/10/2002
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Office of Technology Access, Ethanol as an Aviation Fuel,
www.eren.doe.gov/power/tech_access/docs/51_ethanol_as_aviation_fuel.cf
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33.
Renewable Fuels Association, Changes in Gasoline III, June 1996,
www.ethanolrfa.org/pdf/Gasoline.pdf
34.
Ultralight Aircraft Advisory, Rotax Engine Service Information – Problem
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9/10/2002
35.
Ultralight Aircraft Advisory, Rotax Engine, Fuel Recommendations,
www.ultralightnews.com/features/fuelrec.html, 9/10/2002
36.
US Environmental Protection Agency, Use of Reformulated Gasoline in OffRoad Engines, www.epa.gov/otaq/rfgnonrd.html, 8/10/2002
Orbital Engine Company
33 of 81
Fuel
Program,
E20 FMEA technical assessment
7 Appendix A
Functional FMEA table for Aircraft engine group
POTENTIAL FAILURE MODE AND EFFECT ANALYSIS
FUNCTION FMEA FOR AIRCRAFT APPLICATION
Potential
Cause(s)/Mechanism(s) of
Failure
Function
Cold Starting
-to commence engine
operation
Orbital Engine Company
Engine fails to start
Start time is excessive
Engine starts then stalls
Equipment cannot be used
34 of 81
8 Insufficient startup enrichment
Fuel volatility low at ambient
temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR
range
Gumming
High latent heat of vaporisation of
fuel
Failed decompression valve
Foulled sparkplug
Ignition energy insufficient
Failed engine components
Low compression ratio
No fuel flow
Poor fuel quality
Unsuitable airflow
Flooded engine
Unsuitable spark advance
Fuel pooling
Fuel distribution (cyl to cyl)
Current
Design
Controls
10 no controls in
place
Detection
Potential Failure Mode Potential Effect(s) of Failure
Severity
Item
Occurrence
Prepared by JRM
Core Team: JRM, GBB, LAG, NC1, MJT, DFN
Date: 10/10/2002
10
RPN
800
E20 FMEA technical assessment
Function
Hot Starting
-to commence engine
operation
Engine fails to start
Start time is excessive
Engine starts then stalls
Equipment cannot be used till
cold start is possible
Engine may not restart during
flight if required
10 Insufficient startup enrichment
Fuel contaminated (eg water)
Vapour lock in fuel system blocking
fuel flow
Fuel supply blockage
Operation outside ignitable AFR
range
Failed decompression valve
Sparkplug heat range unsuitable
Gumming
High latent heat of vaporisation of
fuel
Foulled sparkplug
Failed engine components
No fuel flow
Poor fuel quality
Insufficient airflow
Flooded engine
Unsuitable spark advance
Warmup
Engine stalls
Engine cannot drive equipment 10 Fuel volatility to low for ambient
-ensure engine operation Engine power output low Excesive emissions
temperature
when not at operating
Engine not efficient
Poor fuel consumption
Fuel contaminated (eg water)
temperature
Rough engine operation Engine may need to be
Fuel supply blockage
Operation outside ignitable AFR
completely warm before use
range from hot to cold
Fuel system or throttle icing
Unsuitable ignition timing
Poor combustion
Sparkplug heat range unsuitable
Gumming
Orbital Engine Company
35 of 81
Current
Design
Controls
Detection
Potential
Cause(s)/Mechanism(s) of
Failure
Occurrence
Potential Failure Mode Potential Effect(s) of Failure
Severity
Item
RPN
10 no controls in
place
10 1000
10 no controls in
place
10 1000
E20 FMEA technical assessment
Part Load
Engine stalls
-engine operating point
Engine seizure
between idle and full load Rough engine operation
Inefficent operation
Orbital Engine Company
Excessive emissions
Poor fuel consumption
Current
Design
Controls
7 Fuel volatility to low for ambient temperature 8 no controls in
Fuel contaminated (eg water)
place
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Unsuitable ignition timing
Poor combustion
Stuck exhaust valve
Sparkplug heat range unsuitable
Gumming
Foulled sparkplug
Low compression ratio
No fuel flow
Poor fuel quality
Insufficient airflow
Flooded engine
Fuel system or throttle icing
Unsuitable spark advance
Failure of exhaust components 10 Fuel volatility to low for ambient temperature 10 no controls in
(eg catalyst)
Fuel contaminated (eg water)
place
Poor fuel consumption
Fuel supply blockage
Excessive emissions
Operation outside ignitable AFR range
Aircraft cannot maintain altitude
Fuel system or throttle icing
Piston/bore failure through knock/preignition
Unsuitable ignition timing
Poor combustion
Gumming
Foulled sparkplug
Low compression ratio
No fuel flow
Poor fuel quality
Insufficient airflow
Flooded engine
Fuel system or throttle icing
Unsuitable spark advance
36 of 81
Detection
Function
Idle
Engine stalls
-operation at lowest
Rough engine operation
engine power while
Inefficent operation
driving equipment
Potential Cause(s)/Mechanism(s) of
Failure
Occurrence
Potential Failure Mode Potential Effect(s) of Failure
Severity
Item
RPN
10
560
10 1000
E20 FMEA technical assessment
Current
Design
Controls
Failure of exhaust components 10 Fuel volatility to low for ambient temperature 10 no controls in
(eg catalyst)
Fuel contaminated (eg water)
place
Poor fuel consumption
Fuel supply blockage
Excessive emissions
Operation outside ignitable AFR range
Engine cannot drive equipment
Fuel system or throttle icing
Aircraft cannot maintain altitude
Piston/bore failure through knock/preignition
Aircraft cannot climb to higher
Unsuitable ignition timing
altitude
Poor combustion
Gumming
Foulled sparkplug
Excessive emissions
Engine failure
Unsuitable spark advance
Lack of power
Detection
Function
Full Load
Engine stalls
-engine operating point
Engine seizure
full throttle
Rough engine operation
Inefficent operation
Lack of power
Potential Cause(s)/Mechanism(s) of
Failure
Occurrence
Potential Failure Mode Potential Effect(s) of Failure
Severity
Item
RPN
10 1000
Speed Control
-engine operation for
constant speed varying
load
Engine damage
Engine cannot drive equipment
Inefficient operation
Erratic engine operation
naccurate control
Poor control to nominal
speed
Engine exceed maximum
engine speed
8
no controls in
place
10
800
Load Control
- torque backup
Engine Stalls
Inaccurate control
Engine cannot maintain
load
Engine damage
8
no controls in
place
10
800
Orbital Engine Company
10 Fuel volatility to low for ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Piston/bore failure through knock/preignition
Unsuitable ignition timing
Poor combustion
Gumming
Engine cannot drive equipment 10 Fuel volatility to low for ambient temperature
Erratic engine operation
Fuel contaminated (eg water)
Aircraft cannot maintain altitude
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Piston/bore failure through knock/preignition
Unsuitable ignition timing
Poor combustion
Gumming
37 of 81
E20 FMEA technical assessment
Shutdown
-cease engine operation
Orbital Engine Company
Engine damage
10 Operaton lean of set point (high speed
mixture control)
Ignition control defective
Governer control defective
Gumming
Ignitable AFR range
Ignition kill does not stop Engine fails to stop
10 Pre-ignition from hot chamber surfaces
engine
Engine damage upon shutdown
Fault with ignition kill
Gumming
38 of 81
Current
Design
Controls
Detection
Function
Overspeed
Engine failure
-function to limit maximum Poor speed control
engine speed
Engine overspeed
Potential Cause(s)/Mechanism(s) of
Failure
Occurrence
Potential Failure Mode Potential Effect(s) of Failure
Severity
Item
RPN
10 no controls in
place
10 1000
10 no controls in
place
10 1000
E20 FMEA technical assessment
8 Appendix B
Functional FMEA table for Utility engine group
POTENTIAL FAILURE MODE AND EFFECT
ANALYSIS
FUNCTION FMEA FOR UTILITY
APPLICATION
Function
Cold Starting
Engine fails to start
-to commence engine operation Start time is excessive
Engine starts then stalls
Orbital Engine Company
Potential Effect(s) of Failure
Equipment cannot be used
39 of 81
Potential Cause(s)/Mechanism(s) of Failure
7 Insufficient startup enrichment
Fuel volatility low at ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Gumming
High latent heat of vaporisation of fuel
Failed decompression valve
Foulled sparkplug
Ignition energy insufficient
Failed engine components
Low compression ratio
No fuel flow
Poor fuel quality
Unsuitable airflow
Flooded engine
Unsuitable spark advance
Fuel pooling
Fuel distribution (cyl to cyl)
Current Design
Controls
10 Engine Testing
Detection
Potential Failure Mode
Severity
Item
Occurrenc
e
Prepared by JRM
Date: 10/10/2002Core Team: JRM, GBB, LAG, NC1, MJT, DFN
RPN
1
70
E20 FMEA technical assessment
Warmup
-ensure engine operation when
not at operating temperature
Orbital Engine Company
Engine stalls
Engine power output low
Engine not efficient
Rough engine operation
Potential Cause(s)/Mechanism(s) of Failure
Equipment cannot be used till cold 7 Insufficient startup enrichment
start is possible
Fuel contaminated (eg water)
Vapour lock in fuel system blocking fuel flow
Fuel supply blockage
Operation outside ignitable AFR range
Failed decompression valve
Sparkplug heat range unsuitable
Gumming
High latent heat of vaporisation of fuel
Foulled sparkplug
Failed ignition control module
Failed engine components
No fuel flow
Poor fuel quality
Insufficient airflow
Flooded engine
Unsuitable spark advance
Engine cannot drive equipment
6 Fuel volatility to low for ambient temperature
Excesive emissions
Fuel contaminated (eg water)
Poor fuel consumption
Fuel supply blockage
Operation outside ignitable AFR range from hot to cold
Fuel system or throttle icing
Unsuitable ignition timing
Poor combustion
Sparkplug heat range unsuitable
Gumming
40 of 81
Detection
Function
Hot Starting
Engine fails to start
-to commence engine operation Start time is excessive
Engine starts then stalls
Potential Effect(s) of Failure
Occurrence
Potential Failure Mode
Severity
Item
RPN
10 Engine Testing
1
70
8
1
48
Current Design
Controls
Engine Testing
E20 FMEA technical assessment
Function
Idle
Engine stalls
-operation at lowest engine
Rough engine operation
power while driving equipment Inefficent operation
Excessive emissions
Poor fuel consumption
Part Load
Engine stalls
-engine operating point between Engine seizure
idle and full load
Rough engine operation
Inefficent operation
Failure of exhaust components
(eg catalyst)
Poor fuel consumption
Excessive emissions
Orbital Engine Company
41 of 81
Potential Cause(s)/Mechanism(s) of Failure
6 Fuel volatility to low for ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Unsuitable ignition timing
Poor combustion
Stuck exhaust valve
Sparkplug heat range unsuitable
Gumming
Foulled sparkplug
Low compression ratio
No fuel flow
Poor fuel quality
Insufficient airflow
Flooded engine
Fuel system or throttle icing
Unsuitable spark advance
7 Fuel volatility to low for ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Piston/bore failure through knock/preignition
Unsuitable ignition timing
Poor combustion
Stuck exhaust valve
Gumming
Foulled sparkplug
Low compression ratio
No fuel flow
Poor fuel quality
Insufficient airflow
Flooded engine
Fuel system or throttle icing
Unsuitable spark advance
Detection
Potential Effect(s) of Failure
Occurrence
Potential Failure Mode
Severity
Item
RPN
8
Engine Testing
2
96
8
Engine Testing
10
560
Current Design
Controls
E20 FMEA technical assessment
Detection
Function
Full Load
Engine stalls
-engine operating point full
Engine seizure
throttle
Rough engine operation
Inefficent operation
Lack of power
RPN
Failure of exhaust components
(eg catalyst)
Poor fuel consumption
Excessive emissions
Engine cannot drive equipment
7 Fuel volatility to low for ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Piston/bore failure through knock/preignition
Unsuitable ignition timing
Poor combustion
Stuck exhaust valve
Gumming
Foulled sparkplug
Excessive emissions
Engine failure
Unsuitable spark advance
Lack of power
10 Engine Testing
1
70
7 Fuel volatility to low for ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Piston/bore failure through knock/preignition
Unsuitable ignition timing
Poor combustion
Gumming
7 Fuel volatility to low for ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Piston/bore failure through knock/preignition
Unsuitable ignition timing
Poor combustion
Gumming
8
no controls in place
10
560
8
no controls in place
10
560
Potential Effect(s) of Failure
Speed Control
-engine operation for constant
speed varying load
Engine damage
Inefficient operation
naccurate control
Poor control to nominal
speed
Engine exceed maximum
engine speed
Engine cannot drive equipment
Erratic engine operation
Electrical equipment may be
damaged (engine driving a
generator)
Load Control
- torque backup
Engine Stalls
Inaccurate control
Engine cannot maintain
load
Engine damage
Engine cannot drive equipment
Erratic engine operation
Orbital Engine Company
42 of 81
Severity
Potential Failure Mode
Occurrence
Item
Potential Cause(s)/Mechanism(s) of Failure
Current Design
Controls
E20 FMEA technical assessment
Operator injury
Engine damage
Overrun operation
-engine operation when device
drives engine
Engine continues to drive
Overun condition irregular
(shunting)
Overun condition altered
Engine damage during overun
(pre-ignition)
Shutdown
-cease engine operation
Ignition kill does not stop
engine
Engine fails to stop
Engine damage upon shutdown
Orbital Engine Company
43 of 81
Detection
Function
Overspeed
Engine failure
-function to limit maximum
Poor speed control
engine speed
Engine overspeed
Potential Effect(s) of Failure
RPN
10 Operaton lean of set point (high speed mixture control)
Ignition control defective
Governer control defective
Gumming
Ignitable AFR range
2 Pre-ignition from hot chamber surfaces
Fuel supply surge
Gumming
10 Engine Testing
1
100
6
10
120
10 Pre-ignition from hot chamber surfaces
Fault with ignition kill
Gumming
10 Engine Testing
1
100
Severity
Potential Failure Mode
Occurrenc
e
Item
Potential Cause(s)/Mechanism(s) of Failure
Current Design
Controls
no controls in place
E20 FMEA technical assessment
9 Appendix C
Functional FMEA table for Marine engine group
POTENTIAL FAILURE MODE AND EFFECT ANALYSIS
FUNCTION FMEA FOR MARINE APPLICATION
Prepared by JRM
Core Team: JRM, GBB, LAG, NC1, MJT, DFN
Date: 10/10/2002
Function
Cold Starting
-to commence engine
operation
Orbital Engine Company
Engine fails to start
Start time is excessive
Engine starts then stalls
Equipment cannot be used
44 of 81
Potential Cause(s)/Mechanism(s) of
Failure
Current
Design
Controls
8 Insufficient startup enrichment
10 Engine Testing
Fuel volatility low at ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Gumming
High latent heat of vaporisation of fuel
Failed decompression valve
Foulled sparkplug
Ignition energy insufficient
Failed engine components
Low compression ratio
No fuel flow
Poor fuel quality
Unsuitable airflow
Flooded engine
Unsuitable spark advance
Fuel pooling
Fuel distribution (cyl to cyl)
Detection
Potential Effect(s) of Failure
Occurrence
Potential Failure Mode
Severity
Item
1
RPN
80
E20 FMEA technical assessment
Warmup
-ensure engine operation
when not at operating
temperature
Orbital Engine Company
Engine stalls
Engine power output low
Engine not efficient
Rough engine operation
Equipment cannot be used till cold
start is possible
Engine cannot drive equipment
Excesive emissions
Poor fuel consumption
45 of 81
Potential Cause(s)/Mechanism(s) of
Failure
8 Insufficient startup enrichment
Fuel contaminated (eg water)
Vapour lock in fuel system blocking fuel flow
Fuel supply blockage
Operation outside ignitable AFR range
Failed decompression valve
Sparkplug heat range unsuitable
Gumming
High latent heat of vaporisation of fuel
Foulled sparkplug
Failed ignition control module
Failed engine components
No fuel flow
Poor fuel quality
Insufficient airflow
Flooded engine
Unsuitable spark advance
7 Fuel volatility to low for ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range from
hot to cold
Fuel system or throttle icing
Unsuitable ignition timing
Poor combustion
Sparkplug heat range unsuitable
Gumming
Current
Design
Controls
Detection
Function
Hot Starting
Engine fails to start
-to commence engine
Start time is excessive
operation
Engine starts then stalls
Potential Effect(s) of Failure
Occurrenc
e
Potential Failure Mode
Severity
Item
RPN
10 Engine Testing
1
80
8
1
56
Engine Testing
E20 FMEA technical assessment
Part Load
Engine stalls
-engine operating point
Engine seizure
between idle and full load Rough engine operation
Inefficent operation
Orbital Engine Company
Excessive emissions
Poor fuel consumption
Failure of exhaust components (eg
catalyst)
Poor fuel consumption
Excessive emissions
Vessel will not maintain planing
speed
46 of 81
Potential Cause(s)/Mechanism(s) of
Failure
7 Fuel volatility to low for ambient
temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Unsuitable ignition timing
Poor combustion
Stuck exhaust valve
Sparkplug heat range unsuitable
Gumming
Foulled sparkplug
Low compression ratio
No fuel flow
Poor fuel quality
Insufficient airflow
Flooded engine
Fuel system or throttle icing
Unsuitable spark advance
7 Fuel volatility to low for ambient
temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Piston/bore failure through
knock/preignition
Unsuitable ignition timing
Poor combustion
Stuck exhaust valve
Gumming
Foulled sparkplug
Low compression ratio
No fuel flow
Poor fuel quality
Insufficient airflow
Flooded engine
Fuel system or throttle icing
Unsuitable spark advance
Current
Design
Controls
Detection
Function
Idle
Engine stalls
-operation at lowest
Rough engine operation
engine power while
Inefficent operation
driving equipment
Potential Effect(s) of Failure
Occurrence
Potential Failure Mode
Severity
Item
RPN
8
Engine Testing
1
56
8
no controls in
place
10 560
E20 FMEA technical assessment
Function
Full Load
-engine operating point
full throttle
Engine stalls
Engine seizure
Rough engine operation
Inefficent operation
Lack of power
Speed Control
-engine operation for
constant speed varying
load
Engine damage
Engine cannot drive equipment
Inefficient operation
Erratic engine operation
naccurate control
Trolling not possible
Poor control to nominal speed
Engine exceed maximum engine
speed
Load Control
- torque backup
Engine Stalls
Inaccurate control
Engine cannot maintain load
Engine damage
Orbital Engine Company
Failure of exhaust components (eg
catalyst)
Poor fuel consumption
Excessive emissions
Engine cannot drive equipment
Vessel will not reach planing speed
Engine cannot drive equipment
Erratic engine operation
47 of 81
Potential Cause(s)/Mechanism(s) of
Failure
9 Fuel volatility to low for ambient
temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Piston/bore failure through
knock/preignition
Unsuitable ignition timing
Poor combustion
Stuck exhaust valve
Gumming
Foulled sparkplug
Excessive emissions
Engine failure
Unsuitable spark advance
Lack of power
7 Fuel volatility to low for ambient
temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Piston/bore failure through
knock/preignition
Unsuitable ignition timing
Poor combustion
Gumming
7 Fuel volatility to low for ambient
temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Piston/bore failure through
knock/preignition
Unsuitable ignition timing
Poor combustion
Gumming
Current
Design
Controls
Detection
Potential Effect(s) of Failure
Occurrence
Potential Failure Mode
Severity
Item
RPN
10 Engine Testing
1
90
8
no controls in
place
10 560
8
no controls in
place
10 560
E20 FMEA technical assessment
Shutdown
-cease engine operation
Orbital Engine Company
Ignition kill does not stop engine
Engine damage
Engine fails to stop
Engine damage upon shutdown
48 of 81
Potential Cause(s)/Mechanism(s) of
Failure
4 Operaton lean of set point (high speed
mixture control)
Ignition control defective
Governer control defective
Gumming
Ignitable AFR range
10 Pre-ignition from hot chamber surfaces
Fault with ignition kill
Gumming
Current
Design
Controls
Detection
Function
Overspeed
Engine failure
-function to limit
Poor speed control
maximum engine speed Engine overspeed
Potential Effect(s) of Failure
Occurrenc
e
Potential Failure Mode
Severity
Item
RPN
10 no controls in
place
10 400
10 Engine Testing
1 100
E20 FMEA technical assessment
10 Appendix D
Functional FMEA table for Vehicle engine group
POTENTIAL FAILURE MODE AND EFFECT ANALYSIS
FUNCTION FMEA FOR VEHICLE APPLICATION (eg Snowmobile, Motorcycle)
Function
Cold Starting
Engine fails to start
-to commence engine operation Start time is excessive
Engine starts then stalls
Orbital Engine Company
Potential Effect(s) of Failure
Equipment cannot be used
49 of 81
8
Potential Cause(s)/Mechanism(s) of Failure
Insufficient startup enrichment
Fuel volatility low at ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Gumming
High latent heat of vaporisation of fuel
Failed decompression valve
Foulled sparkplug
Ignition energy insufficient
Failed engine components
Low compression ratio
No fuel flow
Poor fuel quality
Unsuitable airflow
Flooded engine
Unsuitable spark advance
Fuel pooling
Fuel distribution (cyl to cyl)
Current
Design
Controls
10 no controls in
place
Detection
Potential Failure Mode
Severity
Item
Occurrence
Prepared by JRM
Core Team: JRM, GBB, LAG, NC1, MJT, DFN
Date: 10/10/2002
RPN
10
800
E20 FMEA technical assessment
Function
Hot Starting
Engine fails to start
-to commence engine operation Start time is excessive
Engine starts then stalls
Equipment cannot be used till cold
start is possible
8
Warmup
-ensure engine operation when
not at operating temperature
Engine cannot drive equipment
Excesive emissions
Poor fuel consumption
7
Orbital Engine Company
Engine stalls
Engine power output low
Engine not efficient
Rough engine operation
50 of 81
Potential Cause(s)/Mechanism(s) of Failure
Insufficient startup enrichment
Fuel contaminated (eg water)
Vapour lock in fuel system blocking fuel flow
Fuel supply blockage
Operation outside ignitable AFR range
Failed decompression valve
Sparkplug heat range unsuitable
Gumming
High latent heat of vaporisation of fuel
Foulled sparkplug
Failed ignition control module
Failed engine components
No fuel flow
Poor fuel quality
Insufficient airflow
Flooded engine
Unsuitable spark advance
Fuel volatility to low for ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range from hot to
cold
Fuel system or throttle icing
Unsuitable ignition timing
Poor combustion
Sparkplug heat range unsuitable
Gumming
Current
Design
Controls
Detection
Potential Effect(s) of Failure
Occurrence
Potential Failure Mode
Severity
Item
RPN
10 no controls in
place
10
800
8
10
560
no controls in
place
E20 FMEA technical assessment
Function
Idle
Engine stalls
-operation at lowest engine
Rough engine operation
power while driving equipment Inefficent operation
Excessive emissions
Poor fuel consumption
7
Part Load
Engine stalls
-engine operating point between Engine seizure
idle and full load
Rough engine operation
Inefficent operation
Failure of exhaust components
(eg catalyst)
Poor fuel consumption
Excessive emissions
7
Orbital Engine Company
51 of 81
Potential Cause(s)/Mechanism(s) of Failure
Fuel volatility to low for ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Unsuitable ignition timing
Poor combustion
Stuck exhaust valve
Sparkplug heat range unsuitable
Gumming
Foulled sparkplug
Low compression ratio
No fuel flow
Poor fuel quality
Insufficient airflow
Flooded engine
Fuel system or throttle icing
Unsuitable spark advance
Fuel volatility to low for ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Piston/bore failure through knock/preignition
Unsuitable ignition timing
Poor combustion
Stuck exhaust valve
Gumming
Foulled sparkplug
Low compression ratio
No fuel flow
Poor fuel quality
Insufficient airflow
Flooded engine
Fuel system or throttle icing
Unsuitable spark advance
Current
Design
Controls
Detection
Potential Effect(s) of Failure
Occurrence
Potential Failure Mode
Severity
Item
RPN
8
no controls in
place
10
560
8
no controls in
place
10
560
E20 FMEA technical assessment
Detection
Function
Full Load
Engine stalls
-engine operating point full
Engine seizure
throttle
Rough engine operation
Inefficent operation
Lack of power
Failure of exhaust components
(eg catalyst)
Poor fuel consumption
Excessive emissions
Engine cannot drive equipment
9
Fuel volatility to low for ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Piston/bore failure through knock/preignition
Unsuitable ignition timing
Poor combustion
Stuck exhaust valve
Gumming
Foulled sparkplug
Excessive emissions
Engine failure
Unsuitable spark advance
Lack of power
10 no controls in
place
10
900
Fuel volatility to low for ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Piston/bore failure through knock/preignition
Unsuitable ignition timing
Poor combustion
Gumming
Fuel volatility to low for ambient temperature
Fuel contaminated (eg water)
Fuel supply blockage
Operation outside ignitable AFR range
Fuel system or throttle icing
Piston/bore failure through knock/preignition
Unsuitable ignition timing
Poor combustion
Gumming
8
no controls in
place
10
560
8
no controls in
place
10
560
Speed Control
-engine operation for constant
speed varying load
Engine damage
Inefficient operation
naccurate control
Poor control to nominal speed
Engine exceed maximum
engine speed
Engine cannot drive equipment
Erratic engine operation
7
Load Control
- torque backup
Engine Stalls
Inaccurate control
Engine cannot maintain load
Engine damage
Engine cannot drive equipment
Erratic engine operation
7
Orbital Engine Company
Current
Design
Controls
RPN
Potential Effect(s) of Failure
Severity
Potential Failure Mode
Occurrenc
e
Item
52 of 81
Potential Cause(s)/Mechanism(s) of Failure
E20 FMEA technical assessment
Engine damage
4
Engine damage during overun
(pre-ignition)
6
Overrun operation
-engine operation when device
drives engine
Engine continues to drive
Overun condition irregular
(shunting)
Overun condition altered
Shutdown
-cease engine operation
Ignition kill does not stop engine Engine fails to stop
Engine damage upon shutdown
Orbital Engine Company
53 of 81
Potential Cause(s)/Mechanism(s) of Failure
Operaton lean of set point (high speed mixture
control)
Ignition control defective
Governer control defective
Gumming
Ignitable AFR range
Pre-ignition from hot chamber surfaces
Fuel supply surge
Gumming
10 Pre-ignition from hot chamber surfaces
Fault with ignition kill
Gumming
Current
Design
Controls
Detection
Function
Overspeed
Engine failure
-function to limit maximum
Poor speed control
engine speed
Engine overspeed
Potential Effect(s) of Failure
Occurrenc
e
Potential Failure Mode
Severity
Item
RPN
10 no controls in
place
10
400
6
10
360
no controls in
place
10 no controls in
place
10 1000
E20 FMEA technical assessment
11 Appendix E
Design FMEA table for 15hp Mercury Marine Outboard
DESIGN FAILURE MODE AND EFFECT ANALYSIS
DESIGN FMEA FOR MERCURY TWO STROKE 15HP OUTBOARD ENGINE 2002 MODEL YEAR
Potential Failure Mode
Potential Effect(s) of Failure
Severity
Function
Potential Cause(s)/Mechanism(s) of
Failure
contains fuel
fuel leak
fuel spill into vessel or waterway
9 hole in tank - material degradation
prevents
contamination of
fuel
seals tank
fuel contaminated
engine lacks power
rough engine operation
8 hole in tank - material degradation
leaks
fuel contamination
engine lacks power
rough engine operation
6 cap distorted, hole in cap - material
degradation
displays fuel level
shows incorrect level
engines stops
2 mechanism jammed, float sinks - material
degradation
vents tank
blockage
vapour release
engine stops
excessive evaporative emissions
5 vent blocked or distorted - material
degradation
allows tank to be
filled
cap cannot be removed
tank cannot be filled - engine stops
8 cap distorted, stuck to tank - material
degradation
prevents debris
entering fuel line
debris passes filter
blockage of fuel lines and primer bulb
mechanism - engine stops
5 screen material attacked by fuel - material
degradation
transfer fuel
blockage
engine stops
lack of power
8 screen material attacked by fuel material degradation
gumming
Orbital Engine Company
54 of 81
Current Design
Controls
10 Material
Compatibility
Tests, Engine
Testing
10 Material
Compatibility Tests,
Engine Testing
10 Material
Compatibility Tests,
Engine Testing
10 Material
Compatibility Tests,
Engine Testing
10 Material
Compatibility Tests,
Engine Testing
10 Material
Compatibility
Tests, Engine
Testing
10 Material
Compatibility Tests,
Engine Testing
10 Material
Compatibility
Tests, Engine
Testing
Detection
Fuel
Pickup
Screen
Plastic Gauge and Cap
Plastic
Fuel Tank
Item
Occurrence
Prepared by JRM
Core Team: JRM, PTG, HWC, LAG
Date: 10/10/2002
RPN
1
90
1
80
1
60
1
20
1
50
1
80
1
50
1
80
E20 FMEA technical assessment
Occurrence
RPN
transfer of fuel
blockage
air leak
engine stops
lack of power
8 tube attacked by fuel, blocking flow material degradation
1
80
holds pickup
screen
screen falls off tube
blockage of fuel lines - lack of power
5
1
50
transfer of fuel
blockage
air leak
fuel leak
engine stops
lack of power
fuel spill into vessel and waterway
9
1
90
retains fuel hose
fuel hoses detaches
fuel leaks
engine stops
9
1
90
seals against fuel
tank
leaks
4
1
40
transfer of fuel
blockage
air leak
fuel leak
tank vented incorrectly - engine stops
fuel leaks
contaminates fuel tank - rough engine
operation
engine stops
lack of power
fuel spill into vessel and waterway
1
90
retains fuel tubing
fuel hoses detaches
fuel leaks
engine stops
1
90
transfer of fuel
blockage
air leak
fuel leak
engine stops
lack of power
fuel spill into vessel and waterway
9 attacked by fuel, distorts blocking flow,
hole is formed allowing air or fuel leak material degradation
1
90
fuel leaks
engine stops
9 fuel hose attacked by fuel - material
degradation
1
90
Function
Potential Failure Mode
maintain
fuel hoses detaches
connection with fuel
connector
Orbital Engine Company
Potential Effect(s) of Failure
55 of 81
Severity
Detection
Fuel Hose
Connector Fuel tank to fuel
hose
Top of Pickup
Fuel
Pickup
Tube
Item
Potential Cause(s)/Mechanism(s) of
Failure
Current Design
Controls
10 Material
Compatibility
Tests, Engine
Testing
tube attacked by fuel - material degradation 10 Material
Compatibility Tests,
Engine Testing
attacked by fuel, material degradation
10 Material
Compatibility
Tests, Engine
Testing
pick up attacked by fuel - material
10 Material
degradation
Compatibility Tests,
Engine Testing
top of pickup distorts or loses rigidity, small 10 Material
chance of leak since at top of tank - material
Compatibility Tests,
degradation
Engine Testing
9 connector attacked by fuel, distorts
10 Material
blocking flow, hole is formed allowing air
Compatibility
or fuel leak - material degradation
Tests, Engine
Testing
9 connector or hose attacked by fuel - material 10 Material
degradation
Compatibility Tests,
Engine Testing
10 Material
Compatibility
Tests, Engine
Testing
10 Material
Compatibility Tests,
Engine Testing
E20 FMEA technical assessment
directs fuel flow
flow direction not controlled
blockage
Potential Effect(s) of Failure
primer bulb cannot prime fuel system
engine will not start
secures primer bulb primer bulb detaches
fuel leaks
engine stops
retains fuel hose
fuel hoses detaches
fuel leaks
engine stops
transfer of fuel
blockage
air leak
fuel leak
engine stops
lack of power
fuel spill into vessel and waterway
pump element to
prime fuel system
fails to pump fuel
engine will eventually start
transfer of fuel
blockage
air leak
fuel leak
engine stops
lack of power
fuel spill into vessel and waterway
transfer of fuel
blockage
air leak
fuel leak
engine stops
lack of power
fuel spill into vessel and waterway
retains fuel hose
fuel hoses detaches
fuel leaks
engine stops
seals when
disconnected
does not seal when
disconnected
fuel leak
fuel line empties
transfer of fuel
blockage
air leak
fuel leak
engine stops
lack of power
fuel spill into vessel and waterway
retains fuel hose
fuel hoses detaches
fuel leaks
seals when
disconnected
does not seal when
disconnected
fuel leak
fuel line empties
Orbital Engine Company
56 of 81
Potential Cause(s)/Mechanism(s) of
Failure
Occurrence
Potential Failure Mode
Severity
Function
Current Design
Controls
6 check valve elastomer is attacked by fuel 10 Material
material degradation
Compatibility Tests,
gumming
Engine Testing
9 fitting corrodes is attacked by fuel - Corrison 10 Material
or material degradation
Compatibility Tests,
Engine Testing
9 fitting corrodes is attacked by fuel - Corrison 10 Material
or material degradation
Compatibility Tests,
Engine Testing
9 check valve elastomer is attacked by fuel 10 Material
blocking flow path - material degradation
Compatibility
gumming
Tests, Engine
Testing
6 bulb is attacked by fuel, become to hard to
10 Material
squeeze or hole is formed and bulb cannot
Compatibility Tests,
hold pressure - material degradation
Engine Testing
9 bulb is attacked by fuel, hole is formed
10 Material
and bulb cannot hold pressure, bulb
Compatibility
distorts blocking flow path - material
Tests, Engine
degradation
Testing
9 connector is attacked by fuel, hole is
10 Material
formed or material distorts blocking flow
Compatibility
path - material degradation
Tests, Engine
Testing
9 connector is attacked by fuel - material
10 Material
degradation
Compatibility Tests,
Engine Testing
1 seal surfaces are attacked by fuel -material 10 Material
degradation
Compatibility Tests,
Engine Testing
9 connector is attacked by fuel, hole is
10 Material
formed or material distorts blocking flow
Compatibility
path - material degradation
Tests, Engine
Testing
9 connector or hose is attacked by fuel 10 Material
material degradation
Compatibility Tests,
Engine Testing
1 seal surfaces are attacked by fuel -material 10 Material
degradation
Compatibility Tests,
Engine Testing
Detection
Engine fuel
connector
Tank fuel
connector
Primer
bulb
Check valve assembly
inlet and outlet
Item
RPN
1
60
1
90
1
90
1
90
1
60
1
90
1
90
1
90
1
10
1
90
1
90
1
10
E20 FMEA technical assessment
debris enters fuel lines and
carburettor
acts as water trap
Potential Effect(s) of Failure
fuel blockages
lack of power
Potential Cause(s)/Mechanism(s) of
Failure
6 screen material attacked by fuel - material
degradation
water enters fuel lines and
carburettor
displays water level water level cannot be seen
8 water trap fills with water or phase
separation - fuel properties
water enters fuel lines and carburettor - 1 material is attacked by fuel and loses
engine stops
translucency - material degradation
transfer of fuel
blockage
air leak
fuel leak
engine stops
lack of power
fuel spill into vessel and waterway
9
retains fuel tubing
fuel hoses detaches
fuel leaks
engine stops
9
transfer of fuel
blockage
air leak
fuel leak
engine stops
lack of power
fuel spill into vessel and waterway
9
maintain
fuel hoses detaches
connection with fuel
connector
housing for
components not located
components
correctly
fuel leaks
engine stops
9
fuel metering affected
8
transfer of fuel
blockage
fuel leak
engine stops
lack of power
fuel spill into vessel and waterway
9
transfer of air
air flow blocked
lack of power
6
mixing of fuel and
air
air and fuel not mixed
rough engine operation
lack of power
6
Orbital Engine Company
corrosion of components
57 of 81
Current Design
Controls
10 Material
Compatibility
Testing
2 Engine Testing
10 Material
Compatibility Tests,
Engine Testing
assembly is attacked by fuel, hole is
10 Material
formed or material distorts blocking flow
Compatibility
path - material degradation
Tests, Engine
Testing
assembly or hose is attacked by fuel, hole is 10 Material
formed or material distorts blocking flow path
Compatibility Tests,
- material degradation
Engine Testing
hose is attacked by fuel, hole is formed
10 Material
or material distorts blocking flow path Compatibility
material degradation
Tests, Engine
Testing
fuel hose attacked by fuel - material
10 Material
degradation
Compatibility Tests,
Engine Testing
corrosion of materials retaining components 10 Material
- material degradation
Compatibility Tests,
Engine Testing
fuel attacks material, corrosion blocks
10 Material
flow path - material degradation
Compatibility
gumming
Tests, Engine
Testing
air flow blocked by corrosion or deposits 2 Material
material degradation, fuel properties
Compatibility Tests,
Engine Testing
air or fuel flow blocked or altered, fuel does 10 Material
not atomise or vaporise - material
Compatibility Tests,
degradation
Engine Testing
fuel properties
gumming
Detection
Carburettor body
Fuel hose
Fuel filter assembly
prevents debris
entering fuel line
Potential Failure Mode
Occurrence
Function
Severity
Item
RPN
1
60
3
48
1
10
1
90
1
90
1
90
1
90
1
80
1
90
1
12
1
60
E20 FMEA technical assessment
Detection
lack of power
poor driveability - rough engine
operation
6 throttle blade corrodes, sticks to carb
body - material degradation
2 Material
Compatibility
Tests, Engine
Testing
1
12
actuator for throttle throttle blade cannot be
blade
actuated
lack of power
stuck at wide open throttle
40
air leak into carburettor
rough engine operation
lack of power
1
60
secures throttle
blade to throttle
shaft
throttle blade not secured
throttle sticks during operation
10 screw corrodes to failure - material
degradation
4 Material
Compatibility Tests,
Engine Testing
10 Material
Compatibility
Tests, Engine
Testing
2 Material
Compatibility
Tests, Engine
Testing
1
seal against
carburettor body
10 throttle shaft corrodes, sticks to carb body material degradation
gumming
6 throttle shaft or carb body corrode material degradation
1
20
mixture
adjustment
fuel air mixture cannot be
adjusted
rough engine operation
6 mixture screw corrodes altering mixture
strength - material degradation
gumming
10 Material
Compatibility
Tests, Engine
Testing
1
60
seals air and fuel
fuel leak
air leak
rough engine operation
6 elastomer attacked by fuel - material
degradation
10 Material
Compatibility
Tests, Engine
Testing
1
60
supports gasket
does not support gasket
fuel leak
9 supports gasket, if gasket seal fuel, fuel
has no effect on cover
2 Material
Compatibility
Tests, Engine
Testing
1
18
Potential Failure Mode
incorrect airflow control
Mixture
screw Oring
Mixture
screw
Throttle
blade
screw
Throttle
shaft
Throttle
blade
controls airflow
Top
carburettor
cover
Occurrence
RPN
Function
Orbital Engine Company
Potential Effect(s) of Failure
58 of 81
Severity
Item
Potential Cause(s)/Mechanism(s) of
Failure
Current Design
Controls
E20 FMEA technical assessment
fuel leak
air leak - rough engine operation
Main fuel
nozzle
Main fuel
jet
Float valve
(needle and
seat)
Float
Potential Cause(s)/Mechanism(s) of
Failure
9 fuel attacks gasket - material degradation
Detection
does not seal
Potential Effect(s) of Failure
RPN
5 Material
Compatibility
Tests, Engine
Testing
5 Material
Compatibility Tests,
Engine Testing
10 Material
Compatibility
Tests, Engine
Testing
1
45
1
18
1
90
Current Design
Controls
prevents ingress of contanimates enter carburettor fuel metering affected
contaminates
rough engine operation
6 fuel attacks gasket - material degradation
seals fuel gallery
fuel leak
9 fuel attacks gallery plug - material
degradation
mixes fuel and air fuel and air do not mix
correctly
rough engine operation
lack of power
6 air or fuel flow blocked or altered, fuel
does not atomise or vapourise - material
degradation
fuel properties
gumming
10 Material
Compatibility
Tests, Engine
Testing
1
60
metering fuel
rough engine operation
lack of power
6 fuel jet corrodes altering metering material degradation
gumming
10 Material
Compatibility
Tests, Engine
Testing
1
60
controls fuel flow fuel flow not controlled
float level incorrect
rough engine operation
lack of power
fuel leak
9 needle and seat corrode - material
degradation
gumming
10 Material
Compatibility
Tests, Engine
Testing
1
90
regulates fuel
level
rough engine operation
lack of power
fuel leak
9 fuel attacks float - material degradation
gumming
10 Material
Compatibility
Tests, Engine
Testing
1
90
fails for seal fuel gallery
Fuel
gallery
plug
Cover
gasket
seals fuel and air
Potential Failure Mode
Occurrence
Function
Severity
Item
Orbital Engine Company
fuel not metered correctly
fuel level incorrect
59 of 81
E20 FMEA technical assessment
Detection
Occurrence
pivots float lever
float cannot move
fuel level incorrect
rough engine operation
lack of power
fuel leak
9 pin corrodes and lever sticks - material
degradation
gumming
10 Material
Compatibility
Tests, Engine
Testing
1
90
actuates needle
valve
needle valve not actuated
fuel level incorrect
rough engine operation
lack of power
fuel leak
9 lever corrodes sticks - material
degradation
gumming
10 Material
Compatibility
Tests, Engine
Testing
1
90
retains float pin
float pin not retained
fuel level incorrect
fuel leak
9 screw corrodes to failure - material
degradation
2 Material
Compatibility
Tests, Engine
Testing
1
18
seals fuel
does not seal
fuel leak
9 fuel attacks gasket - material degradation
5 Material
Compatibility
Tests, Engine
Testing
1
45
contains fuel
does not contain fuel
fuel leak
9 fuel attacks material forming hole material degradation
10 Material
Compatibility
Tests, Engine
Testing
1
90
Potential Failure Mode
Potential Cause(s)/Mechanism(s) of
Failure
Float
bowl
Float
bowl
gasket
Potential Effect(s) of Failure
Severity
RPN
Function
Float
screw
Float
lever
Float pin
Item
Orbital Engine Company
60 of 81
Current Design
Controls
E20 FMEA technical assessment
allows access to
main jet
fails to allow access
cannot be removed
1 corrosion of screw - material degradation
seals float bowl
does not seal
fuel leak
9 corrsion of material to failure - material
degradation
seals fuel
does not seal
fuel leak
9 corrsion of material to failure - material
degradation
seals fuel and air
does not seal
fuel leak
air leak - rough engine operation
9 fuel attacks gasket - material degradation
pumping element
does not pump
lack of power
engine stops
8 diaphragm elastomer is attacked by fuel material degradation
seals c/case
pumping air and
fuel
does not seal
fuel may leak into crankcase
fuel supply may pressurise and
engine will stop
retains check
valve elements
check valve not retained
lack of power
engine stops
Pump
body
gasket
Diaphragm
Check
valve
retainer
Potential Cause(s)/Mechanism(s) of
Failure
Orbital Engine Company
61 of 81
Detection
Potential Effect(s) of Failure
Occurrence
Potential Failure Mode
Severity
Function
Main jet
screw
gasket
Main jet
screw
Item
RPN
10 Material
Compatibility Tests,
Engine Testing
10 Material
Compatibility
Tests, Engine
Testing
5 Material
Compatibility
Tests, Engine
Testing
1
10
1
90
1
45
5 Material
Compatibility
Tests, Engine
Testing
1
45
1
80
1
90
1
16
Current Design
Controls
10 Material
Compatibility Tests,
Engine Testing
9 diaphragm elastomer is attacked by fuel - 10 Material
material degradation
Compatibility
Tests, Engine
Testing
8 corrsion of material to failure - material
2 Material
degradation
Compatibility
Tests, Engine
Testing
E20 FMEA technical assessment
Detection
Fuel pump
housing
Diaphrag
m return
spring
Cover
Occurrence
directs fuel flow
flow direction not controlled lack of power
blockage
engine stops
8 corrsion of material to failure - material
degradation
gumming
10 Material
Compatibility
Tests, Engine
Testing
1
80
houses pump
components
pump components not located lack of power
correctly
engine stops
8 corrosion of materials reatining components
- material degradation
1
80
transfer of fuel
blockage
fuel leak
engine stops
lack of power
fuel spill into vessel and waterway
9 fuel attacks material, corrosion blocks
flow path - material degradation
1
90
retains fuel hose
fuel hoses detaches
fuel leaks
engine stops
9 fuel attacks connection - material
degradation
1
90
returns pump
does not return diaphragm
diaphragm to rest to rest position
position
lack of power
engine stops
8 fuel corrodes spring - material
degradation
10 Material
Compatibility Tests,
Engine Testing
10 Material
Compatibility
Tests, Engine
Testing
10 Material
Compatibility Tests,
Engine Testing
10 Material
Compatibility
Tests, Engine
Testing
1
80
supports
diaphragm not supported
diaphragm edges
fuel leak
9 supports gasket, if gasket seal fuel, fuel
has no effect on cover
1
18
Orbital Engine Company
Potential Failure Mode
Potential Effect(s) of Failure
62 of 81
Severity
RPN
Function
Check
valve
Item
Potential Cause(s)/Mechanism(s) of
Failure
Current Design
Controls
2 Material
Compatibility
Tests, Engine
Testing
E20 FMEA technical assessment
Occurrence
RPN
1
60
fuel leak
10 Material
Compatibility Tests,
Engine Testing
9 diaphragm elastomer is attacked by fuel - 10 Material
material degradation
Compatibility
Tests, Engine
Testing
1
90
fails to seal fuel
fuel leak
9 fuel attacks gasket - material degradation
5 Material
Compatibility
Tests, Engine
Testing
1
45
returns
diaphragm to
position
fails to return pump
diaphragm to rest position
engine will eventually start
6 spring corrodes to failure - material
degradation
10 Material
Compatibility
Tests, Engine
Testing
1
60
directs fuel flow
fails to direct fuel flow
engine will eventually start
6 check valve elastomer is attacked by fuel 10 Material
- material degradation
Compatibility
gumming
Tests, Engine
Testing
1
60
Function
Potential Failure Mode
Potential Effect(s) of Failure
pumps fuel
fails to pump fuel
engine will eventually start
seals fuel
fails to seal fuel
seals fuel
Orbital Engine Company
63 of 81
Severity
Detection
Enrichment
pump check
valve
assembly
Enrichment
pump
spring
Enrichment
pump gasket
Startup
enrichment pump
diaphragm
Item
Potential Cause(s)/Mechanism(s) of
Failure
Current Design
Controls
6 diaphragm elastomer is attacked by fuel material degradation
E20 FMEA technical assessment
Detection
Occurrence
seals air
fails to seal air
rough engine operation
6 fuel attacks gasket - material degradation
5 Material
Compatibility Tests,
Engine Testing
1
30
seals air fuel
mixture
fails to seal air fuel mixture
fuel leak
9 fuel attacks gasket - material degradation
1
45
limits engine
airflow
fails to limit airflow
rough engine operation
6 fuel attacks restrictor plate increasing
aperture - material degradation
5 Material
Compatibility
Tests, Engine
Testing
2 Material
Compatibility
Tests, Engine
Testing
1
12
locates reeds
fails to locate reeds
rough engine operation
lack of power
6 fuel attacks reed block material - material
degradation
2 Material
Compatibility Tests,
Engine Testing
2 Engine Testing
1
12
3
36
10 Engine Testing
3
180
10 Engine Testing
3
180
10 Engine Testing
3
180
6 fuel attacks reeds - material degradation
gumming
10 Engine Testing
3
180
6 fuel attacks screws to failure - material
degradation
2 Engine Testing
3
36
Potential Failure Mode
Potential Effect(s) of Failure
transfer of fuel air fails to transfer fuel air mixture lack of power
mixture
seals fuel air
fails to seal
lack of power
mixture (with reeds)
rough engine operation
seals fuel air
mixture (against
cylinder block)
directs flow of fuel
air mixture
fails to seal
lack of power
rough engine operation
fails to direct fuel air mixture
flow
lack of power
rough engine operation
engine will not start
seals fuel air
fails to seal fuel air mixture
mixture (with reed
plate)
retains reeds
fails to retain reeds
Orbital Engine Company
lack of power
rough engine operation
engine will not start
lack of power
rough engine operation
engine will not start
64 of 81
Severity
RPN
Function
Reed
screws
Reeds
Reed block
Restricto
r plate
Carburettor
gasket
Item
Potential Cause(s)/Mechanism(s) of
Failure
6 fuel attacks reed block material - material
degradation
6 fuel attacks reed seat material - material
degradation
gumming
6 fuel attacks reed seat material - material
degradation
gumming
6 fuel attacks reeds - material degradation
gumming
Current Design
Controls
E20 FMEA technical assessment
provides bearing
surfaces
fails to proide suitable
bearing surface
provides sealing
surfaces
locates major
components
converts
connecting rod
loads to torque
provides bearing
surfaces
fails to provide sealing surface lack of power
rough engine operation
fails to locate major
engine seizure
components
fails to convert connecting rod lack of power
load to torque
fails to proide suitable
bearing surface
lack of power
engine seizure
lack of power
engine seizure
transmit piston
fails to transmit pistons loads
loads to crankshaft to crankshaft
lack of power
transmit load
between bearing
surfaces
allow relative
movement
between surfaces
seals fuel air
mixture
fails to transmit load between
bearing surfaces
lack of power
fails to allow relative
movement
lack of power
engine seizure
fails to seal
fuel leak
lack of power
rough engine operation
compress air fuel fails to compress mixture
mixture
Piston
Potential Effect(s) of Failure
controls opening
and closing of ports
provides a bearing
surface
fails to control opening and
closing of ports
fails to provide a bearing
surface
transmit gas
fails to transmit gas loads to
pressure loads to
the connecting rod
the connecting rod
Orbital Engine Company
engine will not start
lack of power
rough engine operation
engine seizure
engine will not start
engine seizure
lack of power
engine seizure
65 of 81
Occurrence
Potential Failure Mode
RPN
10 Engine Testing
3
240
10 Engine Testing
3
180
2 Engine Testing
3
48
2 Engine Testing
3
36
8 corrosion of bearing surfaces, increased
friction - material degradation
lubricant deficiency
6 Corrosion of rod to failure - material
degradation
10 Engine Testing
3
240
2 Engine Testing
3
36
6 corrosion of bearing surfaces, increased
friction - material degradation
lubricant deficiency
8 corrosion of bearing surfaces, increased
friction - material degradation
lubricant deficiency
6 fuel attacks seal - material degradation
lubricant deficiency
10 Engine Testing
3
180
10 Engine Testing
3
240
5 Engine Testing
1
30
8 hole in piston from - altered combustion
10 Engine Testing
3
240
3
48
3
240
3
240
Severity
Function
Detection
Crank
seals
Bearings
Connect
ing rods
Crankshaft
Item
Potential Cause(s)/Mechanism(s) of
Failure
8 corrosion of bearing surfaces, increased
friction - material degradation
lubricant deficiency
6 corrosion of seal surface on crank - material
degradation
8 Corrosion of crank to failure - material
degradation
6 Corrosion of crank to failure - material
degradation
Current Design
Controls
8 erosion of piston crown will alter port timing - 2 Engine Testing
altered combustion
8 corrosion of bearing surfaces - material
10 Engine Testing
degradation
lubricant deficiency
8 hole in piston, piston seizure, high friction 10 Engine Testing
altered combustion
lubricant deficiency
E20 FMEA technical assessment
seals between
cylinder volume
and crankcase
transfers heat
Potential Effect(s) of Failure
fails to seal
lack of power
hard to start
fails to transfer heat
lack of power
knock
piston overheats, engine seizure
engine seizure
Cylinder block
Piston
Pin
Piston
Pin Clip
retains piston pin fails to retain piston pin
Occurrence
Potential Failure Mode
RPN
6 ring wear, ring jacking, ring stick 10 Engine Testing
combustion temperaures
lubricant deficiency
8 ring wear, ring jacking, ring stick - altered 10 Engine Testing
combustion
lubricant deficiency
8 corrosion of pin clip to failure - material
2 engine Testing
degradation
3
180
3
240
3
48
3
48
3
240
3
24
3
240
3
36
3
36
3
162
3
48
Severity
Function
Detection
Piston
Rings
Item
Potential Cause(s)/Mechanism(s) of
Failure
Current Design
Controls
connects
connecting rod and
piston
provides bearing
surface
housing for engine
components
provides bearing
surface
transfers fresh
charge
fails to connect connecting rod engine seizure
and piston
8 corrosion of pin - material degradation
fails to provide a bearing
surface
fails to house engine
components
fails to provide bearing
surface
fails to transfer fresh charge
transfers exhaust
gas
fails to transfer fresh charge
rough engine operation
lack of power
contains fresh
charge
fails to contain fresh charge
retains carburettor
fails to retain carburettor
fuel air mixture leaks
lack of power
rough engine operation
engine will not start
8 corrosion of pin - material degradation
10 Engine Testing
lubricant deficiency
8 corrosion of materials reatining components 1 Engine Testing
- material degradation
8 altered combustion
10 Engine Testing
lubricant deficiency
6 transfer port is blocked by deposits from
2 Engine Testing
exhaust gas - fuel properties
altered combustion
lubricant deficiency
6 exhaust port is blocked by deposits from
2 Engine Testing
exhaust gas - fuel properties
altered combustion
lubricant deficiency
9 cylinder block corrodes and a hole is formed 6 Engine Testing
in crankcase - material degradation
Orbital Engine Company
engine seizure
engine seizure
engine seizure
rough engine operation
lack of power
66 of 81
8 cylinder block corrodes damaging mounting
face - material degradation
2 Engine Testing
2 Material
Compatibility Tests,
Engine Testing
E20 FMEA technical assessment
Sparkplug
Orbital Engine Company
fails to ignite fresh charge
Potential Effect(s) of Failure
rough engine operation
lack of power
engine will not start
67 of 81
Potential Cause(s)/Mechanism(s) of
Failure
Current Design
Controls
6 foulling, incorrect heat range electrodes - 10 Engine Testing
altered combustion
Detection
ignites fresh
charge
Potential Failure Mode
Occurrence
Function
Severity
Item
RPN
3
180
E20 FMEA technical assessment
12 Appendix F
Figures of 15hp Mercury Marine Outboard Engine
Figure 14 Fuel tank assembly
Figure 15 Carburettor assembly
Figure 16 Carburettor and reed assembly
Figure 17 Crankshaft assembly
Orbital Engine Company
68 of 81
Figure 18 Cylinder block assembly
Orbital Engine Company
69 of 81
13 Appendix G
Design FMEA table for Stihl FS45 Line-trimmer
POTENTIAL FAILURE MODE AND EFFECT ANALYSIS
DESIGN FMEA FOR STIHL BRUSHCUTTER FS45
Prepared by JRM
Core Team: JRM, PTG, LAG
RPN
fuel leak
9 hole in tank - material degradation
10 Material Compatibility Tests,
Engine Testing
1
90
prevents contamination fuel contaminated
of fuel
engine lacks power
rough engine operation
6 hole in tank - material degradation
10 Material Compatibility Tests,
Engine Testing
1
60
seals tank
engine lacks power
rough engine operation
engine stops
6 cap distorted, hole in cap - material
degradation
2 mechanism jammed, float sinks - material
degradation
5 vent blocked or distorted - material
degradation
8 cap distorted, stuck to tank - material
degradation
10 Material Compatibility Tests,
Engine Testing
10 Material Compatibility Tests,
Engine Testing
10 Material Compatibility Tests,
Engine Testing
10 Material Compatibility Tests,
Engine Testing
1
60
1
20
1
50
1
80
Function
contains fuel
displays fuel level
vents tank
Potential Failure Mode
fuel leak
leaks
fuel contamination
shows incorrect level
blockage
vapour release
allows tank to be filled cap cannot be removed
Orbital Engine Company
Potential Effect(s) of Failure
engine stops
excessive evaporative emissions
tank cannot be filled - engine
stops
70 of 81
Severity
Detection
Fuel Tank cap
Plastic
Fuel Tank
Item
Occurrence
Date: 10/10/2002
Potential Cause(s)/Mechanism(s) of
Failure
Current Design Controls
E20 FMEA technical assessment
Occurrence
RPN
attaches fuel filler cap filler cap not attached to
to fuel tank
fuel tank
Debri blocks fuel filter - lack of
power
Fuel cap loss
1 fuel attacks material - material
degradation
10 Test material compatibility
Test running engine
1
10
prevents debris entering debris passes filter
fuel line
blockage of fuel lines and primer
bulb mechanism - engine stops
5 screen material attacked by fuel - material 10 Material Compatibility Tests,
degradation
Engine Testing
1
50
transfer fuel
blockage
engine stops
lack of power
8 screen material attacked by fuel material degradation
gumming
10 Material Compatibility Tests,
Engine Testing
1
80
transfer of fuel
blockage
air leak
fuel leak
fuel leak
engine stops
lack of power
9 tube attacked by fuel, blocking flow material degradation
gumming
9 tube attacked by fuel - material
degradation
10 Material Compatibility Tests,
Engine Testing
1
90
10 Material Compatibility Tests,
Engine Testing
1
90
6 tube attacked by fuel - material
degradation
8 fuel attacks air cleaner - material
degradation
10 Material Compatibility Tests,
Engine Testing
10 Test material compatibility
Test running engine
1
60
Function
seals fuel (against fuel
tank)
Potential Failure Mode
holds pickup screen
screen falls off tube
removes particles
from inlet air
Particles travel through
filter assembly
transfers air
blockage
Orbital Engine Company
Potential Effect(s) of Failure
fuel leak
blockage of fuel lines - engine
stops
Dust and contaminates enter
engine - engine seizure
Severity
Detection
Air
cleaner
Fuel Pickup
Tube
Fuel
Pickup
Screen
Filler cap
attachment
assembly
Item
Potential Cause(s)/Mechanism(s) of
Failure
blockage - rough engine operation 8 fuel attacks air cleaner - material
lack of power
degradation
71 of 81
Current Design Controls
10 Test material compatibility
Test running engine
1
80
1
80
E20 FMEA technical assessment
retains air cleaner
Fails to retain air filter
Current Design Controls
RPN
Dust and contaminates enter
engine, engine seizure
8 fuel attacks material - material
degradation
10 Test material compatibility
Test running engine
1
80
richen air fuel mixture lever cannot move
Engine will eventually start
6 fuel attacks material - material
degradation
10 Test material compatibility
Test running engine
1
60
seal air
seal not maintained
Air cleaner assembly not
secured correctly
dust and contaminates enter
engine - engine seizure
8 fuel attacks material - material
degradation
5 Test material compatibility
Test running engine
1
40
pump element to prime
fuel system
fails to pump fuel
engine will eventually start
transfer of fuel
blockage
air leak
fuel leak
engine stops
lack of power
fuel leak
6 bulb is attacked by fuel, become to hard
10 Material Compatibility Tests,
to squeeze or hole is formed and bulb
Engine Testing
cannot hold pressure - material
degradation
9 bulb is attacked by fuel, hole is formed 10 Material Compatibility Tests,
and bulb cannot hold pressure, bulb
Engine Testing
distorts blocking flow path - material
degradation
gumming
Air cleaner
housing
gasket
Primer bulb
Potential Cause(s)/Mechanism(s) of
Failure
Detection
Potential Effect(s) of Failure
Occurrence
Potential Failure Mode
Severity
Function
Choke
lever
Air
cleaner
housing
Item
Orbital Engine Company
72 of 81
1
60
1
90
E20 FMEA technical assessment
Primer
housing
gasket
Primer
housing
Potential Cause(s)/Mechanism(s) of
Failure
Current Design Controls
RPN
housing for primer bulb
valve arrangement
fails to house components
primer pump will not function engine will eventually start
6 material is attacked by fuel, distorts material degradation
10 Test material compatibility
Test running engine
1
60
transfer of fuel
blockage
fuel leak
engine stops
10 Test material compatibility
Test running engine
1
90
seals fuel
seal not maintained
fuel leak
9 material is attacked by fuel, distorts
and block fuel flow - material
degradation
gumming
9 fuel attacks material - material
degradation
5 Test material compatibility
Test running engine
1
45
fuel metering affected - rough
engine operation
lack of power
engine stops
lack of power
fuel leak
6 corrosion of materials retaining
components - material degradation
10 Material Compatibility Tests,
Engine Testing
1
60
9 fuel attacks material, corrosion blocks
flow path - material degradation
gumming
10 Material Compatibility Tests,
Engine Testing
1
90
6 air flow blocked by corrosion or deposits - 2 Material Compatibility Tests,
material degradation
Engine Testing
fuel properties
6 air or fuel flow blocked or altered, fuel
10 Material Compatibility Tests,
does not atomise or vaporise - material
Engine Testing
degradation
gumming
fuel properties
6 throttle blade corrodes, sticks to carb
2 Material Compatibility Tests,
body - material degradation
Engine Testing
1
12
1
60
1
12
housing for components components not located
correctly
transfer of fuel
blockage
fuel leak
transfer of air
air flow blocked
lack of power
mixing of fuel and air
air and fuel not mixed
rough engine operation
lack of power
controls airflow
incorrect airflow control
lack of power
Throttle
blade
Carburettor body
Potential Effect(s) of Failure
Detection
Potential Failure Mode
Occurrence
Function
Severity
Item
Orbital Engine Company
73 of 81
E20 FMEA technical assessment
actuator for throttle
blade
throttle blade cannot be
actuated
lack of power
Throttle sticks WOT
seal against
carburettor body
air leak into carburettor
rough engine operation
lack of power
Potential Cause(s)/Mechanism(s) of
Failure
Current Design Controls
10 throttle shaft corrodes, sticks to carb body 4 Material Compatibility Tests,
- material degradation
Engine Testing
gumming
6 throttle shaft or carb body corrode 10 Material Compatibility Tests,
material degradation
Engine Testing
Detection
Potential Effect(s) of Failure
Occurrence
Potential Failure Mode
Severity
Function
RPN
1
40
1
60
1
20
secures throttle blade throttle blade not secured
to throttle shaft
throttle sticks during operation 10 screw corrodes to failure - material
degradation
2 Material Compatibility Tests,
Engine Testing
actuates needle valve
fails to actuate needle valve
9 fuel attacks material - material
degradation
gumming
10 Test material compatibility
Test running engine
1
90
seals fuel
fails to seal fuel
rough engine operation
lack of power
engine stops
fuel leak
fuel leak
9 fuel attacks material - material
degradation
10 Test material compatibility
Test running engine
1
90
controls fuel flow
fuel flow not controlled
float level incorrect - rough
engine operation
lack of power
fuel leak
9 needle and seat corrode - material
degradation
gumming
10 Material Compatibility Tests,
Engine Testing
1
90
fuel level incorrect - rough
engine operation
lack of power
fuel leak
9 lever corrodes sticks - material
degradation
gumming
10 Material Compatibility Tests,
Engine Testing
1
90
Needle
valve
Regulator
diaphragm
Throttle
blade
screw
Throttle
shaft
Item
Needle
control
arm
actuates needle valve needle valve not actuated
Orbital Engine Company
74 of 81
E20 FMEA technical assessment
Detection
Low speed
mixture screw
O-ring
Occurrence
pivots float lever
float cannot move
fuel level incorrect - rough
engine operation
lack of power
fuel leak
9 pin corrodes and lever sticks - material 10 Material Compatibility Tests,
degradation
Engine Testing
gumming
1
90
retains float pin
float pin not retained
float lever cannot move
correctly - rough engine
operation
fuel leak
lack of power
9 screw corrodes to failure - material
degradation
2 Material Compatibility Tests,
Engine Testing
1
18
mixes fuel and air
fuel and air do not mix
correctly
rough engine operation
lack of power
6 air or fuel flow blocked or altered, fuel
does not atomise or vapourise material degradation
fuel properties
gumming
10 Material Compatibility Tests,
Engine Testing
1
60
mixture adjustment
fuel air mixture cannot be
adjusted
rough engine operation
6 mixture screw corrodes altering
10 Material Compatibility Tests,
mixture strength - material degradation
Engine Testing
gumming - deposits from fuel
1
60
seals air and fuel
fuel leak
air leak
rough engine operation
6 elastomer attacked by fuel - material
properties
1
60
Orbital Engine Company
Potential Failure Mode
Potential Effect(s) of Failure
75 of 81
Severity
RPN
Function
Low speed
mixture
screw
Main fuel
nozzle
Pivot
retaining
screw
Control
arm pivot
Item
Potential Cause(s)/Mechanism(s) of
Failure
Current Design Controls
10 Material Compatibility Tests,
Engine Testing
E20 FMEA technical assessment
Detection
High speed
mixture screw
O-ring
Main fuel
jet
Elbow
fittings
Occurrence
mixture adjustment
fuel air mixture cannot be
adjusted
rough engine operation
lack of power
6 mixture screw corrodes altering
10 Material Compatibility Tests,
mixture strength - material degradation
Engine Testing
gumming
1
60
seals air and fuel
fuel leak
air leak
rough engine operation
6 elastomer attacked by fuel - material
properties
10 Material Compatibility Tests,
Engine Testing
1
60
metering fuel
fuel not metered correctly
rough engine operation
lack of power
6 fuel jet corrodes altering metering material degradation
gumming
10 Material Compatibility Tests,
Engine Testing
1
60
retain fuel lines
fuel line detach
fuel leaks
engine stops
9 fuel attacks material, corrosion blocks flow 10 Test material compatibility
path - material degradation
Test running engine
transfer of fuel
blockage
fuel leak
engine stops
lack of power
fuel leak
9 fuel attacks material - material
degradation
gumming
Orbital Engine Company
Potential Failure Mode
Potential Effect(s) of Failure
76 of 81
Severity
RPN
Function
High speed
mixture screw
Item
Potential Cause(s)/Mechanism(s) of
Failure
Current Design Controls
10 Material Compatibility Tests,
Engine Testing
1
1
90
90
E20 FMEA technical assessment
Current Design Controls
Detection
Potential Cause(s)/Mechanism(s) of
Failure
RPN
1
18
supports diaphragm
edges
diaphragm not supported
fuel leak
9 supports gasket, if gasket seal fuel,
fuel has no effect on cover
2 Material Compatibility Tests,
Engine Testing
secures pump cover
cover not secured
Fuel leak
Engine stops
9 component corrodes to failure material degradation
2 Test material compatibility
Test running engine
1
18
pumps fuel
fails to pump fuel
fuel leak to crankcase
Engine stops
fuel leak
9 fuel attacks diaphragm - material
degradation
10 Test material compatibility
Test running engine
1
90
directs fuel flow
fails to direct fuel flow
Engine stops
8 fuel attacks check valve - material
degradation
gumming
10 Test material compatibility
Test running engine
1
80
seals fuel
does not seal
fuel leak
9 fuel attacks material - material
degradation
5 Material Compatibility Tests,
Engine Testing
Cover
gasket
Pump
diaphragm and
check valves
Potential Effect(s) of Failure
Occurrence
Potential Failure Mode
Severity
Function
Cover
screw
Cover
Item
Orbital Engine Company
77 of 81
1
45
E20 FMEA technical assessment
Piston
Inlet heat
shield/Gasket
Inlet insulating
block
Potential Effect(s) of Failure
Potential Cause(s)/Mechanism(s) of
Failure
Current Design Controls
Detection
Potential Failure Mode
Occurrence
Function
Severity
Item
RPN
transfers air fuel mix
fail to transfer fuel air mix
Fuel leak
Lack of power
9 fuel attacks material - material
degradation
10 Test material compatibility
Test running engine
1
90
insulates carburettor
from heat
fails to insulate
engine will not start
6 fuel attacks material - material
degradation
10 Test material compatibility
Test running engine
1
60
seal fuel air mix
fails to seal
Fuel leak
Lack of power
9 fuel attacks material - material
degradation
5 Test material compatibility
Test running engine
1
45
shields carburettor from fails to shield carburettor
heat
engine will not start
6 fuel attacks material - material
degradation
5 Test material compatibility
Test running engine
1
30
compress air fuel
mixture
fails to compress mixture
8 hole in piston - altered combustion
10 Engine Testing
3 240
controls opening and
closing of ports
fails to control opening and
closing of ports
engine will not start
lack of power
rough engine operation
engine seizure
no airflow through engine, engine
will not start
8 erosion of piston crown will alter port
timing - altered combustion
2 Engine Testing
3
provides a bearing
surface
fails to provide a bearing
surface
engine seizure
8 corrosion of bearing surfaces material degradation
lubrication deficiency
8 hole in piston, piston seizure, high friction
- altered combustion
lubricant deficiency
10 Engine Testing
3 240
10 Engine Testing
3 240
transmit gas pressure
fails to transmit gas loads to
loads to the connecting the connecting rod
rod
Orbital Engine Company
lack of power
engine seizure
78 of 81
48
E20 FMEA technical assessment
seals between cylinder
volume and crankcase
fails to seal
lack of power
engine will not start
transfers heat
fails to transfer heat
retains piston pin
fails to retain piston pin
lack of power
knock
piston overheats - engine
seizure
engine seizure
Piston
Pin
Bearings
Potential Cause(s)/Mechanism(s) of
Failure
Current Design Controls
Detection
Potential Effect(s) of Failure
Occurrence
Potential Failure Mode
Severity
Function
Piston
Pin Clip
Piston
Rings
Item
RPN
6 ring wear, ring jacking, ring stick - altered
combustion
lubricant deficiency
8 ring wear, ring jacking, ring stick altered combustion
lubricant deficiency
10 Engine Testing
3 180
10 Engine Testing
3 240
8 corrosion of pin clip to failure material degradation
2 Engine Testing
3
48
2 Engine Testing
3
48
connects connecting rod fails to connect connecting
and piston
rod and piston
engine seizure
8 corrosion of pin - material degradation
provides bearing
surface
fails to provide a bearing
surface
engine seizure
8 corrosion of pin - material degradation 10 Engine Testing
lubricant deficiency
3 240
transmit load between
bearing surfaces
fails to transmit load between lack of power
bearing surfaces
10 Engine Testing
3 180
allow relative
movement between
surfaces
fails to allow relative
movement
6 corrosion of bearing surfaces, increased
friction - material degradation
lubricant deficiency
8 corrosion of bearing surfaces,
increased friction - material
degradation
lubricant deficiency
10 Engine Testing
3 240
Orbital Engine Company
lack of power
engine seizure
79 of 81
E20 FMEA technical assessment
RPN
fails to proide suitable
bearing surface
lack of power
engine seizure
provides sealing
surfaces
locates major
components
converts connecting rod
loads to torque
fails to provide sealing
surface
fails to locate major
components
fails to convert connecting rod
load to torque
lack of power
rough engine operation
engine seizure
seals fuel air mixture
fails to seal
fuel leak
lack of power
rough engine operation
9 fuel attacks seal - material degradation 10 Engine Testing
lubricant deficiency
1
provides bearing
surfaces
fails to proide suitable
bearing surface
lack of power
engine seizure
8 corrosion of bearing surfaces,
increased friction - material
degradation
lubricant deficiency
6 Corrosion of rod to failure - material
degradation
10 Engine Testing
3 240
2 Engine Testing
3
lack of power
transmit piston loads to fails to transmit pistons loads lack of power
crankshaft
to crankshaft
8 corrosion of bearing surfaces,
increased friction - material
degradation
lubricant deficiency
6 corrosion of seal surface on crank material degradation
9 Corrosion of crank to failure - material
degradation
6 Corrosion of crank to failure - material
degradation
Current Design Controls
Detection
Potential Cause(s)/Mechanism(s) of
Failure
provides bearing
surfaces
10 Engine Testing
3 240
10 Engine Testing
3 180
10 Engine Testing
3 270
10 Engine Testing
3 180
90
36
ignites fresh charge
fails to ignite fresh charge
rough engine operation
lack of power
engine will not start
6 foulling, incorrect heat range
electrodes damaged through knock or
preignition - altered combustion
10 Engine Testing
3 180
seals fuel air mixture
fails to seal
fuel leak
lack of power
rough engine operation
9 fuel attacks seal - material degradation
5
3 135
Barrel
gasket
Sparkplug
Connectin
g rod
Potential Effect(s) of Failure
Occurrence
Potential Failure Mode
Severity
Function
Crank
seals
Crankshaft
Item
Orbital Engine Company
80 of 81
Engine Testing
E20 FMEA technical assessment
Crankcase
Barrel
Potential Effect(s) of Failure
Potential Cause(s)/Mechanism(s) of
Failure
Current Design Controls
housing for engine
components
fails to house engine
components
engine seizure
8 corrosion of materials reatining
components - material degradation
provides bearing
surface
fails to provide bearing
surface
engine seizure
lack of power
transfers fresh charge
fails to transfer fresh charge
rough engine operation
lack of power
8 excessive piston and bore
10 Engine Testing
temperatures or water in fuel causing
loss of lubrication - altered combustion
lubricant deficiency
6 transfer port is blocked by deposits from
1 Engine Testing
exhaust gas - fuel properties
transfers exhaust gas
fails to transfer fresh charge
rough engine operation
lack of power
contains fresh charge
fails to contain fresh charge
housing for engine
components
fails to house engine
components
fuel leak
lack of power
rough engine operation
engine seizure
provides bearing
surface
fails to provide bearing
surface
contains fresh charge
fails to contain fresh charge
Orbital Engine Company
2 Engine Testing
Detection
Potential Failure Mode
Occurrence
Function
Severity
Item
RPN
3
48
3 240
3
18
18
6 exhaust port is blocked by deposits from
exhaust gas - fuel properties
altered combustion
lubricant deficiency
9 cylinder block corrodes and a hole is
formed in crankcase - material
degradation
8 corrosion of materials reatining
components - material degradation
1 Engine Testing
3
6 Engine Testing
3 162
2 Engine Testing
3
engine seizure
8 corrosion of materials reatining
components - material degradation
10 Engine Testing
3 240
fuel leak
lack of power
rough engine operation
9 corrodes and a hole is formed in
crankcase - material degradation
6 Engine Testing
3 162
81 of 81
48
E20 FMEA technical assessment
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