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Fuel Calibration Question...

pstraub

Well Known Member
Hi all, tried a search with no luck. I am confused about the fuel system calibration on PAP G8-1. Roll main wheels onto 2" blocks (this would give me a slight 'nose down' attitude??) Then add 4 gallons incrementally, roll off the blocks and check the red, no takeoff sticker on the mechanical gauge. Then roll back onto 2" blocks and continue to add 2 gal/time until 16 gal. So why the 2" blocks on the mains? Don't I want the plane perfectly level during this calibration? What am I missing by raising the mains and keeping the nosewheel on the ground? Thanks for any clarification!
 
The purpose of the 2 inch blocks is to put the airplane in the level position for flight which is different than on the ground. But you check the sight gauge on the ground that's why you roll it off the blocks for that portion.
 
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Thanks John....that makes sense. I just wanted to be sure I wasn't misunderstanding the PAP procedure. I appreciate the response!
 
It is not clear to me what impact this "dance" around the 2" blocks has on the fuel level indication. It seems that in level flight the asset of the plane favors having more fuel in the front of the tank which is good as the fuel pick-up is there. Would not that mean that calibrating based on ground asset will trigger the low fuel alarm sooner? If this is the case I don't mind the extra margin provided through a simpler procedure. (To be honest this is what I have done unwittingly... just fishing here for an excuse!:eek:)
 
Loose.

The old float type sending units are well known for being a best, untrustworthy. The idea is to calibrate them with the aircraft in the flight attitude to cut down on their margin of error. We have found after years of flying old Cessna's, Piper and so on aircraft we also make a hard copy of the fill levels with the aircraft on the ground so we can keep it with the aircraft and refer to it on a preflight check list. AS you fill each tank, dip it with a ruler and record the level and amount on that take. You will be amazed at the fact that two tanks don't always read the same even if they look the same, they may be a few gallons off from one another. We put this data on the last page at the back of out POHB so we can use it anytime we are on the road or at home. In the old Cessna's we just made 3X5 cards and stuck it in the clove box.
If you have an IFIS you can also list your electrical voltage hacks along with your levels and amounts. Hope this helps, Yours, R.E.A. III #80888
 
It is not clear to me what impact this "dance" around the 2" blocks has on the fuel level indication. It seems that in level flight the asset of the plane favors having more fuel in the front of the tank which is good as the fuel pick-up is there. Would not that mean that calibrating based on ground asset will trigger the low fuel alarm sooner? If this is the case I don't mind the extra margin provided through a simpler procedure. (To be honest this is what I have done unwittingly... just fishing here for an excuse!:eek:)

Great minds think alike (maybe)... I too took this approach; I'd rather get nervous early on and have a little more fuel..😎
 
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