Repairing Fiberglass Wheel Pants, Part II

I stopped by the shop this morning, to see how the wheel pants were
coming along.

What a difference! All of the wowed-out holes have been backed with
aluminum that has been riveted to the old fiberglass, and then
fiberglassed and filled over and around. High stress areas have been
reinforced, and really high stress patched areas have been filled with
"JB Weld" -- a virtually indestructable epoxy.

Best of all, the old attachment system has been completely upgraded.
The stupid "dzu" connector system (that held the two clamshell halves
together)has been eliminated, in favor of self-locking screws that
won't vibrate loose. This has meant filling in all the large dzu-sized
holes and re-drilling them smaller, but I'm hopeful that the danged
things actually won't "wow" out and come disconnected due to vibration
anymore.

Also, the dumb attachment bolts (that threaded into the struts
themselves) have been eliminated. Instead, my A&P is tapping bolts
into the *struts*, so that they stick out through the holes in the
pants. This allows the use of self-locking nuts and cotter pins -- a
much more secure attachment method -- and should eliminate the problem
of those bolts vibrating loose (we've actually lost two of them in the
last several years!)every few flights.

As usual, I'm impressed with what he's doing. Best of all, because
he's only going to have to paint one color (he thought he was going to
have to paint all four colors, at first), the cost is going to come in
way under estimate.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

(Jay Honeck) wrote in message . com...
I stopped by the shop this morning, to see how the wheel pants were
coming along.

What a difference! All of the wowed-out holes have been backed with
aluminum that has been riveted to the old fiberglass, and then
fiberglassed and filled over and around. High stress areas have been
reinforced, and really high stress patched areas have been filled with
"JB Weld" -- a virtually indestructable epoxy.

Best of all, the old attachment system has been completely upgraded.
The stupid "dzu" connector system (that held the two clamshell halves
together)has been eliminated, in favor of self-locking screws that
won't vibrate loose. This has meant filling in all the large dzu-sized
holes and re-drilling them smaller, but I'm hopeful that the danged
things actually won't "wow" out and come disconnected due to vibration
anymore.

Also, the dumb attachment bolts (that threaded into the struts
themselves) have been eliminated. Instead, my A&P is tapping bolts
into the *struts*, so that they stick out through the holes in the
pants. This allows the use of self-locking nuts and cotter pins -- a
much more secure attachment method -- and should eliminate the problem
of those bolts vibrating loose (we've actually lost two of them in the
last several years!)every few flights.

As usual, I'm impressed with what he's doing. Best of all, because
he's only going to have to paint one color (he thought he was going to
have to paint all four colors, at first), the cost is going to come in
way under estimate.


Sounds like you'll be airborne pronto! Glad it is going so well.
You're doing it right from you're desription. I have used JB weld in
several places for cowling and wheel strut fairing repairs. It is
thick and stays where you put it. One thing I'd like to mention that
you might consider; Southco, Camlock, and Dzus fasteners are spring
loaded cushioned type attachments that give a little under load and
are good for high vibration locations like cowlings, etc. A solid or
hard mount can accelerate cracking if not done perfectly. The original
Dzus may not have been installed correctly which is why they have torn
out.

Regards,
Bruce Cunningham

thick and stays where you put it. One thing I'd like to mention that
you might consider; Southco, Camlock, and Dzus fasteners are spring
loaded cushioned type attachments that give a little under load and
are good for high vibration locations like cowlings, etc. A solid or
hard mount can accelerate cracking if not done perfectly. The original
Dzus may not have been installed correctly which is why they have torn
out.

Yeah, after I posted I started wondering about that. Once everything is
locked in more firmly in place on those wheel pants, only the fiberglass
will be able to flex -- which is probably not a good thing.

I guess we'll have to watch 'em, and really work on our greasers...

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay Honeck wrote:
Yeah, after I posted I started wondering about that. Once everything is
locked in more firmly in place on those wheel pants, only the fiberglass
will be able to flex -- which is probably not a good thing.

I guess we'll have to watch 'em, and really work on our greasers...


I wonder if changing the fasteners and adding the aluminum "backing"
material effectively invalidates the original Laminar Flow Fancy Pants STC
and the 337 that was originally filed on your plane. I think I still
would have called Laminar Flow and asked them what their recommended
repair procedure is, just in case.

--- Jay



--
__!__
Jay and Teresa Masino ___(_)___
http://www2.ari.net/jmasino ! ! !
http://www.oceancityairport.com
http://www.oc-adolfos.com

"Jay Honeck" wrote
Yeah, after I posted I started wondering about that. Once everything is
locked in more firmly in place on those wheel pants, only the fiberglass
will be able to flex -- which is probably not a good thing.

I am very much not a fan of allowing a garden-variety A&P (regardless
of years of experience) modify an aircraft at will. Modification
should be approached cautiously, especially when you are modifying
something designed by degreed engineers with years of experience, and
your education is of the vo-tech variety. No amount of field
experience as a mechanic makes you an engineer.

I used to belong to a club that had an aircraft with a rubber doughnut
(sort of like the Mooney gear but not quite) in the tailwheel
assembly. It was a definite weak point - sometimes it would not last
out the season. And it really wasn't seriously structural - it hardly
carried any weight. So this A&P/IA, a real greybeard with decades of
experience and a reputation that brought owners of expensive aircraft
to his nondescript shop from hundreds of miles away, "fixed" the
problem by adding an Aluminum bracket.

It was great for about three years. Then we noticed that the many
minor shocks that were absorbed by (and which eventually destroyed)
the rubber doughnut were now being transmitted to the tail assembly -
which started to crack. It had to be rebuilt at great effort and
expense by another greybeard - who restored everything to factory
design and told us to leave well enough alone.

The FAA codifies this in regulations that govern how alterations are
to be performed. Of course in typical FAA fashion this doesn't make
anything safer - just more expensive - but while the solution is
incompetent, the problem is very real.

Michael

Yeah, after I posted I started wondering about that. Once everything is
locked in more firmly in place on those wheel pants, only the fiberglass
will be able to flex -- which is probably not a good thing.

I am very much not a fan of allowing a garden-variety A&P (regardless
of years of experience) modify an aircraft at will. Modification
should be approached cautiously, especially when you are modifying
something designed by degreed engineers with years of experience, and
your education is of the vo-tech variety. No amount of field
experience as a mechanic makes you an engineer.

Wheel pants are not structural -- although you wouldn't know it by their
cost. There is nothing in the FARs barring an A&P/IA from making field
repairs to non-structural parts. (Or even owners, AFAIK.)

Which is different, I know, from being SMART to do it -- but Jay M. was
questioning the legality of it all.

Incidentally, this is our first experience flying the 235 without wheel
pants. We trued out at about 135 knots on the way to Wisconsin yesterday,
in absolutely calm air. Since we normally true out around 142, the fancy
pants apparently net us 5 to 7 knots.

Which is almost exactly what the previous owner told us they got him, so I
guess the danged things actually work.

It's still a mystery to me how those huge wheel pants (MUCH bigger than
Piper stock) can be more aerodynamic than the simple (and much smaller)
round tire hanging in the slipstream -- but I can't argue with results!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay Honeck wrote:
Which is different, I know, from being SMART to do it -- but Jay M. was
questioning the legality of it all.

I guess the issue I was trying to raise was NOT who did it, but rather how
it's done. I was obviously in favor of you doing it yourself. I know
that every speed mod that I've put on my plane came with a supplement that
describes maintenance and upkeep of the mod, so it only seemed prudent
that you asked Laminar Flow how THEY think the repair should be done.
Since the Fancy Pants are not the OEM wheel pants, and are installed under
an STC, it would seem that modifying them are "not quite" the same as
repairing standard OEM wheel pants.

--- Jay



--
__!__
Jay and Teresa Masino ___(_)___
http://www2.ari.net/jmasino ! ! !
http://www.oceancityairport.com
http://www.oc-adolfos.com

"Jay Honeck" wrote
Wheel pants are not structural -- although you wouldn't know it by their
cost. There is nothing in the FARs barring an A&P/IA from making field
repairs to non-structural parts. (Or even owners, AFAIK.)

Which is different, I know, from being SMART to do it -- but Jay M. was
questioning the legality of it all.

I'm not questioning the legality of this at all.

There is nothing in the FAR's barring an A&P/IA making field repairs
to sructural parts, either. He is also permitted to make MINOR
alterations on a logbook entry, using acceptable methods and
practices. MAJOR alterations require approved data. Who decides what
is major? Well, in the end the A&P/IA.

So your A&P made a minor mod. What's more, I AGREE that the mod is
minor. It will NOT cause your plane to fall out of the sky. What it
may (and I think will) eventually do is destroy a good pair of wheel
pants.

Michael

So your A&P made a minor mod. What's more, I AGREE that the mod is
minor. It will NOT cause your plane to fall out of the sky. What it
may (and I think will) eventually do is destroy a good pair of wheel
pants.

Well, they were junk before this repair started (or, at least, unusable) --
so they could only go up from there!

I'll talk to my A&P. If I know him, he's already thought this thing
through.

(He's an old EAA-er, and winner of the Antique Aircraft Association's
coveted "Grand Champion" trophy -- so he's not just another wrench...)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay Honeck wrote:

Incidentally, this is our first experience flying the 235 without wheel
pants. We trued out at about 135 knots on the way to Wisconsin yesterday,
in absolutely calm air. Since we normally true out around 142, the fancy
pants apparently net us 5 to 7 knots.

Anyone know how much improvement the stock pants yield?

George Patterson
If a man gets into a fight 3,000 miles away from home, he *had* to have
been looking for it.