AD 63-20-01 Cracked Master Cylinder Mount

leadsledfan

leadsledfan

New member
I have encountered a dreaded issue in my Cruisair. The right brake master cylinder mount has cracked along the pipe where it is welded. AD 63-20-01 calls for the inspection of this area with penetrant dye, but I discovered mine has already failed. My question is, what is the proper way to repair this? Thanks -Adam
 
Apologies, as I could not get photos to load on the forum, but have attached a link to several photos showing the problem. Thanks!

http://s666.photobucket.com/user/leadsledfan/library/Mobile%20Uploads
 
Blimpy,
I agree that the crack needs to be welded to properly repair, and the actual welding will probably only take an hour or so. However, in order to access it, the floor will have to be removed as well as an access panel cut in the firewall.
It is going to end up being a fairly considerable repair, unless I am missing something.
Also, seeing as your Cleveland conversion ended up making you a master on our braking system, I would love to chat with you about the brakes. Thanks!
 
Leadsledfan, I dont think you will need to cut the firewall. It is all pretty visible from the bottom access panel, but removing the floorboard probably will make it much easier. There is one Cruisair that reinforced his brackets and eliminated the A.D. note, but I dont know how he did it. Good Luck. ___Grant.
 
Wow, I just went back and looked at the photos. It appears to have been repaired before by a really poor welder. That is probably why it cracked again. The later Bellancas have a piece of square tube that runs across underneath the master cylinders, and the cylinders attach to that, rather than the tube the ours attach to. The way our brackets are designed, puts a huge bending load on the weld (hence the A.D.). It is even worse if you have newer brakes with the original cylinders. More pedal pressure means more stress on that weld. I am away from my plane, so I dont know how difficult it would be to bolt/clamp an extra bar across, under our cylinders, but it might help. Just a thought. ____Grant.
 
I agree that someone attempted to repair it before, as the weld is nowhere near factory quality (it's crap) and that is probably what led to the crack.
As for not cutting An access panel in the firewall, I don't think you will be able to weld the backside of the tube without doing so, as it is up against the firewall, but of course I would love it if I didn't have to!
I agree that all the pressure is essentially ripping down on the weld, which is aggravated by the fact that I have clevelands.
I am hoping to find a solution that will eliminate the AD if possible, and a separate tube sounds like a good solution.
Does anyone have any photos of the later installation style with a separate tube to support the master cylinders?
Thanks!
 
My 14-13 had a separate square tube sticking straight down about 1-1/2” long welded to the round tube in the photo. Over this square tube is another square tube with the lower cylinder attachment welded (poorly) to it. The outer tube with the attachment arm is a tight slip fit on to the welded inner tube. There is a bolt through both tubes to hold them together. I thought I took photos when mine broke but I am looking through my photos but I don’t see one of this assembly.

The separate tube doesn’t really solve your problem, you will still need to weld it onto the existing round tube and there is not enough room to get to it and weld. :(
 
It almost seems like you had a repair setup on your bird?
Mine has a similar square tube with another length of steel that the master cylinder attaches to.
I am going to have to weld on a split sleeve and bracket.
The biggest pain is going to be cutting an access panel in the firewall.
I am looking for an example 337 of a welded frame repair if anyone has one, so that I can start working on one for this repair.
If anyone has an idea of how to repair it so that it no longer requires the AD inspection, I am all ears!
 
Pull the CD from the feds for N74457. The owner told me (years ago) that he modified his master cylinder mountings and got rid of the A.D. I have no idea how he did it, but if he got rid of the A.D., he must have documented the mods. It is only $10 and about a week to get a CD, so it might be worth the wait. I had pulled records on a couple of dozen Cruisairs over the years, but I dont think I ever pulled this planes records. _____Grant.
 
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