We love it! Krueger flaps retract during reverse thrust

[19AB67 16]

23 minutes ago, skelsey said:

the flap position indicator goes from green to magenta

Now, I got it. Thanx.

[Qavion2 39]

This was one of many modifications to make the thrust reverser system safer. The reverser system uses several microswitches in the thrust quadrant which activate sequentially as the reverse levers are lifted. There was a previous incident where a pilot placed a manual forward of the thrust quadrant prior to takeoff. When the forward thrust levers advanced, the reverse levers contacted the manual triggering the first part of reverser operation. The trigger point was subsequently changed. I have a vague recollection that BA was involved with this one, too (???) 

There was that terrible accident with Lauda Airlines (B767) where the reversers deployed in flight. Note that 767 engines can be fitted to 747s. This resulted in one of the first reverser modifications.

Cheers

[berts 97]

16 hours ago, Qavion2 said:

There was that terrible accident with Lauda Airlines (B767) where the reversers deployed in flight. Note that 767 engines can be fitted to 747s. This resulted in one of the first reverser modifications.

Cheers

This shouldn't happen on the B744, because the reversers can only be deployed on the ground and with the engines running.  There is also an interlock mechanism which mechanically prevents simultaneous movement of the forward and reverse thrust levers, so that each reverse thrust lever can only be raised when the relevant engine's forward thrust lever is in the closed position.

There can occassionally  be a slight lag between each engine's interlock releasing and this can initially prevent all four reverse thrust levers being raised simultaneously.  In this case it usually pays to pause for a second or two after raising the reverse thrust levers before applying reverse thrust. On a non-limiting runway then either idle reverse or partial reverse (approx 70% N1) may be used.    

If a fault is detected in the reverser system then the EICAS message  "ENG REV LIMTD" or "ENG REVERSER" will be displayed . The "...LIMTD" message means that only reverse idle will be available after landing on the affected engine.  However, "ENG REVERSER" is probably the most serious because if another fault is detected in that reverser system then there is a risk that it could inadvertently deploy in flight.

Regards,

Bertie Goddard

[Captain Kevin 586]

2 hours ago, berts said:

This shouldn't happen on the B744, because the reversers can only be deployed on the ground and with the engines running.

Was this not the case on the 767?

[berts 97]

1 hour ago, Captain Kevin said:

Was this not the case on the 767?

I can't answer this for certain because I am not familiar with the B767.  However, I would be rather surprised if Boeing's reverser logic wasn't similar for the same engine type (i.e.. RR, P&W or GE).

Bertie Goddard 

[Captain Kevin 586]

16 minutes ago, berts said:

I can't answer this for certain because I am not familiar with the B767.  However, I would be rather surprised if Boeing's reverser logic wasn't similar for the same engine type (i.e.. RR, P&W or GE).

I would have figured this would have been the case on the 767, but your comment saying that this shouldn't happen on the 747-400 threw me off because I assumed the same would be said for the 767, yet there was the Lauda Air 767 where the reverser did deploy in flight.

[Qavion2 39]

14 hours ago, berts said:

This shouldn't happen on the B744, because the reversers can only be deployed on the ground and with the engines running.

I can assure you the engines don't need to be running. I've done it many times  However to go past idle reverse, you do need the engine EECs powered (which can be done by various methods).

The 767 has the same safeguards as the 747. However, if something in the reverser system is telling you that the aircraft is doing something it actually isn't, then you will get things to happen which shouldn't happen. In theory, you shouldn't be able to move the reversers without pneumatic power, but I've heard a few tales from fellow engineers who said the reversers have moved with pnematics off (We believe it's due to trapped air pressure in the system).... and I've slapped at least one apprentice's hands for attempting to move the levers (because he thought it was safe)

Hope this makes sense

Cheers

JHW

 

P.S. By the way, I haven't tried this in v3, but you should be able to activate a reverser on the ground using APU air, if you pull a start switch (with the Autostart switch ON).. then pull on the respective reverse lever (It's an old engineer's trick)

 

[kevinh 409]

11 hours ago, Captain Kevin said:

I would have figured this would have been the case on the 767, but your comment saying that this shouldn't happen on the 747-400 threw me off because I assumed the same would be said for the 767, yet there was the Lauda Air 767 where the reverser did deploy in flight.

An additional locking mechanism was added to the reverser after the Lauda Air accident.

[rsrandazzo 6,353]

Gents,

I love seeing you guys get into discussion of minute details- because most of them are present here.

For anyone interested- during reverse, glance down at your flap position indicator.  It changes to show the condition- but it takes a practiced eye to see and understand what you are observing...

 

[Captain Kevin 586]

1 hour ago, rsrandazzo said:

For anyone interested- during reverse, glance down at your flap position indicator.  It changes to show the condition- but it takes a practiced eye to see and understand what you are observing...

Yeah, I did that shortly after I read one of the posts. You certainly wouldn't necessarily notice it on landing as you'd be focused on....WEL....landing.

[77west 139]

If you extend flaps to 30, turn off all engines and hyd systems, then select reverse, you can see on the extended flaps display the inboard units in transition: (They go white instead of green)

[Qavion2 39]

6 hours ago, 77west said:

If you extend flaps to 30, turn off all engines and hyd systems, then select reverse, you can see on the extended flaps display the inboard units in transition: (They go white instead of green)

Interesting. This presents a chicken and egg situation (which comes first). With pneumatics not  available (on a GE/RR powered aircraft), the flaps wouldn't move and (I imagine), the expanded display should appear, possibly with amber (inboard) LE indications). The LE flaps should then turn to Primary Electric drive. In Primary Electric mode, the LE flaps are not commanded to retract during reverser ops (system logic). If the flaps are not commanded to retract, the flaps are in the correct position (extended). If the flaps are in the correct position, shouldn't the indications be green?  It may be a timing thing. You'd have to try this on the real aircraft to know the answer.

I'm not sure why you're getting that >CARGO DET AIR message. It shouldn't be shown if the engines are off (system logic).

Cheers

JHW

[77west 139]

19 minutes ago, Qavion2 said:

Interesting. This presents a chicken and egg situation (which comes first). With pneumatics not  available (on a GE/RR powered aircraft), the flaps wouldn't move and (I imagine), the expanded display should appear, possibly with amber (inboard) LE indications). The LE flaps should then turn to Primary Electric drive. In Primary Electric mode, the LE flaps are not commanded to retract during reverser ops (system logic). If the flaps are not commanded to retract, the flaps are in the correct position (extended). If the flaps are in the correct position, shouldn't the indications be green?  It may be a timing thing. You'd have to try this on the real aircraft to know the answer.

I'm not sure why you're getting that >CARGO DET AIR message. It shouldn't be shown if the engines are off (system logic).

Cheers

JHW

This was on a GE 744ER. HYD were all off, as was the APU bleed air. The flaps did not move in the few seconds I took the screenshot. But the indication did change to magenta + inboard kreugers going white.

I cant speak for the CARGO DET AIR message however...

[Qavion2 39]

22 hours ago, 77west said:

But the indication did change to magenta + inboard kreugers going white.

White striped "in transit" (as shown in your screenshot) or did they change to empty white boxes ("up") later? If they were moving electrically, it would take a while for them to move to their commanded position, but I'm not sure why your inboard LE's are in transit in the first place.

 

22 hours ago, 77west said:

I cant speak for the CARGO DET AIR message however...

The Boeing Fault Isolation Manual EICAS Message List specifies:

">CARGO DET AIR Advisory Message: Insufficient vacuum for cargo smoke detection system (Requires any two engines running)"

FIM Chaper 26 /Task 803 provides further information. There is no mention of a time delay for the message, but there may be one to prevent nuisance messages.

Cheers

JHW

[77west 139]

5 hours ago, Qavion2 said:

White striped "in transit" (as shown in your screenshot) or did they change to empty white boxes ("up") later? If they were moving electrically, it would take a while for them to move to their commanded position, but I'm not sure why your inboard LE's are in transit in the first place.

 

The Boeing Fault Isolation Manual EICAS Message List specifies:

">CARGO DET AIR Advisory Message: Insufficient vacuum for cargo smoke detection system (Requires any two engines running)"

FIM Chaper 26 /Task 803 provides further information. There is no mention of a time delay for the message, but there may be one to prevent nuisance messages.

Cheers

JHW

The inboard and mid LE are in transit as I had all 4 reverse thrust levers pulled up, but you don't see the REV indication on the engine screen as there is no movement of the unlock mechanism or sleeves. I didnt leave it long enough to see if the leading edge flaps actually electrically retracted; may have to try again, I only saw the in transit message.

 

RE the CARG DET AIR - perhaps this is a bug that has been triggered; I did have a good play with the different systems experimenting on how it affected the various systems..

 

EDIT: referring to your initial comment I now see what you mean - they should not have reverted to primary electric drive. Perhaps the indication is still triggered though? I dont know, would need a real 747 to try it out... any offers?