xftrplt Posted February 28, 2012 Report Posted February 28, 2012 According to the POH and the placards at the fuel fillers, the usable fuel of my '81 K is 75 gal. (No bladders.) Twice I've checked the usable fuel by running tanks to engine sputter. Each tank takes 32.5 gal., filling above the flapper to the neck. The aircraft is missing 10 gal. of capacity! Any ideas/suggestions? TIA Quote
FAST FLIGHT OPTIONS LLC Posted February 28, 2012 Report Posted February 28, 2012 You have to put the last 5 gallons in real slow. Just because fuel is stuck above the flapper doesn't mean the tank below is exactly full. Not sure this makes sense but I know it to be the case in my K Quote
xftrplt Posted February 28, 2012 Author Report Posted February 28, 2012 Quote: 201-FLYER You have to put the last 5 gallons in real slow. Just because fuel is stuck above the flapper doesn't mean the tank below is exactly full. Not sure this makes sense but I know it to be the case in my K Quote
231flyer Posted February 28, 2012 Report Posted February 28, 2012 I concur. i usually ask for a top off after I land and then again before I am ready to go. Typically the difference is around 9-12 gals. The wing compartments have anti-slosh vents and tend to trap air. One of my flying mentors(20 yrs ago) advised me store the plane with tanks full to prevent condensation. I have lived by the maxim and the added benefit is the gas has plenty of time to settle and free up space for the last few gallons. Quote
aviatoreb Posted February 28, 2012 Report Posted February 28, 2012 Quote: xftrplt According to the POH and the placards at the fuel fillers, the usable fuel of my '81 K is 75 gal. (No bladders.) Twice I've checked the usable fuel by running tanks to engine sputter. Each tank takes 32.5 gal., filling above the flapper to the neck. The aircraft is missing 10 gal. of capacity! Any ideas/suggestions? TIA Quote
Piloto Posted February 28, 2012 Report Posted February 28, 2012 Sometimes when the tanks are resealed the mechanic applying the sealant may plug the upper vent holes on the tank ribs. This will cause air to be trapped on the upper part thus limiting the amount of fuel that can be put in. If the drain bottom holes on the ribs are plugged not all the fuel will be drained out. This can be inspected by inserting a borescope through the filler hole. José Quote
xftrplt Posted February 29, 2012 Author Report Posted February 29, 2012 Quote: Piloto Sometimes when the tanks are resealed the mechanic applying the sealant may plug the upper vent holes on the tank ribs. This will cause air to be trapped on the upper part thus limiting the amount of fuel that can be put in. If the drain bottom holes on the ribs are plugged not all the fuel will be drained out. This can be inspected by inserting a borescope through the filler hole. José Quote
xftrplt Posted February 29, 2012 Author Report Posted February 29, 2012 FWIW, I just returned from a round trip to Vero Beach, FL, flown nonstop both ways from western MD. There were headwinds southbound (5+45 enroute), and knowing my actual usuable fuel was critical. I suggest being ABSOLUTELY sure of your usable fuel, by whatever EMPIRICAL method you choose, not relying on specs. I personally think running each tank until the engine stutters in flight is the only sure method, but I know this has been addressed and debated before in detail. Quote
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