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xms3200
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How Many Jacks Needed To Jack Up A 747

Wed Nov 19, 2008 12:18 am

I was wondering how many jacks are needed to jack up a 747 (all models) off the ground for a gear swing. i know on the 737's, 3 are needed, and the nose jack is installed after all jacking operations are done, mostly as a secondary jack.

Thanks for all replies.
 
474218
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RE: How Many Jacks Needed To Jack Up A 747

Wed Nov 19, 2008 12:27 am



Quoting Xms3200 (Thread starter):
I was wondering how many jacks are needed to jack up a 747

I have never seen more than three! Two (wing) jacks and one (1) nose jack.
 
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jetmech
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RE: How Many Jacks Needed To Jack Up A 747

Wed Nov 19, 2008 4:09 am

Quoting Xms3200 (Thread starter):



Quoting 474218 (Reply 1):
I have never seen more than three! Two (wing) jacks and one (1) nose jack.

I agree that three is the usual (minimum) number of jacks used, but if it is a 747, it would be two wing jacks and a tail jack. The wing jacks are located under the forward spar of the wing centre section, thus, to maintain balance; a tail jack must be used. The 767 / 777 are similar. A nose-jack can be used if desired, but this is for additional stability only. As far as I know, Airbus is different. The main jacks are located towards the trailing edge of the wing, so a nose jack is used to maintain balance.


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Regards, JetMech

[Edited 2008-11-18 20:13:07]
JetMech split the back of his pants. He can feel the wind in his hair :shock: .
 
474218
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Joined: Mon Oct 10, 2005 12:27 pm

RE: How Many Jacks Needed To Jack Up A 747

Wed Nov 19, 2008 4:24 am



Quoting JetMech (Reply 2):
I agree that three is the usual (minimum) number of jacks used, but if it is a 747, it would be two wing jacks and a tail jack. The wing jacks are located under the forward spar of the wing centre section, thus, to maintain balance; a tail jack must be used. The 767 / 777 are similar. A nose-jack can be used if desired, but this is for additional stability only.

Thanks for the clarification. I thought that the tail jack on the 747 was for stabilization, not the front. You learn something new every day.
 
aogdesk
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RE: How Many Jacks Needed To Jack Up A 747

Wed Nov 19, 2008 4:20 pm

The task isn't actually limited to Jacks......it can be Toms, Bobs or Georges too......the maintenance manual doesn't specify.

I'm sorry, I need to get a life.  Smile
 
BAE146QT
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RE: How Many Jacks Needed To Jack Up A 747

Wed Nov 19, 2008 4:59 pm

Did any of you ever see that programme (it was on UK terrestrial TV recently but probably came from Discovery originally) where they dismantled a 747?

It was the first one these guys had done - they were used to smaller birds - and if I remember correctly they used no less than four jacks and two fixed stands (one jack and one stand under each wing, one jack at the front, one jack at the rear). Having done this, they balanced the whole thing on stacks of railroad ties then deflated the jacks and unwound the stands and pulled them away - while running like hell.

I don't know whether they used so many beause they were being cautious or what.

On a further note, my new cat is called Jack. He's about a foot tall and weighs 12.5 pounds. I don't know how many of him you'd need to 'jack' up a 747 but I bet it's more than four.
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Dalmd88
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RE: How Many Jacks Needed To Jack Up A 747

Wed Nov 19, 2008 6:41 pm

Wow, jacking a 777 outside. I know it is legal, but... Wouldn't feel very comfortable doing it. I guess the wind doesn't blow much there.

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