Polish LOT 767 wheels up landing
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r75
Have seen a/c sitting OG in mx with hydraulics on and w/o "safe'd" gear handles, i.e., "tagged." Have seen other techs working other systems run tests requiring movement of same handles, and w/o checking gears for pins or even asking around. Result? Nose goes to ground with surprising ease, noise, embarrassment, and, why sometimes, even causing a delay. Can't speak for 767 tho. As for the mains? The unlock would actuate, but the over center can't move. Something about 100 plus tons of weight just being a little too much for even 3500 psi to lift up and get those tires sliding.
Have seen a/c sitting OG in mx with hydraulics on and w/o "safe'd" gear handles, i.e., "tagged." Have seen other techs working other systems run tests requiring movement of same handles, and w/o checking gears for pins or even asking around. Result? Nose goes to ground with surprising ease, noise, embarrassment, and, why sometimes, even causing a delay. Can't speak for 767 tho. As for the mains? The unlock would actuate, but the over center can't move. Something about 100 plus tons of weight just being a little too much for even 3500 psi to lift up and get those tires sliding.
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If you were to perform a retraction function on the ground in a 74 without the pins in (heaven forbid),you would be well advised to not only keep away from the NLG but also the BLG.You need to perform this function to bleed various components you have changed in the Landing Gear actuation systems,not to mention leak checking.Apologies to all concerned for thread drifting.
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An Air Canada 767 that ran out of fuel, commonly referred to as the Gimli Glider, couldn't get it's nose gear to extend during 'free-fall' extension, due to the strong airflow. It landed on its mains and its nose. As a result the tail stuck way high in the sky when the plane came to rest. The slides were almost vertical, and that's where most injuries were sustained during the evac.
Alternate Gear Extension is done with the lever in the OFF position.
Last edited by Lost in Saigon; 20th Nov 2011 at 00:03.
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It's true that people were injured on the Gimli Glider's slides because the nosegear didn't come down and the tail therefore was elevated, but if the nosegear -had- come down, there would have been far greater carnage because the airplane would have rolled into the autocross crowd on the ostensibly closed runway. With the entire nose on the concrete, the airplane was dragged to a stop far more quickly.
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The Gimli Glider nose gear did extend as per the alt extension procedure. The first indication of trouble was when the nose was lowered after landing and it lowered beyond what the pilots expected. The contact with the runway was described as akin to a shotgun blast beside your ear. Boeing were, in a perverse way, happy to find out that that the over center lock on the nose gear was not aligned properly. This problem was corrected on the assembly line and the aircraft in line operations and problems solved. BTW the cockpit indication on landing in Gimli was "three greens".
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The Gimli Glider nose gear did extend as per the alt extension procedure. The first indication of trouble was when the nose was lowered after landing and it lowered beyond what the pilots expected. The contact with the runway was described as akin to a shotgun blast beside your ear. Boeing were, in a perverse way, happy to find out that that the over center lock on the nose gear was not aligned properly. This problem was corrected on the assembly line and the aircraft in line operations and problems solved. BTW the cockpit indication on landing in Gimli was "three greens".
This is the first time I have heard this. Also please explain how it is possible to get "Three Green" if the nose gear is not locked down.
EDIT: This link says they did not get "Three Green": Gimli: A Race to the Finish
Pearson ordered a "gravity drop" as Pearson thumbed frantically through the Quick Reference Handbook, or QRH. Quintal soon tossed the QRH aside and hit the button to release the gear door pins. They heard the main gear fall and lock in place. But Quintal only got two green lights, not three: the nose gear hadn't gone over centre and locked, despite the "assist" it was given by the wind.
Last edited by Lost in Saigon; 20th Nov 2011 at 00:56.
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Gimli Glider
I thought that the reason the nose gear retracted on the landing run was because the gear lever was left in the off position.
Not sure if the procedure at that time failed to list gear lever in down position after getting the three greens.
You need to remember this happened very soon after the B767 entered service.
Not sure if the procedure at that time failed to list gear lever in down position after getting the three greens.
You need to remember this happened very soon after the B767 entered service.
None but a blockhead
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As SLF with some experience of fault-finding in complex systems, albeit noncritical ones, I think the crew acted very well. Given the fault occurred practically at take-off, was intimately connected with gear movement and didn't seem to be symptomatic of wider problems, the probability is that it wouldn't affect the flight until landing. Thus, taking as much time as possible to fix it is sensible and continuing to the destination while running through diagnostics and taking advice over the blower is eminently sane.
I agree completely with Mr Boeing in that a popped CB should stay that way, through experience of my own in blowing expensive things up. Given that the crew was in contact with tech support, it seems very unlikely that the CB being popped went unchecked or unknown - with all that time in hand, you have the luxury of going into as much detail as you like short of actually disassembling the gear.
Also, it is very hard to imagine that the flight crew lacked the motivation or skills to do a proper investigation of the problem; unless it was a very dysfunctional cockpit indeed with terrible CRM and a nutsoid skipper, I can't see any of the factors present which normally couple bad decisions to bad outcomes.
More information may render any or all of the above moot, of course, and the thoughts of a Sunday afternoon non-pilot are worth the pixels they're written in, but I'd fly across the Atlantic with that crew as happily as I'd down a shot of Żubrówka.
I agree completely with Mr Boeing in that a popped CB should stay that way, through experience of my own in blowing expensive things up. Given that the crew was in contact with tech support, it seems very unlikely that the CB being popped went unchecked or unknown - with all that time in hand, you have the luxury of going into as much detail as you like short of actually disassembling the gear.
Also, it is very hard to imagine that the flight crew lacked the motivation or skills to do a proper investigation of the problem; unless it was a very dysfunctional cockpit indeed with terrible CRM and a nutsoid skipper, I can't see any of the factors present which normally couple bad decisions to bad outcomes.
More information may render any or all of the above moot, of course, and the thoughts of a Sunday afternoon non-pilot are worth the pixels they're written in, but I'd fly across the Atlantic with that crew as happily as I'd down a shot of Żubrówka.
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A preliminary report will be released online on Thursday. According to a member of the commission, the incident was caused by a knocked breaker used by several systems and "located at the bottom, near the first officer's seat", but neither the crew nor manufacturer knew that it may affect gear extension system.
Source
Source
A 'knocked circuit breaker'
Not sure what is meant by that and I can't pretend to fully understand the translation in the article.
However, if a circuit breaker was found to be out after being unable to extend the gear I fail to understand why they would not reset it.
It does remind me, however that the ancillary / additional functions of circuit breakers on the 75 /67 are not all known to the crew.
For example, did you know, on the 757 if you pull and then reset the 'speed card' circuit breakers for the left and right side simultaneously you will extend the RAT ?
One of our crews did this half way across the Atlantic,after both speed cards (vertical IAS tape on the left side of the PFD ) failed and displayed a flag
In attempting to restore operation of these instruments they reset the speed card cb's after which the RAT immediately dropped, much to their surprise.
Apparently this is how maintenance tests the operation of the RAT but no one thought to tell the Pilots.
Not sure what is meant by that and I can't pretend to fully understand the translation in the article.
However, if a circuit breaker was found to be out after being unable to extend the gear I fail to understand why they would not reset it.
It does remind me, however that the ancillary / additional functions of circuit breakers on the 75 /67 are not all known to the crew.
For example, did you know, on the 757 if you pull and then reset the 'speed card' circuit breakers for the left and right side simultaneously you will extend the RAT ?
One of our crews did this half way across the Atlantic,after both speed cards (vertical IAS tape on the left side of the PFD ) failed and displayed a flag
In attempting to restore operation of these instruments they reset the speed card cb's after which the RAT immediately dropped, much to their surprise.
Apparently this is how maintenance tests the operation of the RAT but no one thought to tell the Pilots.
nor manufacturer knew that it may affect gear extension system
Apparently this is how maintenance tests the operation of the RAT but no one thought to tell the Pilots.
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Preliminary report (Polish)
http://doc.rmf.pl/rmf_fm/store/Boeing_raport.pdf
circ. braker C829 BAT BUS DISTR (pos. A1) was found in OFF position after landing
circ. C4248 LANDING GEAR – ALTN EXT MOTOR was ON
C289 is also breaking alternate systems of alternate gear ext. (pict. from Boeing manual on page 5)
C829 in OFF pos. is not indicated on FRD & EICAS
http://doc.rmf.pl/rmf_fm/store/Boeing_raport.pdf
circ. braker C829 BAT BUS DISTR (pos. A1) was found in OFF position after landing
circ. C4248 LANDING GEAR – ALTN EXT MOTOR was ON
C289 is also breaking alternate systems of alternate gear ext. (pict. from Boeing manual on page 5)
C829 in OFF pos. is not indicated on FRD & EICAS
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Some photographs from the preliminary report - showing also a "popped" circuit breaker.
Upubliczniono wst
Upubliczniono wst
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As an FE I find it amusing (in an anti-comedic way) that they did not think to check ALL CBs (not just directly related CBs) when experiencing a fault.
Though I am willing to bet some will still say that even if it had been found the wheels up landing was the "safer" alternative to resetting/holding the CB.
Though I am willing to bet some will still say that even if it had been found the wheels up landing was the "safer" alternative to resetting/holding the CB.
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As an FE I find it amusing (in an anti-comedic way) that they did not think to check ALL CBs (not just directly related CBs) when experiencing a fault.
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Boeing rules on resetting CB's
1. No procedure in current-production airplanes calls for the pulling (and resetting) of any CB's
2. Flight Crew reset of tripped fuel pump control circuit breakers in flight is prohibited. Reset of any other tripped circuit breaker is not recommended unless in the judgment of the Captain, the situation resulting from the circuit breaker trip has a significant adverse effect on safety. These other tripped circuit breakers may be reset once, after a short cooling period (approximately 2 minutes).
Source:
http://www.ukfsc.co.uk/files/Safety%...20Breakers.pdf
Very precise and sane. One cannot start a fire on a plane by resetting a tripped circuit breaker once. One can only do it by burning out wiring by resetting repeatedly/holding in a CB that's being tripped by a shorted out component.
Now the amusing part is that the crew already got a medal for bravery, so it will be a political problem if they are found to have overlooked this little thing.
Don't you just love it when the politicians get involved in these things even before the preliminary report is issued.
2. Flight Crew reset of tripped fuel pump control circuit breakers in flight is prohibited. Reset of any other tripped circuit breaker is not recommended unless in the judgment of the Captain, the situation resulting from the circuit breaker trip has a significant adverse effect on safety. These other tripped circuit breakers may be reset once, after a short cooling period (approximately 2 minutes).
Source:
http://www.ukfsc.co.uk/files/Safety%...20Breakers.pdf
Very precise and sane. One cannot start a fire on a plane by resetting a tripped circuit breaker once. One can only do it by burning out wiring by resetting repeatedly/holding in a CB that's being tripped by a shorted out component.
Now the amusing part is that the crew already got a medal for bravery, so it will be a political problem if they are found to have overlooked this little thing.
Don't you just love it when the politicians get involved in these things even before the preliminary report is issued.
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In recent interview Captain claims that all circuit breakers were checked twice, and none was found popped.
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Had the opportunity to look at cockpit indications in a 767-300ER simulator. With c/b C829 BAT BUS DISTR popped, there are no adverse indications in the cockpit (e.g. no EICAS messages present). Essentially you wouldn't know this c/b was popped unless you physically looked at it and saw it out.
I then took the liberty of putting the simulator at cruise, failed the center hydraulic system, and pulled the C829 BAT BUS DISTR c/b. Incidentally, the gear handle was inop (as expected w/ a ctr hyd sys failure). The ALTN EXT function of the landing gear was inop as well. I then pushed the c/b back in, kept the center hyd sys failed, and the gear dropped when I selected ALTN EXT a second time.
In other words, SP-LPC operated as designed.
I then took the liberty of putting the simulator at cruise, failed the center hydraulic system, and pulled the C829 BAT BUS DISTR c/b. Incidentally, the gear handle was inop (as expected w/ a ctr hyd sys failure). The ALTN EXT function of the landing gear was inop as well. I then pushed the c/b back in, kept the center hyd sys failed, and the gear dropped when I selected ALTN EXT a second time.
In other words, SP-LPC operated as designed.