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The APU is not on during flight, so not a safety thing. It's just for providing power (and bleed air) on the ground (if there's no other power source). E.g. can
by jenny91 1y ago
The APU is not on during flight, so not a safety thing. It's just for providing power (and bleed air) on the ground (if there's no other power source). E.g. can't start up at airports without external power with the APU INOP.
- sterlind 1y agoif you don't have a RAT you need the APU for emergency power if your engines fail in flight.
- addaon 1y agoAPUs have a common mode failure with main engines: lack of fuel. Are there designs out there which require emergency power after engine failure and don’t have a RAT?
- scrlk 1y agoThere was a Mentour Pilot video on the Jeju Air crash that touched upon this. With a dual engine failure on a 737, you lose both generators and fall back to the emergency batteries (no RAT). The aircraft remains flyable, but it's extremely challenging - you need an operational APU to make things a lot more manageable: https://youtu.be/9GbmGUk8Y0M?t=2001 https://youtu.be/9GbmGUk8Y0M?t=2001
- aivisol 1y agoIf I remember correctly it came very useful during US Airways Flight 1549 accident?