Aux. Fuel Pump Question

[BYUFlyr]

Does anyone see anything wrong with leaving the fuel pumps "on" in the pattern when performing touch and goes on a Piper Seneca? Does it affect the aircraft's performance? Fuel mixture?

I think it's a safe practice and I see no drawbacks with leaving them on. Turning them off at 500 AGL just to turn them back on 30 seconds later seems like an unnecessary addition to the workload and increases the chances of inadvertently landing with your back-up fuel pumps "off".

I had a discussion about this with my MEI and I didn't feel like he gave me a good reason to turn them "off" when we're staying in the pattern. The POH does not say that you have to turn them off at 500 AGL. It states that you MAY turn them off above 500 AGL.

We also had the same discussion about cowl flaps in the pattern (leaving them open). Can someone more experienced than me shed some light on this?

 

[Kream926]

fuel flow maybe?

 

[minitour]

I'd go with the POH...check out the Amplified procedures sections and see if it recommends...for example, the 172RG POH specifies leaving the gear down in the pattern. I discussed this with an examiner and after one "gear up" and "gear down" he said I could leave them down...

When in doubt, the POH is set up by the manufacturer...go by that.

I know that doesn't really help, but that's all I got...

-mini

 

[hawg2hawk]

If any A&P's weigh in on this, I'm sure they will tell you it is to increase the service life of the aux fuel pump. It's like the landing light -- it would be safer to leave it on all the time, but then you'd spend a lot replacing landing lights. In many larger aircraft, boost pumps, while not technically the same, are left on at all times during flight.

Remember an aux pump is a backup to provide fuel under positive pressure in case the engine driven fuel pump fails. Having the aux fuel pumps on or off won't affect fuel flow -- that's the function of the fuel control via the mixture and throttle settings.

I'll let someone else cover cowl flaps. I don't feel up to the inevitable argument.

 

[minitour]

I'll let someone else cover cowl flaps. I don't feel up to the inevitable argument.

I'll try ---

Leave 'em open...on the climbout you wont overheat and you probably won't shock cool 'em either...one less thing to worry about should some numbnutz taxi onto the runway when you're on short final...

-mini

*edit*
But again...if the POH says close 'em and open 'em when appropriate...do it

 

[Kream926]

I discussed this with an examiner and after one "gear up" and "gear down" he said I could leave them down...
-mini

really, WTF!!?!?!
mine made me do up and down every time

 

[minitour]

really, WTF!!?!?!
mine made me do up and down every time

yeah well...mine also wouldn't let me use rudder during the maneuvers...so take it for what its worth...

Luckily though we went out and did the maneuvers first so that was the "gear up" and on base was the "gear down" for the first touch and go...didn't touch it the rest of the time...

He either didn't care, didn't know about the POH saying that, or was impressed that I knew and just went with it...I'm thinking it was a "didn't care"

-mini

 

[hawg2hawk]

yeah well...mine also wouldn't let me use rudder during the maneuvers...so take it for what its worth...

Luckily though we went out and did the maneuvers first so that was the "gear up" and on base was the "gear down" for the first touch and go...didn't touch it the rest of the time...

He either didn't care, didn't know about the POH saying that, or was impressed that I knew and just went with it...I'm thinking it was a "didn't care"

-mini

Maybe not. I've ridden with countless instructors and check pilots in a bunch of different airplanes, and every time I see something like this, the reason offered is "so we don't wear out the gear/aux pump/landing light" etc.
Sometimes valid, sometimes not, but hopefully the IP knows AND cares!

 

[minitour]

...hopefully the IP knows AND cares!

word to that!

 

[JB74]

If any A&P's weigh in on this, I'm sure they will tell you it is to increase the service life of the aux fuel pump.

I am not an A&P but I would also guess that is why. Does anyone know how often the aux pump operation is verified? Annual? I would guess that an inop aux pump could go undetected for quite some time if the plane got 100% of its fuel from the engine driven pump.

 

[Dutch]

I'd say that the pumps would be checked prior to each flight or at least daily. The newer 172's I used to fly were checked during engine priming. We used the pump for priming prior to start and the pump operation was obvious (both audible indications and fuel flow meter). The PA44's were the same, could hear the pumps operating prior to engine start.

Dutch

 

[JB74]

Ah, good point. Its 2:00 am and I think my brain already went to bed without me.

 

[Kream926]

not just that but dont you check for increase in fuel pressure during run-up with the aux pump on. i do, and i think poh checklist sais so too. and mini, how on gods green earth did you do a checkride in an RG with no rudder and how the hell did you enter those manuevers correctly? i dont have a PTS around but if im not mistaken it sais to enter manuevers coordinated?

 

[indianboy7]

I don't know which seneca you're flying, but in the seneca III that I fly, putting the boost pumps to "low" makes the mixture too rich and the engines starts stumbling and running rough.......put them on "high" and the engine loses power and almost quits because of too much fuel.....who'da ever thought you'd have to worry about that???.......

 

[nosehair]

It's all about the training, gents. The training. Training a habit pattern.

Gear up. Pumps off. Cowl flaps closed on level off.
Gear down. Pumps on. Cowl flaps as appropriate.

'Round and 'round the pattern repeating those moves until they are automatic.

Sure, once you have the automaticity drilled in, then you can, and should, begin to think about each movement, and tailor to the specific environment.

Most people, however, barely get enough training time in a complex or multi to go beyound the rote automatic to think or get into the "other than checkride stuff'.

If you were trained initially in a retract, and your instructor/ airplane owner wanted to save wear & tear on the gear and made you do the patterns INITIALLY leaving the gear down all the time, you would be set up to land gear up later when you were PIC and had actally raised the gear.

And experience teaches us that doing a critical motion just a few times may not be enough to really drill it in. Of course this varies with each individual. Do you want to bet your life on being able to "remember".

Don't you think it is better to over-do than under-do?

Training. That's all it is.

 

[DrewBlows]

I don't know which seneca you're flying, but in the seneca III that I fly, putting the boost pumps to "low" makes the mixture too rich and the engines starts stumbling and running rough.......put them on "high" and the engine loses power and almost quits because of too much fuel.....who'da ever thought you'd have to worry about that???.......

My guess is that he's talking about a Seneca I, which has the Lycomming IO-360's. I believe the POH says to turn the pumps on for take-offs and landings.

 

[BYUFlyr]

My guess is that he's talking about a Seneca I, which has the Lycomming IO-360's. I believe the POH says to turn the pumps on for take-offs and landings.

Yep... It's the Seneca I

 

[BYUFlyr]

It's all about the training, gents. The training. Training a habit pattern.

Gear up. Pumps off. Cowl flaps closed on level off.
Gear down. Pumps on. Cowl flaps as appropriate.

I'm not talking about omitting them from the checklist, just verifying that they're appropriately set for the current conditions instead of blindly flipping the switch or ducking under the quadrant to automatically close the cowl flaps.

Does this make sense?

 

[MTpilot]

Nosehair Is Wise!

Nosehair knows. It's not about saving money on pumps and lights, it about you getting accustomed to pulling all the knobs and switches the right way at the right time, Don't let some jacka$$ try and do training in a retract with the gear down all the time, it's just stupid.

 

[Chiller]

It's all about the training, gents. The training. Training a habit pattern.

Gear up. Pumps off. Cowl flaps closed on level off.
Gear down. Pumps on. Cowl flaps as appropriate.

'Round and 'round the pattern repeating those moves until they are automatic.

Sure, once you have the automaticity drilled in, then you can, and should, begin to think about each movement, and tailor to the specific environment.

Most people, however, barely get enough training time in a complex or multi to go beyound the rote automatic to think or get into the "other than checkride stuff'.

If you were trained initially in a retract, and your instructor/ airplane owner wanted to save wear & tear on the gear and made you do the patterns INITIALLY leaving the gear down all the time, you would be set up to land gear up later when you were PIC and had actally raised the gear.

And experience teaches us that doing a critical motion just a few times may not be enough to really drill it in. Of course this varies with each individual. Do you want to bet your life on being able to "remember".

Don't you think it is better to over-do than under-do?

Training. That's all it is.

Maybe that "Critical Motion" you mention might be to read the checklist.