To manage fuel properly, one must first find a reliable way of setting the engine to a known operating point for cruise. This means leaning the mixture correctly. For a non-engine-instrumented plane like most PA28s, you would lean until the RPM just drops, and then go a tiny bit rich again. Then check the carb heat still works. Obviously this would be done at a given engine RPM (and MP if VP prop).
Next, determine actual cruise fuel flow. Do two flights, identical profile except for a 30min or 1hr difference in the cruise section length. Start each with exactly full tanks, and compare the refill required. This will give you the fuel usage per hour at that power setting. Never rely on book figures for fuel flow!
If possible, repeat the exercise for two different power settings; one at max cruise power (probably 75% power) and another at about 60% power. The 2nd should yield a much improved range.
Never rely on what anybody previously claims there is in the tank. ALWAYS fill up yourself to the top, or do a physical check to tabs, etc. If the fuel is too low to be physically checked, do not fly - EVER. Even if an instructor tells you there is plenty in there. I have twice walked up to a plane declared by an instructor as having X amount of juice, and it was virtually empty (either because somebody did not log a flight, or maybe fuel theft during the night).
Best thing is a fuel flowmeter (Shadin Microflo etc), especially linked to the GPS. Then you get a constantly recomputed FOB (fuel on board) at the planned destination. Obviously you have to accurately enter the starting FOB into one of these.
Last edited by IO540; 28th Feb 2008 at 07:45.