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Fuel Pump Switch

rockitdoc

Well Known Member
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I am planning my panel and noticed some posters indicating that they like the fuel pump switch above the throttle and next to the flaps switch so they can use it on final.

Why are they using the electric fuel pump in flight? Isn't it there just to start the plane? In my old Bonanza, turning on the fuel pump in flight was a definite no-no as it flooded the engine and then silence ensued.

What am I missing?
 
Your Bonanza has a Continental engine.. different systems than the Lycoming. The Lycoming uses a mechanical diaphragm style fuel pump, with an electric back up. You can run both and not flood out the engine. On your Continental, it will flood the engine, especially if you select High. Most Lycoming guys use the electric back up for takeoff and landind, so if the mechanical pump happen to fail, the engine wouldn't quit until the pump was turned off.
 
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Your Bonanza has a Continental engine.. different systems than the Lycoming. The Lycoming uses a mechanical diaphragm style fuel pump, with an electric back up. You can run

Is it part of the checklist on landing to activate the electric pump? If so, why, when the mechanical pump is working?
 
The electric pump is generally on as a backup in case of a mechanical pump failure at say, 500' AGL. Keeps the heart rate down.

George
 
Is it part of the checklist on landing to activate the electric pump? If so, why, when the mechanical pump is working?

Its on the checklist for takeoff and landing for a lot of low wing certified aircraft.

As far as your EAB, I'd say its up to you.
 
The electric pump is generally on as a backup in case of a mechanical pump failure at say, 500' AGL. Keeps the heart rate down.

George

This.

My checklist has it on for higher risk / high workload phases of flight where in the (unlikely) event the mechanical pump quits, the electric is already running and ideally there is no power interruption.

Electric pump goes off after takeoff at a safe altitude, if the engine goes quiet electric pump back on and return to airport.
 
This.

My checklist has it on for higher risk / high workload phases of flight where in the (unlikely) event the mechanical pump quits, the electric is already running and ideally there is no power interruption.

Electric pump goes off after takeoff at a safe altitude, if the engine goes quiet electric pump back on and return to airport.

A word of caution from my experience:

I've got the Airflow Performance electric pump for my IO-320-D1A, and I can attest that the engine runs fine on solely the electric pump...courtesy of an in-flight failure of the engine-driven pump.

But...

Carefully monitor the mixture if you're ever running on the electric pump alone. My emergency reflex was to go full rich (I was below 5000'), which would've been fine with both pumps operating. But that electric pump is running full blast all the time, versus the mechanical pump whose flow depends on engine speed, and the result was a very rich condition that ultimately stopped the prop. Fortunately, I was about halfway through the base leg at that point and glided to a safe landing.

Now shame on me for not watching the EGTs and leaning, but it was a situation I hadn't trained for (there was nothing in my POH about this! :)), I was a bit rattled from losing the engine the first time and I was preoccupied scouting for alternate landing sites as I made my way back to the airport. Pulled the plugs later and the electrodes were all jet black.

A good addition to the emergency checklist for running on electric boost pump alone: Lean as necessary!
 
Doug-

Thanks for the post - that is good info, and something to file away in the memory banks in case I am ever in that situation. Probably not something most of us would consider in the heat of the moment!

T.
 
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