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Polish LOT 767 wheels up landing

Old 2nd Nov 2012, 14:05
  #381 (permalink)  
 
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Tidbits

C/B s on B-767 are pull/push type.

C/B s pulled by maintenance prior to flight are collared (for amateurs on the forum, this is not a typo for coloured/colored, it means a plastic, distinctively coloured/colored collar is fitted around the CB to make clear that it is out on purpose).

Yes, during abnormal sytem behaviour, checking CB s should be a natural step after completion of QRH procedures, BUT, the alternate gear extension system is FREE FALL, that doesn't quite ring a bell that something electrically could be in the way of gear extension - Oh yeah, the hooks that hold the gear doors locked are operated by electrical motors, rather than hydraulic actuators, during alternate gear extension.

CB s are not monitored by EICAS in a 767, but the fact that the popped CB did not cause any other (obvious) failure on the flight deck did not help to discover the fault in the electric system. Remember that alternate gear extension is one of the systems that have to work when (almost) all electrics on the machine have died - surprising that part of that last ditch portion of the electric system can die unnoticed.

Lastly, the particular position of that CB is prone to being bumped accidentally by pilot s bag, and sits in a corner of the panel that is awkward to view from pilot s seat.

Seems lot of holes lined up.
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Old 2nd Nov 2012, 15:28
  #382 (permalink)  
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EMIT, thanks for these , now the report makes a lot more sense ( to me at least )
Indeed a lot of holes waiting to be lined up. You would not expect that in an old Boeing design , but it proves Murphy is still alive and going strong.
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Old 2nd Nov 2012, 16:50
  #383 (permalink)  
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Indeed - those of us who have tried to 'check CB's' during an abnormal know how hard that can be - a bewildering array of buttons. Without some direction from the QRH it can be extremely difficult to track down the culprit, if any.

EMIT - are you saying that a 'total electrics' on a 767 would render free-fall inop? There is no mechanical over-ride?
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Old 2nd Nov 2012, 17:23
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Bad luck day

Hello BOAC,

Well, just a total electrical failure (also battery dead), would of course not inhibit normal gear extension, because the primary system is hydraulic (the opening of the up latch hooks).
The extension itself is free fall already.

If the total electrical failure is accompanied by hydraulic failure, yes, then you are without gear extension, but for that unlikely combination of failure, there is the back up mode of a belly landing.
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Old 2nd Nov 2012, 17:31
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BOAC,

Bewildering array or not - I think if you look at the picture in the report, you might wonder "why is that one with the little white ring on it pulled out", even if you had never seen a 767 flightdeck or Boeing breaker before.

A simple 10 second scan of the bewildering array might have made you think "what happens if I push this back in"? There being no collar with tag from maintainance to tell you not to...

I gather many pilots have used CB's to shut up annoying buzzers (that might for instance tell them CFIT is a bad idea...), or if not seen the memo's telling them NOT to...

So - given that I am sure your rating gives you a passing familiarity with the bewildering array - back to "why didn't the checklist ask the crew to CHECK CB's"? (or did it?).

Over an hour for the peeps on the flightdeck and in the help centre to think to check the ELECTRICALLY powered backup had ELECTRICITY...
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Old 2nd Nov 2012, 17:32
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Ta - that makes sense of course, I just wasn't clear from your earlier post re the uplocks' activation..
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Old 2nd Nov 2012, 17:36
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Crew checking / resetting CBs can be an option / drill / consideration. However, as BOAC says, given today's poor manuals and low technical training, I would hardly describe it as a "catch all" for situations like this.

I cannot recall the earlier report and/or timings, however, for something like this I would have thought the crew in contact with Engineers on the ground, especially at home base, and they in turn, as required even with Boeing. Certainly half the time I call engineering, I am told to pull / reset CBs X, Y and Z.

AL 1:
After completing the QRH procedure and consultation with the operator's operations centre, the flight crew decided to continue the flight to Warsaw.
ex-EWR
The crew checked correctness of the procedure and then reported to the air traffic control service (ATC) inability to extend the landing gear and asked operations centre for help.
The airplane was directed to a holding zone. Around 12:25 hrs the flight crew declared EMERGENCY situation. At 12:45, after consultation with the Command Post of Air Operations Centre, it was decided to activate ground alert combat aircraft from an Air Force base to check visually the landing gear.
At 13:06 hrs the pilots of combat aircraft informed the Boeing flight crew that the all landing gear was still in the retracted position. During the flight in the holding zone the flight crew consulted their actions with the operator operations centre.
The crew carried out an attempt to extend the landing gear in the gravitational way, which ended in failure. Due to small fuel quantity and unsuccessful attempts to extend the landing gear, the crew decided to execute an emergency landing with landing gear retracted. The plane landed at Warsaw-Okecie aerodrome (EPWA), on runway 33 at 13:39.
So about 90mins from "gear won't lower" to wheels up on runway, and in consulation with their Ops for that ~90mins - having given a heads up ~8hours earlier. Certainly in my outfit, after the 8hours I think I would have had more "help" than I needed on the R/T / ACARS

Looking at the manual extracts, even if they traced the Alt Ext motor in the CB chart, this was not the CB tripped - you had to go back to the power source for that busbar.
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Old 2nd Nov 2012, 17:51
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As I said earlier to Clandestino - there are 'bigger fish to fry' here. It is beyond belief that as NoD says, no-one from Company suggested this breaker. Crew-wise, charliemouse, I agree that a 'one isolated photo' presentation shows it to be obvious, but I would prefer to sit in the cockpit before I passed judgement - and the report does say it is 'very difficult' to see this breaker.
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Old 3rd Nov 2012, 10:09
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From the B767 FCOM:

The alternate landing gear extension system uses an electric motor to trip the locking mechanism for each gear.

No electrical power, no gear extension, regardless of status of the center hydraulic system. This is the precise result when the CB controlling the motors is popped.

Can't seem to find it, but recall from a previous aircraft's QRH a warning to extend landing gear prior to battery depletion in a "Loss of All Generators" c/l.
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Old 3rd Nov 2012, 23:34
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Anyone remember years back when the G-V had a gear wedge against its gear door due to bad sequencing? If I recall that plane circled for hours while every engineer, mechanic, and pilot at Gulfstream ran the array of possible fixes from the mundane to the borderline insane. In the end they got the gear down.

I'm surprised Boeing wasn't brought more into the loop on this during the 9+ hour flight.
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Old 4th Nov 2012, 13:05
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Time

Island-Flyer

The entire flight may have lasted 9 hours, but the tricky problem just came up on final approach to Warsaw. Until then it had just been a case of, lost centre hydraulics, gear will be extended by alternate gear sytem, no need to wake up Boeing for such a straight forward situation.

Joker 72
Code:
No electrical power, no gear extension, regardless of status of the center hydraulic system.
I hope you do realize that with centre hydraulics available, there is no need for alternate extension, and gear can be extended normally, without any electrics (with normal extension, uplocks are released by hydraulic actuators).
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Old 4th Nov 2012, 20:17
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I'd like to bet the problem would have been successfully solved in the olden days with a 3 man flight crew and a Flight Engineer addressing the problem.

Apologies for slight thread drift but talking about popped cbs ....

In the old 747 the problem was often a popped cb normally spotted by the Fight Engineer. Although one event not spotted resulted in doing 2 goarounds in BOS due inability to keep it on the centreline manually or autocoupled. It turned out the cb responsible for the circuit that locked out the outboard ailerons when flaps were up had popped and both approaches were flown using inboard ailerons only. They managed to get down on the third approach and only after parking did they spot the popped circuit breaker.

I seem to remember on the 747 if the nose gear did not come down using the alternate method the third method was for the flight engineer to go down into the lower equipment bay (lower 41, 707 term that remained) and unscrew screws that held it up, after a number had been unscrewed the weight would strip the remaining screws and the nose gear would fall down. I wonder if it was ever used?

To be fair to the LOT guys in the last 10 years I have not had a single flight deck circuit breaker pop on its own accord and I understand the offending circuit breaker was obscured by the first officer's briefcase. I bet the two pilots must be kicking themselves and thinking "if only".

Last edited by suninmyeyes; 4th Nov 2012 at 20:27.
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Old 4th Nov 2012, 20:49
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does anybody know for sure if the PIC is still flying for LOT ?
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Old 4th Nov 2012, 23:15
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He is. . . .
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Old 4th Nov 2012, 23:25
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The entire flight may have lasted 9 hours, but the tricky problem just came up on final approach to Warsaw. Until then it had just been a case of, lost centre hydraulics, gear will be extended by alternate gear sytem, no need to wake up Boeing for such a straight forward situation.
Ah my bad, I had thought I read that they had a hydraulic problem on departure but opted to continue.
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Old 5th Nov 2012, 05:04
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Yes. Why not?
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Old 5th Nov 2012, 05:10
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Island Flyer,

To make sure: the CTR HYD problem developed shortly after departure, but that is no reason not to continue the flight. The 767 has 3 HYD systems. Loosing one is not a daily occurrence, but according Boeing procedures, not a reason to terminate the flight immediately.
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Old 5th Nov 2012, 06:47
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Yeah my knowledge of 767 systems are nonexistent. I know in pretty much all the aircraft I fly if the primary hydraulic system that drives gear extension/retraction fails there is going to be some sort of abnormal gear extension procedure (such as gravity drop, pumping the gear down, or running it off of a separate system driven by a DC pump). I should have guessed larger aircraft would have their primary gear extension driven by multiple hydraulic systems.

If I read it right the failure of the electric motors to release the landing gear uplocks was a completely independent failure (caused by popped CBs) from the hydraulic system failure (which was not caused by the popped CBs that caused the uplock failure)?
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Old 5th Nov 2012, 09:07
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2 comments:
I'd like to bet the problem would have been successfully solved in the olden days with a 3 man flight crew and a Flight Engineer addressing the problem.
It was earlier pointed out here the unusual (electrical) Altn Gear Extend on the 767 was because it was designed wth a Flt Engineer, and a "mechanical wind handle" (or similar). When the Flt Engineer got "removed", the motor to drive this system was implemented.

was a completely independent failure (caused by popped CBs)
Co-incidences are rare, and need to be checked they truly are. Nobody seems to allow for the fact that this CB might have popped when the Altn Extn button was operated? Who knows the condition of the motor / the system? Was there a temporary seizure (frozen water?) in the system somewhere that caused the CB to trip? By the time the aicraft has sat on the runway for X days, been lifted and dragged off to the hangar, who knows what "issues" disappeared / melted away / resolved themselves?

Something, or somebody tripped that CB. The assumption here is that is was "somebody" and others failed to notice / check. It would be pretty hard to prove it was not tripped as per design at the time?
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Old 5th Nov 2012, 09:15
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NoD :
Something, or somebody tripped that CB. The assumption here is that is was "somebody" and others failed to notice / check. It would be pretty hard to prove it was not tripped as per design at the time?
Excellent remark ( as nearly always from you ) . sometimes the obious can be front of our eyes but we keep on looking for the improbable difficult possibilities.
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