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Boeing 747 Landing Gear Question  
User currently offlineLax From United States of America, joined Dec 2000, 2290 posts, RR: 3
Posted (13 years 4 weeks ago) and read 3507 times:

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



12 replies: All unread, jump to last
 
User currently offlineCx flyboy From Hong Kong, joined Dec 1999, 6638 posts, RR: 55
Reply 1, posted (13 years 3 weeks 6 days 23 hours ago) and read 3454 times:

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!!


User currently offlineLax From United States of America, joined Dec 2000, 2290 posts, RR: 3
Reply 2, posted (13 years 3 weeks 6 days 23 hours ago) and read 3436 times:

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





User currently offlineIfix747s From United States of America, joined Nov 2001, 18 posts, RR: 0
Reply 3, posted (13 years 3 weeks 6 days 23 hours ago) and read 3435 times:

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.

User currently offlineLax From United States of America, joined Dec 2000, 2290 posts, RR: 3
Reply 4, posted (13 years 3 weeks 6 days 22 hours ago) and read 3424 times:

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.


User currently offlineAJ From Australia, joined Nov 1999, 2397 posts, RR: 25
Reply 5, posted (13 years 3 weeks 6 days 22 hours ago) and read 3410 times:

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!


User currently offlineAJ From Australia, joined Nov 1999, 2397 posts, RR: 25
Reply 6, posted (13 years 3 weeks 6 days 22 hours ago) and read 3404 times:

http://aviation-safety.net/database/incidents/19900827-0.htm

Click for large version
Click here for full size photo!

Photo © Brian J. Gore



User currently offlineLax From United States of America, joined Dec 2000, 2290 posts, RR: 3
Reply 7, posted (13 years 3 weeks 6 days 22 hours ago) and read 3399 times:

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. (??)


User currently offlineAvi From Israel, joined Sep 2001, 943 posts, RR: 6
Reply 8, posted (13 years 3 weeks 6 days 14 hours ago) and read 3359 times:

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
User currently offlineA330DAT From Belgium, joined Nov 2001, 469 posts, RR: 1
Reply 9, posted (13 years 3 weeks 6 days 13 hours ago) and read 3337 times:

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.

User currently offlineMirrodie From United States of America, joined Apr 2000, 7444 posts, RR: 62
Reply 10, posted (13 years 3 weeks 5 days 14 hours ago) and read 3294 times:
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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
User currently offlineLax From United States of America, joined Dec 2000, 2290 posts, RR: 3
Reply 11, posted (13 years 3 weeks 4 days 20 hours ago) and read 3266 times:

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!!



User currently offlineLax From United States of America, joined Dec 2000, 2290 posts, RR: 3
Reply 12, posted (13 years 3 weeks 3 days ago) and read 3238 times:



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