5
$\begingroup$

I recently watched the Mayday series about TAM Airline Flight 3054. Landing on a short runway with only one thrust reverser in use, and the documentary explained something like:

The old Airbus procedure was to put both engines' controls on IDLE and then put only one of them on REVERSE. The new procedure says that you put both of them on REVERSE, regardless of if one of them doesn't work. The captain seemed to aim at the old procedure, because it is known to be more efficient.

I wonder how it is more efficient? Does the position of the controls for the second motor really influence the behaviour of the first one?

$\endgroup$
6
$\begingroup$

Does the position of the controls for the second motor really influence the behaviour of the first one?

No, it influences the activation of various other systems like the autothrust, the airbrakes, as well as the thrust reversers.

how it is more efficient?

Because in the new procedure the engine with non-functioning reverser starts to spool up before the system realizes the reverser did not deploy and cuts it again, so for a moment it produces forward thrust. The old procedure avoids this.

$\endgroup$
  • $\begingroup$ So if you put the engine control at REVERSE and the reverser is not working, you produce a forward thrust? $\endgroup$ – yo' Oct 29 '14 at 16:33
  • $\begingroup$ @tohecz: Correct. Reverse is a throttle setting above idle. $\endgroup$ – RedGrittyBrick Oct 29 '14 at 16:33
  • $\begingroup$ Ok, that explains it all. Thanks a lot! $\endgroup$ – yo' Oct 29 '14 at 16:34
  • 1
    $\begingroup$ @RedGrittyBrick: Reverse in Airbus is a throttle setting below idle. If the new procedure is to pull both in reverse, the FADEC is clever enough to leave the engine at idle if the reverser did not deploy, otherwise they couldn't make it that. That's in contrast to other aircraft like Tu204 where the reverse is separate control and thrust levers are advanced and reversers failing to deploy caused two incidents and an accident in quick succession last winter. $\endgroup$ – Jan Hudec Oct 29 '14 at 17:54
  • 1
    $\begingroup$ Page 73 of the final report says basically what this answer does. When throttles are put in reverse, the engines automatically spool up. If a reverser doesn't deploy, that engine goes back to idle, but the initial spool up is what makes braking less efficient. $\endgroup$ – fooot Oct 29 '14 at 18:26

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.