Possible Rudder Airworthiness Directive

Steve Pierce

Administrator
Staff member
Graham, Texas, United States
There has been a lot of talk about a possible Airworthiness Directive being released following the January10, 2022 NTSB Aviation Investigation Report on the Structural failure of part # 40622 rudders which are used on most all of our rag and tube Piper aircraft. This report highlights five case of failed rudders, all five had an aftermarket beacon or strobe installed on top. The details are here:


NTSB AIR-22-02
https://drive.google.com/file/d/18yK...ew?usp=sharing


I had a chance at Oshkosh to speak with a friend of mine who happens to be the Director of Aviation Safety at the NTSB and is a Piper owner himself. He showed me the rudder post from one of the failed rudders and I could see pits and the crack emanating from it.




Then in December Piper issued Service Bulletin 1379 addressing the cracking rudders which brought up discussions of an Airworthiness Directive. My opinion at the time and my friend at the NTSB agreed that given the amount of time that had taken place between the incidences and the present and the lack of a Notice of Proposed Rulemaking it was very unlikely.


Piper Service Bulletin 1379
https://drive.google.com/file/d/16Kq...ew?usp=sharing


Fast forward to last weekend when Airframes Alaska posted a video via email and on Facebook stating that there is an Airworthiness Directive coming out and they discussed that the early rudders made from 1025 mild steel were the effected rudders, not the rudders made from 4130 chrome-moly steel that Piper changed to according to drawing 40622 on June 3, 1974.They went on to say that their rudders are made of 4130 and would eliminate the AD. This stirred up a lot of questions about where this information about an emanate AD had come from. I asked that question on Facebook on Saturday evening.





Sunday afternoon I was informed that the FAA had contacted Airframes Alaska inquiring about their stock of rudders because this AD was coming out. I immediately reached out to my contact at the NTSB who was not aware. Then I called Dakota Cub and they had been contacted some time ago asking if there was a way to identify their rudders from Piper rudders. Pieces were starting to click.


Monday morning I called my contact at AOPA who is a Super Cub owner and he had not heard any talk of a forth coming AD and when he started digging around found out no one at AOPA could find anything either.


I did a Google search and came across an FAA Aviation Concern Sheet dated 9/4/2020 and made a phone call to a contact I have in the FAA that works on these types of things. He could not tell me if there was an AD coming out but he could tell me how they do a risk analysis on these types of things and flight controls are high up on the list. It doesn't seem there will be an Emergency AD but I am betting money the Notice of Proposed Rule-making is coming soon. These usually have a 60-80 day comment period, after which the FAA has to read and respond to. This can take a month or more and given backlog on Ads I wouldn't be surprised if it took longer.


FAA Airworthiness Concern Sheet
https://www.faasafety.gov/files/noti...A-18_REV_D.pdf


So my thought process went to an Alternate Method of Compliance. Members of ShortWingPipers.org had discussed the use of inserting a piece of 3/4” 4130 tubing inside the 7/8” rudder post. This takes a little cleaning out of the weld burn through of the rudder steering arm and would also require some rosette welds to make the two tubes one and eliminate the two tubes working inside of each other. I also spoke to Clyde Smith (the Cub Doctor) who's idea is to cut a hole in the top of the rudder post and run a short piece of tubing past the top hinge where the cracking has occurred and rosette welding that in, capping the hole in the rudderpost and recovering the top of the rudder.


Over the weekend I started getting texts, phone calls etc. in response to the Airframes Alaska video. In two of those cases it seems two of the owners have dodged the bullet so to speak. One owns a 1976 model Super Cub so he would have had a4130 rudder from the factory and the other one had a new FAA/PMA'd rudder installed at rebuild about 10 years ago. All FAA/PMA'd rudders are4130 chrome-moly. There has been no PMA granted for a mild steel rudder. I contacted Airframes Alaska, F. Atlee Dodge, Dakota Cub and Univair about identifying their rudders in the field if logbook entries were not available. The only one that is identifiable is Dakota Cub, they have a square hole in one side of the steering arm.




From discussions with the FAA I was told when they looked back into the history of this issue they found12 cases of cracked rudders and several involved major damage to the aircraft. Piper built 45,000 airplanes with this rudder of which about 20,000 are still on the US registry. It is my intent to relay here everything I have learned on this subject and I hope that those commenting to both this thread and the Notice of Proposed Rule-making will be educated with these facts. I feel we need to respond and hopefully avoid this Airworthiness Directive but be aware of the issue at hand and be diligent in the inspection of this area.

Thanks for taking the time to read all of this and educate yourself.
 

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Thanks for the update on this. I am in the middle of a full restoration, and am considering just buying a new rudder to solve any issues down the road.
 
Thanks, Steve.

Could you repeat, or provide a link to, the discussion of which planes have "early rudders made from 1025 mild steel"? Is it all short-wings?
 
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I may be all wet but it seems to me the rudder cracking at the or slightly above the post hinge seems to be linked to the beacon being on the top of the rudder and the aerodynamic stresses put on the rudder from it. Remove the beacon, inspect the post for cracks , pitting and corrosion and call it a day. I could be wrong but I would be willing to bet not just the 5 you mentioned, Steve, but all the cracked rudder posts had beacons on them when they cracked. AD should be pretty simple in my opinion.

If installed, remove beacon. Inspect rudder post for cracks and corrosion. Determine if it is original mild steel or aftermarket 4130 (or after 1974, 4130). If 4130 reinstallation of beacon is permitted, if mild steel, beacons or other items are not allowed to be placed on top of rudder post. If it is desired to place a beacon on the rudder post they might include a reinforcing procedure or something as suggested by Clyde, where you rosette weld a 4130 piece of reinforcing steel into the post for the top foot or so or even the whole length. Probably have to keep it as thin as possible to not affect weight and balance too much. I suggest IF/WHEN there is a comment period for an AD we flood them with something similar to make it as simple as possible or they will do something stupid like require all rudders to be replaced (exaggerating, I don't really think they would do that) or something equally stupid and expensive.
 
Steve, thank you for taking the time to research this and keeping us informed.

Juergen
Pacer N3342Z
 
Thanks, Steve.

Could you repeat, or provide a link to, the discussion of which planes have "early rudders made from 1025 mild steel"? Is it all short-wings?

early rudders made from 1025 mild steel were the effected rudders, not the rudders made from 4130 chrome-moly steel that Piper changed to according to drawing 40622 on June 3, 1974.
 
seems to be linked to the beacon being on the top of the rudder

The beacon sure doesn't help, but the rudder balance forward of the hinge does concentrate the load in the area where the failures occured. Thankfully no tombstones yet and hopefully there'll be a solution that doesn't involve re-covering the rudder. Thanks for the continued investigation Steve...
 
Looking at the NTSB information and the horsepower listed for all the planes whose rudders failed only the PA-18 could come from the factory with the horsepower listed. It is likely all of them were modified by STC to much higher horsepower than they were originally built with. This would have obviously increased the aerodynamic loads on the rudder, especially at higher speeds with the drag of a beacon on top. You are correct that there is a concentration of loads where the failures occurred with the wires, rudder hinge ang the leverage force from the wind on the beacon all concentrating right there just above the hinge. Any small pit or corrosion in that area could easily lead to a crack and failure.
How difficult is it going to be to replace that rudder post?
 
Steve,

I really do appreciate the effort you put into keeping us informed. How would I go about determining if this affects me, either by paperwork, serial number or visual inspection of my rudder?

R/
Greg
 
Steve,

I really do appreciate the effort you put into keeping us informed. How would I go about determining if this affects me, either by paperwork, serial number or visual inspection of my rudder?

R/
Greg
early rudders made from 1025 mild steel were the effected rudders, not the rudders made from 4130 chrome-moly steel that Piper changed to according to drawing 40622 on June 3, 1974.
Piper rudders built prior to June 3, 1974.
 
Other than Univair, who else has rudders for the PA-22?
"All FAA/PMA'd rudders are4130 chrome-moly. There has been no PMA granted for a mild steel rudder. I contacted Airframes Alaska, F. Atlee Dodge, Dakota Cub and Univair about identifying their rudders in the field if logbook entries were not available. The only one that is identifiable is Dakota Cub, they have a square hole in one side of the steering arm."
 
I posted this on the SuperCub forum as well

All we can do is monitor the Federal Register to see if an NPRM is ever issued. If one comes out we need to get EVERY owner and mechanic that works on fabric Pipers to send in comments. The internal sleeve is likely the best fix for this issue short of buying a new rudder.

Even if an AD is never issued, anytime your rudder is uncovered, do a detailed inspection of it. You can buy an endoscope from Amazon for about $50 or less so you can get inside and look around. Just pushing on the top of the rudder with about 10 lbs of force will give you an idea of the integrity of your rudder.
 
In my opinion, not only is dgapilot 100% right, but I would encourage everyone who has an original rudder and has upgraded their horsepower to reinforce it, especially if they are traveling around with a beacon on top adding extra stress. Heck, just reinforce it anyway if you have it uncovered for some reason, even if the AD doesn't happen.
 
Thanks to all! I will advise my A&P of this potential issue. We'll have a close look at 57A's tail post. (She does NOT have a tail beacon)
 
Most of the companies (except for Univair) websites say their rudders are PMA'd for the PA-18. I know the rudders on all these planes are essentially the same, but is it going to cause problems for us if everyone owning everything from a PA-12 to a PA-22 has to replace their rudder and once Univair is out of stock all the others are only PMA'd for the PA-18? Has anyone talked to Airframes Alaska and other companies to see if their rudders are or could be easily PMA'd for the rest of the lineup??
 
Most of the companies (except for Univair) websites say their rudders are PMA'd for the PA-18. I know the rudders on all these planes are essentially the same, but is it going to cause problems for us if everyone owning everything from a PA-12 to a PA-22 has to replace their rudder and once Univair is out of stock all the others are only PMA'd for the PA-18? Has anyone talked to Airframes Alaska and other companies to see if their rudders are or could be easily PMA'd for the rest of the lineup??

You need to go by part number. Check the part number of the -18 rudder and see if it is the same for the -22 or -12. I know the J3 and PA-16 are different, not sure about the others.


Sent from my iPad using Tapatalk
 
I’ve seen more than one Clipper flying around with a J3 rudder. I don’t think the majority of Shortwingers would recognize the difference.
 
I took a look at my rudder last night, it has been repaired at the top hinge with an internal tube, rosetta welded in, or possibly the top of a rudder spliced on. Just went through the logs, no 337 or logbook entry for this repair. Probably best if I just buy a new rudder at this point I'm thinking.
rudder1.jpegrudder2.jpeg
 
Haven't heard back from Airframes but Dakota is PMA'd on the PA18. Univair part number U40622-007 is PMA'd on the PA18, 20 and 22 with a tube for a top beacon and a nav light bezel in the trailing edge tube. Univair U40622-000 has a post on top for the old Grimes nav light and is PMA'd for the J-5C, PA12, 14, 15, 16 and 17. Univair U40622-008 is PMA'd for the PA18, 20 and 22 and has no provisions for any kind of nav ligh nor strobe. Atlee Dodge/Univair U15726-002 is PMA'd for PA18 serial number 18-7509123 and up which is a 1975 model and has the big beacon mount on top and the nav light bezel in the trailing edge tube.

Per my email exchange with the owner of Dakota Cub, he is talking to the MIDO about adding the other models. As usual it takes a lot of paperwork.

Myself personally have no issue installing any of them since they are all the same part number and meet the same drawing but some legal eagle might want to challenge this to which I would pull out AC23-27 Substitution of Parts on Aging Aircraft.

On a side note I have a conference call scheduled with AOPA on this matter tomorrow.
 
Hopefully the AD never materializes. I need to check my logbooks and take a good look at the rudder on my plane. It went on it's back in 1985 and I don't remember if the rudder was replaced or repaired at that time or not. If it was replaced it likely was with a 4130 rudder.
I imagine for a lot of people it won't be so much an issue with the FAA as with getting an IA to sign off the 337. It will be a major repair / alteration. If you are substituting a part number for a rudder that is not PMA'd for your plane some may have a hard time getting it signed off. Then there will be the inevitable wait for parts.
 
I suppose one quick thing to try is to search the NTSB and see if your plane has a record of an accident or incident.
If a record shows it was involved in a flip over or roof collapse, etc, you may have some useful info.
The search is not definitive (only goes back to 1983) but its free to check!

https://data.ntsb.gov/carol-main-public/basic-search

Aviation Investigation Fields
Data available from 1983 and later

Aircraft registration number:
N1234A

Aircraft category:
Airplane

FAR part:
Part 91: General aviation
 
So I experimented with two rudders this morning. One was an old Univair 4130 rudder which was TIG welded when manufactured and the other was an original mid 50s rudder of a Pacer which would have been oxy/acetylene welded . I used a piece of 3/4" OD x .049" wall 4130 tubing as a sleeve. It slid right into the 4130 TIG welded rudder. On the old Pacer rudder I shot some Corrosion X inside the rudder tube and some grease on the 4130 liner tub and lightly taped the tube in all the way to the top of the rudder as my daughter held the rudder. Nice and tight and I can remove it if I needed to. I don't see the two tubes working inside one another and wearing like I was told by an engineer that wanted to see rosette welds to make the two tubes one.

Per my conversation with folks at AOPA today I am seeking ideas for an AMOC (alternate means of compliance) if and when the NPRM (notice of proposed rulemaking) comes out for an AD on this.

I have also requested the accident/incident reports on the 12 rudder cracks that the FAA has identified to see if these were all 1025 steel rudders and if all had rotating beacons installed.

PXL_20230310_142126004.jpg

PXL_20230310_142129290.jpg
 
Hey Steve,

Did you have to do anything to hone or cleanup the inside of the old 1025 tube?

Also; it appears you're using a full length 4130 tube sleeve. Do you leave a little stub sticking out the bottom, so as to aid removal if needed? How do you plan to remove it if needed? Seems to me it could rust in place.

Thanks for your help with all of this. I'm going to upgrade my membership to Shortwingpipers.org.
 
I just happened to have a 6 foot piece of 3/4" tubing handy and used it to see if the idea was feasible. I applied Corrosion X to the inside of the rudder and some grease on the tube and tapped it in. Didn't do any honing, deburring or anything. It slid in with light taps and I can twist and pull it out as well.
 
Hi Steve, would this potentially still apply even if the aircraft had a documented complete restoration along with photos of the rudder tubing, painting, and recovering? Wondering if that could be considered an alternate means of compliance for folks who have already restored their PA-22/20/18 etc.
 
David, I think the problem with that is it doesnt prove the replaced rudder as new or from from salvage. I have the same situation on mine. It landed on its tail. Frame straightend/repaired. No mention of the rudder in logs but assume it had to have been replaced. I also have pics of the complete frame, primed and ready to go.

Sent from my SM-G892A using Tapatalk
 
When I rebuild airplanes all the steel gets blasted to white metal, inspected, epoxy primed and polyurethane top coated. I am pretty certain all the ones I have rebuilt are good for another 50 years but because of this issue I will pay more attention to this known area from now on.

No one knows what will be in the proposal, it is a wait and see and then constructively comment.

As far as replacing a rudder I would hope anyone who installed a new rudder logged it. That is the legal way to do it.
 
One solution maybe; as Steve has shown you can slide a 4130 tube into the tail post. Put the tube in, use the acid test to confirm it’s 4130. Sign it off as performed 4130 test and confirmed the post is 4130.
 
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