Failure of T-Bar Control Column in Cherokee on Approach

[countryman]

CADOR: 2016C0338.

Not withstanding the fact that this incident, which is classified by the Transportation Safety Board as an accident, and is still under investigation to determine a cause, I could not in good conscience belay advising my fellow aviators, aviator friends, instructor cadre, ex-instructor cadre and current flights instructors of the events of Feb 13th, 2016. Moreover, since cracks around the weld of a T-Bar assembly of another Cherokee have surfaced, post incident, through Non-Destructive Testing, (NDT) the statistical odds of a repeat occurrence are increasing.

Succinctly put, on approach to Runway 13 with a student at CYAV, when the aircraft was rounded out to begin it's descent to land, an audible noise of something breaking could be heard through my ANR headset at which time the controls immediately became unresponsive. The aircraft landed without incident and we taxied back to the hangar and advised the CFI and AMO. Immediate inspection revealed a catastrophic failure at the top of the T-bar assembly with the horizontal control bar completely separating from the vertical post (pitch control). Transport Canada and TSB were advised. The subsequent NDT inspection of the T-bar control assembly of a decommissioned Cherokee revealed cracks around the weld joint attaching the horizontal control bar to the vertical post. Visual inspection did not reveal any anomaly respecting the T-bar assembly. The defect was only detectable through an NDT inspection. TSB is still investigating the cause of the failure but it is suffice to say that it has occurred, which apparently is unprecidented, and cracks have been found in a second control assembly. I will update this post when TSB publishes their findings. As an instructor with 2600 instructing hours, I can state with all assurance that I will no longer be instructing in any Cherokee where the T-bar assembly has not been subjected to a NDT inspection.

[GyvAir]

Yikes!

You should ask for that T-bar assembly to keep as a souvenir. Have it and that golden horseshoe of yours mounted above the fireplace!

Thanks for posting.

[countryman]

Thanks for reading GYVAIR and please pass on the message. I figure I won the, "life" lottery. I am not going to push my luck. I suspect we will hear more about this in the future from both TSB and Piper Aircraft Corp. The ramifications of this type of failure are pretty substantial. Fly Safe.

[digits_]

When did the T bar break: during flare, or at the start of the descent ? How did you manage to fly it "without incident" after such a failure ?

[GyvAir]

The narrative from the CADORS gives a little more description of the event:

TSB#A16C0018: The Winnipeg Aviation Piper PA28-140 aircraft, C-GQPN, was on approach to St. Andrews, MB (CYAV) with an instructor and a student on board. Prior to touch down at approximately 50 feet AGL, a snap was heard and the control column response was found to be very sluggish. The pilot was able to round out the aircraft just prior to touch down. The aircraft landed safely and taxied back to the ramp. A maintenance inspection of the control system revealed a complete failure of the control column T-bar assembly. The control column T-bar assembly will be sent to the TSB laboratory for further analysis.

[countryman]

True GYVAIR, I just wanted to stick to the facts. In retrospect, I believe altitude was was probably much lower because we were looking forward so not quite sure of the altitude. The facts were taken out of my scribed journey log entry which was completed shortly after the event, hence the discrepency in the altitude.

[900 HP]

Interesting. I used to instruct on Cherokees in the late 1980s at YAV. I once got cut off in the circuit by another aircraft who was behind me. He turned x-wind at the same time as us and we both turned downwind together. The Cessna 172 never saw me but I saw him at the last second and slammed the controls over hard enough to make the chain skip a few cogs. We just about touched tires. I wonder if that kind of stress could cause the failure? What was the registration on your airplane? I know the mechanic had to reset the chain to line the controls back up on my airplane. I'd have made a note in my personal log for sure that day.

[countryman]

900HP you were very fortunate. Yes, it can get pretty busy at CYAV. The aircraft in question is CGQPN. It is 39 years old with 21,000 hours. I have my suspicions as to the cause of the failure but it is only speculation and that would not be fair to the manufacturer. I will wait and see if the TSB report supports my suspicions. I am sure they will do a thorough job. My mission on AvCanada is to simply get the word out about the unprecedented catastrophic failure of a critical control mechanism on a ubiquitous general aviation aircraft. I have always liked and enjoyed the Piper products. I am hoping a remedy can be found to restore my confidence on the integrity of the t-bar control column.

[Heliian]

CGQPN. It is 39 years old with 21,000 hours.

I have my suspicions as to the cause of the failure

Ya, it's 39 years old and has 21,000 of being smashed by trainees.

Ageing aircraft need more inspection for these types of cracks and corrosion, corrosion being the number one cause of failures at this point. I know nothing of this company in question but this is why you actually have to spend money at your AMO instead of just getting them to do the cheapest annual or saving a few bucks by bringing your own oil.

[photofly]

I know nothing of this company in question but this is why you actually have to spend money at your AMO instead of just getting them to do the cheapest annual or saving a few bucks by bringing your own oil.

I know nothing of the company either, but I can confidently state that if they had not brought their own oil and had bought it from the AMO instead, the T-Bar would not have failed. I'm quite certain of that.

[countryman]

Gentlemen, the point of my post is to simply let pilots know such a failure has occurred. Let's let TSB do their job and tell us why it failed. My mission is to disseminate the incident so those flying such aircraft are aware that cracks could be developing at the weld of their t-bar. Visual inspection of a subsequent t-bar did not reveal any discrepancies however a NDT inspection showed otherwise. This is not an AMO issue. Let's wait for TSB and Piper's reports before jump on human factors.

[cgzro]

This is possibly fatigue. Vibration or repetitive stress induced. 21,000 hrs is a lot of repetitive movement.

Its very difficult to catch this kind of thing. I have had three such failures and trust me my inspections are very detailed. The only way to catch these is to strip the paint and NDT test them...every so many hours. Thats not something that is done in most annuals unless its an AD.

Its probably wise for owners to look for jesus welds and proactively have them checked carefully.

*jesus bolts/welds etc are those that if they fail everybody dies.

[countryman]

Thank you Peter. I actually had to pull over to respond to your message Did you have any failures like mine in a Cherokee? Piper says it is a first. If so I would like to inform TSB as I think a case is building towards an airworthiness directive. If this really isn't the first failure of a Cherokee t-bar control assembly or finding that the weld is cracked, TSB really needs to know this. Please advise, okay? Thanks. Tom

[JasonE]

I actually saw the CADORS the evening it came out. Being that I fly/own a Cherokee I emailed it to the co-owner right away... Any pictures of the failure point? I'm curious myself.

[PilotDAR]

Thanks Countryman, your post is very in formative and appreciated. It has contributed to awareness and thus safety. Is anyone able to post a picture, or parts catalog page? Could Countryman show us the location of the break on such an image?

Yes, important cracks can hide around a weld and even the most diligent visual inspection could miss them.

Over the years, I have participated in a number of "aging aircraft" seminars and presentations . In fairness to the GA manufacturers, they never imagined that their aircraft would still be in service so many decades later. In fairness to the maintainers, there is likely no inspection item to detect this. If a maintainer did an inspection so thorough as to detect this as a routine element of a very thorough inspection, owners of these aircraft would be stunned at the cost. I attended a Cessna aging aircraft presentation in Wichita a few years back. This presentation was a precursor to the issuance of the SIDs. The presenters detailed inspections which Cessna had done on several very aged Cessnas they had bought back.

The details were fascinating. When I consider them in the context of many decades experience working on Cessnas, as well as other types, I applaud Cessna for a pinpoint job of identifying the maintenance weak spots of the various models. We're in new territory in terms of retroactive introduction of airworthiness limitations - but it's not a completely bad idea - just horribly unpopular. I own three airplanes, and like any owner, dislike the idea of more imposed maintenance cost. But, when it comes down to it, an airplane is a consumable, like many other pieces of equipment. There comes a point where it should be considered "consumed". This is widely variable, based upon operating conditions, so really hard to pinpoint.

I expect that the TSB will take a great interest in the reported failure in the Cherokee, as they should. The issuance of an AD would not surprise me, I've certainly seen them issued for less. In the mean time, we maintainers are reminded to be really vigilant during inspections, and we owners are reminded to accept the cost of detailed inspection as the thoroughness we expect.

[countryman]

https://www.dropbox.com/sh/efoyj1r0vzm6 ... cVuSa?dl=0

Here are some photos in my Dropbox because the photos are too large to attach to this site.

[JasonE]

Thank you for posting the images link. I'll be sure to have a good look at mine before I fly next. I don't even see any corrosion around the failure point, so it looks to have broke away in one go. Wow.

[countryman]

Thank you PilotDAR. You did an excellent job of articulating the quandaries of maintaining an aged aircraft. You can appreciate my hesitation of jumping to a conclusion before the TSB report, in all fairness to the manufacture. I have really enjoyed flying Piper aircraft in my ab initio training, CPL and Instructor Rating as well as instructing on them for 2600 hrs. I know fixed pitch propellers are X-Rayed every 5 years. I would have never given the control column a second thought, now, unless the t-bar has been X-Rayed, it will be foremost in my mind, . . . .if I get into the aircraft at all. Yes, I was recently informed of Cessna's SID. An excellent idea. It certainly goes a long way to help maintain one's confidence in the aircraft. I hope Piper comes up with a remedy to help me restore my confidence in the Cherokee aircraft.

[Heliian]

Well, those pictures are interesting.

It's hard to tell from pictures but it definitely looks like cracks and corrosion around enough of the seam to cause it to fail under load and break off.

The thing I find most intriguing is the lack of any protection on the inside of the tube. You can see the heat marks on the inside where it was welded. Was it repaired before? or has the linseed oil or whatever they sealed it with at the time just dissipated?

[countryman]

Hi Heliian. Haha! I am still, "Stumbling" around this site as I have never accessed it before! All good questions that I can not answer. I am just the pilot who was flying the plane when it broke. By sharing my experience and photos I am trying to do my part to possibly prevent it from happening to another unsuspecting pilot with more dire consequences. I will let everyone know when the TSB report is published. Based on the TSB report, I may write Piper about my experience and lack of confidence in the aircraft but that is down the road. Thanks for the questions and engagement. I wish I could give you answers. Please let other Cherokee pilots know, okay?