Safety Alert

[jrichards]

Hi All,

Check your airplanes:

We have encountered a 3400-hour 112 with separation of the left hand pedal shaft crank from the pedal support shaft. See below IPC page and pics.

Although we guess the original crack and fatigue started some time ago, this specimen airplane progressed from normal rudder and steering operations to a rudder jammed full right, and nil steering authority, within the span of taxiing approx 1/2 mile and starting take off roll.

The PIC noted inability to hold center line and safely aborted the take off.

Upon evaluation, the near-totally separated crank was found. All cables were continuous and in proper routes. The cause of failure is not yet known, but signs of corrosion at the suspected original crack site seem to indicate a failure development path of corrosion > fatigue > crack > separation.

During the takeoff roll, all four pedals moved forward into near contact with the firewall, steering authority became nil, and the rudder became full deflected to the right with complete loss of rudder control.

This structure is basically the same for all models. I suggest close visual inspection before further flight.

Jim

 

[Commander91gm]

Re: Safety Alert

Plane must have been flown by a gorilla. The shaft does look pretty bad. The one in my plane is fairly clean.

 

[jrichards]

Re: Safety Alert

Hi Joel,

At the moment, I don't see how pilot over-force could cause this without his/her foot passing through the firewall.

Jim

 

[gmores]

Re: Safety Alert

Wow - gorilla is right! Even with some corrosion I can't see how a pilot could have torn the metal like that. I have an extra set of rudder pedals still mounted on the tubes and I'm going to take a closer look at the construction.

 

[CenAir]

Re: Safety Alert

Looks like a very serious case or corrosion shaft crank, and some other components in the pictures and wouldn't be surprised to see a lot of other parts seriously corroded in the aircraft and wondering if has based for many years outside near or on the ocean?

 

[CenAir]

Re: Safety Alert

Or was underwater in a flood and exposed to seawater and resold after the damage to an unknowing buyer? No A&P should have missed this a long time ago if the plane was getting real annuals before it got the is bad, and bet there is more to this story and plane for many years before a failure like this.

 

[Airotto370]

Re: Safety Alert

Wow - gorilla is right! Even with some corrosion I can't see how a pilot could have torn the metal like that. I have an extra set of rudder pedals still mounted on the tubes and I'm going to take a closer look at the construction.

I had a very similar situation many moons ago with my Warrior. (Quiet in the Peanut Gallery!!). First annual showed a separation at the pedal and column with severe corrosion. Scary stuff.

 

[Pete]

Re: Safety Alert

Not sure how one would get that much corrosion in that area? My IA and myself look all that over during the annual when checking brake fluid etc.

 

[wab003]

Re: Safety Alert

There have been some what might be described ramp rat airframes that when inspected have shown signs of substantial water inside the aircraft from leaking glass and door seals. Add potential extended exposure to sea air and it's not a good omen for keeping corrosion under control. Many of these airframes have a good number of miles/years on them so take advantage of the annual to take a closer look at structure. "No surprises" is the best prescription when flying vintage aircraft.

 

[jrichards]

Re: Safety Alert

Hi All,

Check your airplanes.

We will be disassembling the subject failed shaft assy for further inspection.

Corrosion may have seeded the failure, but clearly the progression was due to mechanical loads. Preliminary review of the load scenarios points to braking loads (symmetrical on the pedals) because steering and flying loads are primarily one-sided with the other pedal just free-slaving.

The system was intended to be tested to pedal load of 200 lbs limit, 300 lbs ultimate, but, interesting enough, the symmetrical case (braking) may have never been tested.

Jim

 

[Lawrence Rippon]

Re: Safety Alert

We are talking about one aircraft, right?

Please don't turn this into another elevator spar.

 

[davloose]

Re: Safety Alert

For the record, at least some of us with cracked elevator spars were happy for the chance to pay for them with money, and not our lives...

And a rudder spar.

 

[Frank]

Re: Safety Alert

Jim - can you describe that in pilot language? Is this the first time it has happened on a Commander?
Also maybe Judi - if she knows which airplane it is can shed some light on history. There has to be more to the story.
The break in the second picture appeared to be new, unless it was washed out by the flash and the first picture showed what looked like rust.
I looked at mine and compared to the one in the picture mine looks brand new.

 

[CenAir]

Re: Safety Alert

Jim - can you describe that in pilot language? Is this the first time it has happened on a Commander?
Also maybe Judi - if she knows which airplane it is can shed some light on history. There has to be more to the story.
The break in the second picture appeared to be new, unless it was washed out by the flash and the first picture showed what looked like rust.
I looked at mine and compared to the one in the picture mine looks brand new.

No question and mine looks brand new too, and as I mentioned in my post 5 & 6 was underwater in a flood and exposed to seawater and resold after the damage to an unknowing buyer, or based for many years outside near or on the ocean I thought after looking at the picture.

Doesn't take much time for an owner to visually check ones own plane as those pictures were scary looking, and wonder how the rest of the plane looks for corrosion.

 

[Lawrence Rippon]

Re: Safety Alert

For the record, at least some of us with cracked elevator spars were happy for the chance to pay for them with money, and not our lives...

And a rudder spar.

Try operating a Commander in Europe. This can become an AD very easily, which when transferred automatically to EASA becomes infinitely more difficult to comply with. Unlike the Spar issue, it is only one aircraft. Things break on aircraft every day, it doesn't mean the whole fleet is affected.

I am due on annual next week so I called my engineer to advise him of Jim's notice. He tells me that inspection of the affected area is part of the normal annual inspection. At least under EASA Part M you know your aircraft is being inspected properly to reduce the risk of these things happening.

 

[marcelo67]

Re: Safety Alert

Thanks for posting,plane is currently under annual .

 

[Pete]

Re: Safety Alert

Lawrence, yes, my IA inspects that area during my annuals. I also inspect the area anytime I check my brake fluid levels. I'm not excited about a possible AD on this situation. The elevator spar is out of sight and would not be accesable for routine inspections, ie at annual.

 

[jrichards]

Re: Safety Alert

Hi Lawrence,

How would we know if we are talking about 1 airplane unless we all check our airplanes?

And to all:

While every annual should, and hopefully does, include an inspection of the flight controls, once you have carefully examined this particular weld you will appreciate the awkwardness of getting your eyes and/or mirror positioned for a good view.

Jim

 

[Commander91gm]

Re: Safety Alert

Didn't do any major dis-assembly to inspect at this time but if you look at the condition of my plane VS the problem aircraft (and my plane is no spring chicken) it says to me that there is more to the story.

The subject aircraft has to have had some unusual event.

 

[wab003]

Re: Safety Alert

Certainly worthy of inspection at every annual just like all bellcranks, torque/push tubes, cables , fittings, etc. As long as the SDR for this single aircraft and the current FAA fervor over fatigue analysis for aging airframes doesn't result in a mandatory eddy current inspection of the tube in every aircraft, it should be no problem. A reasonable visual inspection should be adequate in this case.