Check your RPM gauge for accuracy. Mine is 150 RPM OFF! When reading 2500 RPM I am only turning 2350.The less the RPM the less off the Tack reads. On my Viking 100 RPM is five KTS in speed. Pilots have complained about not getting close to book speed on all sorts of planes only to find the Tach was off. An easy check. There are units on the market that set on the dash that record within one revolution of the prop, your mechanic might have one, or ask for the correct readings if having the prop balanced. Place card the readings. I elected to purchase a battery-operated unit that sets on the dash at all times. On some Vikings the main fuel gauges will not record the amount of fuel on board. Some get a varied reading from time to time. What typically happens is a gauge will read less than full, as the fuel is used up the gauge will began to read correctly. If equipped with an aux tank that sending unit is different and usually reliable. To adjust the main tanks fuel gauges consult with the factory service manual. Your mechanic will have to remove the co-pilot seat. Between the right seat rail and the door jam are two black boxes. Both have adjustment pod for calibrations, adjust to specification. NOT a simple job. The units appear to be moisture and temperature sensitive. I feel any fuel gauges on any aircraft are suspect. On my checklist I have set clock. Not for just the time of day but engine start up time as well. No matter what my gauges say if I have planed a flight for time, distance, fuel burn I land. I ALWAYS top off the tanks on landing, even if it is a short turn around trip. DO NOT use the aux tank if so equipped on climb out OR descents!
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