Another flap oddity

[Chris B]

I used 3M marine grade silicone sealant (clear) and it's now very securely fastened in place.

FWIW, apparently silicone complicates composite repairs since it inhibits bonding and is difficult to completely remove.

Chris

[Boatguy]

I used 3M marine grade silicone sealant (clear) and it's now very securely fastened in place.

FWIW, apparently silicone complicates composite repairs since it inhibits bonding and is difficult to completely remove.

The AMM makes reference to not using silicone based cleaning or polishing agents. But then it specifies silicone sealant be used in other places.

This material is used extensively on composite boats. And FWIW 3M makes a cleaning agent to remove it.

[Rich]

I was right. I have just the stuff to replace it. I'll use the same goop as I did for the jack point to bond it. Then there is this recommended recheck, which Diamond support thoughtfully extracted for me from the AMM:

In case you were itching to know more, here's the gory detail of flap retraction:

As the flaps raise, each flap counterweight (at the outboard end) comes to a point where it is stopped by the up-stop. This up-stop is a pad inside the bottom of the fairing around the counterweight. This is not adjustable.

Each flap continues to be pushed further upward a bit by its extension rod until the #1 limit switch stops the movement of both. The result is that each flap, when retracted, is under a constant slight flex along its length by dint of the extension rod pushing the flap itself against the flexing resistance of the trailing-edge of the upper wing skin, mediated by this little pad.

If the preload is not as indicated for a flap, one adjusts the length of its extension rod so the individual flap movement produces the right preload.

[Rich]

I wound up using some automotive trim adhesive tape to bond my buffer to the underside of the wing. This is really great stuff that I've used for a number of applications. It's only 1/64 inch thick, really pliable, double-stick tape intended for use in mounting various things on the outside of cars, motorcycles, etc.

I found there was some leftover glue from the original installation that was pretty easily removed using an x-acto knife. It seemed to literally be contact cement. I found that before this repair the preload was something like 4 lb. At least not zero, but below spec. After installing its: Left wing is 10 lb., right wing (that I repaired) 8 lb.

It's easy to confirm the little devils are in place a couple of ways. Lower the flaps and look for them, or use a $100 bill and be sure you can slip it between the trailing edges of the flaps/wings with the flaps retracted.

[Tom-B]

Before this thread I never knew these rubber pads were supposed to be there. Today, I confirmed I am missing both so it looks like I will take Rich’s suggestions and get this repaired.

[astaib]

Ok,

I can tell you that my bird doesn’t have neither these pads (SN:40.026).

I understand why the flaps are worn on the contact area...

[Rich]

Ok,

I can tell you that my bird doesn’t have neither these pads (SN:40.026).

Wow, there's no sign they were ever there. In my case the presence of one gave me a clue, but the paint pattern and residual glue told me that right side pad was there in the past.

There's no mention of these as specific items in the AMM or IPC, but without them you have the undesirable contact producing the effect you show in your photos. My right side flap has some of that same scarring remaining. The good news is it's a cheap fix.

[Spinner]

Btw the DA20 has the same pads on the inboard of each flap.

[cptndavid]

looks like a trip to the aircraft department at Home Depot to me.