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LAX
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Boeing 747 Landing Gear Question

Fri Nov 23, 2001 2:34 pm

What's the minimum number of gear legs (out of the 4 bogies on the mains) on which a B747 can land safely?

Suppose 1 or even 2 bogey clusters do not drop into place ..... what's the procedure?

1 stuck bogey means that the Jumbo would be landing on just 12 main gear wheels, which I'm guessing is probably very possible to do.

But, with 8 wheels still tucked underneath on landing, this would cause a total gear collapse upon touchdown, would it not?

Thanks for the help with my "gear" !!  Big thumbs up Smile Smile/happy/getting dizzy

 
CX Flyboy
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RE: Boeing 747 Landing Gear Question

Fri Nov 23, 2001 2:54 pm

Our procedures don't say much.

If any main gear is stuck, we will get a message saying "Gear Disagree". If the lever is down, this means that not all gear were successfully extended. The procedure is to use the Alternate Gear Extend Switch and see if that works. If not, then we simply land on what we have. Our checklist says not to try and taxi the airplane or use the tiller. Braking action will also be affected.

If both body gear are not out, then there is a danger of the aircraft tipping onto it's tail, in which case we are not to use the slides at door one for evacuation.

That's it. There's not a lot to it!!
 
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LAX
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RE: Boeing 747 Landing Gear Question

Fri Nov 23, 2001 3:35 pm

Wonder if it's ever happened....a 747 coming in on less than 18 wheels, that is! What a picture that would make!



 
ifix747s
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RE: Boeing 747 Landing Gear Question

Fri Nov 23, 2001 3:46 pm

It did could be 20 yrs ago SFO Pan Am I think. Took of to low cought the runway lights on the way out ripped up the belly and body gear landed on the wing gear after she rolled to a stop she sat back on her tail. all the fwd escape slides were useless. The nose was way of the ground.
 
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LAX
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RE: Boeing 747 Landing Gear Question

Fri Nov 23, 2001 4:02 pm

YES, you're right, IFIX747's......

On July 30, 1971, a Pan Am 741 hit the light structure at SFO and returned with several useless wheels. The pilot used reverse thrust on just one engine to compensate.

The above episode made an excellent chapter in a book I recently received about non-fatal air crashes.

Interestly (for anybody who might care about such co-incidences) .... The Pan Am SFO problem occurred on the exact same day as another major airline crash. ......
>> Morioka, Japan, July 30 1971 - 162 dead
All Nippon Airways B-727-281 collides with an F-86.
This was the 44th worst air crash (by deaths) in history.
 
AJ
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RE: Boeing 747 Landing Gear Question

Fri Nov 23, 2001 4:31 pm

A United Airlines Boeing 747-422 landed at Los Angeles International with a hydraulic system failure.
The body gear was fully retracted, the wing gear was extended and the nose gear doors were open with no gear extension.
After doing a touch and go to try shake the gear down the aircraft landed on the wing gear alone and settled onto the nose gear doors.
Quite dramatic!
 
AJ
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RE: Boeing 747 Landing Gear Question

Fri Nov 23, 2001 4:41 pm

 
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LAX
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RE: Boeing 747 Landing Gear Question

Fri Nov 23, 2001 4:43 pm

Thanks for that, AJ ... Good one!

Nice pic too!

Boy, that plane was practically brand spankin' new when this incident occurred, huh? (June 1991).

744's didn't enter service until...what...1989. (??)
 
avi
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RE: Boeing 747 Landing Gear Question

Sat Nov 24, 2001 12:23 am

Hi,

Don’t forget that a B747 can be up to 160 Tons lighten when it comes to land.


Click for large version
Click here for full size photo!

Photo © Avi Adin



Click for large version
Click here for full size photo!

Photo © Avi Adin


Long live the B747
 
A330DAT
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RE: Boeing 747 Landing Gear Question

Sat Nov 24, 2001 1:09 am

just like Avi said. It also depends on your load factor too. How heavy is your aircraft? Many passengers? Cargo? Fuel? In the best case it would be near the end of the flight when you lower the gear (meaning you've used-up the fuel from the flight you just did, therefore you weigh much lighter too), making it easier for the remaining gear to support the aircraft. I don't wish this to anyone though.
 
mirrodie
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RE: Boeing 747 Landing Gear Question

Sun Nov 25, 2001 12:32 am



LAX, to which book were you referring?
Sounds interesting.
Forum moderator 2001-2010; He's a pedantic, pontificating, pretentious bastard, a belligerent old fart, a worthless st
 
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LAX
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RE: Boeing 747 Landing Gear Question

Sun Nov 25, 2001 5:59 pm

Mirrodie....

Hi there.

This is that book.......



This book is a nice companion to the "Air Disaster" series by Macarthur Job.
The above book also features a riveting chapter on American Flight 96, this exact DC-10:
Click for large version
Click here for full size photo!

Photo © George W. Hamlin


Flight 96 had a cargo door blow out in mid flight. Quite a ride over Windsor!!

 
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LAX
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RE: Boeing 747 Landing Gear Question

Tue Nov 27, 2001 2:25 pm

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