DA40 Fuel Pump Operation

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Chris
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Re: DA40 Fuel Pump Operation

Post by Chris »

I agree with Dave. I make a point to turn it off and back on when doing circuits in the pattern for just that reason.
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gordsh
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Re: DA40 Fuel Pump Operation

Post by gordsh »

Thanks Dave, I will go back to practicing that by incorporating the fuel pump and prop in my circuits.
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Rich
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Re: DA40 Fuel Pump Operation

Post by Rich »

In my plane operating the fuel pump switch is not what one would think of as muscle memory. I'm unclear to me how the G1000 switch layout is, but the switch in mine is right next to the avionics master and looks just like it. So my muscle memory is to look down and confirm which switch I'm about to operate and then do it. Otherwise :oops:
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pietromarx
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Re: DA40 Fuel Pump Operation

Post by pietromarx »

Having had a couple of electric pumps go out on my last DA-40, I view the thing with some apprehension.

Two questions:

1. Not to be obtuse, what is the logic behind turning the pump on at short final? To me the pump is required for take-off and climb to pattern altitude. I can understand wanting it on in the case of an unexpected go-around, but otherwise you've presumably already made the runway?

2. Does anyone have a thought of when the pump fails? Is it the turning-on, turning-off, or any time while running. Both of my failures were the pump ran fine and then the next time I tried to turn it on I got ... nothing. BTW, both failures were when turning on the pump on final to land.

Thanks


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Rich
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Re: DA40 Fuel Pump Operation

Post by Rich »

Three reasons for turning on the pump on final:

1. You may not yet have the runway made.
2. So the plane doesn't quit on the runway, blocking the five guys behind you in the pattern. :x
3. My wife makes me :D
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Re: DA40 Fuel Pump Operation

Post by BkFlyer »

I use the pump during run up, takeoff and short final. Every CFI has been adamant about it, and that’s across independent schools.

I don’t know what seems weird about having the pump on for the most critical phases of flight, where most accidents happen, and the only phase of flight where power loss/fuel interruption is terrifying.

Some mentioned not using it for run up, only for takeoff. I don’t know- most of the purpose of run up is to simulate takeoff max power conditions. Rather find out the pump is bad on before I’m barreling down a short runway...
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Rich
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Re: DA40 Fuel Pump Operation

Post by Rich »

BkFlyer wrote: Some mentioned not using it for run up, only for takeoff. I don’t know- most of the purpose of run up is to simulate takeoff max power conditions. Rather find out the pump is bad on before I’m barreling down a short runway...
Keep in mind you're not really simulating takeoff at run up, as you're nowhere near max power at run up settings. More like ~50% power.
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Re: DA40 Fuel Pump Operation

Post by thefoxx »

The other question I have - does the electric fuel pump even have enough pressure to take over from the engine driven one?

I know in my DA20 - just operating the stage 1 of the electric fuel pump- the pressure without engine running comes no where near the pressure on the gauge as when the engine is running - even with the prime pump on (without engine running), it's only marginally better than just stage 1.

Which leads me to ask the question above - could the engine still run, just on the electric pump? Or is having the pump turned on during low RPM's just to give it a little bit of extra juice, and not actually take over if the engine pump fails.

Maybe the DA40 is different from the 20 in this respect- i'm not sure?
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Re: DA40 Fuel Pump Operation

Post by BkFlyer »

thefoxx wrote:The other question I have - does the electric fuel pump even have enough pressure to take over from the engine driven one?

I know in my DA20 - just operating the stage 1 of the electric fuel pump- the pressure without engine running comes no where near the pressure on the gauge as when the engine is running - even with the prime pump on (without engine running), it's only marginally better than just stage 1.

Which leads me to ask the question above - could the engine still run, just on the electric pump? Or is having the pump turned on during low RPM's just to give it a little bit of extra juice, and not actually take over if the engine pump fails.

Maybe the DA40 is different from the 20 in this respect- i'm not sure?
My DA40 and new pump do get the PSI up pretty well. But, unless you’re willing to intentionally fly without the mechanical pump, we’ll have to trust the POH...

Note that the engine doesn’t need to run well, it just needs to run enough to keep the prop spinning until you get back on the ground.
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Rick
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Re: DA40 Fuel Pump Operation

Post by Rick »

This has me wondering now... Does anyone know of any instance of a mechanical fuel pump failure in an IO-360 engine, or how to look for such a thing? This would be the ultimate source of information on how well the electric pump performed, if it has ever happened.
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