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Polish LOT 767 wheels up landing

Old 6th Dec 2011, 22:52
  #341 (permalink)  
 
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Duty cycle limits are normally designed to prevent a motor from overheating. Not sure why exceeding them would cause a breaker to trip. Unless, of course, the motor overheated to the point where the insulation burned off the coils and caused a short. But then it presumably wouldn't have worked on the ground.

A mechanical jam that stalled the motor might cause an overload and trip the breaker, but that wouldn't be directly related to duty cycle.
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Old 6th Dec 2011, 22:54
  #342 (permalink)  
 
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Originally Posted by Roo
...But the combined loads further upstream may have caused the BAT BUS DISTR to trip first. ...
C829 = 25 A and C4248 = 7,5 A.
I could say it politely: Maybe possible,
but when i must be honest: NO !
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Old 6th Dec 2011, 23:15
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Bet it was left tripped by engineering after their work. Difficult breaker to see especially if bags papers giraffes & whatever other toot gets piled around cockpits these days.
But every breaker should be looked at intently.
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Old 6th Dec 2011, 23:25
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Originally Posted by IcePack
... Bet it was left tripped by engineering after their work. ...
I bet you are a pilot
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Old 7th Dec 2011, 00:18
  #345 (permalink)  
 
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I bet you are a pilot
Adding on to that...

How would the generators have closed onto the busses with that CB tripped? Since the CB in question controls those (and a large portion of the other, if not all, electrical control units) as well.

IMHO everything is pointing to a CB trip of C829, probably at the activation of the ALT GEAR extension sequence.

I suspect the final report will say the crew failed to identify the C829 as tripped and was unable to resolve that resultant issue in flight (including in discussion with MX).

Even if it tripped but not popped and was "jarred" loose during the "grind-out", as some have suggested, I would still be surprised that a basic "cycling" of the breakers was not done when dealing with an issue as severe as this.

To each their own though, I guess my "archaic" techniques learned as an engineer don't have a lot of room in the age of EICAS.
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Old 7th Dec 2011, 11:01
  #346 (permalink)  
 
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...I'm reminded of a quote from a grizzled old FE.

One of the less obvious benefits of the old 3 man Flt Deck was the fact that Pilots and Engineers (FEs) were trained differently which could produce a parallel and complementary approach to problem solving and priorities.

Given a telescope, a Pilot would naturally look through it, an FE would look at it.......
.......then make sure the Pilot was looking through the right end.
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Old 7th Dec 2011, 12:01
  #347 (permalink)  
 
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Duty cycle limits are normally designed to prevent a motor from overheating. Not sure why exceeding them would cause a breaker to trip.
In fact, this is possible with certain types of DC motors. Overheating may cause permanent magnets to lose some of their strength (way before reaching Curie point when magnets turn into a paperweights), which may cause motor to stall under less than rated load - and then overcurrent protection device will trip, be it a circuit breaker or something else. I've observed this many times while doing servo drive programming. Normally, a thermal protection - if it exists - should kick in earlier, but under certain conditions it is perfectly possible.
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Old 7th Dec 2011, 13:48
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A couple of points interest me.

Will it be worth spending millions on repairing the aircraft which at 14 years of age and with 80,000 flying hours is about 2/3 into its useful life?

I wonder how the flight crew will be handled and if they are back flying yet. LOT may decide the crew have done a great job of the landing and it all depends on whether management regard missing the popped cb as a minor error that any crew might have made or an extremely serious one. There will doubtless be a big debate on whether they did well or not.

It reminds me a litle of the Air Transat glider into the Azores. The crew did a great job of the deadstick landing and saved the plane but might have managed the circumstances that led to it a bit better.

I hope they keep their medals and jobs.
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Old 7th Dec 2011, 19:08
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Today ( Dec. 07. 2011 ) i was hearing that a c.b. found poped- up on the lower panel behind the pilots !
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Old 7th Dec 2011, 23:18
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Wow - really? You are quite up to date...
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Old 11th Dec 2011, 01:20
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"Bet it was left tripped by engineering after their work..."

Pure rubbish. Do a bit of research and find out which systems are powered by the popped c/b. Then, do a bit more research and determine when these different systems are used in the course of operating the aircraft. You will clearly be able to determine that the c/b popped AFTER a certain point in time.....and this point in time was after the flight crew was operating the aircraft.

You wont be able to determine why it popped or exactly when it popped but it should be clear (and easy to determine) that it popped AFTER the aircraft was configured for flight.
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Old 15th Dec 2011, 08:23
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According to rumours from "credible" sources in Warsaw,
LOT's B767 SP-LPC won't be repaired.
Although it would have been, apparently, possible to repair the damaged structures relatively cheaply, neither engine can be repaired economically.
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Old 15th Dec 2011, 12:38
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neither engine can be repaired economically.
They can't be replaced?
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Old 15th Dec 2011, 12:46
  #354 (permalink)  
 
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Bet it was left tripped by engineering after their work.
Standard procedures for maintence is to tag a breaker when it is pulled. The tag should contain who pulled it and why.
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Old 15th Dec 2011, 23:09
  #355 (permalink)  
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Standard procedures for maintence is to tag a breaker when it is pulled.
Might be SOP's for maintenance, but I'm sorry to say as an ex Engineer that SOP's are not always followed.

Not saying this was the case in this incident of course - how would I know - but the possibility is there.

Despite that, the responsibility for checking CB's rest with the Crew before flight and also when a system fails (easy to overlook in the heat of the moment I might add)
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Old 18th Dec 2011, 22:54
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I wonder how the flight crew will be handled and if they are back flying yet. LOT may decide the crew have done a great job of the landing and it all depends on whether management regard missing the popped cb as a minor error that any crew might have made or an extremely serious one. There will doubtless be a big debate on whether they did well or not.
May be a horrible truth what you are saying but why does this crew not deserve the same respect as sully in the Hudson for performing a perfect PERFECT gear up landing resulting in NIL casualties? Sully and crew were (well he did have less time to prepare) subject to a potential disaster as were the LOT crew. Below a news clip in honor of the gentlemen who did their job well!

[quote]
President Bronislaw Komorowski expressed his heartfelt thanks to the crew and the ground workers "on behalf of all Poland, which held its breath while watching the dramatic developments."
Komorowski said the pilot's skill and expertise saved many lives, but also gave the Poles a powerfully "positive" outcome.
The LOT airlines plane carrying 231 people from Newark, New Jersey made the emergency landing Nov. 1 after its landing gear failed to open.
Komorowski decorated the crew members and representatives of airport ground and rescue services with medals. Among them was pilot Capt. Tadeusz Wrona, who became an instant hero in Poland, who was awarded the Officer's Cross of the Order of Poland's Rebirth.
Wrona and co-pilot Jerzy Szwarc landed the plane so carefully that some passengers thought it had landed on wheels until they saw smoke, fire and sparks. Emergency workers immediately doused the plane and nobody was hurt.


Read more: Poland honors crew who made safe emergency landing - seattlepi.com]

Seems to me they are to be handled very well!
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Old 19th Dec 2011, 00:25
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Originally Posted by grounded27 View Post
May be a horrible truth what you are saying but why does this crew not deserve the same respect as sully in the Hudson for performing a perfect PERFECT gear up landing resulting in NIL casualties?

Seems to me they are to be handled very well!
Because the USAir crew had no engines over the middle of a huge city all of a sudden at low altitude. An immediate decision was made that led to a successful ditching.

This crew had all kinds of time to deal with their problem. Time will tell if it was handled properly. There appears to be potential for it looking like an aircraft writeoff due to a popped CB, but that is only speculation at this point(with solid reasoning for that speculation).

However it turns out, this thread is a good reminder to never assume that a second failure happened because of an earlier failure.
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Old 19th Dec 2011, 06:34
  #358 (permalink)  
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Because the USAir crew had no engines over the middle of a huge city all of a sudden at low altitude. An immediate decision was made that led to a successful ditching.
...or was it "over huge bay or river " rather then above "middle of huge city" ?
 
Old 19th Dec 2011, 13:28
  #359 (permalink)  
 
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Originally Posted by Green Guard View Post
...or was it "over huge bay or river " rather then above "middle of huge city" ?
Either way, they had no airport options and extremely little time.
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Old 19th Dec 2011, 19:21
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I'm no "Sully-a-holic" like some, but guess the difference is (in metaphor format);

The US Airways crew were driving along and suddenly found themselves hurtling at a brick wall with 2 seconds to figure out what to do, yet managed to avoid it.

The LOT crew were driving along, just the same, and received a few text messages and roadside alert that there was a brick wall several hundred miles away and to be ready for it. Yet, somehow, they still managed to right into it (as far as the initial report makes it seem at this time)

Just because they were LUCKY enough to not kill or injure anybody does not mean they did an excellent job. If so much as one person ended up in the hospital and/or died due to this landing their heads would be rolling over the CB instead of receiving "medals".

Last edited by aviatorhi; 19th Dec 2011 at 22:50.
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