Quote:
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Originally Posted by
From time to time pilots have observed fuel stains on the nosewheel
wheelpant of our club's 172SP. The only time I have actually seen fuel
dripping from the engine was when I watched a pilot turn the auxiliary
fuel pump on for what seemed to me to be an excessively long period of
time. The fuel appeared to be dripping out of one of the two plastic
hoses that come down through the cowling just ahead of the firewall. I
have assumed that the cure is to prime the engine according to the POH:
5. Auxiliary Fuel Pump Switch -- ON.
6. Misture -- ADVANCE until fuel flow just starts to rise, then return
to IDLE CUT OFF position.
7. Auxiliary Fuel Pump -- OFF.
When I follow this procedure, I never see fuel stains on the nosewheel
wheelpant.
One of our pilots has suggested that fuel should not drain from the
engine when the auxiliary fuel pump is left on too long. He thinks
there is a leak in the fuel system.
Does anyone know the answer to this question?
Thanks
Stephen Ashley
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I own a 2001 Cessna 172SP with 350 hours on it. I just had the fuel servo overhauled after the plane exhibited similar fuel dump on the fairing after shutdown. You can get fuel dump if the engine floods due to overpriming at start, but fuel dump at shutdown may indicate a gummed up servo. Have an A&P remove the bottom cowling and look around the control arm connectors to the servo for leaks and look into the throttle body for gum up. The performance issues are subtle in this problem and you may not notice the reduced take off performance or loss of power at altitude due to overrich mixture.By the way, Lycoming blames this servo gum up problem on overpriming but I prime by the POH. The issue needs an AD for inspection of the servos in my opinion.