IAH We Have A Problem: UA 767 Gear Collapse (pics)

LAXintl · Fri Aug 16, 2013 3:52 pm

According to United spokesperson -
During routine overnight maintenance the nose gear of a 767-300W collapsed while parked at the gate.

Link with photos:
http://www.nycaviation.com/2013/08/p...apsed-at-gate-at-iah/#.Ug5F5pL-mm4

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StTim · Fri Aug 16, 2013 3:59 pm

Oops.

Some Technician will have some explaining to do.

codc10 · Fri Aug 16, 2013 4:16 pm

Fortunately, nobody was under the aircraft when the gear collapsed. Could have been much, much worse.

0newair0 · Fri Aug 16, 2013 4:19 pm

Mechanic A: Did you put the gear pins in?
Mechanic B: Yeah, sure did!
Mechanic A: Ok, Gear up
Mechanic B: Oh F*ck!...

Inbound · Fri Aug 16, 2013 4:20 pm

Aww, I'm sure they'll eventually find some pilots to blame for this LOL
At least no one injured.

peterinlisbon · Fri Aug 16, 2013 4:21 pm

Someone fkkkd up for sure. Probably moved the landing gear switch assuming that the ground-mode protection would work and it didn't. At least the damage doesn't look too bad - the engines didn't touch the ground, and it probably came down softly so probably just some scrapes to the bottom of the nose, plus the landing gear I guess.

F9Animal · Fri Aug 16, 2013 4:27 pm

I have a question!! I have ridden brakes many times when towing planes. Never thought once of touching anything, besides what I was trained on. However, while training newbies on the process, I always wondered, what would happen if someone hit the landing gear lever?

LZ129 · Fri Aug 16, 2013 4:35 pm

Reminds me a lot of this incident a few years back here at FRA: http://www.fotocommunity.de/pc/pc/mypics/712194/display/5685377

readytotaxi · Fri Aug 16, 2013 5:03 pm

Quoting peterinlisbon (Reply 5):
Probably moved the landing gear switch assuming that the ground-mode protection would work and it didn't.

I would like to ask a couple of questions.
Ground-mode protection, is this fitted to all aircraft Boeing/AB to prevent such accidents?
If someone moved the landing gear lever to up, why only the nose retract and not main under carriage attempt to retract?

pygmalion · Fri Aug 16, 2013 5:18 pm

yes all Boeing aircraft have ground mode protection.

The nose gear folds in the direction the tire rolls so there is relatively little resistance. The main goes up sideways and would have to drag the tires sideways, It could happen on ice but not on dry or wet pavement. There just isn't enough force in the landing gear actuation system for that.

readytotaxi · Fri Aug 16, 2013 5:34 pm

Quoting Pygmalion (Reply 9):
There just isn't enough force in the landing gear actuation system for that.

What would follow that course of action, the motor/pump would try and then burn/fail out?

pygmalion · Fri Aug 16, 2013 5:40 pm

No, nothing would happen actually. the actuator would just push against the gear but its not enough force to move it against the airplane weight. The hydraulic system has cooling etc and just supplying pressure wont make it overheat. The pumps maintain 3000 psi while they are on as part of their normal operation and vary flow based on demand. Its designed to operate this way.

readytotaxi · Fri Aug 16, 2013 5:42 pm

Quoting Pygmalion (Reply 12):

Thank you.

litz · Fri Aug 16, 2013 5:46 pm

At least this was a 767... This has happened on other models, and the jetway rips the door off.

kgaiflyer · Fri Aug 16, 2013 5:57 pm

Quoting 0NEWAIR0 (Reply 3):
Mechanic A: Did you put the gear pins in?
Mechanic B: Yeah, sure did!
Mechanic A: Ok, Gear up
Mechanic B: Oh F*ck!...

You think that couldn't happen?

I was on an Atlantic Coast Airways CR2 flying as United Express -- IAD-BNA -- one Sunday morning when we circled after takeoff and landed again. The pilot came out of the cockpit and explained that the landing gear was locked down and couldn't be retracted. For the inconvenience, the FA gave us *all* the Nutri-Grain bars we could eat and *all* the instant coffee with powdered creamer we could drink. The paperwork took less than an hour.

[Edited 2013-08-16 11:03:37]

DocLightning · Fri Aug 16, 2013 6:16 pm

The link in the OP says that UA used the word "collapsed."

To me that implies a gear failure and not necessarily human failure.

0newair0 · Fri Aug 16, 2013 6:20 pm

Quoting kgaiflyer (Reply 15):
I was on an Atlantic Coast Airways CR2 flying as United Express -- IAD-BNA -- one Sunday morning...

It's worse when it's on a DL int'l flight and the aircraft has to circle around Bumblef***, Georgia trying to get below max landing weight so someone can take the pins out. The fear that comes over the mechanics face when the radio call is made is slightly amusing.

[Edited 2013-08-16 11:23:33]

AA737-823 · Fri Aug 16, 2013 7:24 pm

Quoting DocLightning (Reply 16):
To me that implies a gear failure and not necessarily human failure.

Yes, but notice that the nose wheel doors are OPEN (and now crushed), while they'd normally be SHUT.
So something had caused the gear sequence to start, unless maintenance had them open by coincidence, yet no one standing there on a ladder to get injured...

migair54 · Fri Aug 16, 2013 7:42 pm

Quoting litz (Reply 14):
At least this was a 767... This has happened on other models, and the jetway rips the door off.

Or if this happens to a B787 it will be all over the news in few mins.....

Quoting Pygmalion (Reply 9):
yes all Boeing aircraft have ground mode protection.

All the planes nowadays have that, WOW (weight on Wheels protection) but sometimes for maintenance they have to override, put the plane in flight mode.

I know another case, During a check on the hangar, a plane was being tested for some issues and the WOW was out of protection, so they were trying some system like flaps, they after setting all the different positions the engineer outside command to the one in cockpit to put them up, and the engineer set the gear up instead of the flaps, you can imagine

kanban · Fri Aug 16, 2013 7:45 pm

remember nothing is fool proof because fools are becoming more ingenious all the time

CF-CPI · Fri Aug 16, 2013 7:59 pm

Do we have a registration for this unfortunate 767? I wasn't able to download the pic, and it's hard to read off the original site. Maybe someone's got good eyesight.

sankaps · Fri Aug 16, 2013 8:11 pm

Quoting migair54 (Reply 19):
Or if this happens to a B787 it will be all over the news in few mins.....

And that would have nothing at all to do with the proven track record and installed base of the 767 compared to the 787, as well as recurring glitches in the 787 that all appear to tie back to design / manufacturing / QA issues of course.

calpsafltskeds · Fri Aug 16, 2013 8:19 pm

I believe it's N674UA, which arrived in IAH last night with no further activity. There was a ferry IAH-SFO today that cancelled. Don't know if the ferry was scheduled prior to the incident or not.

KELPkid · Fri Aug 16, 2013 8:26 pm

Just look on the bright side...

One less 767 in UA's fleet

(well, if the plane wasn't moving, the odds are pretty good that the repair costs won't exceed the fair market value...) So maybe it will just be out of service for several weeks instead.

Viscount724 · Fri Aug 16, 2013 8:41 pm

Not the first time.

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Photo © Frank skinner

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Photo © Andy Muir

Valcory · Fri Aug 16, 2013 8:52 pm

Quoting peterinlisbon (Reply 5):
Someone fkkkd up for sure. Probably moved the landing gear switch assuming that the ground-mode protection would work and it didn't.

You need to have hydraulics on and the gear handle in the up positiion for the gear to go up. Even with hyd on you have to use the gear overide switch to get the gear handle up.

CF-CPI · Fri Aug 16, 2013 8:56 pm

Quoting CALPSAFltSkeds (Reply 23):
I believe it's N674UA

This is one of their last 767-322 deliveries and would have been a two-class Hawaii ship in 'battleship' colors. There's a recently-issued Gemini 1/400 model of it, complete with winglets.

flylku · Fri Aug 16, 2013 9:38 pm

There is one fool proof solution to this: go back to fixed gear.

If this was N674UA I was just on it a couple weeks ago: FRA-EWR. Surprised me that it was a two class config but then I thought maybe it was CO metal.

CcrlR · Fri Aug 16, 2013 9:44 pm

Quoting F9animal (Reply 6):
I have a question!! I have ridden brakes many times when towing planes. Never thought once of touching anything, besides what I was trained on. However, while training newbies on the process, I always wondered, what would happen if someone hit the landing gear lever?

If someone actually pulls the lever up on the ground, nothing will happen. First, there is a locking system to keep someone from raising the lever(and if needed, it can be raised on the ground by disabling the locking system), and there is weight on wheels sensors as well that would keep the gear from going up. You can also disable that too by pulling circuit breakers and the aircraft will think it is in the air. There has to be something the crew/mechanics did to make the nosegear unlock on the ground. The company's investigation should shed light on what happened.

par13del · Fri Aug 16, 2013 9:52 pm

Quoting litz (Reply 14):
This has happened on other models, and the jetway rips the door off.

I was looking the the open door and wondering whether the jet bridge was actually in contact with the a/c at the time of the collapse.

KC135Hydraulics · Fri Aug 16, 2013 10:57 pm

Maybe it was a simulated retraction gone bad. On the KC-135 we can check various landing gear components for leaks in some situations, without having to jack the aircraft. We call it a simulated retraction because HYD pressure is ported to start the gear retraction sequence, but the gear does not actually retract because the pins should be installed. Since there is weight on wheels, we need to use the override trigger on the handle to actually raise the gear handle to the up position.

The mains aren't such a worry but the nose is critical. It has folded up many times on Tankers. The pin absolutely must be in or the nose will drop. It's an IPI step (in process inspection) step to verify all the pins are installed prior to doing this task.

Could be a leak check gone bad!

Norcal773 · Fri Aug 16, 2013 11:33 pm

Quoting kanban (Reply 20):
remember nothing is fool proof because fools are becoming more ingenious all the time

This is the best quote on this thread! Kudos.

Goldenshield · Fri Aug 16, 2013 11:42 pm

Quoting 0NEWAIR0 (Reply 17):
Quoting kgaiflyer (Reply 15):I was on an Atlantic Coast Airways CR2 flying as United Express -- IAD-BNA -- one Sunday morning...
It's worse when it's on a DL int'l flight and the aircraft has to circle around Bumblef***, Georgia trying to get below max landing weight so someone can take the pins out. The fear that comes over the mechanics face when the radio call is made is slightly amusing.

This is why many carriers have added "GEAR PIN --- CHECKED (STOWED)" to their originating checklists.

[Edited 2013-08-16 16:42:50]

winstonlegthigh · Sat Aug 17, 2013 1:57 am

Quoting Viscount724 (Reply 25):
Not the first time.

The cushion/padding under the CV 744 is an especially nice touch.

Quoting kanban (Reply 20):
Remember, nothing is fool proof because fools are becoming more ingenious all the time.

How true. Well done.

[Edited 2013-08-16 19:02:23]

CALTECH · Sat Aug 17, 2013 2:04 am

Quoting Inbound (Reply 4):
Someone fkkkd up for sure. Probably moved the landing gear switch assuming that the ground-mode protection would work and it didn't.

A push of the Lock Override would allow the LG lever to be put in the Up Retracted position.

Quoting F9animal (Reply 6):
I always wondered, what would happen if someone hit the landing gear lever?

If there is hydraulic pressure, nose will retract, mains will not on landing gear with at least 2 tires per axle. Now if the airplane has only one main tire per landing gear, they probably could retract.

Quoting readytotaxi (Reply 8):
I would like to ask a couple of questions.
Ground-mode protection, is this fitted to all aircraft Boeing/AB to prevent such accidents?
If someone moved the landing gear lever to up, why only the nose retract and not main under carriage attempt to retract?

There is a Lock Solenoid that does not allow the LG lever to move from the Down and Locked Extended position with the WOW activated. But there is a manual Lock Override that takes just a simple push to override the Lock Solenoid however.

Quoting Pygmalion (Reply 9):
The main goes up sideways and would have to drag the tires sideways, It could happen on ice but not on dry or wet pavement. There just isn't enough force in the landing gear actuation system for that.

Do not believe it could even happen on ice. The 737 when it is up on jacks, needs about 4 inches of clearance between the tire and the ground so the outboard tires can clear the ground as the outbd tires swing approximately 4 inches below their starting point. With the 767 Wheels being farther apart, the clearance needed is more than the 737. Those actuators do not have enough power to lift the weight f the airplane.

Quoting migair54 (Reply 19):
All the planes nowadays have that, WOW (weight on Wheels protection) but sometimes for maintenance they have to override, put the plane in flight mode.

Do not believe the airplane needs to go into AIR Mode to retract the gear, just use the LG Lever Lock Override.

Quoting Valcory (Reply 26):
You need to have hydraulics on and the gear handle in the up positiion for the gear to go up. Even with hyd on you have to use the gear overide switch to get the gear handle up.

AVENSAB727 · Sat Aug 17, 2013 2:31 am

Will the 767 be fixed?

CONTACREW · Sat Aug 17, 2013 2:36 am

Quoting AVENSAB727 (Reply 36):

Yes it will be fixed aircraft will be out of service for a while.

EK345 · Sat Aug 17, 2013 2:43 am

Is the L1 door missing!?

EK345

Moose135 · Sat Aug 17, 2013 2:48 am

Quoting CF-CPI (Reply 27):
This is one of their last 767-322 deliveries and would have been a two-class Hawaii ship in 'battleship' colors.

You can't see the N-number in the linked photos (and I haven't found anymore about it) but the incident aircraft is in the new post-merger colors.

United1 · Sat Aug 17, 2013 3:01 am

Quoting EK345 (Reply 38):

Is the L1 door missing!?

Doubtful....the L1 door lifts up into the fuselage...that's how it looks when it's open.

aerorobnz · Sat Aug 17, 2013 3:11 am

Quoting EK345 (Reply 38):
Is the L1 door missing!?

767 aircraft hv internal lifting doors, not external swing doors. No damage there thankfully

SXDFC · Sat Aug 17, 2013 3:30 am

IAH We Have A Problem... Surely you can't be too serious?

Quoting CF-CPI (Reply 21):
Do we have a registration for this unfortunate 767?

Picture seems to indicate that the registration was N67*UA, someone said it might be N674UA.

Quoting KELPkid (Reply 24):
Just look on the bright side...

One less 767 in UA's fleet

Could have been worse.. could have been another 787!

aerorobnz · Sat Aug 17, 2013 3:48 am

Quoting SXDFC (Reply 42):
IAH We Have A Problem... Surely you can't be too serious?

Deadly serious, and don't call me Shirley.

Imagine if it was a 787...the media would have a field day..lol

toltommy · Sat Aug 17, 2013 4:00 am

Quoting par13del (Reply 30):
I was looking the the open door and wondering whether the jet bridge was actually in contact with the a/c at the time of the collapse.

Aside from the autolevel, the jetbridge should never be in contact with the aircraft. Mind the gap!

Grisee08 · Sat Aug 17, 2013 6:05 am

And just where the hell was THIS GUY when all this occurred?

tcfc424 · Sat Aug 17, 2013 9:16 am

So...I was just a ramp rat, but aren't the pins that are placed upon aircraft arrival and removed after pushback designed to prevent this? I used to ride brakes as well and never even considered touching anything other than what I was trained on in the cockpit...it was tempting though!

All of that in mind, if they were performing maintenance at the gate, I would assume the jetbridge was up to the aircraft given the absence of airstairs. If they were not on board, however, it is common practice to retract the jetway for RON aircraft after it has been serviced and secured for the night.

Sad to see such a beautiful aircraft on its face...same with the Lufthansa pic.

AA737-823 · Sat Aug 17, 2013 9:32 am

The amount of misinformation here is getting disturbing.

I can speak to AT LEAST the 737 (all generations) and 747:
When you override the gear handle latch, THE GEAR WILL COME UP.
There is no "WOW" sensor that disables the gear. In general, engineers try to keep the landing gear system as simple as possible, because we like for it to work, and having an additional relay in the AIR/GND logic loops simply adds unneeded complexity.

We do this procedure to leak check the lock actuators fairly frequently. Put in the pin. Turn on hydraulics. Raise the gear handle. HISS! Fluid starts flowing.

celestar345 · Sat Aug 17, 2013 11:09 am

If my memory serves me right, the weight on wheel sensor, which in turn goes into the air/ground relay system doesn't affect the activation of landing gear extension/retraction, which is another reason why the landing gear downlock pin must be installed! So if procedures are not followed or someone being too curious and decided to play around and touch everything in the cockpit... hmm...

Where I work we always say "The black boxes inside the aircraft creates mysteries and causes many things that cannot be explained by human knowledge"... Over the years we have incidents even Boeing will scratch their heads... ( RAT uncommand retract... overwing slide auto deployment...)

But human stupidity beats it everytime... the best story we had was that due to one word in Cantonese language of saying 'CORRECT' sounds exactly the same as the English word "ARM', a newbie asked his supervisor whether he can open the cabin door and got the reply "Make sure it is in the correct position before opening".

Well I am sure you guys can all guess what's next....

xjet · Sat Aug 17, 2013 11:55 am

Just as background, the 767 doesn't use WOW for the main gear to determine ground or flight mode. It is actually part of the tilt mechanism on the main gear trucks. When the gear is tilted forward the plane is in the air... The nose gear does have a strut compression sensor but it only deals with stall warning and caution message logic for the most part. The gear handle solenoid is based on the tilt of the main gear. You can actually hear these click once the mains leave the ground. The override switch is there to release the solenoid in a case of air/ground logic failure to allow putting the gear down in flight. As has been mentioned by most, this is likely a case of a gear pin whoopsie. I could see how it would be possible to see the flag for the steering bypass pin and think that the nose gear retraction pin is installed.

msp747 · Sat Aug 17, 2013 1:29 pm

Quoting United1 (Reply 40):
Doubtful....the L1 door lifts up into the fuselage...that's how it looks when it's open

Quoting aerorobnz (Reply 41):
767 aircraft hv internal lifting doors, not external swing doors. No damage there thankfully

This seemed to be a popular design in the 70's, with it appearing in the DC-10 and L1011 too. Any reason manufacturers went away from it? Too maintenance intensive? Unreliable? Just Unnecessary?

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