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Post-Trip Maintenance/Flap Tape Replacement

Ironflight

VAF Moderator / Line Boy
Mentor
As we crossed the great expanse of West Texas on our return from California, winding our way through the Davis Mountains while dodging late-summer thunderstorms, the clock on the Val’s EFIS ticked over the 1200 hour mark, making her one of the higher-time -8’s flying. A little less than five years ago – it will be five years in a week and a half – we lifted off together for the first time. New plane, new engine, new prop….and new RV pilot! I have constantly remained amazed at how little maintenance has been required. Maybe it was my background with “affordable” spam cans, always wondering when the next financial bombshell would hit. But more likely, it is new components and a sound design that has lead to the reliability we have enjoyed.

Nevertheless, maintenance IS required, and it is always a good idea to catch up after a long trip. The airplane tucks in to the hangar like a horse after a long ride – panting a bit, dirty and sweaty – ready for a little rest, but still restless, wanting to go again. I had a few things on my list before we even left, planning ahead with orders so that parts would be waiting on our return. New flap tape was high up, as were tires. The standard van’s anti-chafe tape was crackling away, embrittled by whatever lives in the Houston atmosphere. The tires – well, I fly a lot, and we go through tires because we go through landings! On top of that, we were due for that oil change while still over the West Texas desert, so the cowling had to come off – and when that happens, it is time to look for oil leaks(a few drops here and there), inspect my ECI Category “A” cylinders for leaks (none), check the plugs(yup – 600 hours is long enough)….all those things under the hood. All in all, still in pretty good shape considering the mileage we put on together – 23 hours in ten days this last time out.

It was all pretty much standard stuff, taking a half a day or so. Well, except for the flap tape – a couple of notes might help someone down the line on that. There are a few ways I know of to protect the paint on the flaps where they wear on the bottom of the top wing skin. You can use the UHMW tape on the underside of the wing skin, on top of the painted flap – or go with the stainless steel tape on the flap surface instead. I went with the UHMW on the top of the flap the first time, and yes, I am replacing it, but still feel it gave good service. I thought about putting it under the skin this time, but that would have meant fully removing the flaps, and I wasn’t in the mood. I can do this once every five years. The old stuff was very brittle, and the outer layer just peeled right off in chunks. There appear to be three layers to the tape – and outer UHMW layer, a middle layer that is something much more flexible, and an adhesive layer.

The easiest way to get at the whole leading edge was just to disconnect the pushrods from the actuator – thane the flaps hang straight down. Removing the old tape took me maybe two hours- I wanted to be very careful to avoid damaging the paint. As I mentioned, the outer layer chipped right off – applying a little heat from a gun made it even easier. I used a plastic stir stick from West Systems for much of the scraping, along with a broader scraper I made from a flat scrap of canopy stock. Once the outer layer was off, I could peel up the middle layer, which most often brought the adhesive layer with it, leaving a clean surface. The middle layer could be peeled off a little at a time with great effort, but would break off after about a half inch. Very hard on the finger tips. But – apply some heat from the gun as you peel it off (apply the heat to the part you are ABOUT to peal of – you’ll get hot fingers a few times till you figure it out) and great strips come off at once.
There will be a little pure adhesive left in place – scrub it with some Goof-Off and you’ll be all done (I love that stuff!). It probably took me an hour and a half for the first flap, and half an hour for the second – the learning curve is steep, but quick.

Putting the new tape in place takes a touch of art. We ruined the first piece by peeling off all the backing paper and trying to apply it all at once. Big mistake – the tape stretches, you get wrinkles - it’s NOT pretty. Fortunately, I had extra, so we tried again. This time, I put a masking tape line on the flap where the aft edge of the tape would be. We laid the UHMW tape out flat and peeled a quarter inch of backing paper off from the long edge. With one person holding the free end, the other carefully applies it to the flap along the masking tape line. Then one person can start at an end, peeling the backing tape off and burnishing the UHMW on to the flap to get air bubbles out. It took me about 15 minutes per flap to install the new tape – and once again, it is almost invisible!

Yes, there is a bit of an art to it – if it’s your first time, consider buying an extra roll of tape for the first screw-up. You really only get one shot at it. And make sure that your finger tips are scrubbed surgically clean, or you’ll embed some dirty fingerprints underneath. Visual flap indicators are easily applied to the flap surface under the tape to keep them from rubbing away – renew them before you lay new tape down. The Val looks very Natty in her new tape – you’d never know the flaps weren’t freshly painted! Don’t worry – the girl still has some age marks – a few leading edge chips and wheel pants that have been repaired a few times. But she’s mechanically top notch, especially considering how often (and how hard) she can be ridden.

Paul
 
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Thanks Paul - I'm about to do the same thing with my 5 yr old RV-7A.

I'm thinking about putting the tape underneath the wing this time. Has anyone reading this thread found that they were unhappy with how the paint wears over the years?
 
I've put the tape underneath the wing skin on both of my 10's and the 7, and am very happy with it. I changed the tape I put on the flap skin on my 6 years ago, and did not like going through the process Paul just detailed here. I'm pleased with the results so far.

Vic
 
I tried it and was not happy.

Thanks Paul - I'm about to do the same thing with my 5 yr old RV-7A.

I'm thinking about putting the tape underneath the wing this time. Has anyone reading this thread found that they were unhappy with how the paint wears over the years?

Dust or some other matter immediatley scratched my paint. It may depend on the type of paint, color, etc... if it shows scratches or not. The good part is the scratches are hidden by the tape when you put it on the flap. I left the tape under the wing and simply added it to the flap.
 
A better alternative...

A better alternative than UHMW tape is 3 inch leading edge tape made byPM Research in Wellsville NY. It does not yellow or get brittle. It was about 3$/ft when I bought mine several years ago, but worth every penny. Search for PM Research for previous post on this.

Erich
 
I've put the tape underneath the wing skin on both of my 10's and the 7, and am very happy with it. I changed the tape I put on the flap skin on my 6 years ago, and did not like going through the process Paul just detailed here. I'm pleased with the results so far.

Vic


Did you put the tape just on the bottom of the top skin overhang? It doesn't look practical or required to put the tape on the diagonal brace due to the rivets and the distance away from the flap.
 
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I placed mine on the flap and the wing skin for only 1/2 inch in. I keep it waxed with Wet Paint.
 
PPF tape easily lasts 8+ years, peels off w/o any mess in one piece, won't yellow. I know, I just removed and replaced some 8 year old tape in order to make some unrelated repairs.
 
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