When is a fuel pump needed on GA aircraft? I am a flight simmer and have noticed that you can leave the fuel pump off and start/fly the aircraft. When would you use the fuel pump?
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4$\begingroup$ Considering it's a SIM, I wouldn't count on it being 100% accurate. Unless, of course, it was developed by Boeing, Airbus, or another manufacturer for actual training of actual pilots. $\endgroup$– FreeManCommented Oct 14, 2015 at 19:58
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$\begingroup$ IVAO, eh? Ah well.... :P $\endgroup$– SentryRavenCommented Oct 14, 2015 at 20:36
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1$\begingroup$ @FreeMan Ftr, many flightgear models do a good job of stimulating fuel and electrical systems. $\endgroup$– flyingfischCommented Oct 16, 2015 at 20:45
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3 Answers
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On a low wing monoplane you'll need a pump all the time. There will be a mechanical pump fitted to the engine for the purpose. On a high-wing monoplane the engine is often gravity feed.
However, during critical phases of flight (specifically take-off and landing) you wouldn't want to have that fail so a second auxiliary electric pump is fitted that the pilot switches on beforehand and can switch off once that phase is over.
The Pilot's Operating Manual will give specific recommendations for use on any given type.
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$\begingroup$ Thanks for the answer! Unfortunately flight sim doesn't have very accurate POH's $\endgroup$ Commented Oct 14, 2015 at 18:45
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1$\begingroup$ Actually all aircraft, high or low wing use engine driven pumps and auxiliary electric pumps. $\endgroup$ Commented Oct 23, 2018 at 20:01
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Refer to the POH for the aircraft but in the PA-28-161 I fly the electric fuel pump is used on take off, landing, and while practicing maneuvers like steep turns and stalls. Most GA planes are configured with either a gravity feed fuel system (like the Cessna 172) or an engine driven fuel pump (Piper Cherokees) that can be supplemented with an electric fuel pump should it quit or become partially inoperative. The FAA has a nice document on it here (see pump feed systems) their opinion is,
The engine-driven fuel pump acts as the primary pump. The electric pump can supply fuel should the other fail. The electric pump also supplies fuel pressure while starting and is used to prevent vapor lock during flight at high altitude.
The switch you see in the cockpit controls the electric pump. As far as I know there is no way to turn off the mechanical pump (not that you would really want to).
The general startup procedure for carbureted PA-28's (low wing mono planes (fuel tank below engine)) often involves turning the fuel pump on, checking for fuel pressure, then turning the pump off. This can also help to prime the lines with fuel, if the lines are dry you will need a few extra cranks of the engine to draw fuel in with the mechanical pump which drains battery power.
Since you claim you can fly with out the pump running we can assume it is an engine pump driven plane however smaller turbine planes that still fall under the GA header may require an electric fuel pump to feed the engine.
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$\begingroup$ In FS I fly the PA34 seneca v(low wing) and a less known light sport tecnam eaglet (high wing) and both have fuel pumps. But thanks very much for the info $\endgroup$ Commented Oct 14, 2015 at 20:45
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Virtually all GA aircraft, high or low wing, use both an engine driven fuel pump and and electric auxiliary fuel pump. Typically high wing GA aircraft will use the aux pump only for priming the engine (fuel injected engines) as gravity feed from the main tanks offers a backup in case of EDP failure. The aux pump is used on low wing aircraft, both for priming the engine as well as a backup in critical phases of flight where EDP failure could be disasterous such as takeoff and landing. This is due to the low wing arrangement requiring siphon feed from the tanks to the engine.
answered Oct 23, 2018 at 20:07
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$\begingroup$ The carb 172/152's like the 172P do not have an electric pump, especially the older ones. I'm not so sure that the 172P I trained in even had a mechanical pump, here is a similar POH that doesn't show a pump in the feed system at all. $\endgroup$ Commented Oct 23, 2018 at 22:01
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$\begingroup$ Hmmm, I don't know. I flew a Cessna 172N a few weeks ago (I'm a real private pilot) and it had a fuel pump switch, which is presumably the electric backup one referred to above. I have flown the 172N and 172M as well as PA-28 Arrow and Archer and I think they all had fuel pumps? $\endgroup$– atom88Commented Sep 18, 2020 at 3:58