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C-170B control yoke failure

Well done, he was a quick thinker.
I've heard various stories over the years of loss of pitch control and how it was dealt with, so I've practiced final approaches with trim, power and flaps only. I've never done an actual touchdown, I take over the stick at the very end, but I think I could manage a decent landing.
 
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BC12D-4-85 said:
....... Good the pilot had a spare onboard. ...
Click to expand...

I didn't see anything in the report about the pilot having a spare aboard.
Never seen one of these u-joints fail,
but I have seen them so worn out that they flop around and the owner replaces them.
Never seen a u-joint included in the usual on-board collection of spares & tools either.

Maybe this one was worn out to the point of flopping around,
and that's why he had a spare along?
Better to replace before failure IMHO.
 
This is being discussed on the Cessna 170 Association forum. The failure was of the center pin of a McFarlane supplied U joint installed last year, the fact that it was installed in a 170B in not important as this U joint is used in many Cessna models. If you have replaced one of these U joints in the last year or two you should take a look.

Tim

ps: BC12D-4-85 thank you for posting this. It may be a good idea if you were to edit the title of this thread to remove the 170B reference and let everyone know it applies to Cessna control yoke u joint failure.
 
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hotrod180 said:
I didn't see anything in the report about the pilot having a spare aboard.
Never seen one of these u-joints fail,
but I have seen them so worn out that they flop around and the owner replaces them.
Never seen a u-joint included in the usual on-board collection of spares & tools either.

Maybe this one was worn out to the point of flopping around,
and that's why he had a spare along?
Better to replace before failure IMHO.
Click to expand...

He was referring to the " spare " yoke on the right side.

Glenn
 
PerryB said:
Well done, he was a quick thinker.
I've heard various stories over the years of loss of pitch control and how it was dealt with, so I've practiced final approaches with trim, power and flaps only. I've never done an actual touchdown, I take over the stick at the very end, but I think I could manage a decent landing.
Click to expand...

Friend of mine did exactly that in his Super Cub when the inner connect tube broke inside the torque tube... Trim and power, dumped the flaps at touchdown and did not use the brakes... tail came up and was a bit scary but it did not nose over... I think he had a slight uphill long runway also...

Brian


Sent from my iPhone using Tapatalk
 
They all wear...the question is whether or not the word "out" applies here or potentially to others across the Cessna line. If it's truly a new McFarlane product (https://www.mcfarlaneaviation.com/products/category/universal-joints-cessna-aircraft/), then note: "An examination of the airplane revealed that the pin in the universal joint for the pilot-side control tee (flight control yoke) had failed. The part has been retained for further examination and testing by the National Transportation Safety Board Materials Laboratory in Washington, D.C." This will become important.

I've been in Cessna's that have had worn control parts. Not sure if it was the U-joint or other behind the panel components. Pin the control shaft lock and move the ailerons I assume is common during daily or annual inspections to initially look for wear. Owners get used to wear so are not the best to note the problem. Good mechanics are worth every $ in that case.

Edit: I hope they take into account the life of the plane since the component was installed...any potential stress from weather or whatever that may have done bad to the part. But if it's a straight up failure I'm sure it'll be noted when they get some examples to test for strength or integrity of staying together.

Gary
 
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bat443 said:
This is being discussed on the Cessna 170 Association forum. The failure was of the center pin of a McFarlane supplied U joint installed last year, the fact that it was installed in a 170B in not important as this U joint is used in many Cessna models. If you have replaced one of these U joints in the last year or two you should take a look.

Tim

ps: BC12D-4-85 thank you for posting this. It may be a good idea if you were to edit the title of this thread to remove the 170B reference and let everyone know it applies to Cessna control yoke u joint failure.
Click to expand...

So is this a McFarlane part that failed?
 
too bad they don't show pin sideways, looks like they are peened over to retain.... can't tell if it's un peened, or broke or?????
 
I have this friend (NO! Really at least one...) who was towing at a glider contest in a very ratty '60 C-182; I was working ground ops, and rotating to a more appropriate tug. Over the fence, flaps 40*, flair, and the yoke came off in his hand. Calmly reached over and finished on the passenger yoke. He flew the rest of the launch line from the right seat, but couldn't see the strut-mounted mirror. Good thing it was experienced glider guiders. Never missed a beat, in a high stress situation. He still has my highest respect, I couldn't have done that. Ya' can't make this stuff up.

Thanks. cubscout
 
hmmm let's see...

they NOW harden the outside of new pins, for last year and a half, to harden it more & prevent outer pin wear....

yet the one that failed the pin broke in half... it was already too hard.... hmmmm..
 
Read it....thanks Mike. They claim the unit failure is due to radial stress from galling and stiction of the rivet in the assembly. Would movement of the ailerons apply a potential periodic bending moment on the rivet as well, especially if the control was gust pinned and wind rocked the ailerons? I wonder if they should spec an anti-galling pre-lube like moly paste (like used in auto CV joints) or similar to help prevent the problem? What's Cessna's lube - MIL-L-7870 oil? Then there's the all important rubber sleeve to exclude contaminants.

25hrs/100hrs/1 year...who's going to do all that instead of replace? Does a Service Bulletin preclude an AD or mandatory for Part 91? Lots of questions.

Gary
 
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mike mcs repair said:
no mechanics or engineers were harmed or included in this new document... they Lawyers have this....
Click to expand...

CYA to the rescue...

It takes the NTSB months to years to determine probable cause...yet the manufacturer was able to generate a Service Bulletin in a month since the part failure and attribute the likely cause for failure to outsourced production methods and outdated specs.

They may have had prior knowledge (I assume) and finally decided to alert the mandatory compliant 135 operators. Part 91 will have to wait for the FAA's AD or just pony up for a McFarlane Christmas gift . Not saying they're negligent here...just maybe post and finally pro-active.

Gary
 
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Yes that makes sense on holding in the worn rivet and pins. However if the rivet fractures in two locations there's not much to hold one half of the joint and control yoke from pulling away from the other if the half pins surrounding the rivet move out of the center block. In this case the rivet was identified to have failed and associated parts may have fallen out (no rubber sleeve installed?).

McFarlane came up with lot numbers of affected parts quickly. They must have had some prior knowledge and in later production lots took steps to improve their product.

An AD will likely follow for Part 91 ops.

Gary
 
As a fellow mentioned on the 170 forum, based solely on the photos shown and estimated hours used, I find it hard to believe it broke from wear or galling. Perhaps a bad rivet install.


Sent from my iPad using SuperCub.Org
 
Guess we'll have to wait and see if the FAA issues an AD. If it's potentially defective parts that compromise primary flight controls then they likely will.

Follow here: https://www.faa.gov/regulations_pol...ctives/?tab=recent&viewType=table&startRow=51

Nothing yet and they may take a different approach via a NPRM or Emergency AD. How else is a Part 91 pilot or maintenance personnel supposed to know what to look for or how to comply?

Gary
 
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mit greb said:
they put out a service bulletin
Click to expand...

BC12D-4-85 said:
And who receives that info directly without searching their website?

Gary
Click to expand...
Don't count on receiving service bulletins. I have purchased several new Cessnas. Periodically I would receive a letter in the mail that a service bulletin had been issued. But they would not tell me what it was. The letter said to go to a Cessna Service center to find out. I am my own service center, why couldn't they just tell me what the issue was? Usually it was just some small lawyer statement.
 
I think if McFarlane sold a part directly to a customer then the customer might be notified if MF keeps track. They do per their SB-9 Rev. A: "This service bulletin has been distributed to all customers for whom McFarlane Aviation, Inc. has sales records indicating the purchase of affected parts."

If MF sold the part initially to a distributor then they would not have part traceability unless the distributor chose to get involved via their customer database. Then there's the inevitable that planes get moved from owner to owner...and who's going to follow that trail?

Cessna would maintain a database of their aircraft but only to a point. Don't know that point. Road motor vehicle manufacturers do it via recalls by VIN filed with the NHTSA: https://www.nhtsa.gov/recalls

An FAA AD would become public knowledge. Aircraft owners and operators are then responsible for compliance. FAA's AD portal: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/MainFrame?OpenFrameSet

Edit: Question. Do mechanics receive Service Bulletins or is there a subscription list available?

Gary
 
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the one sever load I could think of is if they use the yoke lock pin, and maybe this went through a good windstorm or a few???
 
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