My Vent Repair

[Bartman]

I have been working on radios, antennas, running new RG 400 and found radio noise was relieved when I did an in-flight mag check. The mag was sent out so I decided to use the power of Mooneyspace and fix my roof vent with the blessing of my IA. There are several threads recently about this so I researched and used all of the collective wisdom. I do have a couple of things to add, and some pictures too. Although I learned from many threads regarding the vent problems and repairs, I found these two threads most helpful with a link to original step by step content from @rogrbal and subsequently updated by @carolinaflying in the link below.

 

 

https://mooneyspace.com/applications/core/interface/file/attachment.php?id=50929

 

I ordered the spring steel wire from McMaster-Carr and it was easy to find on their website and cheap too.  Removal of the front and middle sections of the air plenum required drilling some rivets, and getting the control mechanism out was not fun, but I did not remove the rear section.  Overall not complicated at all, just time consuming and a perfect project for a motivated owner/IA combo.  The old wire was bent at the control arm and there was obviously a previous attempt to repair, but with less than optimal results.  The wire loop at the post on the control arm was not a tight spiral, and the cable was not aligned properly setting it up for failure.  After removal of the old wire I stuck the little nozzle tube for the Tri-Flow into the end of the cable housing and just sprayed intermittently until it came out the other end and let it soak in well.

The key for me was making the loop that attaches to the control arm post SMALLER in diameter than the post itself.  I used a 10d nail driven into the workbench all but about 3/8 inch.  Use Vice Grips to wind around the 10d nail and keep pulling hard and it made a perfect spiral around the nail.  Don't cut off the excess because it is used to "un-spring" it just enough to fit tightly around the post, then trim the excess.  The cable housing was originally on the opposite side of the set screw as shown in the pics and I think it was out of alignment when in the vent open position and caused the wire to be prone to failure. I adjusted it several times for best result both open and closed, but it is never gonna be perfect. JB Weld came in handy to attach a washer on top of the post and I have my doubts as to whether it will stay, but the spiral is very tight on the post and I don't think it will come off.  After attaching to the control arm then run the new wire from the inside and out the overhead vent.  Had to use a small piece of the wire to make a little hook and pull the cable housing up where it is supposed to be because it slipped down out of alignment.  I made the loop for the vent door wrapped around a very small screwdriver, but it does not have to be perfect like the control end.

The attachment on the vent door is ferrous metal and riveted to the aluminum door and had rusted so I cleaned as best I could and put some zinc chromate on it, followed by some white rattle can paint as seen in the photo with the tape measure.

As you can see in the pics below the door opens a full two inches.  I'll be wearing a mask for the test flight, because I pulled out some of the 40 year old hog hair and damn it was nasty but again I didn't remove the rear section of plenum so I'm sure it is full of dirt and dust.

I don't know how many feet were in that 1/4 pound of wire, but I got it right first try and have the rest left over. 

[DualRatedFlyer]

@Bartman you couldn't have made this post like a week earlier??  I just replaced mine the other week and your write-up would have definitely helped.

A few things I think we did different.

I removed only the front headliner in my F, and not the rear.  I didnt have to drill any rivets or even remove the plenum.  I simply removed the metal screws that hold the control mechanism to the metal plate that attached to the plenum and was able give myself enough room to run the new wire, attach it, and reinstall it without removing the plenum.  I probably did around 4 wraps on the vent door side and then compressed them with a pair of pliers to make a nice symmetrical stack, like a bunch of dimes on top of each other. 

Interesting that my control mechanism didnt have the spring attached to it like yours.  It looked like the cable had been replaced in the past (and stranded safety wire used and installed....) so perhaps it was lost then.

Thanks for the writeup.