Model II rudder assembly failure

[dcy92444]

January 12th, 2010 I went flying, while landing I caught a bit of a cross wind. When I flared the plane weather veined slightly to the left. I gave the plane right rudder to compensate but nothing happened. I ended up upside down off the runway and suffered some damage to the plane. It has sat until this past week when I began repairs. While removing the fabric off the plane I notice the right rudder was jammed at the fire wall. After further investigation I found the right rudder assembly on the right side of the plane had failed. I have posted photos and would suggest you check your own rudder controls for this condition.

[Av8r3400]

I'm glad to hear you are alright, but sorry to hear about the damage to your plane.

This is one of the few areas that all Kitfoxes should be inspected, regularly. There is even an updated set of rudder peddles from Kitfox, that I believe coincide with a service bulletin, that have extra reinforcing on them in the area of these welds.

I would encourage every Kitfox owner to inspect their rudder peddles on a regular basis and if you don't have the updated peddles, get them. I think the gussets are also available separate so that you can reinforce your current peddles.


These are very rudder-active planes and if a peddle breaks, there will be trouble!

I hope your repairs go well and you are back flying soon!!

[carlisle]

I've heard of this problem. I believe the actual SB from Kitfox applies to Vixen's but I see that in the Kitfox LLC catalog, there are reinforcement kits for all models. Has anyone installed one of these? I think they're just triangular gussets that are welded in the junction between the vertical and horizontal components of the rudder pedal cross tubes.

Chris Carlisle
Model 2, 582, C box
Sioux Falls, SD

[cap01]

this is a common occurence, of the three kitfoxs that ive had dealings with . one had a failure similar to this one , the other had one bend but didnt break and the third , mine, were modified before she flew . its well worth the time and trouble to check and install the gussets . the pics are of my modified peddles

[Av8r3400]

The reinforcing kit has gussets that can be welded or riveted in place. The new peddles (what I got from Kitfox for my IV project) has a wrap around reinforcement (like in cap01's pic) and the gussets welded on. Much more secure.

[carlisle]

OK. Pulled my rudder pedal assemblies. Inspection is all ok but especially given the pictures on this post, I'm not gonna feel comfortable without reinforcements. So, took them down to my friendly mechanic buddy. He agrees. My intent was for him to offer some suggestions about methods, materials, etc. Instead, he recognized my ignorance and took them away from me and said he'd take care of it. Probably won't cost much either as he owes me a couple of favors. He's gonna fabricate triangular gussets out of 4130 sheet and weld them in.

Will get pics when finished.

Chris

[carlisle]

Finally got my rudder pedal mod finished. Had to order the .050 chromolly as there didn't seem to be one square inch of the stuff in the entire city of Sioux Falls. Then my mechanic buddies helped with building templates, sheer cutting the steel, and most importantly doing a professional job of welding them in. The welder dude is quite an artist and therefore has a backlog of jobs from local experimental types and the local FBO so it took longer than I expected but was worth it. The finished product is beautiful and inspires confidence.

[cap01]

nice job , they must have replaced the lower tube , cant see where they repaired the tare . did they powder coat it or is it paint ? i guess now youll have to do the other one to match . maybe you can get back in the air soon although its probably not too good of flying weather in s d this time of the year .

[carlisle]

No. I'm not the original poster but I have a model II and have heard of this failure before so made the modification anyway. There were no cracks or signs of failure before I did it although I have to say, especially with some of the rudder slamming I've done on landings, I'm surprised there aren't more failures. I'd guess I'm capable of 400 lbs or so pressure on these thin tubed pedals and the gussets are good insurance. One might get away with a yaw axis failure in other planes but not in this one.

Chris

[cap01]

the broken rudder peddles are pretty common . of the three kitfoxs that ive had anything to do with , one had one break , another had one bent but not broken and mine i installed gussets before it ever flew .

[t j]

What really puts the stress on the rudder pedals is getting hard on the brakes after landing or holding both brakes and doing a full power run up.

[cap01]

your absolutely correct t j . i cant hold the plane at full power with the brakes . can barely hold it doing mag checks . ive learned not to even try , if i have any running above 3600-3700 i always tie the tailwheel down .