Auxiliary power unit
30
MENTIONS
8
EPISODES
7
PODCASTS
Search complete. 30 mentions across 8 episodes found for "Auxiliary power unit".
Sep 25, 2026
Hilbert FlumingtopCORRESPONDENT
It wasn't.
Hilbert FlumingtopCORRESPONDENT
The story they told was about an APU exhaust.
Hilbert FlumingtopCORRESPONDENT
Little thing.
Hilbert FlumingtopCORRESPONDENT
Sits at the back of the aircraft.
Herman PoppleberryHOST
The kart didn't go very fast.
Herman PoppleberryHOST
That also tracks.
Herman PoppleberryHOST
That APU story is exactly the point.
Herman PoppleberryHOST
The small ones are the ones that get you.
speaker_0NARRATOR
What are the engine fire zones? The engine power section, the engine accessory section.
speaker_0NARRATOR
Except for reciprocating engines, any complete powerplant compartment where no isolation is provided between the engine power section and accessory section, any APU compartment, any fuel burning heater or other combustion equipment installation, the compressor and accessory sections of the turbine engine, a combustor, turbine, and tailpipe sections of the turbine engine installations that contain lines or components carrying flammable fluids or gases.
speaker_0NARRATOR
What different types of fires can occur in an engine compartment? On reciprocating engines, fires can result from fuel leaks spraying on hot engine parts, exhaust leaks blowing hot gases onto components, or cowling and electrical faults.
speaker_0NARRATOR
On turbine engines, failures can cause turbine blades to melt or separate, damaging the exhaust duct, nearby structure, or fuel lines.
speaker_0NARRATOR
Where are most APUs located in modern jet transport aircraft? In the tail cone of the fuselage.
speaker_0NARRATOR
What is the function of an APU? An APU provides electrical power and compressed air when the main engines are not operating.
speaker_0NARRATOR
What are two sources of compressed air from an APU? Bleed air from the APU turbine compressor or air from a load compressor driven by a free turbine in the engine.
speaker_0NARRATOR
Where in maintenance information based on the ATA 100 system would you find instructions for inspecting and servicing the engine of an airborne APU? In section 49-20.
speaker_0NARRATOR
How is most of the troubleshooting done for modern APU? by fault codes generated by the FADEC.
speaker_0NARRATOR
What ensures that an APU will not be shut down while it's too hot? The APU fuel control uses automatic time delay feature that closes the bleed air valve, removes most of the load, and lowers the APU temperatures before shutdown.
speaker_0NARRATOR
What prevents the APU exceeding its safe operating limits when the bleed air valve is wide open? The FADEC monitors the load and adjusts fuel flow to keep the APU within safe operating limits.
speaker_0NARRATOR
What is used to prevent a heavily loaded APU from exceeding its maximum EGT? A load control valve adjusts the pneumatic load to keep EGT within limits.
Dennis AdamsGUEST
or idling.
Dennis AdamsGUEST
A lot of trucks, they'll go to APUs and reduce the cost of idling trucks, too, as well.
Dennis AdamsGUEST
So APUs is a type of system, a small generator, basically, attached to the tractor.
Dennis AdamsGUEST
And you'll run your APUs, which consume a lot less fuel.
Dennis AdamsGUEST
But if you can't afford that, then if you're a truck without an APU, then you have to conserve your idling.
Dennis AdamsGUEST
You know, anywhere when you park or if you're at a shipper and receiver, you know, you have to turn your truck off and not idle that truck to burn excess fuel that you don't need to.
Bowen YangHOST
Right, because after about 36 seconds, the backup battery power engaged.
Bowen YangHOST
But the main auxiliary power unit, the APU, it took two agonizing minutes to fully come online and restore the primary instruments.
speaker_6HOST
Two minutes in a supercell is an absolute eternity.
Bowen YangHOST
I looked into the engineering of the APU to understand that delay.
Bowen YangHOST
It's essentially a small turbine engine in the tail of the aircraft, right?
speaker_6HOST
Yeah, exactly.
Adil TagnaoutGUEST
Okay.
Adil TagnaoutGUEST
so regarding the base maintenance you have all the time in the world to perform your task so you come in the morning you take your job card you have all the time to read the AMM the documentation no one is pressuring you no one is telling you we have no time you don't have to be quick and you have all the tools needed so you perform a heavy maintenance that's why the base maintenance is related to the heavy maintenance So you can have an engine removal, maybe an APU removal, windshield, landing gear, maybe.
Adil TagnaoutGUEST
So you have all the time in the world.
Adil TagnaoutGUEST
You can take a coffee.
Lane DeAugustineGUEST
You don't just turn the key in your car.
Lane DeAugustineGUEST
You have this thing called an APU, an auxiliary power unit, that starts the jet from the ground.
Lane DeAugustineGUEST
They had a start cart? I mean, come on.
Lane DeAugustineGUEST
They have a cart sometimes? You're right.
Christopher FeinsteinHOST
When an engine starves of fuel, the turbine blades spin down, the electrical generators cut out, and the main electrical bus goes dead.
Christopher FeinsteinHOST
When that happens, an onboard emergency auxiliary power unit kicks on and automatically restores backup power.
Christopher FeinsteinHOST
As the APU fired up, it booted the satellite terminal one last time, initiating a sudden, desperate log-on handshake.
Christopher FeinsteinHOST
Seconds later, the second engine flamed out.
Christopher FeinsteinHOST
The Doppler data recorded during that final partial transmission revealed something terrifying.