APU Usage

[skiandsurf]

On the X, some guys go by the "Climb Checklist" that lets you turn it off then, at 18,000 feet. I think that is a little late.

I would rather turn it off during the "After Start Checklist", and not turn it on until the "After Landing Checklist".

But I also like the idea of a "Quiet Shutdown Checklist", for those easy flights with little to no cleanup needed.

 

[gutshotdraw]

Some real rough math just for the G-Wiz fleet:

APU burn approx 180 pph G-IV, approx 210 pph G-V/450/550. Lets say 190 pph avg since IV's outnumber the V fleet 3-1

Real rough guess of average 500 APU hours/year/airframe (it's actually probably higher)

Last number I heard for total fleet was 58 aircraft

Let's say $4.50 a gallon average (wouldn't you love to know what our real fuel price average is after all our fleet discounts with Signature et al?)

190 pph*500hrs*58= 5.51 million pounds / 6.67=826 THOUSAND gallons*$4.50=$3.17 MILLION in fuel for APU burn. Just for the G-Wiz fleet.

I was startled by the numbers myself. I'm actually guessing the number is higher. Of course, "actual mileage may vary."

 

[TCA]

Dang 'Gut" didn't know we could turn em off. I thought we just left them running and did a hot hand-off...

 

[Flex-ible]

At Flex, APU start is generally 30-45 minutes before scheduled departure. It might be up to an hour if it's really hot or cold. We leave it run if the turn is less than an hour or so. If the last leg is empty, normally the PNF will clean the cabin during the flight so we can shut down without powering the APU up and head straight to the hotel. The quiet is nice!

 

[Sparse]

General guideline at CS is to start it 30 minutes prior to an owner flight. We do not start the APU on taxi in unless it is a real quick turn. Of course good judgement make dictate another pattern, based on the circumstances.

 

[gutshotdraw]

Dang 'Gut" didn't know we could turn em off. I thought we just left them running and did a hot hand-off...

Wish that was every trip amigo! What really sucks is getting to level off and realizing you forgot to shut the bloody thing down (not that I've ever done that).

See you this week maybe....been working harder on vacation the past three weeks than I do on the job

 

[CA1900]

On the X, some guys go by the "Climb Checklist" that lets you turn it off then, at 18,000 feet. I think that is a little late.

I would rather turn it off during the "After Start Checklist"...

You must have a better ACM than the Excel! :laugh: On a hot day, we need the extra air to keep the thing to cool on the ground. Our normal checklists have us kill it at 10,000; if it's not a hot day, I'll often shut it down on the taxi out to cut down the noise on takeoff.

 

[DO-82 driver]

Thanks Flex and Sparse.

 

[bailey3083]

At Flex, APU start is generally 30-45 minutes before scheduled departure. It might be up to an hour if it's really hot or cold. We leave it run if the turn is less than an hour or so. If the last leg is empty, normally the PNF will clean the cabin during the flight so we can shut down without powering the APU up and head straight to the hotel. The quiet is nice!

That is the rule but I have seen plenty of people rub the APU for hours.

 

[CA1900]

That is the rule but I have seen plenty of people rub the APU for hours.

Uhhhhhh.... huh huh huh....