AD 79-20-10 has come due on my Twinkie, and I'm mulling over the options.

Have any of you installed the Piper kit 763 893?

If so, how long should it take? I've got lots of sheet metal experience, so should be capable of it. Just wondering what's involved to see if it's worth it, or if I should keep doing the inspections every 50 hrs. Also, would like to know how to tell if the kit has already been installed by looking at the ailerons (hate digging through years of logbook entry).

Thanks!

I have done a number of them. It takes about six hours to do one. There is an AMOC that makes it easier, otherwise you are pulling the skins off of it.

There were four versions of the nose rib, and only the last one terminates the AD inspection which I believe is every 100 hours and requires removal of the aileron.

I usually end up looking at the nose rib with a video scope to tell what is installed. I was going to write an article showing how to tell whether it has been done, but it was more work to write than I wanted to do for free and ICS doesn't pay for articles, even technical ones written by an IA.

If you are around NorCal you can drop by some time and I will tell you what you have.

Thanks Kristin,

Maybe I'm reading it wrong, but my impression is that it's due every 50 hours, which seems like a lot of removing / installing ailerons for inspection. Might be worth 6 hours per side, although it'd probably take me twice as long.

Thanks for the help!

Jon,

The operative paragraph is:

(a) Within the next 50 hours in service, after the effective date of this AD, unless already
accomplished within the past 50 hours in service and at intervals not to exceed 100 hours in
service thereafter, inspect in accordance with paragraph "Instructions" in Service Letter No. 850
dated April 18, 1979, Parts 1, 2, 3, 4a, b and c or equivalent inspection.

You need a few specialized specialized tools that if you are an A&P you might have and be familiar with.

Read up on the AD and the SB, then as Kristin suggests slide a borescope into the leading edge to see if the mod has been completed.

Clarence

Old thread discussion that seems it never went anywhere.

The new nose ribs have an insert in the rib web so as I recall (I may need to double check it) if each rib (two per aileron) has two layers, your good. In addition, you are supposed to add rivets to the nose rib so if you do find you have the new ribs, also check the additional rivets as I have inspected many aircraft all signed off but done incorrectly. I think you add rivets through the skin/rib visible without tools on the exterior, and I think through the rib into the spar as well.

The actual issue with this AD note is that unless you purchase the nose rib kit, you can't get the service installation instructions which explain how to not only install the kit, but how to identify that it has in fact, been installed. The AD goes on about doing the work but falls short of diagrams showing the revised installation. This is true of several AD notes on the Comanche for some reason (like the outboard aileron hinge also).

I think I have that diagram if needed from a kit awaiting installation in my 180 These nose rib kits are getting expensive and almost every aileron I have found in salvage yards have incorrect nose ribs and OBD hinges

Maybe your already done with this AD?
Will

Actually, there were four different iterations of those nose ribs. The first was just thin, formed aluminum. How anyone thought that would last is beyond me. The next iteration had an insert, as did #3 which only covered slightly more. That one had an earlier SB and kit and also had, I think, an AD. But that one cracked too, so the final fix for AD 79-20-10 was the 4th iteration.

Here is iteration #3:

Here is the final terminating nose rib, installed using the AMOC.