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Control reversal

Michael White

Well Known Member
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,
 
cannot be reversed

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

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

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
 
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.
 
Can you say... PRE-FLIGHT???

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".
 
Thumb's up - aileron's up

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".
 
Michael White said:
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/
 
a lesson

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.
 
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
 
Control Check

A big part of military and/or airline flying is always following the established procedure, ie. doing things the same way every time. After hundreds/thousands of hours, it all becomes second nature, but you still follow the checklist, every single time. Different aircraft will require different methods or techniques, eg. most GA aircraft will allow an external manipulation of the control surfaces while visually verifying correct movement of the stick, while as mentioned previously, larger aircraft with hydraulic powered control surfaces mandate the control check after startup, often with ground crew assistance, though many have a control surface position indicator on the panel. You've probably noticed most departing airliners extend take off flaps when just starting to taxi out of the pushback/engine start up position on the ramp, followed shortly thereafter by a full deflection control check - that doing things the same way every time thing. Flying off the boat in the Navy, we were taught to just prior to the cat shot off the pointy end (where an aborted take off is not an option) to, among other things, do a final "cockpit wipeout", stick moved to all 4 corners, checking for full and complete control movement. So you usually fly an aircraft where the controls "can't" be misrigged. Establish the habit pattern now, for the day that you fly something that can be.
I find it very interesting that the Spectrum accident was a test flight, as was the video most of you have seen (can't find the link at the moment) of the DeHaviland Caribou that way overrotated and did sort of a tight loop right into the ground. Story I'd heard was the control lock was still installed. Two accidents involving control surfaces with professional test pilots onboard. One wonders, does a preoccupation with the test card of the moment lead to a glossing over of the basics.

Doug Seward
Seattle area
-4, wings
 
It happened on our F-117: "The first production aircraft, number 785, was delivered in the spring of 1982. It crashed and was destroyed on take-off on 20 April, badly injuring the pilot, Bob Riedenauer of Lockheed, who never flew again. The accident was traced to reversed wiring in the flight control system." Rosie
 
RV reversed trim....

Years ago, a twin (I think a Piper) bellied in shortly after takeoff. The trim motor had been replaced and the cables reconnected (backwards) and the mechanic put his young assistant in the cockpit and asked for "UP" trim. He observed the tab and was satisfied. As it turned out, the assistant had moved the trip wheel 'UP', which of course, in a Cessna anyway, is down trim. The tab had indeed moved 'down' which is 'up' trim but the unfortunate pilot kept adding more up trim as the control became heavier and heavier. The trim cables were reversed.

This can and has been done on the RVs with electric trim controls........be very careful, :eek:
 
I remember the F-15 control reversal accident while at Ramstein AB. It can happen, even to the best, so be vigilant and always question the condition of your ship.

Very sad for all concerned.

Quote:

""Board Partly Clears Airman in F-15 Crash


An Air Force review board has partly cleared the name of an F-15 mechanic who committed suicide in 1996 rather than face a court-martial for a fatal repair error.

Evidence showed that TSgt. XXXXXX did not perform the botched control rod maintenance at issue, although he did check the work and found nothing wrong.

In addition, several previous incidents in which other mechanics made the same mistakes should have alerted the Air Force to a potential problem, according to the board.

"We did not think XXXX was totally free of all responsibility," said Lee Baseman, chairman of the correction board. "But it was our view that he was unduly carrying the burden for a series of missteps that went back at least 10 years."

In May 1995, XXXX and TSgt. YYYYYY were carrying out maintenance on an F-15C based at Spangdahlem AB, Germany, when YYYYY accidentally crossed flight control rods while reinstalling them. XXXX did not catch the miscue, which made the airplane impossible to control in the air. It subsequently crashed, killing Maj. Donald G. Lowry Jr. (Great GUY!!)

Air Force authorities charged XXXX and YYYYY with dereliction of duty and negligent homicide. XXXXX shot himself in October 1996 during a break in court proceedings. Commanding officers then accepted YYYYY request for administrative separation, on grounds that the interests of the service would be best served by bringing the tragic case to a swift conclusion.

Similar crossed-rod cases occurred at least twice before the Spangdahlem crash, noted the review board-once in 1986 and again in 1991. But in both instances the problem was caught before takeoff.

In its conclusions, the board stated, "After the Black Hawk shootdown [in 1994], the demand for accountability for this accident may have been pursued with such zeal as to leave fairness and equity behind. The fatal crash was a tragedy waiting to happen, yet the decedent was singled out to pay for an accident that could have been prevented anywhere along the 'chain of events' had any of the numerous individuals involved made different decisions.

"Most disturbing was the way the Air Force leadership allowed this case to be handled. The Air Force's representatives resisted the inclusion of potentially exculpatory evidence from the review and report and managed to have a good deal of it excluded from consideration in the pending trial."

Following the death of Lowry, the Air Force took steps to prevent such a mix-up from happening again. The control rods are now color-coded to ensure proper installation, and the maintenance technical manual warns against the mistake. All flight control systems must now be checked any time the control rods undergo maintenance. " "

Ref: Journal of the Air Force Association, June 1998 Vol. 81, No.5, Peter Grier

Unquote
 
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The following doesn't apply to RVs, but could be applicable to some other aircraft types.

When you do your control check, make sure you check that both ailerons are moving in the correct direction - don't just check one of them and assume that the controls are working in the correct sense.

A coworker had the misfortune to be at the controls of a T-33 that had one aileron control hooked up the wrong way. If the stick was moved one way, both ailerons moved up. Move the stick the other way and both ailerons moved down. They managed to climb away to a safe altitude, but determined that they didn't have adequate control to do a landing in the wind conditions. They went to a clear area, and ejected from the aircraft. My coworker came out OK, but the back seater's ejection seat failed, and he was killed.
 
FWIW, a local EAA chapter member (in Utah) who has some inside contact mentioned is that the Spectrum's aileron and flap controls were incorrectly reattached following an unrelated modification. Most of the reports out there are inaccurate.
 
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