Preflight & Misrigged Controls

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Rory

Pre-takeoff checklist
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Rory
There’s a current thread on pre-flight checks in which a contributor mentions mixed-up controls.

The NTSB/FAA Safety Team has made a great video on this about a real case. I’m creating this separate thread on the video because of how powerful it is, and because it has only 1500 views on YouTube. To their considerable credit, the young pilots and the mechanic agreed to participate in the video.

After watching it, I did a search of the NTSB database and was surprised to learn that this is a more frequent cause of accidents than one might think.

The video:

 
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Jaques Cousteau's kd, Ari Onassis's kid both died from backwards aileron rigging on separate airplanes. I ALWAYS do a pre-flight control check and watch them while doing it. It has killed a surprising number of experienced pilots.
After a heavy check at the airlines the flight control check was a big deal.
 
I was just told this evening about an airplane that had the pitch trim wired backwards on the pilot's yoke...was interesting right after takeoff, apparently.:eek:
 
Two PA-12 fatal accidents have occurred in the past few years from initial flights after rebuilds with the elevator rigged backwards.
 
Thanks, Rory! Enjoyed that one.
 
Flight controls free and correct, but it does take special attention to make certain the trim is going the right way.
 
steingar said:
Flight controls free and correct, but it does take special attention to make certain the trim is going the right way.
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I was taught to watch the yoke while manipulating the control surfaces as you walk around and do the pre-flight. Is the yoke moving in the proper direction for the given control surface movement?
 
Bill Jennings said:
I was taught to watch the yoke while manipulating the control surfaces as you walk around and do the pre-flight. Is the yoke moving in the proper direction for the given control surface movement?
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That's how I do it. "Towards me, away from me"
 
I am taught the side of the yoke you are raising, point your index finger on the hand on that side as reminder "I'm pointing to the aileron that should go UP". I know I can reason it out, I know how it works, but this just is an easy way to not ever be mistaken. I point to the one that goes up. Simple.
 
Bill Jennings said:
I was taught to watch the yoke while manipulating the control surfaces as you walk around and do the pre-flight. Is the yoke moving in the proper direction for the given control surface movement?
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Yup, that too. I used to watch the trim tab on the Cherokee during the preflight to make certain it went the right way. I have to admit, I hadn't checked that on the Mooney, but I'll start. Not that hangar gremlins are going ot re-rig my trim controls, but it isn't a bad habit to be in.
 
Yep, even on a partnership plane, where I know a lot more about maintenance, I still check that on every preflight. I want to keep that habit for when I fly rentals, which I still do occasionally. Mixed-up controls would be a bad thing. :eek:
 
I never understood how a mechanic can f*** up so bad and rig a cable in reversed fashion. I also never understood how an IA can sign off on an improperly rigged control surface too.
But I do understand how pilots don't care enough for their own life during pre-flight, especially after maintenance involving control surfaces. They just want to get in the air, no matter what, pre-flight or not. (okay, I am being sarcastic here)

Also, why are the kids sitting in front of a 172 while talking about autopilot and digital trim? :)

My mechanic is reinstalling my stabilator as we speak. If you don't hear from me after this weekend, that's because he screwed up and I was stupid enough to not check the flight controls.
 
steingar said:
Yup, that too. I used to watch the trim tab on the Cherokee during the preflight to make certain it went the right way. I have to admit, I hadn't checked that on the Mooney, but I'll start. Not that hangar gremlins are going ot re-rig my trim controls, but it isn't a bad habit to be in.
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Isn't it technically an anti-servo tab?
 
steingar said:
The Cherokee's certainly was. To be honest, I don't even know what it looks like on the Mooney but I will find out next time I see it.
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The short body mooneys don't have elevator trim tabs. The entire horizontal moves.
 
Paulie said:
The short body mooneys don't have elevator trim tabs. The entire horizontal moves.
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On the 201, the entire tail trims, including the vertical stab. I’d assume it’s the same for the short body.
 
BigBadLou said:
My mechanic is reinstalling my stabilator as we speak. If you don't hear from me after this weekend, that's because he screwed up and I was stupid enough to not check the flight controls.
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noted...
 
It seems like one could easily design control cable or rod systems in such a way as to make misrigging like this impossible. Turnbuckles in different positions, male/female threaded portions set up so they can only go one way, different sized bolts and eyes, that sort of thing.

No?
 
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FastEddieB said:
It seems like one could easily design control cable or rod systems in such a way as to make misrigging like this impossible. Turnbuckles in different positions, male/female threaded portions set up so the can only go one way, different sized bolts and eyes, that sort of thing.

No?
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Even simpler, color coding!
 
If his/her knowledge of aerodynamics/physics is not so great, a builder can make the mistake of thinking an upward deflection of the elevator trim tab is "up" trim when of course it's the opposite. I've heard of DAR inspectors catching this on Experimental builds. You don't need that pesky reversal issue when you're flying a plane for the first time...ever.

I was soooo careful when rigging my pushrod/bellcrank setup for elevator actuation too, as an over-center condition can lock up the controls. The way Van's specifies the lengths of tubing for the system, this is probably impossible to do, but just thinking about it gave me the willies. Lots of experience here in doing it the right way from model airplane linkages.

Same goes for autopilot roll/pitch servos. Gotta put positive stops on them to prevent going over-center.

During the "free and correct" part of the run-up check, when I move the stick to the left, I like to think that the left aileron is tipping its hat to me (going up, that is!).
 
On my walk around I visually look at the trim tab because I'm older and not flexible enough to look over my shoulder to see the trim tab. (Cessna 172) The rentals I fly are older and the little indicator pointer is unreliable. Recently I did my walk around and the trim tab was all the way down. I have no clue why unless someone's kid was playing around in the cockpit. I think I am strong enough to hold the nose down but have no desire to test it out. Lesson learned, I think in the future if I forget to look at it in the walk around I will probably shut down and get out and check.
 
FastEddieB said:
It seems like one could easily design control cable or rod systems in such a way as to make misrigging like this impossible. Turnbuckles in different positions, male/female threaded portions set up so the can only go one way, different sized bolts and eyes, that sort of thing.

No?
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Yes, its very possible. Usually done with pushrods, based on what I've seen. Grob gliders, probably among others, do that because glider pilots are authorized under Part 43 preventive maintenance to disassemble and reassemble gliders for trailering. It's not unheard of in the older Schweitzers to connect things backwards, but it can't be done with the Grobs.
 
jsterner said:
On my walk around I visually look at the trim tab because I'm older and not flexible enough to look over my shoulder to see the trim tab. (Cessna 172) The rentals I fly are older and the little indicator pointer is unreliable. Recently I did my walk around and the trim tab was all the way down. I have no clue why unless someone's kid was playing around in the cockpit. I think I am strong enough to hold the nose down but have no desire to test it out. Lesson learned, I think in the future if I forget to look at it in the walk around I will probably shut down and get out and check.
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The Skycatcher needed almost full nose-down trim to prevent continued climbing, at 2400 rpm <= 2000 MSL. Throttle back to 2000 rpm and it was more stable. But the CFI insisted on 2400 (recommended cruise per POH), and the checklist did not list re-centering the trim tab after landing, just before take off.
 
FastEddieB said:
It seems like one could easily design control cable or rod systems in such a way as to make misrigging like this impossible. Turnbuckles in different positions, male/female threaded portions set up so the can only go one way, different sized bolts and eyes, that sort of thing.

No?
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Agreed. I assume the designers/manufacturers started doing that with the newer airplanes. But of course we're stuck with no safety measures for airplanes that are older than us.

When I am disconnecting any cables/rods that could easily be re-connected reversed, I mark them with color Sharpie or tape to identify them correctly. It's better to take an extra minute earlier to prevent confusion and wasted hours later.
 
SoCal RV Flyer said:
If his/her knowledge of aerodynamics/physics is not so great, a builder can make the mistake of thinking an upward deflection of the elevator trim tab is "up" trim when of course it's the opposite. I've heard of DAR inspectors catching this on Experimental builds. You don't need that pesky reversal issue when you're flying a plane for the first time...ever.

I was soooo careful when rigging my pushrod/bellcrank setup for elevator actuation too, as an over-center condition can lock up the controls. The way Van's specifies the lengths of tubing for the system, this is probably impossible to do, but just thinking about it gave me the willies. Lots of experience here in doing it the right way from model airplane linkages.

Same goes for autopilot roll/pitch servos. Gotta put positive stops on them to prevent going over-center.

During the "free and correct" part of the run-up check, when I move the stick to the left, I like to think that the left aileron is tipping its hat to me (going up, that is!).
Click to expand...

I learned it when turning the yoke, thumbs up, aileron up
 
MauleSkinner said:
Grob gliders, probably among others, do that because glider pilots are authorized under Part 43 preventive maintenance to disassemble and reassemble gliders for trailering
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Perhaps it used to say that? I sure can't find anything like that in part 43. But, I would like a reference...
 
Capt. Geoffrey Thorpe said:
Perhaps it used to say that? I sure can't find anything like that in part 43. But, I would like a reference...
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I can’t quote FAR chapter and verse on it but one of the required tasks in the Practical Test Standards is to demonstrate knowledge of proper assembly procedures.

Gliders are made to be easily assembled and disassembled. It would be quite inconvenient if an A&P had to sign it off every time.
 
Is there a statute of limitations?

Long ago, back in one of my previous lives, I was asked to test fly a Cessna 150 after a fairly major rebuild. So, being as it was fresh out of maintenance, I did what I thought was a pretty thorough preflight inspection. Controls free and correct, Yup. Looked out at the ailerons and they were doing what they were supposed to do. Looked at the elevator and rudder and they were doing what they were supposed to do. Runup normal. Everything good to go. I started to taxi and noticed the steering seemed to be a bit stiff. It took a bit of brake to make it go where I wanted it to. Ok, no big deal. Maybe it needs to be "broken in" a bit. Got to the end of the runway, turned around, and applied power for take off. The plane immediately veered hard to the left. What the heck?!? Immediately pulled power or I would have gone off the left side of the runway. Upon closer inspection, I discovered that the rudder was hooked up backwards. Those little surfaces are really effective with just prop blast going over them.

Bottom line to this is that sometimes we see what we want to see. It is not enough to just go through the motions. We must make sure that we understand what we are seeing and make sure it is correct.
 
MauleSkinner said:
Yes, its very possible. Usually done with pushrods, based on what I've seen. Grob gliders, probably among others, do that because glider pilots are authorized under Part 43 preventive maintenance to disassemble and reassemble gliders for trailering. It's not unheard of in the older Schweitzers to connect things backwards, but it can't be done with the Grobs.
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The Blanik L-13 had a problem with the elevator control connection. It was easy to flip the control on connection. An AD required that the connection be painted to color match.

I don’t think it is in Part 43 to allow the glider pilot to assemble the glider. It is part of the POH and it is part of the oral and PTS (I need to go check a recent PTS).
 
BillTIZ said:
I don’t think it is in Part 43 to allow the glider pilot to assemble the glider. It is part of the POH and it is part of the oral and PTS (I need to go check a recent PTS).
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Yeah, I'm not finding it in Part 43 either...I know I've seen it somewhere beyond the PTS.
 
MauleSkinner said:
Yeah, I'm not finding it in Part 43 either...I know I've seen it somewhere beyond the PTS.
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Some years ago, it was in part 61 for glider pilots - you had to get training in assembly. I guess if it's in the POH, then you are good to go (glider or power, installing or folding).
 
FastEddieB said:
Could the key be it’s not considered maintenance?

“Maintenance means inspection, overhaul, repair, preservation, and the replacement of parts, but excludes preventive maintenance.”
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That's where some people argue that a pilot can't replace wings on something that is designed to have removeable wings without an A&P signoff because you are replacing parts (including the bolts / pins for folding wings) and it doesn't fall under the list of things in preventive maintenance.

Obviously, glider pilots do this all day long. Similar, Avid Flyer and derivatives - and when you get to an S-LSA (as opposed to E-AB) then, well...

From another forum:
"I'm an experienced Army pilot who recently purchased an Avid Flyer Speedwing Model C, Mark 4. I was contacted by a pair of FAA Inspectors who live in the area and were conducting ramp checks. The gentlemen approached me while I was in the hanger doing maintenance and inspected me. They informed me of the following with regards to my Avid Flyer experimental airplane....
...
2) Folding then unfolding the wings requires and writeup and inspection by an A&P in the aircraft logbook."

Obviously nonsense for an E-AB aircraft. But for something else?
 
Capt. Geoffrey Thorpe said:
That's where some people argue that a pilot can't replace wings on something that is designed to have removeable wings without an A&P signoff because you are replacing parts (including the bolts / pins for folding wings) and it doesn't fall under the list of things in preventive maintenance.
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I think a case could be made that replacing means something different from reinstalling.

To me, replacing implies installing a different part. If you say to me, "I've decided to just go ahead and replace my propeller", I'd assume you mean with a new or different one, not reinstalling the old one.
 
I don't have time to look up the references right now, but this is from thenFAA's Glider Handbook...
The assembly of a glider to include the installation of glider wings and tail surfaces is classi ed as operations functions not preventative maintenance. This information can be found in Amendment 43-27, published in 52 FR 17276, May 6, 1987 which is an amendment to 14 CFR part 43.
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