Control reversal

[Michael White]

I originally posted this in another thread, but thought it would be better off in a thread all it's own.

Originally Posted by L.Adamson
A bit off topic, but has anyone seen the NTSB report on the Spectrum 33.

After 45+ hours of flight, some re-working took place in the area of the assembly that connected the aileron linkages. The linkages were mis-rigged when replaced, which gave reversed aileron control. The aircraft banked nearly 90 degrees after takeoff, which caught the wing tip and cartwheeled.

I know this type of mistake has occured with numerous aircraft, but it always surprises me that no one seems to notice the reversed control surface movements.

L.Adamson

L.Adamson,
My dad and I learned this lesson (the hard way, of course) with one of his R/C models a few years back. The reason is because the ailerons are the one control that can be reversed and remain undetected until you're in the air and it's too late.

Think about it...if the rudder's reversed, you'll notice it during taxi (why does it go left when I push right?). If the elevator's reversed, you won't get off the ground (and will probably need to replace the prop, too). The only way you'll notice reversed ailerons on the ground is with an in-cockpit control check where you're specifically looking for reversed throw (stick goes left, left aileron goes DOWN, something's wrong here). A little complacency here and it's easy to miss (Dad and I have both been flying R/C for almost 40 years...and we both missed it!). Then, on takeoff, one wing dips a little...opposite stick to catch it...the wing dips more (because ailerons are reversed)...and the instinctive reaction is more opposite stick. By the time your brain catches on, it's too late...the wingtip hits the ground and over you go. I wouldn't be surprised if this is just what happened to the Spectrum pilot, but I haven't heard for sure.

The advantage of R/C is that you get to walk away from all your landings, and the only thing that gets hurt is your ego. Since our mishap, Dad and I do control surface checks before every flight looking for reversed controls. It's a habit now, and only takes a few seconds. Might be worth adding to your pre-takeoff checklist.

Best,

[ericwolf]

Moose,

I agree that this is a good idea in a rented spam can, but RV ailerons cannot be accidentally reversed as far as I can figure. They are controlled by pushrods and bellcranks and can only be hooked up one way.

[Mel]

BEWARE of things that "CAN'T BE DONE". SOMEONE will find a way!!!!!!!

[Ironflight]

Mel's right...every time you make something fool-proof, someone comes along and invents a better fool....

I have flown a lot of different airplanes in my life, and whether or not the checklist says it or not, the last thing I do as I taxi on to the runway is say "Flight Controls - Free and Correct". You just never know!

Of course, with a lot of swept wing aircraft, you can't see the ailerons from the cockpit, and in that case, you really need to check it during a preflight, or, as is done with many military aircraft, with a crew chief looking and signaling to the pilot as they go through the checks.

I guess this is really a cautionary tale for test-flying - never assume that things have been put back together properly, even if you have done it yourself. When I am doing disassembly-type maintenance, I write myself a checklist before taking things apart, and then use the same thing in reverse to make sure I haven't forgotten anything when it goes back together.

And then I check it again....

Paul

[rv6ejguy]

Reversal would be difficult on an RV however a jammed surface for many reasons is very possible. Ailerons or an elevator that won't move won't be of much use. Free and correct also covers forgotten external control locks which many RVs use. Put it on your checklist and take the 10 seconds to do it.

Not doing this has killed quite a few people in the last 10 years. I can recall at least 3 other incidents besides the latest one. So easily preventable.

[JoeG]

Years ago when I started taking flying lessons, I read about a guy who had crashed because his ailerons were rigged incorrectly. Since that time, I ALWAYS check for proper rigging on my walkaround. Its easy to do on the 172 and Aeronca Champ that I usually fly.

During my aileron inspection, I manually push and pull the aileron to its limits, simultaneously watching for opposite deflection on the other aileron and then for proper movement of the yoke or stick. When I push the aileron up, the yoke or stick should turn or move towards me and the other aileron should go down. (I wonder, will I be able to see this movement on an RV???)

Of course, as IronFlight said, you also have another opportunity when you run your pre-takeoff checklist for "free and correct".

[BrickPilot]

A very easy mental cue I was tought was during the preflight/runup "free and correct" check, when holding the yoke or stick and moving it to the left, hold the yoke/stick with your thumbs pointing up. They should always point to the upwards-deflected aileron... hence the reminder "thumb's up - aileron's up".

[Roadster]

Originally Posted by Michael White

Then, on takeoff, one wing dips a little...opposite stick to catch it...the wing dips more (because ailerons are reversed)...and the instinctive reaction is more opposite stick. By the time your brain catches on, it's too late...the wingtip hits the ground and over you go. I wouldn't be surprised if this is just what happened to the Spectrum pilot, but I haven't heard for sure.

Yep. That's exactly what happened...

The Spectrum 33, which is awaiting certification by the Federal Aviation Administration by 2008, had undergone more than 40 test flights without incident at the Spanish Fork-Springville airport. But as the plane took off around 4 p.m. on Tuesday, it began to roll to the right, causing the right wing to clip the ground, "cartwheel," and eventually crash in a pasture northwest of the airport, Spanish Fork Police Lt. Carl Johnston said.

http://www.heraldextra.com/content/view/187804/3/

[Peter Costick]

I didn't realise that this aircraft was destined for production. I guess that this would mean the guys working on it were professionals. Just goes to show that even the most experienced can make mistakes. A lesson for anyone.

I always check for correct aileron movement in my preflights, comes from the days when I was a glider pilot and we would often remove wings for trailering.

I hadn't heard of the thumbs up ailerons up idea but I really like it. I'll use that myself from now on.

[mandm1516]

I can't say with 100% confidence, but it seems to me a few years back an F-15 (C or E--can't remember) crashed on takeoff for this same reason--ailerons were reversed after some maintenance work. Lots of people had the chance to catch it and didn't.

Mike