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Thrust Reversers Cause Of 990?  
User currently offlineTwa747100 From United States of America, joined May 1999, 600 posts, RR: 0
Posted (16 years 1 month 14 hours ago) and read 1484 times:

They say that the cause of 990 is the thrust reversers on the engines
~ This cant be true its physically impossible for them to open in mid air
Why? There is a sensor in truck that when pressed then and then only can the reversers open up.
~ If this is true its a big booboo for Boeing!
Well, what do you all think?

9 replies: All unread, jump to last
User currently offlineDeltaAir From United States of America, joined May 1999, 1094 posts, RR: 0
Reply 1, posted (16 years 1 month 13 hours ago) and read 1395 times:

The problem was suposedly corrected right after the Lauda accident. If it was a thrust reverser problem wouldn't be an equally important part of the engine manufactuer.

User currently offlineMirage From Portugal, joined May 1999, 3125 posts, RR: 13
Reply 2, posted (16 years 1 month 13 hours ago) and read 1392 times:

"They say that the cause of 990 is the thrust reversers on the engines"

They who???

User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 3, posted (16 years 1 month 13 hours ago) and read 1386 times:

Don't know who "they" are, but that's just one possibility I'm sure will be considered.

As far as it being "impossible" for the reversers to deploy in-flight, yeah, they're not *supposed* to, but Murphy's Law and the Lauda crash show that it can indeed occur, even with the air/ground safety logic. In fact, check out this link for the Lauda report:


They mention 3 different possible scenarios that caused the reverser to deploy, and were unable to determine which one caused the crash. According to one of the appendices, it appears that the main problem was with Pratt 4000-series engines, and not so much the JT9D, RB211, and CF6 engines on the 767 fleet.

Interesting reading.....

User currently offlineSp-deluxe From , joined Dec 1969, posts, RR:
Reply 4, posted (16 years 1 month 13 hours ago) and read 1385 times:

CNN websites says under the developing stories section that one of the crew members on the Egypt air flight reported having trouble with the thrust reversers hours before the accident.

AND to twa747-100 i think the crash of a Lauda 767-300 when one of the reverse thrusters deployed midflight suggests that is possible!!

In that accident the pilots could have only possibly pulled out of the catastrophic deployment within 6 seconds of deployment.

What happens when one engine (only) deploys its reverse thust the one wing wants to go up and the other wing down.

However in the Lauda incident there was extensive fuselage breakup inflight, because of the immense stresses on the aircraft, did this happen on egyptair

User currently offlineNavion From United States of America, joined May 1999, 1027 posts, RR: 1
Reply 5, posted (16 years 1 month 13 hours ago) and read 1383 times:

I'm afraid the characteristics of this crash could be consistent with an uncommanded thrust reverser deployment. I sure hope that didn't happen, especially since Boeing put a lot of effort into designing a supposedly foolproof fix. I sure hope that is not what happened. This is pretty serious business. By the way, if the Egyptair pilots who flew the aircraft to New York sensed a problem with the thrust reversers, then why would the aircraft continue on?

User currently offlineHmmmm... From Canada, joined May 1999, 2114 posts, RR: 5
Reply 6, posted (16 years 1 month 12 hours ago) and read 1377 times:

It was my understanding that commercial airliners have fuse pins in the engine mounting pylons. The logic was that, in the event that an engine starts developing a mind of its own, it would shear the pin and fall away, hopefully saving the wing and everything else. Does the 767 not have fuse pins?

An optimist robs himself of the joy of being pleasantly surprised
User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 7, posted (16 years 1 month 11 hours ago) and read 1370 times:

IMHO (and I'm not an engineer) the fuse pins have certain uses, but they can't mitigate the effect of just *any* engine problem.

For example, if the aircraft had to make a full gear-up landing, the fuse pins would allow the engines to detach rather cleanly during the landing sequence with a better probability of not compromising the wing fuel tanks.

The big problem with a reverser deployment inflight is the immediate adverse aerodynamic effect it can have. For example, if you're running the lake in your speedboat and stick a canoe paddle in the water (wide face foward) on one side of the boat, you're going to start turning to that side in a hurry.

For a discussion of this as it affects the Lauda crash, see the report at:


User currently offlineDanny From Poland, joined Apr 2002, 3534 posts, RR: 3
Reply 8, posted (16 years 1 month 6 hours ago) and read 1348 times:

In fact - the Egyptair is said to have broken up in midair. A radar observation said that it looked like an explosion. There are so many similarities to the Lauda crash. The sudden loss of altitude, break up, and not to forget - both aircraft used the same type of engines, the PW4060.
And I also heard that not ALL the engines were fixed...

User currently offlinePerthWA From , joined Dec 1969, posts, RR:
Reply 9, posted (16 years 1 month 5 hours ago) and read 1348 times:

how about we wait till we havea little more information before we go and make all these assumptions  

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