Model IV Rudder pedal AD

[Norm]

I have heard rumors about an AD for the Model IV rudder pedals.
Something about extra gussets as the rudder might break without reinforcement. Does anyone have a link to the AD or pictures of what needs to be done.
Thanks in Advance
Norm

[t j]

Here's the Service letter. http://kitfoxaircraft.com/images/serviceletters/SL-47.pdf

In the catalogue upgraded pedals on page 31 and the kit to reinforce old pedals on page 32. http://www.kitfoxaircraft.com/images/PDF/KApartscat-rev032916.pdf

Here's what I did.
11852

[DesertFox4]

Norm, on Kitfox Aircraft's website you can click on the "Home" button top left and a drop down menue will give you service letters and service bulletins.
Under service letters look at number 46 for the rudder pedal problem. It does not show a fix in the letter so go into service bulletins and there is a drawing for a Vixen Model 5 reinforcement proceedure at number 38.


The riviting of the gusset worked.
Most welded gussets in place to reinforce the vertical rudder pedal tube and another small gusset to reinforce the tube that the rudder cable attaches to.

This issue also affected earlier models too.
Do a search on our site for rudder pedal reinforcement. The photo below came from a thread from a model 2 issue but is the same fix.

Here is a photo of a pedal assembly that has been reinforced.
11851

[Norm]

Thank you DF4 and TJ. If I rmember right mine only has a gusset on one end of each pedal. On the list.

[HighWing]

Sorry to be a naysayer, but I don't think the pictures shown are an answer to the problem of failure due to metal fatigue from the torque of the pedal attachment tube to the torque tube. The riveted fix in the drawing mentioned for the Series 5 does not resemble the welded triangular gussets pictured. The triangular welded gussets would be OK if they were welded tangentially on the surface between the two right angle tubes. Those welded mid diameter would help protect the 90 degree angle between the two tubes, but do very little to prevent twisting of the torque tube as it relates to the vertical tube. I discussed this issue with a friend this morning using a white board and his fix put the triangular gusset in the tangential position, but his preferential fix was the Series 5 fix, but welded in place after trimming and forming the "gusset" to the tube Contours. Incidentally, he is a veteran of the failure. He feels grateful he didn't have a center console, but that is another story.

Check out the "Great Gussets" article in the most recent Experimenter - page 26. It demonstrates both preferred Gusset designs.

[beeryboats]

Well crap! At this rate I'll never get this airplane flying again. Now I have to take it apart again.
Jay

[dholly]

This is a very important AD to be proactive with. I had a failure on landing and feel quite fortunate that I didn't wreck the plane. Admittedly, I went overkill on the fix but what the heck.

[beeryboats]

Wow! Yeah, I admit that is a scary break. But I don't see the point of the heavy reinforcement 90 degrees to the point of stress. Seems to me they didn't use heavy enough tube. Is that the repair Kitfox recommended? Now sure where to turn at this point. I'm almost ready to break in a remaned engine and now this. Kind of a gut punch.

[beeryboats]

Just went to the Kitfox web site and printed all the SB's and SL's that I need to look at. That will keep me busy for a while. Not happy at all. What a mess.

[Northof49]

Norm
Here's a pic of my peddles , that I believe have the SB in question applied..

[Ramos]

Just went to the Kitfox web site and printed all the SB's and SL's that I need to look at. That will keep me busy for a while. Not happy at all. What a mess.


I don't know, looks like the guys here have come up with some pretty straight forward solutions for this situation. Be happy you have an AC right now to tinker with. You will be in the air before me, guaranteed! ;)

[beeryboats]

You guys be the judge. Here is what I have. Built in 1994. Looks like he ignored the letter.

[av8rps]

I fixed mine on my 4 before it failed and glad I did. I flew a friends airplane once that had a pedal fail after I needed to stomp on a pedal during a strong crosswind gust, and let me just say.... it can really ruin your day. Since that experience I will not fly a kitfox unless that mod is done.

I had a friend that fabricates and welds for a living weld on gussets that triangulates both the rudder pedal tube as well as the small control arm where the rudder cable attaches. I've put over 400 hours on my Kitfox since with no issues. And fwiw, because I fly floats I use much more pressure on my rudder pedals than a land based Kitfox because when my water rudder is down in the water there is a lot of water drag whenever the water rudder is turned.

I'll try to find a picture to post tomorrow.

[Norm]

I think we should all be thankful that KitFox keeps us safe by putting these ADs together. Not all will apply but be thankful that we have the option of learning from others experience rather than having an issue and then having a large repair job. I checked my pedals and it appears one pedal was done but not the left one. As the Service bulliten says to check before every flight and repair at the next annual. I will repair before the next annual but in the meantime I will inspect before every flight. Thanks for all the replys.



Just went to the Kitfox web site and printed all the SB's and SL's that I need to look at. That will keep me busy for a while. Not happy at all. What a mess.

[beeryboats]

As I'm preparing for my first inspection since I've owned it, I have found a lot to do. But now that I've read all those service letters, I see there is much more that needs to be looked at.

As far as the pedals, I see Kitfox sells new and they also sell a repair kit. But was there drawings published as far as a do it yourself repair?

[Av8r_Sed]

Here's the non-welded alternative I went with. Templates were made out of thick card stock. Parts cut out of 4130 sheet and bent to wrap the tube. Eventually glued and riveted.

[beeryboats]

Thanks Paul. That looks good. Looks like you made room to get at the brakes.
Jay

[GWright6970]

I went with the factory solution from John and Debra. Not shown are round tubes that you cut and slide inside the existing long horizontal tubes that the pedals are attached to. The last photo shows these inserts, and their location. The rivet holes pass through the existing tube, and the new inserts, for added strength. Long rivets are then installed along with structural adhesive.

[dholly]

Don't put it off. I found out last week that failure to comply claimed another beautiful KF 4-1200 at my home airport. :(

[cap01]

gw, curious about the picture you posted that show both sets of master cylinders. just wondering about the ones that use the remote reservoir that have the springs on the piston shafts, if they came that way? reason I'm ask is that I'm in the process of replacing my matco master cylinders with grove and i haven't seen the springs before and if i need them.

[Guy Buchanan]

Here's what I have. All three joints have straps welded around.

[jiott]

Guy I really like your welded straps. As a mechanical engineer, that fix looks the best to me.

[GWright6970]

gw, curious about the picture you posted that show both sets of master cylinders. just wondering about the ones that use the remote reservoir that have the springs on the piston shafts, if they came that way? reason I'm ask is that I'm in the process of replacing my matco master cylinders with grove and i haven't seen the springs before and if i need them.

Chuck, mine came with the springs. We will have to ask the forum if they are required, as I have no idea. Great question!

[jrevens]

Chuck, mine came with the springs. We will have to ask the forum if they are required, as I have no idea. Great question!

Some master cylinder designs have the external springs and some have them internally installed.

[Renaud]

Sorry for the stupid question, but i am about to reinforce my pedal tube assembly (finally, after 10 years flying with the original model IV design, it is time to do it...).
I am strugling to remove the plastic bushings at the end of the torque tubes. Are they supposed to be glued inside the tube? If possible I will try to reuse them.
Thanks!
Renaud
KF model IV

[Jfquebec]

They are not glue inside,,just free .

[Renaud]

Ok thanks. Well, not so free on mine, will have to try a press with special tools. I will let you know!
Renaud

[Jfquebec]

In building manual,they say to sand the tube with dremel tools to have free mouvements..

[Renaud]

OK, I finally got them out. I actually felt a lot more confortable pulling hard on them knowing they were not supposed to be glued! Thank!
Now the real work starts, making and welding the gussets.

[cap01]

thanks for the answers regarding the springs on the master cylinders . reason i asked is that I'm replacing the matco master cylinders with grove with the remote reservoir. i don't see anything in the grove catalog with springs , just curious .