"Play" in flight controls.
 

Hi,

I'm flying a medium turboprop, and have twice written a remark in the technical log about "play" in the flight controls. It's in both pitch and roll, and when flying level at 200+ KIAS the yoke can be moved at least 5 mm fore and aft without any reaction at all from the aircraft. The yokes can also be moved independently of each other. The answer from the technical department is, that there is some loose rivets in the controls, and they have to be replaced with larger ones, but not until the end of the year.
What says the wise people of pprune? -Does it seem reasonable?

Cheers :-):suspect:

The AMM for the aircraft type will have limits on allowable play in the system. As your maintenance department appears to well aware of the issue, and apparently have scheduled replacement of components in connection with a larger check, the system is presumably still within limits.

"The AMM for the aircraft type will have limits on allowable play in the system."

But you just try getting these published limits out of your engineering department and see the result??!!

It could rapidly become quite time consuming if technical departments were to answer questions from individual crews. Most companies will have a technical pilot or equivalent position who should be the person aircrews go to for answers.

Barkingmad
 

When I asked a few technical questions of our maintenance people that just said read about it yourself........ And emailed the AMM to me !

In 35 years of aircraft maintenance, I've never heard of any extended deferred defect that involves loose control component rivets. Worn rivets/holes steadily worsen and enlarged holes could even scrap the part concerned when the repair is eventually carried out.
Do allowable 'free play' limits include loose fasteners? I'd interpret free play as accumulated hinge pin or bearing wear.
Loose rivets in the control circuit may well be acceptable iaw specific maintenance manual limits but I've not come across it before.
We all live and learn (hopefully). :)

Just an update..
I contacted the airlines engineering department, and they were not able to find any documentation for allowable "play" in the flight controls. They actually said that they knew what the answer would be, if they contacted the manufacturer...
It looks like someone in the technical has made a bad judgement call, and the controls will be fixed now :)

If the defect has been correctly deferred, then there will be a reference in the Techinical Log against which that deferral can be verified.

EG Play in flt controls within limits as laid down in AMM 27-blah-blah-blah blah. Repeat inspections to be carried out every xyz flt hours/days/cycles etc
Final action, to be repaired at xyz flt hours/days/cycles, A check,etc

If it's not deferred in accordance with any known documentation then a design deviation will need to be sought either from the airline/manufacturer's design office or NAA (or both).

Otherwise the engineer who signed it off in the log will be getting a visit from quality department. :eek:

I have no experience in checking control columns on smaller turboprops, but on the Boeings it is done in some way like this; first one of the two control columns is blocked in neutral, with trims at zero. Then a specified amount of force is exercised on the free column; eg 2 lbs on ailerons from what I recall. This should give a certain degree of deflection on the free column, whose limits are specified in AMM. If the degree of deflection is too high, that same AMM gives you a list of items to check for wear and play - mostly bushings and rod connections. If rivets are loose they should be in alert phase, certainly not deferring it till end of the year. They also should be aware on which items cannot be repaired with oversized bolts or rivets, chapter 27 is too important.
This is Boeing of course, but the AMM for smaller turboprops must have similar limits, your engineering dept sounds unprofessional from what I read.