Virgin 744 right wing gear stuck half up

[Jeroen Hoppenbrouwers]

A/C has landed safely.


http://www.dailymail.co.uk/news/article-2890093/Virgin-Boeing-747-flight-Gatwick-Las-Vegas-returns-airport-landing-gear-fault.html

http://avherald.com/h?article=47f7b9f9

[Hardy Heinlin]

Moved here from "Pit" subforum:

http://avherald.com/h?article=47f7b9f9&opt=1

http://www.dailymail.co.uk/news/article-2890093/Virgin-Boeing-747-flight-Gatwick-Las-Vegas-returns-airport-landing-gear-fault.html

landing video:

http://www.bbc.com/news/uk-30625945

RHS MLG not extended.....

fc

[Jeroen Hoppenbrouwers]

When you look at

https://www.youtube.com/watch?v=JoWS_SHe4gU

it seems that the touchdown is pretty hard, almost no flare. Could this be due to the pilots intentionally trying a bang to get the gear to release? Or due to hyd #1 being inop (the initial problem they returned for, I believe) and thus the controls being slightly unfamiliar and thus the flare being understeered?

Also, nice reverser slat retraction demo and just a few spoiler panels up.

Who is going to deliver the .situ?      :mrgreen:



Hoppie

[Hardy Heinlin]

Pretty hard, yes, I thought so too. Guess the final sinkrate is 1 wheel diameter in less than half a second, i.e. circa -400 fpm or more.

Another possible reason: If the aircraft would float too much, there wouldn't be enough inertia to compress the good gear strut down, and the aircraft would bank towards the missing gear at high speeds (it will bank later, when the aircraft slows down).

In the next PSX update, for such scenarios, I will push the wing on the good gear side a bit more up.

If anyone likes to reproduce this incident: in addition to the right wing gear extension malfunction, pull the circuit breaker C30 on P6; that will fail the alternate right wing gear extension as well.


Cheers,

|-|ardy

[United744]

Hi,

Incredible! Great landing!

Did the gear get stuck during retraction or extension? Seems it caught the door and got stuck during extension?

[John H Watson]

Could this be due to the pilots intentionally trying a bang to get the gear to release?

That would probably be the worst time to do something like this. With the bogeys compressed on the other gears, the faulty gear would drop only far enough to have the tyres rest on their sides and wouldn't move to the lock position and the wheels would probably drag on the runway.

If it was a hydraulic system problem, the gear should have gravity extended. I suspect something mechanical. By the looks of the wing gear door, something has broken off the end. (EDIT) Looking again, the door section is still there. The angle was misleading.

https://www.youtube.com/watch?v=ChPLaXqO0eQ

[Arkady]

I would guess it may have been an over weight landing.  It can be performed within certain guidelines (such as suitable runway/conditions, performing it smoothly!, not using auto-land & ensuring it is performed below the runway limited gross weight & landing climb limited gross weight) and many airlines/bean counters put varying amounts of pressure on crews to do them as opposed to dumping fuel even though we perhaps never get to do one (and are probably lucky to get to even try it in the simulator as it typically isn't included in most training programs due to time/money constraints).   Between the video and the g-meter record onboard mx will be going over this pretty thoroughly.  But the whale is a tough old girl.

[John H Watson]

Seems to be a #4 hydraulic problem

http://www.pprune.org/rumours-news/553657-virgin-landing-gear-incident-lgw-5.html#post8801645

[GodAtum]

just making a situ file. it wont be exact but ill try to get the gist of what happened.  However i cannot find the gear malfunction option, only a gear disagree one.

Flight tracker here

http://www.flightradar24.com/data/flights/vs43/#526ac78

Video with ATC: http://www.youtube.com/watch?annotation_id=annotation_1131974921&feature=iv&src_vid=zLpRu1EzyGE&v=ZqDP-FMgTy8

[CarlBB]

Hi...
Just discussing and had a thought about cabin crew and esp. if they would then serve anything else but more so, if they'd serve alcoholic drinks given that an evacuation of the aircraft upon landing is a strong possibility?
Any thoughts/knowledge in this area?
Thanks
Carl

[jonb]

There would be reduced braking action with one truck up so my thoughts would have been you don't want to float but you don't want to come down too hard either for  obvious reasons. It looks from what I've seen online like they dumped more fuel out of the right wing to stop it listing over on landing,interesting.

[GodAtum]

Ive uploaded a situ here: https://www.dropbox.com/s/8pm6fgkcq64v0sk/Xplane%20-%20EGKK%20-%20VS43.situ?dl=0

Climbing to FL320 out of EGKK - KLAS, approaching BEKSA waypoint. Gear disagree R wing armed for FL300 & circuit breaker C30 on P6 pulled. You'll have to plan a diversion and dump fuel as appropriate.

In my runtrhough, I used the WILLO3D STAR, dumped fuel at the GWC holding point, overflew EGKK 26L @ 2000 ft to let the engineers see what the problem was, then landed on 26L.

[Hardy Heinlin]

Perhaps one should add a hyd sys 4 fluid leak at a time after the TE flaps have been extended, so that the right outboard elevator fails before the flare.

In the real incident, the outboard TE flaps are fully extended, aren't they? Well, perhaps they are extended electrically? If so, hyd sys 4 and the right outboard elevator might fail earlier.

Note: The EICAS elevator display just shows the outboard elevators. When the right side fails on the display, it doesn't mean the right inboard has failed as well. It hasn't. Just the right outboard has failed. The other 3 elevator surfaces are intact. So, actually only 25% of the control authority is lost.


Note 2: Internet weather updating should be disabled in the situ. Does anybody know the respective METAR data?

[GodAtum]

thanks for the info. i dont think xplane simulates a landing gear failure as all mine were down when i landed, even though in PSX it said the R wing was UP.

[Hardy Heinlin]

GodAtum, in PSX that right wing gear is really up. You will also notice the yaw moment to the left in flight due to the asymmetric air drag.

In the real incident, although the the right outboard elevator is inop (and maybe spoilers 5-8 as well), hyd sys 4 still powers the lower rudder:

https://www.youtube.com/watch?feature=player_detailpage&v=JoWS_SHe4gU#t=40

It's difficult to reproduce this partial failure. It doesn't look like a total failure of hyd sys 4.

[John H Watson]

In the real incident, although the the right outboard elevator is inop (and maybe spoilers 5-8 as well), hyd sys 4 still powers the lower rudder:

The lower rudder is powered by two sources. (Sys 2 & 4)

The lower rudder can still be powered by system 2

Rgds
JHW

[Hardy Heinlin]

Ah, right, sure, of course ... :-)

So it can be reproduced by a total #4 hyd failure indeed.

Theory: As #4 hyd actuates both wing gear L & R, the final failure lies in the alternate right wing gear extension, i.e. not enough gravity, respectively mechanical blockage? I.e. one cannot "blame" #4 hyd as it lies in the nature of a depressurized #4 hyd that hydraulic extension is out of service.


|-|

[Jeroen Hoppenbrouwers]

Any guesswork on how close the #3 cowling came to touching the tarmac? From the video it seems less than the thickness of the cowling fairing... the point of lowest approach is not when touching down as the wings then still are providing lift, but when the speed drops low enough for the wings to sag and the aircraft is still moving, so waggling a bit. I would not be surprised to learn that the #3 cowl misses paint at the bottom (but is still serviceable).


Hoppie

[John H Watson]

Theory: As #4 hyd actuates both wing gear L & R, the final failure lies in the alternate right wing gear extension,

Correct. The Alt Extension system has one electric motor actuator per gear which has to perform a number of functions. Cables and cams are involved.

The electric motor released the doors successfully, but it looks like something got out of sequence. The process is quite complex:

"When the electric motor actuator is initially energised,

*A door safety valve connects door actuator ports to return [to prevent hydraulic lock]
*Lock keys in the electric motor actuator are disengaged allowing the door to start to open

The electric actuator is then de-energised by a switch on the [bogey] uplock mechanism, until the door is greater than 45 degrees open.

It [the electric actuator] is re-energised by door linkage sensor circuit, to drive the uplock hook open allowing the gear to free-fall to the DOWN and LOCKED position. A pair of springs hold the gear in this condition."

[Jeroen Hoppenbrouwers]

I witnessed the alternate extension test of a 757 recently, and saw how the right gear managed to hit (BANG!) the door on the way down. That led to a number of technicians hurrying to the mechanism and inspect the damage and the probable cause. These mechanical systems are very itchy to adjust, apparently.


Hoppie