737 spoilers

[flightleader]

I'd appreciate if someone can enlighten me in this.

My airline has many 737-400. Off late a lot of them have the same noticeable character or problem if you like. With A/P engaged, the control wheel would displace either to left or right whenever speedbrake is in use. Generally the more spoilers deployment the more control wheel displacement. Sometimes up to 2.5 unit on the aileron trim scale.

IMO, the spoilers are not even resulting the AP correct for it by the right amount of aileron input. Anyone has a better explaination?

The enginnering staffs in this company definately do not know how to retify it. What maintainance action can be done to remove this problem?

Thanks.

[Nil further]

Same thing last week in 300 , spoiler mixer replacement was required . Try cycling the spoilers up + down on the ground without moving the ailerons , go outside and look at the panels , if they have stowed correctly . The aircraft i had a problem with , the flight spoilers were not stowing correcly after deployment , this was first clue to problem .

The aircraft was displaying the exact same thing you describe , in flight with a/p engaged spoiler deployment resulted in approx 2 units aileron input by the a/p to keep wings level .

Engineers deduced flight spoilers not deploying symetrically and replaced spoiler mixer . I was told at the time by an engineer that adjusting the cables does not cure this problem as the correct rigging is to do with the mixer unit .

Hope this helps .

NF .

p.s. this is fairly basic 73 stuff , id be worried if your engineers dont understand it !

[Rainboe]

I don't remember this from the 2 years I flew the -400. However, if you suspect asymmetric Spoiler displacement with autopilot engaged, have you tried retracting, disengaging a/p and holding ailerons firmly, selecting same spoiler again to feel for roll input?
I recall on the 737 the ailerons feel jittery when spoilers are deployed.

[BOAC]

As 'nil further' says, it is not unknown, but to have 'a lot' of a/c doing it is odd. I agree with NF about your engineers!:D