LH 744 TK nose gear down

[Profit Max]

Uli reports on flyertalk:

"some minutes ago the nose gear of LH 744 TK broke down. Pax bound for DEL had already boarded. TK was still at the gate.

744 now sittings on her nose at the gate.
Hope seat bealts were applied already.

happened at FRA during push back"

Profit Max

[Charles Darwin]

happened at FRA during push back

Hope the tug driver is ok.

[rotornut]

Lufthansa jumbo jet collapses on nose at Frankfurt
Mon May 15, 2006 3:12 PM ET

FRANKFURT, May 15 (Reuters) - A Lufthansa AG jumbo jet collapsed on its nose at Frankfurt airport when the front landing gear gave way as it was preparing to fly to New Delhi, an airline spokesman said on Monday.

The 242 passengers and 16 crew members on board the Boeing 747-400 had to abandon the plane after the nose sank down onto a waiting tow truck.

"No one was injured. Everyone was able to leave the aircraft via the passenger bridge," the spokesman said.

The passengers were being put up in Frankfurt hotels on Monday night and were due to take a different flight to New Delhi on Tuesday morning. The original flight -- LH760 -- had been due for takeoff at 1150 GMT Monday.

"The cause of the fall is not yet known. It's very unusual," said the spokesman.

The plane was relatively new and had been delivered to Lufthansa in December 2001.

The spokesman added that the incident had been reported to German air accident investigators.

Boeing spokespeople in Berlin and Brussels were not immediately reachable for comment.

[lamer]

idle chit chat and pics here (http://www.airliners.net/discussions/general_aviation/read.main/2772612/)

http://img459.imageshack.us/img459/1993/dabtknosegearcollapsed011pi.jpg

http://img179.imageshack.us/img179/6725/dabtknosegearcollapsed023mr.jpg

[Captain Airclues]

LH use the tugs that lift the nosewheel clear of the ground before pushback. Does anyone know if there is any form of 'weak link' release mechanism on this type of tug in case of a pushback with the brakes applied? I'm not saying that this is what happened, I'm just interested to know what would happen if it did.

Airclues

[Intruder]

Since the 747 nose gear retracts forward, even such a weak link would not work when pushing "back".

AFAIK, there is no such weak link on the 747 itself or any other airliner. There IS a weak link in the tow bar normally used with a conventional tug, but I don't know if there is such a mechanism in the sort of tug that lifts the nosegear.

[The Bartender]

The shear-pins (the weak link) on a conventional towbar will not prevent the tug-driver from ripping the nosegear out of the airplane. The shear-pins are there to prevent the towbar from trying to turn the nosegear if the steering is pressurized, or to turn the nosegear past maximum angle.

As for pushing and pulling, the aircraft will either move it or loose it...

Ever stomped on a beer-can? That's the sound right there.. Horrible.. :uhoh:

[GotTheTshirt]

Bartender,
That is exactly what the tow bar shear pin does. It stops the tug from ripping the nose leg out if for example the brakes are on. The "head" latches onto the nose gear and that is connected to the towbar by the shear pin.
If the shear load is exceeded the Tug goes on its merry way with the towbar leaving the head firmly attached to the nose leg.
I had one shear one night and the head dropped down onto the tarmac but before the guy could hit the brakes the head dug into the tarmac and jacked the nose wheels clear of the ground :}
Some towbars have a secondary link that prevents the head from becoming completely detached. Probably to avoid just that !:)

[Capt Claret]

About a year or so ago, a VirginBlue 73 had its nose wheels lifted off the ground during push back at YPDN.

The story I heard through the grapevine was, that some weeks prior a "pushback person" replaced a sheared shearpin with a bolt and forgot to remove the bolt. On the night of the incident the pushback commenced with the brakes still applied, and the nose wheels were lifted clear of the ground as the aircraft rotated about the main wheel axles.

I believe the aircraft ferried to BNE for inspection with the gear down, after blocking one of only three aerobridges for most of the ensuing day. :eek:

[klink]

It's not a good time for the 747 nose section these days:E

[flyerire]

Looking at the damage in those pictures, i would say that unfortunately this plane will be a write off!:{

[The Bartender]

Some towbars have a secondary link that prevents the head from becoming completely detached. Probably to avoid just that !:)

That's the one, and it is not designed to fail on the designs i've seen... The result is that the shear-pins give protection for the steering and max angle, but the bolt keeping the head attached to the towbar will not prevent pushing or pulling the nosegear out of the aircraft..

[Taildragger67]

Looking at the damage in those pictures, i would say that unfortunately this plane will be a write off!:{

Mate if they got VH-OJH (the Bangkok golf cart) going again, this'll be a very small bit of panel work by comparison.

[lasernigel]

Isn't this the Germans just practising their nose dive routine before the World Cup??:ok:

[cjhants]

bartender,

most towbars (and all large aircraft bars such as B747) have two types of shear pins. axial which shear when the turn pressure is too great, and torque which shear when the straight line push or pull is too great.

so if you push when the brakes are on the torque should shear before damage to the gear. not an expert in towbarless tugs, but somebody from douglas, goldhoffer etc must lurk on here.

[RevMan2]

A poster on airliners.de (quoting "usually well-informed LH sources"...) reports that the nose gear gave way during a leak check being performed on conclusion of some hydraulics repairs. All this immediately prior to push-back (or lift-and-carry-back in this case).

[JW411]

I remember going up to the viewing deck at FRA some years ago with my lad who was beginning to show an interest in aviation (he is now doing his ATPL).

One thing that raised my eyebrows that day was the sheer speed at which the LH tug drivers were pushing aircraft back including 747s. Michael Schumaker would have found it difficult to keep up.

I have no idea of how many thousands of times I have been pushed back since 1978 and I was quite frankly astonished.

Has anyone else out there noticed this phenomenon?

[Captain Airclues]

I agree JW. They seem to be faster at FRA than in other places which is why I was interested to know about the 'weak link' sysem on these tugs. Not as dangerous as doing the external checks on the FRA cargo ramp at night though. :ouch:

Airclues

[Charles Darwin]

Yesterday a tugdriver clocked 10 knots on the IRS, pushing my 752. A bit on the faster side, I´d say. At CDG, Paris.

[DBate]

Checks were performed on hydraulic system one. The gear lever was selected up according maintenance procedure. You all know what happened thereafter.

Nobody was hurt, passengers left the aircraft via the airbridge, the tugdriver saw it coming and rushed out of his truck.

Aircraft is now in the hangar, further checks are being performed to access the damage and find out what went wrong.

[Taildragger67]

passengers left the aircraft via the airbridge,

... which one suspects was now a tad higher than the door sill?

And what condition was the door itself in at this stage? I've heard that contretemps between doors & jetways usually go in favour of the latter.

[ExSimGuy]

Isn't there a "Weight On Wheels" function input to the gear system that won't allow the gear to be retracted on the ground?:confused:

[spannersatcx]

Isn't there a "Weight On Wheels" function input to the gear system that won't allow the gear to be retracted on the ground?:confused:

Yes but you can override it.

[hetfield]

Maybe the german hydraulics are a little stronger than usual.

[ExSimGuy]

Yes but you can override it. Only reason I can think that you'd want to override it was if the aircraft was on a jack - but then there'd be no WOW and you wouldn't need to override it:)

or am I missing something?

(going back to my experience of 707's and 74/4 and 74/3 , many moons ago!)

[Joetom]

Just for info.

The QF744 in BKK was repaired at greater cost than value of aircraft pre accident, Insurance picked up value tab and QF paid the rest to avoid the term Hull Loss, interesting to know tab that QF picked up.???

[DBate]

Nosegear Safety Pin fitted correctly?


According to my information the Safety Pin was fitted. A mechanic told me that the pin seemed to have sheared. I don't know if that is possible or not.

I guess we have to wait for the official BFU report.

[goforjoli]

According to my information the Safety Pin was fitted. A mechanic told me that the pin seemed to have sheared. I don't know if that is possible or not.

I guess we have to wait for the official BFU report.

:confused: given the correct pin, the chance to get it sheared is.......

[CR2]

http://i8.photobucket.com/albums/a40/greenlander/IMG_2256.jpg

http://i8.photobucket.com/albums/a40/greenlander/IMG_2259.jpg

http://i8.photobucket.com/albums/a40/greenlander/jumbo2.jpg

http://i8.photobucket.com/albums/a40/greenlander/jumbo1.jpg

[Sleeping Freight Dog]

Thanks CR2 for the close up photos. It appears there is quite significant
fuselage damage to the forward portion of the aircraft. Wouldnt be
surprised if this bird becomes a hangar queen for next few months.

[blueloo]

jOETOM - Think you will find that the insurance company dictated whether aircraft was repaired or not. Also think you will find the rest of your details a tad skewed.

[Bangkokeasy]

The damage is not nearly as severe as that incurred to the Bangkok golf cart. I can't recall what was paid out to repair that (there were a lot of figures bandied about at the time and it should be possible to find out), but I am fairly sure jOETOM's information is roughly correct. The repairs to that bird included 3 new engines, a new forward fuselage and wing repairs. For this one, the engines and wings would seem to be untouched for a start.

[Plastic Bug]

Don't know about you guys, but something doesn't look right from those pix.
If the airplane was just sitting there humming along with a tug and towbar hooked up, and someone threw the gear lever up with hyds pressurized (utilizing the override), the airplane would only fall about 4-6 feet. If the nose gear came up.
The idea being that the tow bar/tug combo should sorta stop the nose gear from moving forward. Not sure of the tug there, but it's gotta weigh at least 40,000 pounds. Round number there, but that sort of tug is usually HEAVY.
That sure looks like a LOT of damage from a let's say 8 foot fall from a static position. Heretics may believe that the 747 is made from tin foil, but I can say with some knowledge that the airplane is just a bit tougher than that.
We have the photos that show the result of whatever happened, that is not in question. That the lower section basically pancaked when it "fell" on a tractor? Well, there has to be more to this than we will probably ever know.
Conjecture...
It's all geometry. Draw a picture of the nose of an airplane with a nose gear sticking down. Attach a towbar to the gear and a tug. Now, try to move the gear forward and see what happens to the angle of the towbar and the gear considering that the airplane and the tug don't move.
The towbar and gear would act like a jack until the shear pins on the bar failed. Then...KA-WHUMP!
The question I have is: Considering that there SHOULD have been some sort of downlock pin installed (hopefully, a real one), what is the likelyhood that the downlock pin would fail and the hydraulics would have enough oomph to overcome the static force of the presumably chocked/braked aircraft and the braked tug to allow the aircraft to raise up and come down on the aforementioned tug?
Again, we have the pictures, so I'll leave you with this: Just because the likelyhood of something bad happening is most extremely remote, it doesn't mean that it probably won't happen.
I must tell you that I, as an Engineer, have in the past grasped the gear handle with hydraulics pressurised and raised that handle to the UP position whilst on the ground.
I haven't landed an aircraft yet.
It is a most unnerving thing to do, but there are occasions where the procedure is a welcome alternative to dragging the aircraft into the barn and jacking it up. Follow the procedures, use the correct equipment and it's unnerving but perfectly safe.
Weird stuff happens, ya just can't avoid it.
PB

[threemiles]

The tug has a cutout in the middle. The fin that you see is very slim. The plane fell into the cutout.

[Charly]

This aircraft is in service again. Probably looked worse that it was. :}

[threemiles]

The cut out is to catch falling aircraft.:}
However I would like to know why the gentleman in the second photo is carrying very small road cones around?
If the a/c as has previously been stated is back in service is this counted as a small incident, hence the small cones...I hope never to see any larger cones.:suspect:

Plane catching tug cut outs, small road cones and sunglasses, though we know that there is no speed limit in this country and the sun never shines - very strange, you're right, I didn't realize _all_ the details

[spannersatcx]

The control handle is provided with a landing gear lever lock to prevent movement to the gear UP position, when the airplane is supported on the gear.

The landing gear lever lock can be bypassed by depressing the lock overide button.

This manual overide can be used when performing certain tests or in an emergency.

[DBate]

Original posted by Charly:
This aircraft is in service again. Probably looked worse that it was.

The aircraft is definitely not back in service.

Regards,
DBate

[golfyankeesierra]

Perhaps Charly ment: "the tug is back in service"?

[Charly]

Yes, your right, the AC is not back in service. Just checked the Intranet. I copied a message from one of our collegues without crosschecking.

[a123]

This is why you should report heavy landings !!!!!

Poor training and egos they thought they were the best dont blame the aircraft now you pimpals.

[Charly]

Don't mention the war.


War? What war? :}

Heard, that the same thing happened to a Northwest Airline years ago. The nose wheel pin doesn´t seem to be designed too mechanic friendly....

[Airbubba]

>>Heard, that the same thing happened to a Northwest Airline years ago. The nose wheel pin doesn´t seem to be designed too mechanic friendly....

Northwest had a 747-200 nosegear collapse at Changi (SIN) a few years ago. Maintenance had substituted an Airbus gear pin (like everything thing else, they are thinner and lighter than the Boeing part). The gear pin had a locally improvised handle attached and the handle caught the gear door when the door cycled for a ground test. Luckily, no one was injured...

[dixi188]

Same thing happened at Gatwick in about 81 or 82 to Northwest 747. Incorrect nose pip used. Also Northwest had a turbine failure the same day at LGW.

[DBate]

Dislodged lock-pin led to Lufthansa 747 nose-gear collapse
David Kaminski-Morrow, London (01Jun06, 15:16 GMT, 222 words)

German investigators have discovered that the nose-gear door of a Lufthansa Boeing 747-400 dislodged a locking pin during a hydraulic test, causing the gear to retract while the aircraft was parked at a Frankfurt Main gate.

The nose-gear retracted while the aircraft was preparing for pushback at Frankfurt, ahead of operating a service to Delhi, on 15 May. The 747’s nose settled onto the pushback tractor and the jet’s forward fuselage underside suffered heavy damage.

Preliminary examination of the aircraft by German investigation agency BFU has revealed that the aircraft was undergoing a test of its hydraulic system following indications of a leak.

As part of the test a locking pin was inserted into the nose-gear strut to prevent retraction while the landing-gear retraction mechanism was activated from the cockpit.

But a spokesman for BFU says that the movement of the nose-gear doors led to the pin’s becoming “disconnected” from its position. While the pin remained intact, he says, it was no longer able to prevent the nose wheels from retracting.

BFU is studying the design of the pin which, says the spokesman, had not been supplied by Boeing but which had been specially-made.

Boeing is to assess the damage to the aircraft, a five-year old example registered D-ABTK. There are no indications as to when the 747 might return to service.

Source: Air Transport Intelligence news

[JamesA]

Thx for the info DBate. Once again use of wrong equipment, pressure to do a quick job and the whole thing goes to the dogs. I was involved in the follow up to a similar situation three or four years ago. The lads were working a landing gear problem in TLV, and it was hurry, hurry. No correct nose gear pin to hand, but there was a DC-10 alternate centre gear pin in a vehicle. It held for a couple of selections and then shook itself out. You know the result.
Perhaps one day we will learn and act on the old adage 'Less haste - more speed.'

[Joetom]

Sounds like another case of you pay 4 what you get.

Pilots and cabin Crew have books/information avail on aircraft.

Engineers are expected to work from memory often, this problem of gear retractions during maint is long running and many more to follow I'm sure, think the maint manual states aircraft locking pins shoud be used during these checks.

The most common reason for the 747 nose gear retracting on these checks is the use of a non approved locking pin, it's easy to fit and remove, but the nose doors can easy remove the pin when the gear is operated in this fashion.

Interesting to know how many 747s have dropped on the floor during these operations.

A tip for anyone doing these opetations, 747s have 2 locking pin locations for the nose gear, use both is not a bad idea.!!!

[JamesA]

Joetom, to go along with your post, and engineers being expected to remember procedures. Manuals were always held in the line office or the hangar. An advance in enabling information to be at the worksite, especially regarding line operations, was the reader printer. But if the engineer or mechanic didn't take all the cross references it meant back to the source or use his/her memory. Now I have seen a few, and it is a small few, companies have laptops installed on board, fewer have printers. This is a great leap forward and it will be a great money saver when these items are installed on all aircraft. Think about it all Maintenance Directors and Managers - this month's money saver - get the above installed on the whole fleet now - it is cheaper than a gear collapse.
But above all, the witholding of information whether intentionally or not is probably the underlying cause of repeat malpractices throughout the industry. Basically a method of communicating mistakes or failed shortcuts is needed. I know there are various forums, but not everybody is aware of these. I fell upon one the other day 'AMTOnline.com' for techies. I will post the repeat of this Lufthansa mishap there and hope it will be of help to others. Between us we need to publicise sites and occurrences as much as possible and hope it helps someone, somewhere.

[Airbubba]

>>Preliminary examination of the aircraft by German investigation agency BFU has revealed that the aircraft was undergoing a test of its hydraulic system following indications of a leak.

As part of the test a locking pin was inserted into the nose-gear strut to prevent retraction while the landing-gear retraction mechanism was activated from the cockpit.

But a spokesman for BFU says that the movement of the nose-gear doors led to the pin’s becoming “disconnected” from its position. While the pin remained intact, he says, it was no longer able to prevent the nose wheels from retracting.

BFU is studying the design of the pin which, says the spokesman, had not been supplied by Boeing but which had been specially-made...

_______________________________

Wow, sounds like a repeat performance of the SIN NWA incident I described above, down to the "specially-made" part:

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