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APU Operations

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400A

Well-known member
Joined
May 26, 2003
Posts
1,760
I am looking for some advice on APU operation. I would like thoughts from Hawker and Non-Hawker Operators. Ours is available in flight, so here are the questions I have.

Start up and Shut down Altitudes?

Generator on or off?

Shut down Loaded? Gen, or Gen and Bleed?

Any other tips are welcome. Thanks
 
A lot of that stuff is very specific to the APU and the airframe; your plane's manual is where I'd start for that.

On the Excel, we can start it at or below 20,000, run it at or below 30,000, and we're supposed to start it and shut it down totally unloaded.
 
A lot of that stuff is very specific to the APU and the airframe; your plane's manual is where I'd start for that.

On the Excel, we can start it at or below 20,000, run it at or below 30,000, and we're supposed to start it and shut it down totally unloaded.

I am very aware of the Limitations, but there are different schools of thought even from the instructors as far as daily ops. The Generator for example. After start up on the Hawker you do a Gen Amps/Volts check that requires you to trip the APU Generator. Some say leave it off to protect it in the event of a spike, and some say put it back on line.

Hawkers take of with the APU Bleed for Pressurization and then you open the Main Air Valves. They can only all three be on for 1 minute. Some people are just shutting the APU down at that point (Loaded) and others including myself, close the apu bleed valve, insuring I do not get a bleed valve fail, and then shut the APU down later.

We ave the same APU as the Excel, I think, (GTCP-150) and the Manufacturer recently sent out a "recommendation" to shut it down fully loaded.

These are the kind of tips I am looking for.
 
The Hawker 800a I fly has the old 30-92c model. That thing won't run in the air so no question. As soon as weight is off wheels it shuts down. We shut it down unloaded. Wish I had one of those 150's. Have a good day everyone.
 
Challenger 604
APU bleed on/open for takeoff, generator off, shut down once flaps up (unloaded).
After landing we start the APU and transition to APU bleed and generator, as our packs are high flow with the APU. We shut the APU down (post flight) loaded with bleeds open as per Bombardier.
 
Hawker
APU GEN TRIP, APU BLEED AIR ON
DEPART
MAIN AIR VALVES TO LP
APU BLEED AIR OFF
LARGE RUSH OF AIR (TO AVOID BUMP)
MAIN AIR VALVES TO HP
CLIMB CHECKS, SHUT DOWN APU
 
Falcon 2000:

Push the green button and let the ECU do the rest!

Never operate it in flight, although you can below FL350 (yea, right!)
 
CE 750 Typically turn off climbing through 10,000 and on descending through 10,000. The ECU does the job wait for the amber bleed air light, then bleed air off.
 
Lear 60, push the start button, and let the computer do the rest. Shutdown, press the stop button.

Ground-only unit.

Previous life in the airlines, start was automatic, and shutdown was on a load-shed timer...so that unit would shutdown after unloading and cooling.

Inflight use of that unit was at our discretion and subject to the needs at a particular gate or airport and or length of taxi, etc...

Always used to take off and landings in low vis/auto land environment.

But in the end, we did what the checklist told us to. We never re-thought that sort of stuff. Changes to SOP's came several pay-grades above ;-)
 

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