SB-00116 Regarding Autopilot Servo Attach Brackets Published

[seagull]

How the die penetrant works.
The procedure; Clean the surface and apply dye, spray or brush. Allow it to set for 5-30 minutes, wipe off. Apply developer, look for cracks.

 

[jacoby]

My understanding is that if you use the spray as directed then it will make even the smallest of hairline cracks obvious to spot with the naked eye. I see no obvious cracking, but chose to address the SB anyway albeit via an alternate, hopefully equivalent, method.

Take look at the instructions: https://magnaflux.com/Files/Instructions/How-to-Do-Visible-Dye-Penetrant-Testing.pdf and https://magnaflux.com/Files/Instructions/Penetrant-Testing_Process-Guide_Methods-A-B-C-D.pdf (method C).

You need to use the developer to see the cracks. After you wipe off the visible dye the developer pulls any remaining dye out of the cracks and makes them visible to the eye.

 

[N8DAV8R]

Upon familiarizing myself on SB 00116 again I noticed that continued inspection is acceptable if no failure is detected. My condition inspection will begin in about six weeks. If in six weeks there is still no indication of failure I may elect to continue to inspect. Why potentially create a problem where there is none?

I see no obvious cracking, but chose to address the SB anyway albeit via an alternate, hopefully equivalent, method.

I am interested in the forums opinion. I'm learning just like everyone else on here and am genuinely open to criticisms.

I'm generally with Jayson on this one. Primarily because I'm not aware of anyone finding rivet issues on an IS with Garmin servos yet. The record seems pretty consistent on failure having been on legacy Dynon systems, with a dimensional error on the parts that would explain things. I may have just missed those examples being shared or they weren't. Even if none have been found it doesn't mean they are immune, but the SB does allow for continued inspection. The bracket is in a location that should be accessed for regular inspections anyway,

I'm a 'by the book' guy so I can appreciate someone doing the SB repairs in any case, which I have done on a customer airplane. If that's the thinking, I would expect the SB to actually be followed and not use alternate and even modified hardware. This is not to say I think the bracket is now at risk (I really don't), just that the whole procedure seems inconsistent in terms of intention to follow the SB and documentation.

Anyway, it sounds like a fun afternoon working on the airplane and it's rewarding to feel like you made an improvement. It's also a good opportunity to experiment with the penetrant so I like that part. I have a hunch you'll still end up checking those bolts at inspection (I would) and in the long run you'll spend more time on them than if they were left alone or riveted per the SB.

 

[WJaviation]

Yep I definitely did not apply the developer . Which I have a can of... RTFM!

Yeah I thinking leaving it be and simply inspecting is totally reasonable and probably the more conservative approach. My rational was that Vans was willing to admit that the LP4-3 rivets were simply inadequate for the installation and as a result, were failing. I don't know what sort of forces are taking places back there during flight, but i use the AP all the time and if there is a mysterious "right combination" of AP, turbulence, and aircraft weight to cause a failure or a crack and if there are examples of them failing on other birds, then I wanted them fixed . I suppose I just wanted a stronger system, although based on my method that remains to be seen.

I did quite enjoy "building" again. Makes me want to get another kit!

 

[bobg56]

I dont beleive so. The dye penetrant will find and highlight the smallest of cracks. I think its simply finding the little gap between the edge of the LP4-3 rivet and the underlying material. Before i applied the dye I inspected closely for any signs of smoking rivets, or residue from rivet movement. Then I dried and cleaned the surface with acetone and and inspected again.

My understanding is that if you use the spray as directed then it will make even the smallest of hairline cracks obvious to spot with the naked eye. I see no obvious cracking, but chose to address the SB anyway albeit via an alternate, hopefully equivalent, method.

I am interested in the forums opinion. I'm learning just like everyone else on here and am genuinely open to criticisms.

Actually you would wipe the red dye off and apply the white developer on next, the red dye would seep into any crack and the white developer would high light the crack. Sometimes we would use a rivet gun to lightly vibrate the area to help the red dye seep into the cracks better....

 

[subpar_bucker]

At 141 hours with my Garmin servos, my brackets look brand new. This might be the first SB that I comply with via annual inspections.