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Korean 773 Blows MLG on ldg with clip ...

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Korean 773 Blows MLG on ldg with clip ...

Old 1st Jul 2018, 14:23
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Originally Posted by Capn Bloggs
You will note that the left bogie is almost flat, meaning it is on the ground...
It has *been* on the ground, but as the aircraft has bounced back upwards, it has been lifted off the ground and has not had time to tip back to the usual "dangling" orientation on approach.
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Old 1st Jul 2018, 14:42
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You will note that the left bogie is almost flat, meaning it is on the ground...
It has *been* on the ground, but as the aircraft has bounced back upwards, it has been lifted off the ground and has not had time to tip back to the usual "dangling" orientation on approach
That is correct nonsense. If you watch the video in slo-motion, you see it has been lifted up off the runway. You can see the puff smoke is behind the gear from the momentary touch, and when watching you can see the left gear land again. Too many frames to post here...
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Old 2nd Jul 2018, 00:03
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Having gone backwards and forwards through the video a few times, it looks to me the left wheels do not leave the ground after the first touch. Look at the left engine's height above the ground.

It looks to me that, through no action on the crew's part, the right wing dropped at the last second and the right bogie touched firmly. In my view, the PF had the aeroplane nicely set up for a decent touchdown until the @#$% dropped out of the right wing.

Also of interest is the sparks start well after touchdown, indicating the axle may not have given way on touchdown, but later on.

Unlucky...
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Old 2nd Jul 2018, 01:16
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Originally Posted by Capn Bloggs
Having gone backwards and forwards through the video a few times, it looks to me the left wheels do not leave the ground after the first touch. Look at the left engine's height above the ground.

It looks to me that, through no action on the crew's part, the right wing dropped at the last second and the right bogie touched firmly. In my view, the PF had the aeroplane nicely set up for a decent touchdown until the @#$% dropped out of the right wing.

Also of interest is the sparks start well after touchdown, indicating the axle may not have given way on touchdown, but later on.

Unlucky...
The two applications of near full nose up deflection (aft stick) of the stab just prior to touchdown drove the mains into the runway.. Yes it was setup pretty good after all the sillyness, should have just let it settle in.
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Old 2nd Jul 2018, 08:42
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This is not the first time KA did that type of landing.

This one is from 2012...Looks like it is pretty much identical, in terms of the PIO...
watch?v=OoK_dbLDfA0
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Old 2nd Jul 2018, 12:37
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Note puff of smoke from momentary touch, then the bounce, front wheels of assembly up, (no smoke) then contact again with full smoke...



front wheels up on bounce
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Old 2nd Jul 2018, 12:49
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Originally Posted by cappt
The two applications of near full nose up deflection (aft stick) of the stab just prior to touchdown drove the mains into the runway.. Yes it was setup pretty good after all the sillyness, should have just let it settle in.
I dont think the pilot did anything wrong. The gear (and specifically the axles) are designed to take harder landings than that and the fact that the rear axle failed points to mechanical failure not pilot error.

If you look at the BA 777 crash at LHR where both landing gear assemblies were ripped off and the right MLG bogie was snapped in half, all the individual axles survived intact.
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Old 3rd Jul 2018, 00:58
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Originally Posted by Underfire
Note puff of smoke from momentary touch, then the bounce, front wheels of assembly up, (no smoke) then contact again with full smoke...
No. That smoke is from the rear wheels. The front wheels haven't even reached the ground yet. The next few frames clearly show another large cloud of smoke when the front wheels touch down. There is no bounce.
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Old 29th Sep 2019, 15:50
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Corrosion cracking caused Korean Air Boeing 777 main gear axle failure on landing: http://newsinflight.com/2019/09/29/c...re-on-landing/
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Old 30th Sep 2019, 12:30
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A bit wobbly, but youíd need to be closer to see what the actual touchdown was like. Iíd be surprised if it was that bad though.

Anyone know what peak G the BA777 hit in the LHR glider incident ?
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Old 30th Sep 2019, 12:53
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Originally Posted by Meester proach
Anyone know what peak G the BA777 hit in the LHR glider incident ?
2.9g oooooooooooooooooooo
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Old 30th Sep 2019, 14:29
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Originally Posted by Speed of Sound
2.9g oooooooooooooooooooo
= 638 tonnes No wonder it got a bit bent.
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Old 30th Sep 2019, 15:16
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It is initially a stable approach, with a bit of low level corrections going on, but none of the magnitude needed to overstress the MLG. The touchdown shock is extended over the wheel un-tilting, and the compression of the MLG shock. That looks to have been within the normal limits in the video. The landing loads assume symmetrical loading across the MLG, however the single gear impact has to be considered.

I would be suspecting corrosion fatigue of the attach section around the steering bearing. It doesn't appear to be the axles, it appears to be a failure of the structure around the vertical bearing.
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Old 30th Sep 2019, 16:59
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Originally Posted by fdr
I would be suspecting corrosion fatigue of the attach section around the steering bearing. It doesn't appear to be the axles, .
ďJapanese investigators of Korean Air Boeing 777-300 that suffered serious damage to its rear wheel axle of the main landing gear conclude that corrosion contributed to failure.Ē


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Old 30th Sep 2019, 21:45
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Originally Posted by Speed of Sound


2.9g oooooooooooooooooooo
Is that all ? Enough to shove the main gear through the wings. Seeing as Boeing hard landings start at 1.8 G , Iím quite surprised how low
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Old 1st Oct 2019, 20:45
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Originally Posted by Speed of Sound
“Japanese investigators of Korean Air Boeing 777-300 that suffered serious damage to its rear wheel axle of the main landing gear conclude that corrosion contributed to failure.”
thanks.

I went back later and read the report after my post.... the report was well done. The aft bogie has the hardest time of loads on takeoff and on landing. It is subject to higher torsional and bending loads than the other axles.

[The B777 has great control authority and handles crosswinds well. Looking back in some data I see one particular TO in that tail number that got a 46kt crosswind gust on the takeoff, and required much less than full rudder to maintain centerline. It does exhibit spoiler walkdown but only when there is a lot of wok n' roll going on. This incident should indicate that SIWL is a factor to consider if wing down is being contemplated as a XW technique. I have to dust off notes on a investigation I did years ago on a series of gear trunnion failures that were occurring to a carrier, the gear was quite often coming up through the upper spar cap which makes for a long day. Through the cobwebs however, the inputs immediately before touchdown and the touchdown attitude can alter the magnitude and type of loads that the gear is subjected to

One oddity of the 777 was a weirdness of directional stability in a strong crosswind, at low speed... rather surprisingly with strong crosswinds, the plane initially has a tendency to turn away from the wind. Once some speed has been achieved on the roll, this reverses slightly to a more normal weathervaning tendency. Another slight oddity is that in stable strong crosswinds, the aircraft responds to a rudder alignment prior to touchdown by effectively jacking the tail upwind, and the cockpit offset from the centerline doesn't come back towards the centerline quite as it does with say, the B747, or 757/767/737. Nice plane though, pity it has so much fuel on board]

Last edited by fdr; 1st Oct 2019 at 21:08.
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Old 2nd Oct 2019, 10:53
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Originally Posted by Meester proach

Is that all ? Enough to shove the main gear through the wings. Seeing as Boeing hard landings start at 1.8 G , Iím quite surprised how low
The main issue was that touchdown was on the grass before the runway. That probably limited the vertical loads, but also meant the gear dug in and was sheared off.
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Old 3rd Oct 2019, 06:48
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Originally Posted by Capn Bloggs
If it's a Boeing, I'm not going!
More like "If it's a Boeing, IT's not going".
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Old 3rd Oct 2019, 06:57
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Originally Posted by FullWings
Yeah. A little bit wobbly but Iíve done far worse than that.
I've aborted at far less. Definitely a try-again landing. You don't play games with a 73-meter airliner full of innocent bysitters. My guess would be a "veteran", "ex-air-force" captain, "the right stuff", and very young inexperienced FO. And my bet would be, the FO called for abort... in a whisper. Korean Air 8509 comes to mind. Followed by the general Korean Air's reputation. Could've been much, much worse.
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Old 3rd Oct 2019, 18:20
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Originally Posted by UltraFan
I've aborted at far less. Definitely a try-again landing. You don't play games with a 73-meter airliner full of innocent bysitters. My guess would be a "veteran", "ex-air-force" captain, "the right stuff", and very young inexperienced FO. And my bet would be, the FO called for abort... in a whisper. Korean Air 8509 comes to mind. Followed by the general Korean Air's reputation. Could've been much, much worse.
Those are some bold assumptions based on a cellphone video, maybe keep it down a little till the report comes out.
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