Windshield fabric issue

[LarryV]

that is what I am worried about. Yes the skylight is a fairly easy fix. But not everyone wants one, or wants to put their airplane under the knife and not fly. The strip is a simple and inexpensive fix for a problem I never expected I would have an issue with. If it’s only the cost of the strip holding anyone back, I would gladly buy it and install it for them to add some safety to things. But if we could get the AD to mandate the strip on all airplanes with fabric tops. It would help everyone be more safe.

Be careful what you ask for.

I spent 12 years as a fed writing regs and sub regulatory guidance - and I was one of just a handful with any actual field experience. The rest were staff trained as lawyers who didn't no beans about what they were regulating.

Let me give you fair warning that if someone comes forward and says "OMG! We need an AD on this!" Similarly clueless staff at the FAA will want to oblige.

To some extent they are limited in their ability to do so as cost of implementing an AD comes into play, especially if the risk is small in terms of both number of potential accidents and in terms of numbers of injuries or fatalities.

But that cuts both ways. The smaller the size of the fleet expected the lower the total compliance burden, even if costs for individual owners are high.

The PA-28/PA-32 wing AD has been stuck in the process for years, because the PA-28/PA-32 fleet is huge and the compliance burden is very high, both individually and collectively and that is measured against only2 spar failure related accidents, and then only in high time aircraft used intensively as trainers.

The PA-20 and PA-22 fleet is a lot smaller and even if costs of compliance were high per aircraft the total burden would be low enough that yet another AD would face less resistance. So be careful what you ask for.

There's also already a very long history from the original service bulletin through the original AD and several amendments. That history and the eventual exclusion of Dacron fabrics reflects the poor aging characteristics of cotton and linen fabric, which was the cause of the problem at the time.

Today, the cause is probably due to the loss of collective knowledge in the field about fabric covering in general and about covering PA-20s and PA-22s in particular.

I suspect the incidents that have occurred recently on PA-20 and PA-22 aircraft are due to one or more of the following:

- lack of proper cleaning and prep of the channel, leading to improper adhesion; and/or
- not wrapping the fabric all the way through the channel and down on to the tube under it; and/or
- failure to reinforce the leading edge of the channel with a pinked tape, as well as the area behind it on the fuselage.

I also suspect there's more of a bias toward lighter fabrics to save weight. For example, using Ceconite 102, Superflight 102 or Polyfiber Medium, rather than the slightly heavier (3.5 to 3.7 oz per yard rather than 2.7 to 3.16 oz per yard) 101 and heavy duty grades, especially in areas prone to higher pressure gradients. That doesn't make all that much sense given that grade A cotton weighted 4.5 oz per yard.

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In short, an AD requiring a strip to be installed might at best just be a band-aid that masks a larger issue of slippage in general covering practices.

It's also really not necessary as it's easy to visually inspect that area every time you refuel, and it's not hard to inspect the underside of the fabric in that area at each annual or 100 hour inspection through the zipper in the head liner for the trim.

And, this might be a real shocker, but as an owner there is nothing that prevents you from inspecting the fabric in those areas more often, and bringing it to the attention of your AP or AP/IA if you see something that concerns you.

[RRHall]

After reading this thread I looked at the PA-22/20 I am restoring. The fabric is reinforced with a pinked tape around the top and through the channel but does not extend to the carry through tube. Would adding a tape to bring it down to the carry through do anything or should I leave it and add the aluminum strip at the top, or do both?
I've done some fabric work and I have no qualms about getting it on I just worry that if I try and add a full strip from the top of the fuse through the recess for the windshield and around the carry through that when it comes time to install the windshield it won't fir or will be very difficult to get in due to the thickness of the fabric. The plane is covered in 101 fabric.

[MrBill]

I never used anything to seal my screen, hell its so tight in there anyway. No problems.

No, I did use the neoprene 1/8" tape. 1-strip around the whole windscreen. I remember that seeming like it was nothing comparing it to all that old silicon caulking I had to dig out, remove and clean and clean.. What a nightmare.
RRHall, thats a tough question to answer with liability issues. ha. Cannot advise extending it because it is not a fix (legally) surely cannot tell you to do it anyway because it may hide the fact it ever needed to be extended but personally I would do the strip, more so because of your situation. I wouldn't be able to fly around in comfort knowing there is a hidden cheat but that is why I drink.
Oh, everything I say here is a lie,
Bill Clinton

[MrBill]

RRHall,
There is a fix without replacing the whole length of fabric to the tail and you know it as well since you have done fabric work which goes hand in hand with complying to the STC's instructions. Do you like sewing by hand laying on top of your airplane? Nothing to legally glue to but a short length can be sewn and covered with tape then you, your IA and the gas station attendant will know.

[laserjad]

I owe a huge debt to spdcrazy and the shortwing piper forum.

Two weeks after spdcrazy's spontaneous sunroof report, our PA 22/20 was due for annual.

Having just read the post, I looked very closely at the roof fabric and found that there was about 1/8" fabric showing behind the reinforcement aluminium strip that looked like it had previously been sitting underneath the strip.

Thought a little investigation might be prudent.....

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[laserjad]

Found that the v channel was full of corrosion, resulting in zip fabric attachment.
Not only that, but the leading edge of the fabric had been sawed through by the channel/windshield interface, producing 2 parallel strips of fabric about an inch wide.
So the only things holding the leading edge of the roof fabric on were the half a dozen self tapping screws that attach the aluminium strip !!!!!!IMG20210309115247.jpeg

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[MrBill]

Dang got that just in the nick of time!

[laserjad]

For clarity, the windshield is replaced by brown paper, so that when I steel brushed the v channel, I didn't fill the cockpit with oxidised steel flakes!

You can see to the left, only a half inch of the fabric is still intact.IMG20210309115253.jpeg

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[laserjad]

When the AD was done, the tape used to reinforce the roof fabric within the v channel was only an inch and a half and therefore not wide enough to attach to the the spar carry through tube.

Just one of those errors that could ruin you day!!IMG20210309120716.jpeg

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[laserjad]

At least the tape fabric helped prevent the self tappers from ripping through the ceconite.

As earlier discussed, I have steel brushed down to solid metal and applied a rust converter followed by an epoxy primer.

Hoping to glue the fabric leading edge to the channel , then overlay a big arsed tape IAW the AD, this weekend.IMG20210309145507.jpeg

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