Viscount724
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A340 Thrust Reverser Question

Fri Apr 11, 2008 9:27 pm

The photo below of an A340-300 appears in an article on EK in last week's Aviation Week magazine.



I'm just curious if anyone can speculate why the thrust reversers are deployed on the inboard engines only. Are they designed to deploy sequentially, first on the inboard and then on the outboard? In that case perhaps the outboard reversers just haven't opened yet since the aircraft has obviously only just touched down.

Or would there be a reason why they would intentionally only deploy the inboard reversers?

P.S. Just before I was ready to post the above I spotted the following thread from 3 years ago, so I think my question is answered. It sounds like the outboard reversers on the 343 don't deploy until the nosegear touches down.
http://www.airliners.net/aviation-forums/tech_ops/read.main/114744/
 
fr8mech
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RE: A340 Thrust Reverser Question

Fri Apr 11, 2008 9:49 pm

More than likely, the #1 reverser in inoperative and on MEL. There is a chance that the #4 may be inoperative and the crew decided to use only the inboards to avoid assymetrical reverse.

The poster in the thread you cited says that the nose gear does NOT have to be on the ground for outboard reverser.
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Viscount724
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RE: A340 Thrust Reverser Question

Sat Apr 12, 2008 12:07 am



Quoting Fr8mech (Reply 1):
The poster in the thread you cited says that the nose gear does NOT have to be on the ground for outboard reverser.

Right, I misread that posting. I see it's referring to the main gear, not the nose gear.
 
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HAWK21M
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RE: A340 Thrust Reverser Question

Sat Apr 12, 2008 9:49 am

Just curious.
Does the MEL usage on T/R imply that the opposite side position need be deactivated too?
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FBU 4EVER!
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RE: A340 Thrust Reverser Question

Sat Apr 12, 2008 10:53 am

There is an interlock mechanism between no. 1 and no. 4 thrustlevers to ensure that both outer engines are at idle reverse thrust before reverse thrust can be increased, thus avoiding thrust assymetry. This feature does not exist for the inner engines, and thrust levers can be moved directly to max. reverse thrust. There is no need to lower the nosewheel to the ground for idle reverse but recoommended that the nosewheel is on the ground before increasing reverse thrust beyond idle.
This interlock may be inoperative in open position provided both outboard thrust reversers are considered inoperative.
It may also be inoperative in locked position provided no operation or procedure prdicated on thrust reverser use. Outboard thrust is not available. This according to A340 FCOM MEL.

So I think the plane is dispatched on MEL 78-30-02 with failed interlock mechanism.
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tpa36r
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RE: A340 Thrust Reverser Question

Sat Apr 12, 2008 10:25 pm

Could it be for the same reason the A380 only uses 2 and 3 TR's? FOD?
 
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zeke
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RE: A340 Thrust Reverser Question

Sun Apr 13, 2008 12:40 am



Quoting Fr8mech (Reply 1):
More than likely, the #1 reverser in inoperative and on MEL. There is a chance that the #4 may be inoperative and the crew decided to use only the inboards to avoid assymetrical reverse.

Maybe

Quoting FBU 4EVER! (Reply 4):
There is an interlock mechanism between no. 1 and no. 4 thrustlevers to ensure that both outer engines are at idle reverse thrust before reverse thrust can be increased, thus avoiding thrust assymetry.

Most prob
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VTBDflyer
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RE: A340 Thrust Reverser Question

Sun Apr 13, 2008 4:08 am

Quoting TPA36R (Reply 5):
Could it be for the same reason the A380 only uses 2 and 3 TR's? FOD?

Actually, the A380 doesn't have TR's on the outboards. I believe they did this to reduce FOD risk and weight savings, along with less mx work. http://www.airliners.net/aviation-forums/tech_ops/read.main/223901/

VTBD

[Edited 2008-04-12 21:10:34]
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