Stuck Ailerons

Bman.

Bman.

Pre-takeoff checklist
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Bman.
I thought I would drop a quick line about my flight today... well almost flight. The weather was a fantastic - 60 degrees, LV winds and severe clear. I called up the FBO to have the plane (Archer II) pulled. I walked out to the plane and begin my preflight. I did my usual routine running through everything on the checklist just as I have from day one. I was ready to go.

I fired up the engine, all gauges gauges in the green, check my electrical equipment - all set, check controls - free and clear. Make my call from the ramp that I am heading to the runway.

As I am back taxing the runway, I decide to practice my "dive away, climb into" procedures... only to find the ailerons are stuck! And I mean... stuck. Not, they feel a little sticky or "different" but stuck in the neutral position. I taxi down to the run-up area to make sure I wasn't losing my mind or bound up in a headphone cable or something. Nothing - it's clean. Elevator is smooth, free and correct. It was as if there was a gust lock on the yoke.

Obviously I wasn't going anywhere so I taxied back to the FBO with my ailerons that only want me to go one direction. I park the plane, shutdown and open the door to start talking to the lineman about what was going on. I gave the yoke a few shakes (as I did down at the run-up area) and presto - they freed right up.

I still wasn't going anywhere and sent the plane in for inspection and decided we might as well do the annual a little early as well. I have heard of surface control failures but I wasn't expecting one (now or ever) like this. I am glad it happened on the ground but I am at a loss as to what was going on. FOD? Pulley or pushrod that wasn't happy with something? Either way, I hope the mechanic can come back with some theories since the ailerons are back to free and correct. It's going to be much more difficult now that the binding went away to find the cause. I am glad to do the annual so they can really dig into the controls and check everything.

If FOD was the root cause, where did that FOD come from? Why were the controls free and correct prior to engine start and free during the walk around..but then bind up during taxi? Strange.

This is going to stick in mind for some time. The next time I go practice steep turns, I am going to think "I hope the ailerons don't stick here!". Not very easy on the mind of a student pilot, that's for sure.

In the meantime - http://www.aopa.org/News-and-Video/All-News/2002/December/1/Out-of-the-Pattern-Part-12-of-12

Benjamin
 
Excellent theory and the second thing I though of right after headphone cable. AP master was off. Maybe the switch is lose/faulty... The switch doesn't feel fresh at all.


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Bman. said:
Excellent theory and the second thing I though of right after headphone cable. AP master was off. Maybe the switch is lose/faulty... The switch doesn't feel fresh at all.


Sent from my iPhone using Tapatalk
Click to expand...


Next time pull the breaker to check. Might need to do that in flight someday. ;)
 
It's fun when it happens on landing, but I've had students hit the switch with their knees at the beginning of taxi as well.

Just something to think about, your initial reaction was correct. If you don't know, don't take it airborne..
 
my mantra in any aircraft is "controls-free, clear, correct response". Probably a valid addition. Roll right, I should be looking at an aileron over my right shoulder, roll left, and same. Granted there are some -isms to be had with FBW controls, but that much is still the same.
 
I'm suspecting it's not the autopilot itself. You should be able to overpower the autopilot while on which while making flying difficult isn't a hard lock up as you describe. It's possible that the control cable bound on or near the servo.

You didn't indicate what sort of plane this is. The times I've seen a bind up and release it has been a torque tube/rod that had something that snagged on a structural part (in my case it was the trim actuator that had a set screw on a coupler work out and as catching on the stringer it was passing through.
 
My one time (in over 50 years) the controls were free.
In fact, the rudder pedals seemed just a bit too free (the almighty was looking out for me)
I had my daughter hold the brakes and got out (Skyhawk)
Lo and behold the little cable ends to the rudder yoke were dangling and waving in the prop wash.
Obviously I taxied back in and had a friendly word with the fbo.
Stuff happens. be alert.
 
Dr. O said:
My one time (in over 50 years) the controls were free.
In fact, the rudder pedals seemed just a bit too free (the almighty was looking out for me)
I had my daughter hold the brakes and got out (Skyhawk)
Lo and behold the little cable ends to the rudder yoke were dangling and waving in the prop wash.
Obviously I taxied back in and had a friendly word with the fbo.
Stuff happens. be alert.
Click to expand...

That should have been caught on the preflight inspection. :yes:
 
This summer, it was extremely warm in Seattle. I flew my Fly Baby one afternoon, landed, and taxied to the gas pumps.

After filling up, taxied to the runup pad, and discovered a "hitch" in the ailerons. As the aileron went left and right, there was a kind of thump in the stick as they passed neutral.

Sitting stationary outside exposed to the sun on this 95-degree day, the left aileron/aileron well had expanded enough that inboard trailing edge of the aileron was contacting the aileron well.

Fifteen minutes in the shade, and the interference was gone.

The guy who built my airplane got a wee bit too precise in the aileron fit. I've been flying this airplane nearly 20 years, and this is the first time it had happened.

Ron Wanttaja
 
Happened to me once. In the air.

I took off, locked the autopilot, and realized that I forgot to latch the door. In the course of maneuvering around doing side slips trying to get some pressure on the door, I realized my ailerons became locked and would not go past level in one direction.

I called up my home drone to let them know my situation (rudder only steering), and they gave me the inactive runway that I happened to be lined up with and I got it down without incident. I didn't realize what happened until I shut the power off. Miraculously, the ailerons were free again.

I never disconnected the autopilot, and it didn't disengage by itself. There was so much force I was afraid I'd break a cable or something, so I didn't try to force the ailerons over neutral.
 
There is a plethora of things that can cause exactly that to happen. Unless they find something obvious quickly, you may as well do the annual since you're gonna end up opening the plane up that far anyway checking the control rigging system.
 
Dr. O said:
My one time (in over 50 years) the controls were free.
In fact, the rudder pedals seemed just a bit too free (the almighty was looking out for me)
I had my daughter hold the brakes and got out (Skyhawk)
Lo and behold the little cable ends to the rudder yoke were dangling and waving in the prop wash.
Obviously I taxied back in and had a friendly word with the fbo.
Stuff happens. be alert.
Click to expand...

This is why I'm glad I have the rear window.. I can actually look back and watch the rudder wag! Granted, I'm particular about rudder and elevator (particularly the elevator with it's crimped fitting) control cables during pre-flight.
 
mkosmo said:
This is why I'm glad I have the rear window.. I can actually look back and watch the rudder wag! Granted, I'm particular about rudder and elevator (particularly the elevator with it's crimped fitting) control cables during pre-flight.
Click to expand...

Yep, Lots of planes it's easiest to do the check real quick from the right seat as you climb in so you can easily just look back.
 
Not the OP's problem, but related: In some early models of Cherokees with the bowtie yokes and the push-pull engine controls, the mixture control can interfere with the yoke when it's in idle-cutoff or nearly so, potentially getting "caught" in the left side of the bowtie on the co-pilot's yoke.

Has caused some concern if the pilot is doing a "controls-free and correct" check prior to engine start.
 
mkosmo said:
Granted, I'm particular about rudder and elevator (particularly the elevator with it's crimped fitting) control cables during pre-flight.
Click to expand...

You can see that crimped (swaged) fitting alright. What you can't see is the other end of those cables, the swages at those ends, the bellcrank they're attached to with small bolts, nuts and cotter pins, the push-pull rod from that bellcrank to the control tee, the pushrod's bolts and nuts and pins, the pivot bolt, bushing and nut that the tee swings on and the U-joints and other hardware associated with transmitting elevator commands to the system. Lots of places for failure, so any unusual feel or noises or stickiness should be investigated. That control tee is made of thinwall steel tubing that has a bad habit of corroding internally if rainwater gets through the windshield and drips down through the glareshield and into the tube. There have been some failures. Cessna published an SB on it around 15 years ago.

Now, don't you feel better knowing about all that stuff that you can't see?
 
Dan Thomas said:
You can see that crimped (swaged) fitting alright. What you can't see is the other end of those cables, the swages at those ends, the bellcrank they're attached to with small bolts, nuts and cotter pins, the push-pull rod from that bellcrank to the control tee, the pushrod's bolts and nuts and pins, the pivot bolt, bushing and nut that the tee swings on and the U-joints and other hardware associated with transmitting elevator commands to the system. Lots of places for failure, so any unusual feel or noises or stickiness should be investigated. That control tee is made of thinwall steel tubing that has a bad habit of corroding internally if rainwater gets through the windshield and drips down through the glareshield and into the tube. There have been some failures. Cessna published an SB on it around 15 years ago.

Now, don't you feel better knowing about all that stuff that you can't see?
Click to expand...

Didn't know about the control tee (which is mildly alarming and worth watching for), but I figured the rest of the bolts, nuts, pins, bushings, bellcranks, and other hardware would out-last those thin crimped/swaged fittings.
 
mkosmo said:
Didn't know about the control tee (which is mildly alarming and worth watching for), but I figured the rest of the bolts, nuts, pins, bushings, bellcranks, and other hardware would out-last those thin crimped/swaged fittings.
Click to expand...

Those swaged cable assemblies are tested to at least 60% of the cable's proof load, which in that elevator cable's case is 2000 lb. 60% is 1200 lb, much more than you'd ever be likely to put on it and maybe more than the structure could handle.

I usually find cables failing where they pass over rub strips, through fairleads, and over pulleys that have too little arc of contact, or their bearings are seized through neglect, so they don't turn. Some dirt sticks to the thick grease that's in the cable, and it acts like sandpaper as the cable rubs over these nonmoving bits and wears the wires until they break. Once in a great while we might find one that is failing right at the swage because someone tightened the attaching bolt until the clevis couldn't pivot, and so the swage repeatedly bends the cable and it fails at the end of the swage. In a few airplanes the cables suffer internal corrosion. And some have systems that use pulleys that are far too small, bending the cable too tightly, causing internal stresses and rubbing between the individual wires that wear it out. The flap-equipped Citabrias have that problem. There's an SB on that, too.

In the cabin roof of the 150/172/180/185 airplanes there's a cluster of small nylon pulleys that guide the aileron and flap cables. I find worn cables there in at least half the airplanes I inspect, cables worn to or past the limits specified in AC43.13 and sometimes broken wires sticking out. It's a stinker of a place to get at, so lots of guys don't bother. Airplanes parked outside without proper external gustlocks will wear out cables at places like that even though the airplane might have very few hours on it. The controls surfaces are constantly wiggling in the wind, wearing out cables and pulleys and surface hinges. Everything. A Cessna control lock is a joke.

https://www.tc.gc.ca/eng/civilaviation/certification/continuing-alert-2010-01-185.htm
 
Last edited:
Dan Thomas said:
Those swaged cable assemblies are tested to at least 60% of the cable's proof load, which in that elevator cable's case is 2000 lb. 60% is 1200 lb, much more than you'd ever be likely to put on it and maybe more than the structure could handle.

I usually find cables failing where they pass over rub strips, through fairleads, and over pulleys that have too little arc of contact, or their bearings are seized through neglect, so they don't turn. Some dirt sticks to the thick grease that's in the cable, and it acts like sandpaper as the cable rubs over these nonmoving bits and wears the wires until they break. Once in a great while we might find one that is failing right at the swage because someone tightened the attaching bolt until the clevis couldn't pivot, and so the swage repeatedly bends the cable and it fails at the end of the swage. In a few airplanes the cables suffer internal corrosion. And some have systems that use pulleys that are far too small, bending the cable too tightly, causing internal stresses and rubbing between the individual wires that wear it out. The flap-equipped Citabrias have that problem. There's an SB on that, too.

In the cabin roof of the 150/172/180/185 airplanes there's a cluster of small nylon pulleys that guide the aileron and flap cables. I find worn cables there in at least half the airplanes I inspect, cables worn to or past the limits specified in AC43.13 and sometimes broken wires sticking out. It's a stinker of a place to get at, so lots of guys don't bother. Airplanes parked outside without proper external gustlocks will wear out cables at places like that even though the airplane might have very few hours on it. The controls surfaces are constantly wiggling in the wind, wearing out cables and pulleys and surface hinges. Everything. A Cessna control lock is a joke.
Click to expand...
Are there any particular external gust locks you'd recommend? The column lock not protecting the cables makes a lot of sense. I've seen a lot of padded external locks but never decided on a specific to purchase yet.
 
mkosmo said:
Are there any particular external gust locks you'd recommend? The column lock not protecting the cables makes a lot of sense. I've seen a lot of padded external locks but never decided on a specific to purchase yet.
Click to expand...

Re that control tee failure: https://www.tc.gc.ca/eng/civilaviation/certification/continuing-alert-2010-01-185.htm

I make them when I need them. Sometime wood, sometimes aluminum, all with some sort of padding such as closed-cell foam.

See these: http://www.aircraftspruce.com/menus/ps/coversaircraft_gust.html
 
mkosmo said:
Are there any particular external gust locks you'd recommend? The column lock not protecting the cables makes a lot of sense. I've seen a lot of padded external locks but never decided on a specific to purchase yet.
Click to expand...

External ones are easy enough to make.
 
Do you move the ailerons as part of preflight? It's a good practice and make sure yoke and opposite aileron move accordingly. May you did and I missed it.
 
I always flip the aileron up when I do my walk around to check hinges, wicks and push rod. I always glance up to make sure the yoke moved in the correct direction and make sure no one is on the other wing waiting for a pinched finger when I move the aileron back up to neutral.
 
Bman. said:
I always flip the aileron up when I do my walk around to check hinges, wicks and push rod. I always glance up to make sure the yoke moved in the correct direction and make sure no one is on the other wing waiting for a pinched finger when I move the aileron back up to neutral.
Click to expand...

Well, sounds like you did your job. Both preflight, and taxi check. You caught a problem that may have led to a grim report.

That said, since you were taxiing for takeoff, would this trigger an NTSB report for flight control failure??
 
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