Reverser Locked out

[The Actuator]

What are your thoughts about being able to dispatch on a 747 with a reverser locked out. I'm refering specifically to wet/slippery runway ops. There is a performance graph to calculate your accellerate-stop distance required without any reverse but it would seem a little crazy to me? any thoughts

[CaptSnails]

All the aircraft I have flown including now the A340 do not take into account in their performance calculations reverse thrust. It's considered a bonus. All stopping distances wet or dry are calculated without reverse, so really one of four reversers locked out is really a none issue.
I believe it's a certification issue.

[777AV8R]

Reverse thrust is NOT a certification requirement on transport aircraft and as such is not a requirement to have to satisfy the certified Flight Manual.

That said, however; company flight operations manuals may deal with dispatch items in a more conservative way. ie No dispatch to airports with rain in their forcasts etc.

The MEL also deals with reverser lockouts as well.

Operating techniques and flight crew training manuals also deals with the issue.

Having operated different aircraft with reversers locked out in my years has never been a difficult issue. That said however; airmanship tells us that symetrical reverse on operating units and very careful use of reverse with twin engine aircraft with one side locked out needs some care and attention.

[have another coffee]

Interesting to know is how reverse thrust is used in JAA wet runway take off calculations. As there is a huge penalty on having a reverser locked out in this condition I assume reverse thrust is somehow used in the accelarate-stop distance.
Anyone?

[cirrus01]

If my memory serves correctly, it was standard ops to use only the No. 1 and No. 3 reversers on the DC 10 s if at all possible when landing away from base. Reasoning being that quite often the Reversers would partially deploy and/or not retract (cables sheared)......this would mean a lengthy delay at the line station as manually winding the translating sleeves back and the lockout proceedure takes some time way up there on the No. 2 .

[springbok449]

JAA performance is totally different, was looking up the perfomance manual and was surprised to see the differences in performances, not sure of the ins and outs anymore but will look it up next time I go to work and will post...

[Motormouse]

Capt Snails posted the correct answer,as did 777AV8r
reverse thrust is not counted in performance.

[m&v]

capt snails'
FCOM 2.04.10p2/3 stipulate the requirements for a 'operable'Reverser,or inop rev'dispatch penalties.
As othres have pointed out under Jar,one gets credit for the rev ON WETRUNWAY OPS..The 777 was the only Boeing type to 'actually'perform the 'wet acc/stop distance test.
A step towards the Jar/Faa(long awaited )Harmonization of rules:p

The original question did query the performance prudence on WET operations.I'm a little surprised as I thought SAA applied the JAR regs(Boeing performance'B),covering the rev'credit:D

[The Actuator]

Yep, it's more about wet runway ops. The mel says operations with one locked out is not recommended. But they do provide additional figures in the AFM for operations with no reverse on a wet runway - obviously a huge penalty. The normal figures for a wet runway include symmetrical reverse. What happens if you lock out number 1 and then you lose number 2 prior to V1. - No symmetrical reverse!!

[springbok449]

Reading my posts I realise I should not have written JAA perf. is totally different but there was something wrtiten down as regards to wet runways and huge perf. penalties, as I said will look it up and then post.
Apologies and regards...

[m&v]

Interesting Perf' review though!!
Cheers..
Now if the screen height with WET OPS is 15',at the end of the clearway(JAR)-what is the estimated height crossing the end of the runway...........
:rolleyes:

[Mad (Flt) Scientist]

Since the above amendment was issued it has been permissible to consider the use of reverse thrust for the accel-stop case on a wet runway for a FAR 25 certified aircraft. I suspect that the 747 graphs referred to in the original post have been compiled in accordance with this latest revision to this part of the rules.

I think the current JAR 25 regs are similar, but can't check them here.

Therefore I'm afraid that the definitive statements being made to the effect that reverse thrust is not a cert issue are not strictly correct.

[CaptSnails]

777AV6R just to clarify my previous post when I said its's a certification requirement I meant the performance calculations for accelerated stop dinstances and landing distances are without reverse thrust by requirement. (At least that's what I think, please correct me if I'm wrong)

m&v Thanks for your point but what we were actually reffering to is the performance calculations mentioned above and all those in the FCOM's are without the use of reverse thrust.

[The Actuator]

From what I#m reading here - it seems as if one should be happy to depart in this condition despit the fact that the MEL says it is not reccommended??? #m looking for opinions and ideas here guys because I don#t think one should. It may well be possible and show all the figures but somebody is going to ask why you went if there is a balls up.

[mutt]

Accounting for the effects of THRUST REVERSERS on DRY runways is not permitted, however, the FAA have only recently started to account for the effects of WET runways.

The B747 was certified under the older regulations where the WET/CONTAMINATED takeoff information supplied from Boeing was "ADVISORY", this information used FAA AC-91-6B as the basis for using a 15 feet screen height and THRUST REVERSERS for stopping.

The B747 information specifically states that "STOPPING DISTANCES ARE BASED ON THE USE OF SYMMETRIC REVERSE THRUST".

We went further with the MEL and turned their “not recommended” into a “prohibited”.

777AV8R, the WET/CONTAMINATED data for your machine was based on the use of One Reverser. The penalties for zero reverser thrust are quite severe.

Mutt.

[CaptSnails]

Actuator although I have never flown the 747, I find it difficult to comprehend that the actual MEL states that ops on a wet runway with 1 reverser locked out are not recommended. Are you sure it's not talking about contaminated runways?

The A340 which I fly has no such problem on wet runways, there is however a speculation for thrust reverser's to be used for deceleration on contaminated runways.

[Motormouse]

Do you mean the operators' MEL, or the manufacturers MMEL, from which the operator may make his (sic) own MEL.

Sometimes operators add their own restrictions to suit their own
operation and previous operational experience.

If for example,an operator has had an aircraft skid off a wet runway when a reverser is 'locked out', that would represent a costly occurrence, so the mel is re-written to protect the operator
from risk exposure,'bolting the stable door after the horse has gone'.

[m&v]

CaptSnails.
Did I misunderstand again??
The FCOM stipulates that 'reverse'must be operable,or take a 'penalty'-the original question,on 'wet' runways.
FCOM 2.04.10,stipulates just that!!
Cheers..:)

[CaptSnails]

I'm affraid you did m&v section 2.04.10 talks about FLUID CONTAMINATED RUNWAYS not WET.

Which was exactly what I was talking about in my previous post. I fail to see why you desperately attempt to prove me wrong. Anyway no hard feelings, all the best to you mate I'm sure we both are just trying to pass on as much info as we can.

[m&v]

capt snails,on the 320 the Wet info just precedes the FLUID INFO.
Complete with Wet definition of 3mm,the next page talks about the conditions,and the only reference to the 15'screen,and reverser requirements..
Cheers:D

[CaptSnails]

Forgive me I was under the impression we were talking about B747 and A340 (4 eng a/c) not A320.

[springbok449]

Seems that all A/C have different rules.
I looked it up in the Perf. manual the other day, there is even a difference between the 737/700 and 737/300. For T/O in the 700 on a dry runway you don't take reverse into account but you do an a wet RWY however on the 300 you take reverse into account on both wet and dry...

[timzsta]

Interesting point M&V, particularly if the clearway is the max permissible (ie 50% TORA). Would suggest its not much!