Suspicious Aileron PushRod

FlySince9

FlySince9

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Jerry
Not a mechanic, so excuse if the names don't match the part... I was doing a preflight on one of the clubs Skyhawks. Checking the aileron push-rod, on the left wing, which I was taught (many years ago) during Primary training, should be free enough to kind-of wiggle if you reach in there and twist it back with your fingers, appeared to be jammed to one side and not movable. On further inspection, it appeared to have a bend in it, about the point where it entered the wing, with the aileron in the full up position. I removed the inspection plate but was unable to get a good look at the attach-point of the rod. The bell-crank appeared okay... I grounded the airplane until a mechanic got a look at it... What could cause something like that? Do you think it was a grounding item? :dunno:
 
Those ailerons can be beaten to a pulp if not properly secured on the ground in high winds.
 
kgruber said:
Those ailerons can be beaten to a pulp if not properly secured on the ground in high winds.
Click to expand...
Well, I flew the airplane a week ago and didn't notice the problem, then... Airplane "normally" has gust lock installed...
 
FlySince9 said:
Well, I flew the airplane a week ago and didn't notice the problem, then... Airplane "normally" has gust lock installed...
Click to expand...

THe push rod is steel. The ailerons are aluminum. You should see aileron damage before the steel starts to deform. I'd give the ball joint a shot of lube and then GENTLY twist the rod with a wrench to see if the lube did anything to free up the swivel joint.

Memory fails me if that push rod is normally bent. What does the one on the other side look like?

Jim
 
weirdjim said:
THe push rod is steel. The ailerons are aluminum. You should see aileron damage before the steel starts to deform. I'd give the ball joint a shot of lube and then GENTLY twist the rod with a wrench to see if the lube did anything to free up the swivel joint.

Memory fails me if that push rod is normally bent. What does the one on the other side look like?

Jim
Click to expand...

The "stare-and-compare" is what alerted me that something was not right... The other one is straight and has the "expected" play in it...
 
Just talked to the mechanic... Evidently, someone, during some kind of MX on the aileron re-installed the push-rod so the inherent bend, that is suppose to be in the vertical plane, was rotated 90 degrees to the horizontal plane... He has removed the aileron and is correcting the "mistake." All you students out there... That is why you don't assume that because the aircraft has flown recently, it is "probably" okay... Evidently this has been this way for sometime... I flew the airplane last week and didn't notice it... It was just that the thing got jammed to one side that it was finally noticed... :blueplane:
 
FlySince9 said:
Just talked to the mechanic... Evidently, someone, during some kind of MX on the aileron re-installed the push-rod so the inherent bend, that is suppose to be in the vertical plane, was rotated 90 degrees to the horizontal plane... He has removed the aileron and is correcting the "mistake." All you students out there... That is why you don't assume that because the aircraft has flown recently, it is "probably" okay... Evidently this has been this way for sometime... I flew the airplane last week and didn't notice it... It was just that the thing got jammed to one side that it was finally noticed... :blueplane:
Click to expand...

There is no "inherent bend" in a Skyhawk aileron pushrod. That rod is bent because it's damaged and needs to be replaced. They get bent when the airplane is parked without the control lock in and a wind on the tail whacks the ailerons hard against the stops; the mass balance weight helps impart enough shock to buckle the rod.

A bent rod has little compressive strength and could fail further under heavy flight loads. At the least, it puts the ailerons out of rig.

Dan
 
FlySince9 said:
Just talked to the mechanic... Evidently, someone, during some kind of MX on the aileron re-installed the push-rod so the inherent bend, that is suppose to be in the vertical plane, was rotated 90 degrees to the horizontal plane... He has removed the aileron and is correcting the "mistake." All you students out there... That is why you don't assume that because the aircraft has flown recently, it is "probably" okay... Evidently this has been this way for sometime... I flew the airplane last week and didn't notice it... It was just that the thing got jammed to one side that it was finally noticed... :blueplane:
Click to expand...

I find it interesting that he gave you a story like that. Was he trying to blow you off or does he think its ok? Let us know what you find about it next time you fly!


-VanDy
 
Dan Thomas said:
There is no "inherent bend" in a Skyhawk aileron pushrod. That rod is bent because it's damaged and needs to be replaced. They get bent when the airplane is parked without the control lock in and a wind on the tail whacks the ailerons hard against the stops; the mass balance weight helps impart enough shock to buckle the rod.

A bent rod has little compressive strength and could fail further under heavy flight loads. At the least, it puts the ailerons out of rig.

Dan
Click to expand...

Could a bent rod be caused by a frozen rod end bearing as well?
 
gismo said:
Could a bent rod be caused by a frozen rod end bearing as well?
Click to expand...

I doubt it. the bolt holding it to the aileron would spin before it transmitted enough torque to bend a 1/4" steel rod.
 
Caused by pilots with no "pride of ownership." Aircraft left to the whims of the elements.
 
weirdjim said:
A feller that signs his name with A&P after it says that there is. YOu say there is not. Care to show your credentials in the civilian 172 arena?

Jim
Click to expand...

Canadian Aircraft Maintenance Engineer, category M1, the equivalent of an American A&P/IA. Looked after several 150s, lots of 172s, 182s, 180s and 185s among other airplanes, in a flight school for 16 years and am now looking after many different Cessnas.

Is that good enough?

Dan
 
kgruber said:
Caused by pilots with no "pride of ownership." Aircraft left to the whims of the elements.
Click to expand...
And some of those "elements" could be another clueless pilot blasting parked airplanes with prop or rotor wash. I learned long ago to install my gust locks anytime the plane is parked outside a hangar, even when the wind is pretty much guaranteed to remain light while I'm away from the plane unless it's not possible for another aircraft to get behind it.
 
weirdjim said:
A feller that signs his name with A&P after it says that there is. YOu say there is not. Care to show your credentials in the civilian 172 arena?

Jim
Click to expand...

If Dan is correct, (Tom has confirmed) does it really matter? :rolleyes:
 
I knew you guys would be a great source... I am going to pursue this further... This is a club airplane and the mechanic works for the club. I don't know why someone would blow smoke about something critical... I will get to the bottom of this and let you all know how it turns out...

Thanx for your expertise!


:thumbsup:
 
Tom-D said:
I doubt it. the bolt holding it to the aileron would spin before it transmitted enough torque to bend a 1/4" steel rod.
Click to expand...

I'm not so sure. The bolt should sandwich the rod end bearing between the flanges of the aileron attach bracket. If the bearing was frozen it would have to physically rotate within the bracket, the bolt itself might not rotate at all.
 
On a related note

I was preflighting a 172 and noticed a small bend in the lower lip of the aileron. Looked like it had over-traveled, hit the pushrod and bent.

Is this normal or is the bend there for clearance? I didn't think to check.

I noted no damage to the pushrod, hinges or rest of the aileron so I went flying.
 
dell30rb said:
On a related note

I was preflighting a 172 and noticed a small bend in the lower lip of the aileron. Looked like it had over-traveled, hit the pushrod and bent.

Is this normal or is the bend there for clearance? I didn't think to check.

I noted no damage to the pushrod, hinges or rest of the aileron so I went flying.
Click to expand...

That's part of the 172's aileron design, for clearance at full down aileron. It's fine.

Dan
 
dell30rb said:
On a related note

I was preflighting a 172 and noticed a small bend in the lower lip of the aileron. Looked like it had over-traveled, hit the pushrod and bent.

Is this normal or is the bend there for clearance? I didn't think to check.

I noted no damage to the pushrod, hinges or rest of the aileron so I went flying.
Click to expand...

Normal, look close and you will see it is to perfect no to be manufactured.
 
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