A330 Thrust Reverser Question

[bigbob]

MEL says:

When one reverser inop select REV on BOTH thrust reversers
When Both reversers inop DO NOT select thrust reversers

Anyone know what the reason is apart from the obvious fact that they dont work?

Cheers.

[rudderrudderrat]

Hi Bigbob,

Yes. Airbus changed their philosophy a while ago after a couple of runway over runs due crews failing to close all the Thrust Levers on landing, having dispatched with a Thrust Rev locked out.

This power point presentation explains.

[ATIS]

Another reason is the difference between reverse idle and idle power. The engines deliver a higher thrust at reverse idle. So if you have both reversers locked out, you are just going to end up with a higher forward residual thrust. Therefore an increase in landing distance and a possible embarrassing overrun.

[CONF iture]

Originally Posted by bigbob

MEL says:
When one reverser inop select REV on BOTH thrust reversers
When Both reversers inop DO NOT select thrust reversers

This does not seem to be the proper quote from the MEL ... (?)

At least one thrust reverser is required for dispatch.
The airplane can be dispatched with one inop T/R as long as the Maintenance procedure has been applied. The proper deactivation of a T/R implies that this one is secured in the stowed position and the engine won't accelerate to idle rev even if that T/R is selected.
Now, if the airplane is dispatched with one deactivated T/R, and the second T/R becomes inop in flight, that second engine would still accelerate to idle rev upon application, therefore it is not recommended to select it.
The same applies if the airplane is dispatched with both T/R operative, but one or even both become inop during flight, it won't be recommended to select the defective T/R(s).

I think it's all getting a bit more confusing and an event like Congonhas will happen again ...

[catiamonkey]

Idle rev is a whole lot lower than CL or TOGA.

[CEJM]

Originally Posted by CONF iture

This does not seem to be the proper quote from the MEL ... (?)

At least one thrust reverser is required for dispatch.

Must be company specific then. According the MMEL you can dispatch with both reversers INOP (maintenance procedure applies). And according to the MEL in our company we can also dispatch with two reversers INOP.

[shortfuel]

Not just A330, all Airbus FBW A/C

Originally Posted by CONFiture

The same applies if the airplane is dispatched with both T/R operative, but one or even both become inop during flight, it won't be recommended to select the defective T/R(s).

Above is incorrect. That's the old procedure...

Originally Posted by my MEL

-After touchdown :
. If one thrust reverser is inoperative, use both thrust levers when applying reverse thrust.
Note :
.
ENG (affected) REVERSER FAULT caution is displayed on ECAM E/WD after thrust reverser
is selected.

If both thrust reverser are inoperative, do not move thrust levers to reverse.

Rudderrudderrat gave a link to an Airbus PPT explaining everything and why proc has changed. It says it all. Or refer to FCTM AO20 p16/18.
My MEL does not require 2 T/R for dispatch, hence neither does the MMEL.

[Cough]

Small bus, but a still a bus.

I have had several (individual!) failures in flight that should have led to Rev being inoperative on one side. Now previously I would have only pulled the one reverser, but since the update came out we have been selecting both reversers anyway.

Guess what - On 4 out of the 5 times this has happened since the change, I have still achieved reverse deployment on the supposedly failed reverser. Obviously, if reverse is locked out then it isn't going to happen, but if its only inop on the status page then its worth a try.

[CONF iture]

CEJM and shortfuel, thanks for mentioning the MMEL as it is, I didn't know. It is true that a MEL company can be sometimes more restrictive.

shortfuel and Cough, is it possible you don't fully grab the difference between :

1. MEL and applicable maintenance procedures applied before dispatch
2. Malfunction after departure when MEL does not apply anymore

[shortfuel]

Everything is possible...but:

Originally Posted by FCTM AO20 says

This section provides recommendations on thrust levers management in case of inoperative reverser(s). These recommendations are applicable in case of in-flight failure (including engine failure) and/or in case of MEL dispatch with reverser(s) deactivated.

So I copy-pasted the MEL extract because it was easier for me AND because in that particular case the in-flight failure procedure described in the FCTM was identical to the MEL operational proc (as mentioned above).

[Cough]

Confiture

I do... We do the procedure in the MEL for an ADD dispatch and the proc in the FCOM for an in flight failure.

Seems they are the same....

Just a quick edit to add that the procedure of not selecting the thrust reverser associated with an in flight failure was removed from our manuals about a year ago. Since we changed I have found that they can indeed still work.

[CONF iture]

... Getting very curious about it now ... it is not that I don't believe you guys but I don't figure out how an engine would not accelerate to REV IDLE if T/R applied at touch down after a REV malfunction developed in flight ?

shortfuel, would you paste the full extract of that FCTM paragraph ?
Thanks.

[Cough]

It does accel, but only briefly. The powers that be have proclaimed that reduction in landing distance is insignificant compared with a mis selected reverser.

[shortfuel]

Here you go: