Interesting Control problem Issue

[pelmet]

"A13O0229: The Field Aviation Inc. DHC-8-300 aircraft (C-GNUD) was on the take-off run when the pilot noticed excessive elevator forces on the pitch controls. The aircraft became airborne momentarily but engine power was immediately reduced and the take-off was aborted. While taxiing back the pilot noted that the elevator could not reach its full travel limit. Two subsequent high speed runs were performed with the same elevator forces being experienced. The aircraft returned to the hangar for further troubleshooting of the flight control system. The aircraft was being flown for the first time since it was repainted, which required the flight controls to be removed. This work was contracted to another facility which had installed and balanced the flight controls and the maintenance release indicated dual maintenance signatures on the maintenance release as per current regulations. It was eventually determined that the counterweights on the elevator spring tab had been installed in reverse. This prevented elevator spring tab full travel which increased the aerodynamic loads on the pitch control at a high speed. The counterweights were than installed in accordance with the AMM procedures and subsequent testing revealed no further faults. The return flight to CYYZ was uneventful."






I do remember on a couple of different larger types coming out of major checks doing an external check of all flight controls and tabs if possible for appropriate and proper direction of movement. One was provided in detail on a post maintenance checklist. The other type did not have this so I did it myself.

But perhaps on some types not everything can realistically be checked on the ground.

[Brown Bear]

Doc and I flew a DC3 on a test flight after a wing pull. He handed me control and asked if I noticed anything strange with the aileron trim. Yup, it was backward. In our defence, although we may have checked the trim travel before take off (we probably didn't) you can't see the trim tab from the front seats. Not that either of us would have noticed the direction of travel so early in the day?

[ahramin]

Yep. Got into a 90 one day and noticed the rudder trim was backwards. Had been that way since the aircraft was repainted a year previous. Owner's comment: "Well turn it the other way then." .

[Liquid Charlie]

Happened with a 748 -- aileron swapped out -- no test flight and to make it worse no one knew that a test flight and a procedure was required -- 2 great guys lost their lives ---

[pelmet]

Don't people check the flight controls and trim tabs for proper direction on the test flight after a major inspection from outside the aircraft? It only takes a few minutes. That is just common sense.

[Beefitarian]

Don't people check the flight controls and trim tabs for proper direction on the test flight after a major inspection from outside the aircraft? It only takes a few minutes. That is just common sense.

I agree yet... Not so much?

[ahramin]

I have come to the conclusion that the only thing to do when work has been done on flight controls is to assume that both engineers have screwed it up and check everything for:

Free travel independently and when all controls are moved together,
Correct direction of travel, and
Stops at the correct places fully expecting to find multiple problems.

Also there are often procedures in the MM and FCOM that must be followed.

I prefer to give engineers the benefit of the doubt but after the number of fatalities we have seen over the years I just don't see that as an option in this case. You have to walk up to the aircraft knowing in your head that it's been done incorrectly and force the aircraft to convince you otherwise.

[iflyforpie]

I put together the aileron trim system by the book on an SC.7 Skyvan and it wound up being backwards. I crossed the cables the other way and it worked fine with no clearance or travel issues. Must have been a drawing error.

I had another one on a Cessna 207 that had been completely torn down; ailerons backwards. The photos in the service manual were very poor quality so you could not tell if two cable crossed or just went very close to each other before turning and the cables had been routed months previously before wings or ailerons were installed.

Finally, I was working on a Navion Rangemaster and I got one of its tele flex controlled trim tabs backwards. When I checked the sense, I was only looking at the left elevator out of the entry door.... I could not see the right elevator and rote had me conditioned to only looking at one.

All of these happened within about a month of each other. All of them were discovered by me before dual inspection and remedied.... but it just goes to show how easy it is to get things backwards.

Now I am struggling with trying to change a J3 elevator control system to a Super Cub one. It sure is fun trying to meld two different aircraft types together.

For control checks, every time before I fly.... correct sense, correct position verified by eyeballs, not gauges, indicators, or cockpit controls.

[cncpc]

I have heard that if you rig the ailerons on the single Otter as per the De Havilland instructions, the aircraft will crash.

[boeingboy]

I have heard that if you rig the ailerons on the single Otter as per the De Havilland instructions, the aircraft will crash.

I find that very difficult to believe.

[flyinthebug]

I recall an incident with a King Air A100 at Air Thunder in the 90s. The elevator was rigged backwards and when they pulled back on the yoke, the nose went down and visa versa. They got her in the air and somehow managed a controlled crash on the train tracks near YQT. My memory of this event is vague, but I do remember the Captain saying he couldn't understand what was happening on the take off roll, and for some reason he continued to try to get her in the air.

Luckily the pilots did an amazing job to get her down without killing anyone. The plane was pretty broken up but the crew walked away. My question was...how did they miss this in the pre flight??

Like has been said above, ESPECIALLY after a re rigging, be sure to check your flight controls!! This is part of every DI and pre take off checklist...doing an actual DI and thorough pre flight will someday save your life.

When you check for full deflection of the ailerons, rudder & elevator...be sure to LOOK inside the cockpit and SEE what the controls are doing (if you cant see in, have your FO stand in the cockpit and confirm the deflection is in the correct direction). I have seen countless pilots doing their DI and they do grab the aileron and see if it offers full deflection in each direction...but they fail to look inside to see what the yoke is doing as they check. Just pulling and pushing on an aileron, rudder or elevator and looking for full deflection is useless, unless you are able to confirm that the yoke (and rudder pedals) are doing what you are commanding it to do. Same idea for when in the cockpit...be sure to look outside when you are checking "controls free and CORRECT" pay close attention to the correct part. Ive seen too many just go through the motions and never even look outside.

My 2 cents, fly safe all.

[oldtimer]

Many moons ago, an air operator from Fort Smith NWT imported a single Otter from overseas and had it reassembled in Villeneuve AB rather than at his home base. The AME was not familiar with the Stoneboat and hooked up the aileron controls so instead of being differential, they either went full up or full down. The airplane crashed on take-off, killing the owner, the AME and a helper. In the accident investigation it was discovered that the aileron cables and the aileron balance cables disconnected at the same point in the fuselage so it was possible to hook the turnbuckles up wrong. There was a picture of the airplane, taken the day before the accident, where a TC inspector came to sign off the ferry permit and parked a TC owned SUV by the airplane which was sitting with all flaps and ailerons full down. Apparently nobody noticed the discrepency.
When I was flying the Metro, it started out as a silly joke but became a procedure. Taxing out, I would roll the wheel full right turn, look the right seater in the eye and say "Up Yours". The right seater would look out to see the right aileron up and then would do the same to me.
I also read of an incident in the USA where a A and P mechanic rolled trim tabs full deflection both directions as a required procedure but did not return them to neutral so he was sued. But he won the lawsuit because it was determined to be the responsibility of the pilot to ensure the flight controls at set properly for flight. This got me thinking, which is also dangerous so with a buddy of mine, we got into a Cessna 140 and I put my left foot on the right rudder pedal on the left side and my right foot on the left rudder pedal on the right side and then tried to do a coordinated normal turn. It was a disaster, sort of.

[YYZSaabGuy]

Many moons ago, an air operator from Fort Smith NWT imported a single Otter from overseas and had it reassembled in Villeneuve AB rather than at his home base. The AME was not familiar with the Stoneboat and hooked up the aileron controls so instead of being differential, they either went full up or full down. The airplane crashed on take-off, killing the owner, the AME and a helper. In the accident investigation it was discovered that the aileron cables and the aileron balance cables disconnected at the same point in the fuselage so it was possible to hook the turnbuckles up wrong. There was a picture of the airplane, taken the day before the accident, where a TC inspector came to sign off the ferry permit and parked a TC owned SUV by the airplane which was sitting with all flaps and ailerons full down. Apparently nobody noticed the discrepency.

Having both ailerons down wouldn't produce roll issues (I wouldn't think), so the crash resulted from.......what?
Stall shortly after unstick or right after leaving ground effect, due to excess drag?

[oldtimer]

I cannot remember if both ailerons went up or down after take-off. All I remember from the accident report is that the airplane crashed on airport property after rolling to the left, killing the 3 people on board. The point is that just because the cables are hooked up and all the safety wires are done correctly, the airplane still may not be configured correctly.
Now the Up Yours comment was something we did as a "chuckle" but it did reinforce the fact that the flight controls would move freely and at least part of the control system was operating correctly. So any time I saw a maintenance entry that required a dual signature, we made a concious effort to verify correct operation of controls and as a result, never had a problem or incident.
I would sometimes ask a junior co-pilot where a particular trim tab would be if the trim was in full deflection and a surprising number could not figure it out quickly. It was surprising on how many would miss a rudder trim tab in full deflection on the external walkaround and also fail to notice the cockpit trim tab indicating full deflection in the same direction. I also wonder why a junior pilot would not make mention that the external elevator trim tab on a Navajo is full down but the trim indicator in the cockpit shows the trim in the take-off range. They miss the fact the trim tab is also a servo tab so being full down with the elevator control full forward while stationary on the ground is normal and correct.

[StandingBy]

I recently talked to an FAA delegate who related a story of an aircraft that crashed with ailerons rigged backwards after they had been visually inspected EIGHT times. From experience I can see how this would happen (maybe not after eight tries) if the proper care is not taken to avoid miscommunication during a control check.

[AOW]

I recall an incident with a King Air A100 at Air Thunder in the 90s. The elevator was rigged backwards and when they pulled back on the yoke, the nose went down and visa versa. They got her in the air and somehow managed a controlled crash on the train tracks near YQT. My memory of this event is vague, but I do remember the Captain saying he couldn't understand what was happening on the take off roll, and for some reason he continued to try to get her in the air.

Luckily the pilots did an amazing job to get her down without killing anyone. The plane was pretty broken up but the crew walked away. My question was...how did they miss this in the pre flight??
.

The elevator wasn't rigged backwards, the stabilizer trim motor had been worked on, and not installed properly. The result was the leading edge of the stabilizer wasn't attached to anything, but was in the right spot until air loads acted on it. All control checks were normal, TSB found the crew did everything right. After rotation they pitched straight up, climbed 500+ feet, stalled and pitched straight down. They had no pitch control due to the loose stabilizer. The thing that probably saved their lives was the quick thinking pilot who added power as they were pointed at the ground, causing a nose up pitch, and arresting their descent.

The TSB has all of the boring details

[flyinthebug]

I recall an incident with a King Air A100 at Air Thunder in the 90s. The elevator was rigged backwards and when they pulled back on the yoke, the nose went down and visa versa. They got her in the air and somehow managed a controlled crash on the train tracks near YQT. My memory of this event is vague, but I do remember the Captain saying he couldn't understand what was happening on the take off roll, and for some reason he continued to try to get her in the air.

Luckily the pilots did an amazing job to get her down without killing anyone. The plane was pretty broken up but the crew walked away. My question was...how did they miss this in the pre flight??
.

The elevator wasn't rigged backwards, the stabilizer trim motor had been worked on, and not installed properly. The result was the leading edge of the stabilizer wasn't attached to anything, but was in the right spot until air loads acted on it. All control checks were normal, TSB found the crew did everything right. After rotation they pitched straight up, climbed 500+ feet, stalled and pitched straight down. They had no pitch control due to the loose stabilizer. The thing that probably saved their lives was the quick thinking pilot who added power as they were pointed at the ground, causing a nose up pitch, and arresting their descent.

The TSB has all of the boring details

Thanks for the update and link AOW. It was a long time ago and many of the details were lost (in my memory) over the years. I do remember the crew was praised for how they handled the situation. I appreciate the accurate information.

[Popol]

The oem rudder trim switch for an aircraft that I was working on was out of production. There was an sb to replace it with a different type of switch...

It was done as per the sb and the trim was backward!

By the way, there is no need for 2 engineer to do a dual check on control. The guy making the dual can be an apprentice ir just about anybody approved under an amo to do a dual check on flight control