I was under the impression that some aircraft do not require that the thrust reversers to be operational, and that the 737 was one of them.

On September 16 my Southwest flight RNO-LAX was about to pushback when the jetway was moved back to the door and the pilot announced that he had "a thrust reverser light" and we couldn't go to LAX without that functioning. Considering the length of 24R at LAX (the usual runway) I suspect that brakes would have been enough. Is the thrust reverser always required on a 737-700, it is a Southwest company rule, is the light in question more serious than just an inability to use the reverser?

I was very worried because I needed to make in international connection at LAX and every flight on every airline to every airport in the LA area was sold out. After about a 1 hour delay a contract mechanic called out by Southwest had resolved the problem.

This maybe the wrong form for this comment, but the Southwest pilot did a superb job of explaining the function and operation of the reversers and kept us informed of the test procedures. It seems that something called "built in test equipment" showed the reverser to be working correctly.

I can't speak to the B737 specifically, because I don't have access to its MEL.

But, a few things that can keep an aircraft from departing with an inop reverser. Weather at origin or destination. Other items on the aircraft that may be on MEL (speedbrakes, auto-brakes, etc.).

Further, there's a difference between an inoperative reverser and an indication system that's inoperative (thrust reverser light). There are some aircraft where the light can be put on MEL if it does not illuminate when deployed...this would include EICAS indication, but the reverser will have to be rendered inoperative. But, if the reverser shows "in-transit" or "full reverse" even with the reverser deactivated per the MEL, that tends to be a no-go item.

Again, this varies form aircraft type to aircraft type.

In this case maybe they go a warning of some kind on the reverser just before pushback. Or an actual light wasn't working.

While you can go without the reverser, it has to be locked out physically on the engine (at least on the planes I fly), and the fault has to go in the tech log, and the MEL has to be consulted. Not a massive deal, but it will cause a delay if it happens right before pushing.

"a thrust reverser light"

is a fault indication. Something is wrong with one of the reversers. You cannot depart with that light on.
So you test the reverser and check the BITE indication and see what it says. Then either the reverser is now serviceable, or it needs to be deactivated for departure. In good weather most airliners can depart with one reverser inoperative, as long as it is deactivated.
To deactivate a reverser, you mechanically lock it in fwd thrust position, and deactivate the operating mechanism. This is a job for a mechanic.

At my airline the thrust reverser can be put on MEL and flight released in most cases. Going to LGA both thrust reversers are required, and going anywhere with a short runway (DCA, BUR, etc) both would be highly desirable.

Could it also have been because of rejected takeoff requirements at Reno?

As Tristarsteve correctly pointed out - this was not a TR that was inop, but a fault in the system. The potential for an uncommanded inflight deployment makes this a no-go item.

trijetsonly wrote:

Could it also have been because of rejected takeoff requirements at Reno?

The usual runway , and the one we used that day is 16R, and it is 11,000 feet long. I think several other posts answered my question explaining that the cause of the error had to be resolved and the reversers could have been locked out if necessary. I was watching the mechanic through the window and he operated the reverse thrust mechanism several times before declaring it resolved. The pilot never said if it was a faulty indicator or if something had to be fixed. Reverse thrust worked at LAX. I easily made the flight to Auckland, where I am writing this post.

Yes, able to depart without reversers but as others have noted, they need to be deactivated (physically on the reverser). I actually know the person(s) who did the engineering on those parts.

A very real possibility is that on the last landing, the pilot did not stow the T/R in a timely manner and a maintenance message (fault) was set which probably illuminated the "light" the pilot was referring to. To clear the maintenance message and light, the ground crew used BITE (Built In Test Equipment) to perform a ground test. The BITE test must of passed because If the BITE test had failed, the ground crew would have locked out the T/R if the MEL allowed the T/R to be deferred.

Example of an EEC BITE test after EEC change : http://www.sjap.nl/eec-bite-test-channel-b-737-678900/

Some good reading: https://www.boeing.com/commercial/aerom ... 01txt.html

The Master MEL specifies one reverser required for dispatch on the -700.

Performance penalties can be quite restrictive.

BoeingGuy wrote:

green12324 wrote:

At my airline the thrust reverser can be put on MEL and flight released in most cases. Going to LGA both thrust reversers are required, and going anywhere with a short runway (DCA, BUR, etc) both would be highly desirable.

Just out of curiosity, why are both reversers required for LGA? The runways aren’t that short. As you know, the auto brake settings command a given deceleration rate, with or without reverses.

Are they required for SNA?

Required for landing at LGA or for take off? Could be RTO that is the issue?

As was stated above, most T/R faults on a 737 are stow faults. These can usually cleared on the Engine Accessory Unit while operating the T/R on the ground. As was stated earlier, on inop T/R imposes operational restrictions. Dispatch concurrence is required for an MEL. The MAX has a different system. The EEC controls operation and may be less prone to nuisance fault messages.

With one T/R inoperative you're performance is as good as if both were inoperative since you obviously would not be activating only the remaining serviceable T/R.

JAGflyer wrote:

With one T/R inoperative you're performance is as good as if both were inoperative since you obviously would not be activating only the remaining serviceable T/R.

I disagree...

JAGflyer wrote:

With one T/R inoperative you're performance is as good as if both were inoperative since you obviously would not be activating only the remaining serviceable T/R.

Why not???

I think utilizing one T/R with the other inoperative is up to the operators and would certainly impact operation restrictions (runway length for landing changes). Would also impact RTO operations.

The main concern with using only one T/R is asymmetric thrust which would need to be countered with rudder. Since we're talking a small amount of thrust being reversed I don't think it requires much rudder deflection to be honest.

trpmb6 wrote:

The main concern with using only one T/R is asymmetric thrust which would need to be countered with rudder. Since we're talking a small amount of thrust being reversed I don't think it requires much rudder deflection to be honest.

It doesn’t. I’ve used one reverser on the 737NG because on the other T/R inop many times, and the asymmetric effect is minor and easily offset with gentle rudder pedal steering inputs.



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aklrno wrote:

I was under the impression that some aircraft do not require that the thrust reversers to be operational, and that the 737 was one of them.

On September 16 my Southwest flight RNO-LAX was about to pushback when the jetway was moved back to the door and the pilot announced that he had "a thrust reverser light" and we couldn't go to LAX without that functioning. Considering the length of 24R at LAX (the usual runway) I suspect that brakes would have been enough. Is the thrust reverser always required on a 737-700, it is a Southwest company rule, is the light in question more serious than just an inability to use the reverser?

I was very worried because I needed to make in international connection at LAX and every flight on every airline to every airport in the LA area was sold out. After about a 1 hour delay a contract mechanic called out by Southwest had resolved the problem.

This maybe the wrong form for this comment, but the Southwest pilot did a superb job of explaining the function and operation of the reversers and kept us informed of the test procedures. It seems that something called "built in test equipment" showed the reverser to be working correctly.

It might have been a thrust reverser UnLocked light meaning that the reverser was not fully stowed or the reverser interlock was inop. .
The reverser can be inop as long as it's locked in the stowed position Mechanically. It could also have been a faulty or dirty Proximity sensor .

Dispatch with TR inoperative usually has minimal impact in normal operations because performance is not predicated on TR use most of the time.

trpmb6 wrote:

BoeingGuy wrote:

green12324 wrote:

At my airline the thrust reverser can be put on MEL and flight released in most cases. Going to LGA both thrust reversers are required, and going anywhere with a short runway (DCA, BUR, etc) both would be highly desirable.

Just out of curiosity, why are both reversers required for LGA? The runways aren’t that short. As you know, the auto brake settings command a given deceleration rate, with or without reverses.

Are they required for SNA?

Required for landing at LGA or for take off? Could be RTO that is the issue?

Sorry, I should have specified. Required on the 737-800/900/900ER/MAX9 for landing. 737-700 would technically be allowed to go to LGA w/ T/R deferred (based on CA/dispatcher discretion).