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Bird380
1st Apr 2009, 00:04
Hi Guys
Can anyone tell me please, why does the whole aircraft moves when we check B777 elevators on ground after starting engines.:ugh:

Flight Detent
1st Apr 2009, 03:32
My best guess is a combination of moving a pair of quite large masses of elevator structure, together with their associated counter-weight systems.

...and maybe a touch too enthusiastic with the controls!

Cheers...FD...:)

FCS Explorer
1st Apr 2009, 09:50
maybe the airstream from the engines that hits the elev?
ever seen a 757 tail when TO-thrust is set? some scary shaking there.

oz in dxb
1st Apr 2009, 12:23
I think it is to do with the movement of the PCU (power control units) for the elevator if you move the controls too fast.
Slower movement of the contol column will not result in this.

Regards,

Oz

Old Smokey
1st Apr 2009, 12:35
oz in dxb has it correct in one hit, and that's the official words from Boeing.

Eaaasssy does it, particularly when the controls are towards the end of their travel (a control position that would not be used in flight except in the most extreme cases).

For the record, that applies to ALL control surfaces (and probably most aircraft), it's just that the Elevator produces the most noticeable shudder in the aircraft in the B777.

Regards,

Old Smokey

411A
1st Apr 2009, 15:20
it's just that the Elevator produces the most noticeable shudder in the aircraft in the B777.



Ditto with the L1011, except that if you pull back (or push forward) on the pole, the entire horizontal tail assembly moves, not just the elevator.

In a word...easy does it.

Bird380
1st Apr 2009, 17:47
Thanks guys :ok:, is this feature present in any other fly by wire aircraft!!?

glhcarl
1st Apr 2009, 18:43
Thanks guys http://static.pprune.org/images/smilies/thumbs.gif, is this feature present in any other fly by wire aircraft!!?

Has nothing to do with "fly by wire" it works the same way with the "cable and rod" systems. It is as simple as moving a large amount of weight at the end of a long aluminum tube, with the MLG acting like a fulcrum.


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