Rudder Failure - NTSB Notice 2252

[skywagon8a]

know of any existing AD's with an AMOC that requires inspection of steel tubing that is covered by fabric?

curious what the AMOC is for similar issues..

It's up to you to develop the AMOC for your particular application. An AMOC is just a method of giving you wiggle room to comply. The contact person is mentioned at the bottom of the AD.

 

[Scott 2020]

for those who are talking about repairing an old ass rudder...are you being serious?

you do realize you can get a new rudder for less than $1500? $750 for the rudder and another $750 (at most) for the cover job.

barely a drop in the bucket compared to the cost of owning an airplane

its not like they're trying to AD your 1025 steel fuselage.

$1500 is half a years flying budget for some. More importantly nobody wants to part with that kind of money, endure the associated hassels and downtime, if the remedy is not well thought out.

I looked at rudder availability and theres already backorder/leadtime issues.

So far I don't see sufficient rational to make this an immediate replacement issue. Visual inspection plus perhaps internal camera inspection followed by a simple reinforcement procedure within next 500hours or five years for example, would be a response prportional to the risk.
S

 

[dgapilot]

I’ve gotten two or three AMOCs in the past. You have to show that the proposed method provides an “equivalent level of safety”. It is up to each owner to develop the AMOC, and most times it is applicable to only one serial number airplane unless you go for an STC like a Sutton Exhaust or the various STCs for T-34 wing spars.

I have an AMOC for sealed struts that were drilled. Have to do the ultrasonic inspection, apply the corrosion treatment and weld up the holes. Turns them back into sealed struts. Biggest issue is the ultrasonic inspection is going to run $880 to inspect the 4 struts!


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[dgapilot]

Should FAA decide to move on this, remember that it will first be an NPRM with a request for public comment. Anyone that will be impacted should keep an eye on the Federal Register to see if an NPRM comes out and submit comments if it does. Unless they decide to do an Emergency AD, any rulemakeing will take at least 3 to 5 years.


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[dgapilot]

Basically handcuffed until some sort of directive materializes yes, but doesn't prevent discussion on the issue that could develope a recommendation in responce to the proposed rule making, whever that happens.

To achieve reinforcement of the area (assuming no visable damage is detecte), drive rivets or cherrymax would work in lieu of rosette welds so no fabric work required.

The problem I see is getting a snug fitting tube past the hinge points. The hinges were of course gas welded so internal deformation of the rudder tube is likely. I've looked at mine and the weld point is visable on the inside of the tube. Possibly could be polished with an abrasive bit on the end of a long extension.

AC43.13 allows clearance og .063" for an internal sleave but it antisapates welding the sleave to the tube at the joint.

The ID of the tu e is actually larger than 3/4". 7/8 OD with .035 wall is .805" or so so a 3/4" OD tube is within the clearance limit in AC43.13.

It appears the real concern here is the potential loss of rudder control due to the failed rudder getting tangled with the stab wires. I'd certainly like to see more work done on whether or not this could actually happen. Its clear the top of the rudder ends up close to or in contact with the stab wire. The key question is can it actually prevent movement of the rudder to the extent that cannot be overcome by the pilot's foot.

A more comprehensive analysis of the potential failure scenarios will indicate how urgent the issue is. So far the failures have left the bulk of the rudder intack and functional with positive outcomes in terms of injuries or deaths. This suggests time is available to find a practical, balanced solution.
S

Keep in mind that a lot of airplanes were built with sleeves rosette welded at places other than where a tube joint is. PA-16 has a sleeve under where the aft gear fitting is located and I think Pacers and TriPacers have the same reinforcing tube. The rosettes are what hold them in place. If you can’t find a tube that is a slip fit, you can always get one with a thicker wall and turn it down on a lathe. That’s how the lower forward part of the longerons are on a Rose Parrakeet, it has a 23” long turned sleeve there.


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[BC12D-4-85]

A reduction in elevator or horizontal trim authority was noted in one PA-12 accident (ANC20LA059), maybe others. The flopped over rudder top acted like an extra elevator that caused a sudden nose up condition with limited rudder control. And that required a quick response to keep the nose down. Plus they lowered the float rudders to help assist the rudder maintain directional control. Not what we'd want during critical phases of flight.

Gary

 

[Hardtailjohn]

I think a tube slid inside is a corrosion nightmare in the making. I've got a PA12 that's getting a new post of 4130. It's uncovered now, so it'd be stupid not to.
John

 

[bob turner]

I would wait a bit for the AD.

Internal sleeves don't seem to be much of a problem. Most Cub fuselages have longitudinal splices that don't match 43-13, and when cut open, they are usually pristine inside, even from 80 years ago and wasted outside.

 

[cubdrvr]

As far as I can tell the struts on my '59 A model are original.......for sure for the past 25 yrs. I hope this rudder issue doesn't mimic the knee jerk response
they used for the cub struts.

 

[akwing]

As far as I can tell the struts on my '59 A model are original.......for sure for the past 25 yrs. I hope this rudder issue doesn't mimic the knee jerk response
they used for the cub struts.

lol