Cargolux nose gear collapse in Shanghai.

[My 737]

The nose gear of TCV collapsed on the ramp as maintenace where working on the gear, no injuries but a bit of damage one would think, any news or pictures?
Brgds.

[SMOC]

Here you go :{

http://www.campus-site.nl/cargolux/

Let's hope they remember to remove the tailstand before they restore it to the level position.

[haughtney1]

someone forgot to put the lockpins in by any chance?:ugh:

[Hunter58]

Certainly makes boarding somewhat easier...

But how can you mix up an Antonov with a 747?

[Founder]

Does anyone know what happened to this aircraft? why did the nosewheel gear collapse? Airliners.net doesn't give a good explenation... =(

http://images.airliners.net/photos/middle/6/5/3/994356.jpg
http://images.airliners.net/photos/middle/5/5/3/994355.jpg

[Che Xindamail]

After towing, they tried to close the nose landing gear doors without gear pin in place. Don't know the exact procedure for closing the doors, I guess a bit of hydraulic pressure and ooops...

[Airbubba]

Yep, deja vu all over again...

http://aviation-safety.net/photos/displayphoto.php?id=19990815-I-0&vnr=2&kind=I

[nitro rig driver]

yes you need hyd pressure to close the doors but don't you don't need anypins in the gear----------

unless one puts the gear lever in the up position
then it does what says on the tin :uhoh: :uhoh:

[matkat]

There is a handle in the gear well to open/close the NLG doors if someone was operating this handle then they would be dead.From the pics it would appear the NLG retracted as it should with the doors opening as They should but contacting the ground,as a B747 engineer for many years I can assume one of 2 things occured either an accidental operation of the gear lever(unlikely as it has to be pulled out and raised)or more likely a problem with the gear handle module in that it was electrically disconnected and removed from the panel this operation release the down lock bungee and allows the gear to retract under the weight of the aircraft.

[nitro rig driver]

matkat
yes the maint handle for the ng doors in just outside the door hinge line (400)
classic is inside but they still be a lot shorter than before.
my guess is someone tryied to cycle the door using the gr lever-
all very well if ALL the pins are in.
also on a 400 no bungee cable-thinks that is only on the classic
but still pins in and CBs pulled etc

[matkat]

matkat
yes the maint handle for the ng doors in just outside the door hinge line (400)
classic is inside but they still be a lot shorter than before.
my guess is someone tryied to cycle the door using the gr lever-
all very well if ALL the pins are in.
also on a 400 no bungee cable-thinks that is only on the classic
but still pins in and CBs pulled etc
Nitro as You can probably understand all My time is on the classics(and -300s)sorry if any mistake in My post.

[crash gang]

http://www.airliners.net/open.file/592651/M/

[Taildragger67]

Wish I could dig up a shot of that forlorn-looking Ansett 747 sitting on 16R at YSSY when its NG failed to extend...

But wait!! I did: http://www.airliners.net/open.file/021003/M/

[superpilut]

Talk about a negative learning curve..:{

[Airbubba]

Just spoke with a mechanic in PVG who watched it happen.

He said the ground engineer was removing some box from under the panel and the box snagged on the gear lever when he pulled it out. Apparently the mains were pinned but the nosegear was not.

[SMOC]

Assuming he was removing the F/Os FMC. I'm not sure how he could 'snag' the gear lever, it has to be pulled out (extended) over an inch prior to lifting out of the 'DN' detent, plus you will have to press the LOCK OVRD button with your other hand to get beyond the 'OFF' position to 'UP'.

So there must be a little more to the story. :ok:
http://www.airliners.net/open.file/921999/L/

[Airbubba]

>>Assuming he was removing the F/Os FMC.

Uh, I don't know much about maintenance, but isn't that a CDU, not an FMC?

[JamesA]

SMOC
Airbubba is correct, it is a CDU, but often referred to as the FMC.

To remove the right CDU, it is necessary to raise the gear handle. Hence the warning in the Maintenance Manual to install all the gear pins prior to commencing a CDU. It is in fact repeated if it is the right CDU to be removed.

If this is the cause, it is not the first time nor I suspect the last. Heat of the moment, etc., I remember a couple of instances on DC-8s where promising careers came to abrupt ends due to the same reason except they were Carousels or similar in those days.

Just be thankful nobody was squashed.

[Taildragger67]

If Airbubba is right, this could've been lots nastier - all cycling up and the whole thing settling on its engines. Ouch.

[GearDown&Locked]

oh... they tune 747's suspension into a more sporty look now do they?

[Jordan D]

May sound a stupid question, but what's the situation with the aircraft and is it back on all its wheels (question coming from a SLF, so please don't flame).

Jordan

[Airbubba]

It was still taking a bow a couple of days ago for Chinese New Year. It's on the large cargo ramp north of the main terminal (I don't have my PVG Jepps handy). You can spot it a long way off since its tail is significantly higher than the other 74 tails on the ramp.

[CR2]

Back on its wheels as of yesterday. Repair time? Some say 6-7 weeks, depending on the condition of section 41.

I'm told the trouble started with nose-gear doors that wouldn't close. MLG pins were in, NLG (obviously) not.

[nitro rig driver]

Just spoke with a mechanic in PVG who watched it happen.
He said the ground engineer was removing some box from under the panel and the box snagged on the gear lever when he pulled it out. Apparently the mains were pinned but the nosegear was not.


CR2
there seems to be a difference of opinion then !!!

Matakat
no worries that's what forums are all about-"getting shot down";)

[CR2]

Differences of opinion are ok...

3 months repair is the lastest...

http://i44.photobucket.com/albums/f38/CR2747/TCVRecovery.jpg

[Taildragger67]

Is it just me, or does this seem to be a not-that-uncommon occurrence in 747s? Are other types similarly afflicted?

[Airbubba]

>>there seems to be a difference of opinion then !!!

CR2 probably has some very good sources, I sure don't have a different opinion.

I just got a brief sound bite from the ground engineer after arrival in PVG, seems like the part about the mains pinned but the nosegear wasn't is in agreement with what CR2 heard. The engineer mentioned that "all the breakers were pulled", maybe that was for the hydraulic problem. Another guy was probably trying to pull a CDU or something and somehow the gear handle was moved out of the way or bumped to the up position.

Since the aircraft didn't move for the pupose of flight and there were no injuries, the actual cause of this ground accident may never be made public even if the repairs run into the tens of millions of USD.

[CR2]

Airbubba: PM.

[RatherBeFlying]

You can see a band of wrinkles running up from the ground to under the heraldic shield:ouch:

Likely just the tip of the damage iceberg:uhoh:

[Good ROC]

This confirms what the old Sir Isaac Newton said about the 747´s
"you can not raise the gear whilst on ground, you can only lower the plane"
Sorry!

[FlyingConsultant]

Ok, another stupid SLF question:

Ehem, wouldn't it be easy to just not allow the gear to retract ever when the aircraft doesn't move? I assume this is a hydraulic system engaged via an electric signal (which might be wrong, ignorance speaking here)- why not have a movement sensor that blocks the signal if the a/c stands still? Install an override for testing in a stand etc.

That way, the default setting is save, you have to act when you go into the unsafe mode.

Just curious

FC

[sky330]

wouldn't it be easy to just not allow the gear to retract ever when the aircraft doesn't move?

It is done :) The gear cannot retract as long as the aircraft is on the ground via the ground/air sensor.

Problem here is that all securities had been by-passes for maintenance and/or errors and fall-back procedure (gear pins) had not been respected.

[FlyingConsultant]

Thanks, glad common sense exist in a/c design.

Still, Wow. It is unclear to me why this safety would be by-passed ever for on-the stand maintenance. Again, just an SLF, but it seems to me that the override should be a switch dedicated to the function, covered with a big sticker that says "only touch if you really want to move the gear while on the ground and/or you are certain you won't break anything if overriding this sensor".

[Swedish Steve]

In the days when I worked in the hangar, I never moved the gear lever out of down unless the nose jack was in place. I remember it vividley. It was a sacrosanct rule. Nose gears can retract so easily you cannot trust the downlock pin.
Last year I was visited by two young engineers from main base. They changed a main gear door jack. To test it they put in all the pins, hyds on then put the gear lever up. I could not believe it. I was so stunned I did not say anything.
Is this the way its done nowadays? Do we trust the downlock pins?
I don't.

[Kace]

@Good ROC:
Brilliant! So true!

@Taildragger67:
The mains probably wouldn´t have retracted even if the pins had not been in place. A huge force is required to overcome the friction of the tyres being moved sideways (ok, I know the body gear would move forwards, but still). Moreover, the wing gear´s outboard tyres and the body gear´s aft tyres would have to be moved downwards first in order to retract. Meaning the entire airplane would have to be lifted by the gear actuators! I´m not sure if they could manage that, especially if the airplane was loaded. I was taught on 737 maintenance that for this reason the main gears would not retract even if the handle was to be moved to up with hydraulic pressure available and no gearpins would have been installed. Ofcourse, I would never try this!

@Swedish Steve:
In my hangar days I do remember the cycling of a single 747 main gear while the other gears had locking pins in them. Those other gears were ofcourse pressurized as well but did not move a bit. So therefore I do think the downlock pins will hold quite nicely. Especially since the lock is in the overcenter position. But indeed, I would have the airplane on jacks as well before playing any of these games!

[sled dog]

Latest repair time ( via a friendly " mole " at CV ) is reckoned to be three months. Ouch ! :mad:

[crash gang]

Sounds about right, think that was the time taken to repair the EVA AIR 747 at Heathrow by BA Engineers.

[ARINC]

Not having any in depth knowledge of 747 systems, I'm still frankly astounded that you can retract the gear with weight on. I've always pinned the U/c of jets to prevent inadvertant gear up when they are jacked, and was thankfull on one memorable occasion when some joker tried to retract the gear with me still in the nosewheel bay of a Sea Harrier.

[Farmer 1]

Not having any in depth knowledge of 747 systems, I'm still frankly astounded that you can retract the gear with weight on.

Could not disagree less, ARINC. I've only operated one type with retractable undercarriage, and any weight on any of the wheels prevents them from being retracted.

I cannot come up with a reason for there ever being a need to retract the undercarriage while the aircraft is on the ground, with or without power; or imagine such an event without major damage being caused, and possibly injury or death. This is a Murphy if ever there was one.

Anyone?

[Volume]

I cannot come up with a reason for there ever being a need to retract the undercarriage while the aircraft is on the ground, with or without power

Sometimes it is helpful to have the option to override any logic. The guys in the Concorde would have been lucky if they would had the chance to override the ground sensor with the severed wiring and power the hydraulic system with two engines not running, just to get that damn gear up and the drag reduced.

If you safe one aircraft by the override mechanism, it is worth the dozen of aircraft sitting on the ramp with the gear retracted by some clever mechanic.

[Farmer 1]

But the difference is that in this incident the aircraft is on the ground, and the operating mechanism, as I understand it, is in the wheel bay.

Why does anyone need to enter a wheel bay and deliberately retract the undercarriage when the aircraft is not on jacks?

Am I missing something obvious? Please be gentle.

[nitro rig driver]

quote:
I cannot come up with a reason for there ever being a need to retract the undercarriage while the aircraft is on the ground, with or without power; or imagine such an event without major damage being caused, and possibly injury or death. This is a Murphy if ever there was one.

There are plenty of reasons to simulate a gear up situation on the ground and to actuly swing the gear with a/c on the ground.the big differance is one is done on jacks (normally) and the other is done FOLLOWING the maint manual procedures (boeing not only designed the plane but the maint manual aswell).things like replacing hydraulic valves or pipes will need tobe pressure/leak checked-this can be done without a full gear swing as most airports in the world will not have the jacks readly avail for your a/c type-and they are big expensive things to have or ship.
The downlock pins used by maint will stop the gr moving-fullstop.
due the overcentering of the mechenism they are not resisting the full power on the actuators

quote:
I cannot come up with a reason for there ever being a need to retract the undercarriage while the aircraft is on the ground, with or without power; or imagine such an event without major damage being caused, and possibly injury or death. This is a Murphy if ever there was one.

There are plenty of (maint) reasons to simulate a gear up situation on the ground and to actually swing the gear with a/c on the ground.the big difference is one is done on jacks (normally) and the other is done FOLLOWING the maint manual procedures (Boeing not only designed the plane but the maint manual as well).things like replacing hydraulic valves/actuators or pipes will need to be pressure/leak checked-this can be done without a full gear swing as most airports in the world will not have the jacks readily avail for your a/c type-and they are big expensive things to have or ship.
The downlock pins used by maint will stop the gr moving-fullstop.
due the over centering of the mechanism they are not resisting the full power on the actuators

hope this helps

[SMOC]

It is no simple method to get the gear up, it is a very deliberate action and the override system is installed as said for the benefit of the cockpit crew, so that in the event of a failure of the system to think it's off the ground the crew can have a quick check to ensure the gear is centered and in the tilt position and then in a two handed operation, remove the guard (classic) push the LOCK OVRD button (-400) and with the other hand pull (extend) the gear lever out to clear the detent and then lift it through OFF and into the UP detent.

These are some reasons to move the gear lever on the ground:
1. You want to check the retract system (put it on jacks select gear up) very impressive to watch.

2. You want to leak check the "UP" side of the system (put the down-lock pins in). Using the override, select gear up.

3. You want to check the gear doors (put the down-lock pins in). Using the override, select gear up.
There is a manual release for the doors (one left side of nose gear other left body gear wheel well), but they don't open hydraulically they just free-fall open then close hydraulically, this is why you will have to use the gear lever if you want them to open hydraulically.

4. You want to get the F/Os CDU/FMS which may foul with the gear lever (put the pins in). Using the override as well select gear to up or off.
The original CDU on the classic didn't foul with the gear as it was half as big and could be moved to avoid the gear lever.

So basically if you're going to deliberately move the gear lever, deliberately put the pins in.

[ARINC]

The guys in the Concorde would have been lucky if they would had the chance to override the ground sensor with the severed wiring and power the hydraulic system with two engines not running, just to get that damn gear up and the drag reduced.
.

Not quite sure of the relavence here.....That was Weight off



These are some reasons to move the gear lever on the ground:
1. You want to check the retract system (put it on jacks select gear up) very impressive to watch.
2. You want to leak check the "UP" side of the system (put the down-lock pins in). Using the override, select gear up.
3. You want to check the gear doors (put the down-lock pins in). Using the override, select gear up.
There is a manual release for the doors (one left side of nose gear other left body gear wheel well), but they don't open hydraulically they just free-fall open then close hydraulically, this is why you will have to use the gear lever if you want them to open hydraulically.
4. You want to get the F/Os CDU/FMS which may foul with the gear lever (put the pins in). Using the override as well select gear to up or off.
The original CDU on the classic didn't foul with the gear as it was half as big and could be moved to avoid the gear lever.
So basically if you're going to deliberately move the gear lever, deliberately put the pins in.

But surely all this is done on Jacks !!! No need whatsoever to have a live system with weight on...an accident waiting to happen

[Swedish Steve]

But surely all this is done on Jacks !!! No need whatsoever to have a live system with weight on...an accident waiting to happen
Well actually no. It is very common to move the gear handle with the downlock pins in and no jacks. The biggest problem is we don't have jacks on the line.
The problem with the B747 is that the nose gear downlock pin is out of sight. It is high up in the bay and the visual access is very poor, unless the fwd doors are open.
The other B747 problem is that it is a big aircraft. I am lucky, I work on the line by myself. If I put the pins in, they will stay in until I take them out. At a main base there will be many people working the aircraft at the same time, and if you select UP with hyd px on and someone else has removed the pin (or it has fallen out as happened at BA recently!), the nose gear will retract.

[Farmer 1]

quote:
I cannot come up with a reason for there ever being a need to retract the undercarriage while the aircraft is on the ground, with or without power; or imagine such an event without major damage being caused, and possibly injury or death. This is a Murphy if ever there was one.

Actually, that was my quote, and it was a bad one. I should have said, "while the aircraft is on the on the ground with weight on the wheels."

Despite the various attempts by some obviously very clever people above, I'm afraid I'm at the bottom of the class on this. I still fail to see how, if you have weight on the wheels and you raise those wheels, those wheels are actually going to rise. All I can see happening is the aircraft is going to sink. This is, after all, exactly what happened in this incident, and others. What is going to support the aircraft's weight? Weight on wheels, remember - no jacks.

If the preceding paragraph is, by some miracle, correct, then we return to question which I seem to have stolen: why should an aircraft have designed into it a system to raise the undercarriage whilst on the ground, with weight on the wheels?

Perhaps it should be called an aircraft lowering system.

[SMOC]

why should an aircraft have designed into it a system to raise the undercarriage whilst on the ground, with weight on the wheels?


They haven't, the system is designed so to stop the gear from being selected up if a body gear is not centered or if the gears are not tilted, if either of these is the case the gear, wheel well and landing gear doors will be damaged which may result in a hydraulic leak/loss.

The fact the A/C is on the ground means the gear is not tilted and therefore means the gear lever is prevented from being selected up.

The OVRD system is installed to allow the flight crew to select the gear up in case the gear lever is prevented from being selected up after checking the gear is centered and all the main gear are in the correct tilt position. i.e. a failure in the gear lever lock system.

So basically it's a maintenance procedure to use lock override as a way to function test those items that are used during gear up selection.

Hope that helps Rgds SMOC.

[Farmer 1]

By George, I think I've got it!

SMOC, and others, thank you. I'm sure your patience will be rewarded in heaven.

Farmer.