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Comment by thecosmicfrog

1 year ago

Aircraft with INOP APUs can generally be "air started" with a ground-based high-pressure air system. It's relatively common and I've been on a plane that had to do the procedure. It was entirely undramatic other than engines being started before the pushback, but I doubt most passengers even noticed.

Now, interestingly, the 787 is a "bleedless" aircraft, so it doesn't use high-pressure air from the APU to spool up the engines. I believe it can use its hefty bank of lithium-ion batteries to start its engines if the APU (and associated electrical generator) is INOP.

Not a pilot/engineer - just an enthusiast. Someone more au fait with the 787 might be able to correct me on the above.

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thecosmicfrog

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hinkley  1 year ago

My understanding is that there was a push to modify the U shaped tow trucks they use to position planes to have a battery powered system to start the engines.

The idea being that the APU isn't particularly clean burning, not compared to power plant emissions. It's been a long while since I've heard anything about that plan, for or against.

  • thecosmicfrog  1 year ago

    Interesting! Although it'd (presumably) only be useful for the 787, short of heavy modification to existing aircraft. Even the Airbus A350, an aircraft from the same era, uses a traditional bleed system. If planes continue down the bleedless route I can see it happening.