A320:Thrust lever management incase of Inop Reversers

[320p]

Hi,

FCTM AO-020 P 15/22 recommendations on thrust levers management applicable in case of in-flight failure (including engine ailure) and/or in case of MEL dispatch with reverser(s) deactivated for NO REVERSERS OPERATIVE states:

If no reversers are operative, the general recommendation is to not select the reverser thrust during RTO and at landing.However, the PF still sets both thrust levers to the IDLE detent, as per normal procedures.

Any specific reason for this recommendation and what are the consequences of taking both thrust levers to Max Rev or Idle Rev detent in this case?
For G+Y system failure or Electrical Emegency Cofig ,on landing should we take Thrust lever only to idle postion?

Thanks.

[hetfield]

Any specific reason for this recommendation and what are the consequences of taking both thrust levers to Max Rev or Idle Rev detent in this case?Check this:

TAM Airlines Flight 3054 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/TAM_Airlines_Flight_3054)

[A319-100]

I believe that selecting the thrust reversers when they are not working will give you a margially higher thrust than ground idle which is less than ideal for stopping with a G&Y HYD failure. This is from memory though so standing by to be corrected!

[320p]

Hi hetfield,

This was the reason I initiated this question.I thought that after TAM accident,it would be both Thrust levers to max reversers in case of all failures affecting landing performance,but this FCTM section created the doubt.

As such Airbus is recommending Rev Idle for long dry R/W and I have observed pilots have got so used to it that even after having briefed that they would use Max Rev on wet runways,probably due habit interfernce took only Idle Rev. And on top of this you have this FCTM procedure!!

[rudderrudderrat]

Hi 320p,
I thought that...it would be both Thrust levers to max reversers in case of all failures
Please explain the advantage of selecting Max Rev on both (or even idle reverse), when no thrust reversers are deployed.

[i_like_tea]

The problem with the Tam accident was that one thust lever was left in CLB on landing.. Thus one engine gave reverse thrust one gave climb thrust.
The failure here therefore being the understanding of settle idle thrust, not the failure to set rev thrust.

[320p]

Hi A319-100;

I too was told a similar logic ,but could not confirm it either from the FCOM or other sources.That makes me wonder if the increase in N1/EPR is linked to Thrust lever postion,irrespective of the actual Reversers position??


Hello rudderrudderrat,

For the reason mentioned above and my thoughts mentioned in my earlier post#4 regarding habit interference.Also in my Sim sessions we were advised to go for Max Rev as a procedure (except for low speed RTO).However,if increase in thrust is a fact which I acknowledge to be unaware of ,then FCTM recommendation would be logical.

Thanks

[Blinkz]

As I understand things if you depart with one or more reverser's inop the FADECS are set so that if reverse thrust is selected then you don't get anything more then ground idle.

In the case of a G+Y failure the FADECs obviously haven't been changed so if you select reverse, either idle or max then you get the requested power setting but without the reverse doors! Not useful when trying to land with barely any braking or spoilers!

[320p]

Hello Blinkz,

Does it mean that with any in flight failure leading to Rev inop,if thrust lever is moved to max reversers detent you will get corresponding increase in thrust even though reversers are not deployed?? Looks rather unlikely to me.

Would you have any FCOM or any other documentary reference?

[lomapaseo]

As I understand things if you depart with one or more reverser's inop the FADECS are set so that if reverse thrust is selected then you don't get anything more then ground idle.



what kind of logic circuit does this reliably?

[I-2021]

Would you have any FCOM or any other documentary reference?

Hi 320p,

Check DSC 70-70 Actuation Logic. If you meet the actuation logic criteria, the idle will shift from modulated to reverse idle, which is slightly higher, thus decreasing landing performances. The effect is negligible if one engine is affected, hence the procedure of normal handling of reverse thrust in case of one reverse inop. It becomes of a greater impact in case of both reversers inop.

[AFD]

If no reversers are operative, the general recommendation is to not select the reverser thrust during RTO and at landing.However, the PF still sets both thrust levers to the IDLE detent, as per normal procedures.

i'm not that sure the recommendation is intending to activate the REVERSE IDLE.
It's says only IDLE not REVERSE IDLE so i think it is related to the selection of forward positive idle(thr levers idle) which is quite unaderstandable.

on top of that airbus MEL says as follows:

FOR LANDING
Before the touchdown, ensure that both engine thrust levers are set to IDLE detent forthe flare.
�œ After touchdown, if one thrust reverser is inoperative:
Use both thrust levers when applying reverse thrust.
Note: ENG (affected side) REVERSER FAULT alert is displayed on the EWD
after selection of the reverse thrust.
�œ After touchdown, if both thrust reversers are inoperative:
Do not move the thrust levers to reverse.

this mel operational procedure was amended after the TAM accident in sao paulo,in which one thr lever was left in clb detent position,not allowing the spoilers to be deployed( for spoilers to be deployed we need both levers in idle and spoilers armed or if not armed at least one reverse selected and the other lever not forward than idle)

[EMIT]

Hello 320p,

Good question, good remark about habit patterns.

The elevated idle is activated by the thrust lever going to the reverse position, not by actual deployment of the reverser.

To give you an idea of the amount of thrust, see below:
(numbers for IAE V-2500, checked personally after TAM event)


Normal idle N1 – 22% N2 – 57%


Reverse range idle N1 – 27% N2 – 66%


About habit patterns: 21 years ago, the Lauda Air B-767 crashed due to inflight deployment of a reverser. After that, all B-767 worldwide flew with both reversers deactivated for a long time, about a year and a half. Boeing then specifically instructed to keep pulling the reverse levers to the reverse interlock stop, just to stay in the habit.


I do think the TAM accident has to do with habit as well: the PF had to do something out of the usual, pull both trhust levers to idle, then pull only one lever further back into reverse. In the half second that the movement would take, his hand made an execution error, left the one thrust lever "behind" just one step too soon. ("behind" in movement, so forward in position, if you catch my drift).


The post by Blinkz is wrong, or at least, not worded accurately: the thrust is elevated slightly, but certainly not to the value of "full reverse" when the reverse is not actually deployed.

[spleener]

Not sure this is directly relevant:
In mid 90's CX had an A330 leave a big S-mark in BKK when landing with one reverser inop [locked out].
Airbus procedure [at that time] was both rev levers to max. Problem was apparently that the fuel control logic was not made aware of the locked out reverser, due to a "kink" in the sense line, and gave forward thrust....
Pilots were said to have made their own S-marks in sympathy!
Informal, and later Airbus, policy changed abruptly to idle reverse only on the inop reverser.

[I-2021]

Hi spleener,

I didn't really understand the scenario, did they have a reverse unlocked in flight ?