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Old 31st Jul 2007, 09:44
  #743 (permalink)  
discountinvestigator
 
Join Date: Mar 2006
Location: A oneworld lounge near you
Posts: 144
What do I not understand?

Following most of the thread (admits not all of it, yet) and digging in the books has confused me sufficiently to produce the following thrust lever scenarios. This is an academic partial fact study and does not represent anything to do with the actual accident. Please feel free to tell me what the hell I do not understand at the moment. Warning: The following scenarios could be littered with errors and should not be relied upon in any way when flying the aircraft or for training pilots about landing with a reverser locked out.

These scenarios make no comment about crew cross check, quick reference handbook procedures, minimum equipment lists etc etc.... The purpose is to build an understanding in my mind and not to imply any criticism of Manufacturer "A" or any pilot.

The five roll out scenarios with autothrust engaged and number 2 engine reverse locked out are:

Option 1 TL1 Full Reverse, TL2 CL detent SELECTED

LVR ASYM message on PFD (Lever asymmetry)
No ground spoliers/no speed brake as inhibited with Flap config Full
No auto brake, but manual braking and anti-skid available

The autobrake selection would still show ON, which actually means ARMED and not ON, and the DECEL light would be unlit. The wheel page would show autobrake ON, which means armed....

Engine 1 receives FADEC reverse signal, both Main Landing Gears depressed and TL Reverse angle selected from at least one spoiler elevator computer. Attempts to provide the selected reverse thrust.

Engine 2 with autothrust selected will undergo a transient power change from bug speed power and increase towards "donut" power as the airspeed drops and then limits at CL detent power.

Option 2 TL1 Full Reverse TL2 above "at or near idle" SELECTED
No LVR ASYM message as the CL detent is not used for TL2.
No ground spoilers
No autobrake, but manual braking as above and autobrake displays as option 1

Engine 1 as option 1

Engine 2 with autothrust selected will undergo a transient power change from bug speed approach requirement to the limit of donut power

Option 3 TL1 Full Reverse TL2 "near idle" SELECTED
No LVR ASYM message
PARTIAL spoiler deflection, all come up to 10 degrees. FULL spoiler deflection shown on the wheel page.
Cannot work out what is happening with autobrake from the books, (help?) but manual brakes should be available. Displays as per option 1.

Engine 1 as option 1

Engine 2 will go to the near idle power

Option 4 TL1 Full Reverse TL2 "idle" SELECTED
No LVR ASYM message

Partial spoilers on first gear touchdown and then FULL spoilers on second main gear. Full spoilers shown on display from first gear touchdown.

Autobrake available and works

Engine 1 as option 1

Engine 2 goes to one of the three idle options. Is it ground idle, flight idle or reverse idle (which is higher than "forward" but forward is not defined...!) (Help?)

Option 5 TL1 Full Reverse TL2 "reverse" SELECTED
No LVR ASYM message
ENG 2 REVERSER FAULT
Partial spoilers on first gear touchdown and then FULL spoilers on second main gear
Autobrake activates on same logic as second main gear to work as requested (but limited by runway contamination etc).

No warnings on the engine page
No warnings on the wheel page
No aural warning
No master warning light
No system displays called
No local warnings

The amber REV lights on the EPR display go to green on Engine 1 and stay amber on Engine 2.

Engine 1 gives selected reverse thrust, engine 2 provides slightly higher than idle but which one...

Many thanks for your consideration of this scenario. Once I have got this lot sorted out in my mind, then I will look as the psychological error modes for the slip, lapse, rule based and knowledge based mistake classifications.

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