Gelcoat repair

On Nov 19, 5:58*am, wrote:
On Nov 18, 9:17*pm, Uncle Fuzzy wrote:





On Nov 18, 4:12*pm, Craig wrote:

On Nov 18, 3:35*pm, glider wrote:

*The process is very messy and can be hazardous to your health.
And it takes many, many hours of careful preperation.
*Labor intensive.
*As JJ said, mass balance of controls *is very important.
* 400-1000 hours is possible...no joke.
*Polyurethane may be best way to go.
*GA

Jim Phoenix nicely documented the refinish on his Nimbus 3.http://www..jimphoenix.com/?page_id=42

Heck, anything less than 18m will seem like a cakewalk. *Just don't
plan on having a social life this winter...

Best regards,
Craig Funston

Jim Phoenix reads RAS from time to time, so I'll try not to tell any
lies. *I corresponded with him quite some time ago, about the time I
was re-finishing a small portion of my fuselage with gelcoat.
Regarding the gelcoat vs poly, *I'm pretty sure he said if he had it
to do over again, he wouldn't gelcoat, he'd shoot polyurethane.- Hide quoted text -

- Show quoted text -

I've refinished in both Acrylic Urethane and polyester topcoat
(commonly called "gelcoat'). From my experience, each has it's place.
Gelcoat goes on thick and is tolerant of a lot of sins. Amatuer
spraying skills don't make a disaster. It does get hard and takes
quite a bit of work to sand out and polish. Life expectancy, if done
right and stored properly, should be plenty long.
It is comparatively inexpensive- roughly $500 for a 15 meter glider
for material and catalyst.
AU- I use PPG Concept as suggested by JJ and others, requires
excellent preparation and as perfect a surface as you can get because
it does not have much thickness. Gloss is great and is sands easier
than gelcoat.
BUT. Time and effort, from my experience with both is that the extra
time in prep before spraying AU exceeds the difference to sand out and
polish gelcoat.
AU is outstanding in UV protection and far exceeds gelcoat with
respect to weathering.
AU costs about 2 1/2 times as much as gelcoat.
AU must be sprayed in a safer environment and MUST be done using full
positive pressure protection gear as it contains what is essentially a
nerve toxin(aliphatic isocyanate).
Gelcoat is easier for fixing up that occasional ding.
So- long winded- which to use and why.
We did our ASK-21's in AU because of amount of time in weather and
harder life.
We do others in gelcoat for easier touchup, lower cost , and less
toxic exposure.
If you are going to do one glider one time as a beginner, I would
suggest polyester finish.
JJ likes AU but remember he has a huge amount of experience that a new
person won't have. Choice may well also be affected by availability of
experienced help.
FWIW
UH

UH,

I am guessing the "gelcoat" is Prestec, made by Simtec Coatings? I
sprayed my Apis with it. I do like using it also. The guys at Simtec
will tell you they call it a "polyester topcoat".

The one nagging problem I can't seem to get away from is that here in
the Pacific NW, my Apis grows nasty blisters in the paint every year
around this time. I have a well insulated trailer, with a vent. But, I
am not able to run power to the trailer for a heat source and a small
fan.

Cheers,
Brad

Jim Phoenix reads RAS from time to time, so I'll try not to tell
any
lies. *I corresponded with him quite some time ago, about the time I
was re-finishing a small portion of my fuselage with gelcoat.
Regarding the gelcoat vs poly, *I'm pretty sure he said if he had it
to do over again, he wouldn't gelcoat, he'd shoot polyurethane.- Hide quoted text -


Yup, I still believe that. Gelcoat is very forgiving for the amateur
(like me), but I was shocked at how much weight it adds, and when done
poorly, you can add a lot of weight covering up bad spray jobs. Flight
controls expecially get heavy with gelcoat and I ended up shooting the
elevators on the Nmbus with polyurethane because I couldn't get them
mass balanced within limits - very frustrating. If I had to do it
again, I would do the gelcoat removal and sanding and profiling and
priming myself then have a pro shoot on the polyurethane. Polyurethane
is dangerous if not applied in a proper envirnment due to it's
hazards.

With regard to Bob K.s reading of part 43, he's right - almost... 43.1
applicability reads "This part does not apply to any aircraft for
which the FAA has issued an experimental certificate, unless (here's
the fun part) the FAA has issued a different kind of certificate for
that aircraft [Amend #39, eff. 01 SEP 2004].

So what that means is that if your glider was a TC'd model with a
standard airworthiness issued and you somehow got an experimental
certificate for it later, well then part 43 does apply to you. Sounds
kinda crazy I know, but it's happened in the GA world - but is much
more prevalent in the air carrier world when STC developers need to
take a TC'd aircraft and put it into experimental R&D or some such
thing while they perform test flights to satisfy the FAA, then the
aircraft goes back to Standard Airworthiness after the test flights
are done and the STC is approved - bottom line is that 43 continues to
apply throughout the experimental life of the project. Too much info
probably, but hey there ya go.

Jim

Oh, yeah also I'm an A&P and was an IA at the time so I could do all
that work myself, the average glider pilot would need to work under
the supervision of an A&P and have it signed off appropriately,
depending (as Bob and Hank have said) on your airworthiness
certificate or ops limitations requirements - seems they are all
different.

Jim

On Nov 19, 9:34*am, Nimbob wrote:

...With regard to Bob K.s reading of part 43, he's right - almost... 43.1
applicability reads "This part does not apply to any aircraft for
which the FAA has issued an experimental certificate, unless (here's
the fun part) the FAA has issued a different kind of certificate for
that aircraft [Amend #39, eff. 01 SEP 2004].

So what that means is that if your glider was a TC'd model with a
standard airworthiness issued and you somehow got an experimental
certificate for it later, well then part 43 does apply to you...

Jim, please help me be sure I understand this:

The way I read the text of 43.1, it states that part 43 does or does
not apply to a certain aircraft depending on the type of airworthiness
certificate issued for _that particular aircraft_.

But the way you are describing your interpretation, you seem to be
saying that 43.1 says that part 43 applies or does not apply to _all
aircraft of a particular type_ depending on whether or not the
manufacturer has obtained type certification for that aircraft type.
Do I understand your interpretation correctly?

This issue is of particular importance for owners of sailplanes where
some units imported into the US were certified as experimental,
racing, and for which a standard airworthiness certificate was never
issued, but for which the factory has obtained type certification for
that model.

Thanks, Bob K.

Anybody ever use PolyLux?

It's what George Applebay uses on all of his aircraft. It can be
sprayed through a regular spray gun. SimTec has to be shot through a
much more expensive spray gun. Also, PolyLux is much cheaper.

On Nov 19, 12:46*pm, Scott Alexander
wrote:
Anybody ever use PolyLux?

It's what George Applebay uses on all of his aircraft. *It can be
sprayed through a regular spray gun. *SimTec has to be shot through a
much more expensive spray gun. *Also, PolyLux is much cheaper.

I've sprayed Prestec successfully using a Laquer gun, and also a HVLP
conversion gun. 1.8mm tip and thinned per specs with Acetone.

That being said, only rarely do I get a non-orange peel finish, but
the stuff cuts easily if you get to it within a day of setting.

Brad

On Nov 19, 12:46*pm, Scott Alexander
wrote:
Anybody ever use PolyLux?

I've used a bunch of their 670 primer and their 300 gloss topcoat. The
primer was pretty good but nothing special. I really liked the 300
series, though; it sprayed on nice with a cheapie Harbor Freight
touchup gun and 1.4mm nozzle. Their gelcoat for molded parts was
pretty good, too.

The issue I had in dealing with PolyLux is that they're a small
company with little web presence. I haven't worked with them lately,
but when I last did there was no catalog of products on the web, and
when I needed information I had to actually phone them up. Also, I'd
sometimes call and find that what I wanted wasn't in stock and
wouldn't be batched for several weeks.

Thanks, Bob K.
www.hpaircraft.com

On Nov 19, 1:46*pm, Bob Kuykendall wrote:
On Nov 19, 12:46*pm, Scott Alexander
wrote:

Anybody ever use PolyLux?

I've used a bunch of their 670 primer and their 300 gloss topcoat. The
primer was pretty good but nothing special. I really liked the 300
series, though; it sprayed on nice with a cheapie Harbor Freight
touchup gun and 1.4mm nozzle. Their gelcoat for molded parts was
pretty good, too.

The issue I had in dealing with PolyLux is that they're a small
company with little web presence. I haven't worked with them lately,
but when I last did there was no catalog of products on the web, and
when I needed information I had to actually phone them up. Also, I'd
sometimes call and find that what I wanted wasn't in stock and
wouldn't be batched for several weeks.

Thanks, Bob K.www.hpaircraft.com

I use a standard gun with Prestec also, but thin with a slow or medium
lacquer thinner. Dupont 3602S is my favorite. The slow thinner lets
the finish to flatten out so there's a lot less orange peel. Another
trick is to just fog on the first coat and allow it to tack so that
the following coats don't run off. I run the paint on the thin side
and use multiple lighter coats that tack slightly between coats to
build up a flat finish, sometimes as many as 5 or 6 coats. If I have
concerns about pot life while spraying I'll store the gun in the
fridge between coats. If you're blending into an existing finish
extend the spray area a little each time so the thickness tapers out
onto the existing gelcoat. At the end of spraying you can fog the
feathered edge with thinner only to get it to flatten out.

Craig

On Nov 19, 6:20*pm, Craig wrote:
On Nov 19, 1:46*pm, Bob Kuykendall wrote:





On Nov 19, 12:46*pm, Scott Alexander
wrote:

Anybody ever use PolyLux?

I've used a bunch of their 670 primer and their 300 gloss topcoat. The
primer was pretty good but nothing special. I really liked the 300
series, though; it sprayed on nice with a cheapie Harbor Freight
touchup gun and 1.4mm nozzle. Their gelcoat for molded parts was
pretty good, too.

The issue I had in dealing with PolyLux is that they're a small
company with little web presence. I haven't worked with them lately,
but when I last did there was no catalog of products on the web, and
when I needed information I had to actually phone them up. Also, I'd
sometimes call and find that what I wanted wasn't in stock and
wouldn't be batched for several weeks.

Thanks, Bob K.www.hpaircraft.com

I use a standard gun with Prestec also, but thin with a slow or medium
lacquer thinner. Dupont 3602S is my favorite. *The slow thinner lets
the finish to flatten out so there's a lot less orange peel. *Another
trick is to just fog on the first coat and allow it to tack so that
the following coats don't run off. *I run the paint on the thin side
and use multiple lighter coats that tack slightly between coats to
build up a flat finish, sometimes as many as 5 or 6 coats. *If I have
concerns about pot life while spraying I'll store the gun in the
fridge between coats. *If you're blending into an existing finish
extend the spray area a little each time so the thickness tapers out
onto the existing gelcoat. *At the end of spraying you can fog the
feathered edge with thinner only to get it to flatten out.

Craig- Hide quoted text -

- Show quoted text -

Std HVLP gun with 1.8 nozzle for Prestec. Note that excess thinning
can increase porisity in finished coats which ain't so good.
UH

..
Jim, please help me be sure I understand this:

The way I read the text of 43.1, it states that part 43 does or does
not apply to a certain aircraft depending on the type of airworthiness
certificate issued for _that particular aircraft_.

But the way you are describing your interpretation, you seem to be
saying that 43.1 says that part 43 applies or does not apply to _all
aircraft of a particular type_ depending on whether or not the
manufacturer has obtained type certification for that aircraft type.
Do I understand your interpretation correctly?



Thanks, Bob K.


Bob - I left out the word "previously" when I copied 43.1 - but it
doesn't really change anything, it still means the same. Let's read it
again:

43.1applicability reads "This part does not apply to any aircraft for
which the FAA has issued an experimental certificate, unless (here's
the fun part) the FAA has PREVIOUSLY issued a different kind of
certificate for THAT aircraft [Amend #39, eff. 01 SEP 2004].

If your glider was a U.S. TC'd model with a US standard or "other
special airworthiness certificate" issued and you somehow got an
special airworthiness - experimental certificate for it later, well
then part 43 does apply to you... that is - a U.S. Standard
Airworthiness Certificate (I should have been more clear in my earlier
message).

Now, the other important word I re-typed in all caps is the word THAT.
In this instance the rule means THAT aircraft right there - not that
make, model or series aircraft. This is how the rule actually works.
We've actually had applicants in my FSDO apply for an experimental
certificate for their very modified Cessna 180 for the purpose of
exhibition and racing. If I recall correctly, we sent them over to the
MIDO and they got an experimental for R&D instead, but I may be
thinking of a different deal involving a PA-12, in any case, part 43
still applied to THAT airplane - not all PA-12's or C-180's.

Some gliders are TC'd in other countries, but not in the US (pre-1993
moratorium issue here) but the 43.1 rule does not apply in this case,
because it does not have, nor ever had - a US Airworthiness
Certificate of any kind (there are a few kinds actually). So the
Nimbus can be experimental and part 43 does not apply (unless the Ops
Limitations specifically make it apply - that's yet another story).

A couple of other examples: The PW-5 first came over as experimental,
part 43 does not apply to THOSE original experimental PW-5s because
they were born in Poland, exported to the US and never had a US
airworthiness certificate. Later, PZL obtained US type certification
for the PW-5 and they had standard US airworthiness certs issued to
them and voila part 43 now applies to just those TC'd serial numbers
that came in after the TC was issued.

I believe the 304 was the same thing, originally they all came in
experimental. Then they got a TC for the the 304, and if you bought a
new 304 that was eligible for type certification in the US, you get a
standard airworthiness for it, and part 43 would apply. Or maybe you
want to get an experimental for it, if you can get an experimental
certificate for a foreign built glider after a US TC has been issued -
more power to ya. But I would be surprised if you did.

Now, if you somehow talked an FAA inspector into giving you an
experimental for YOUR TC'd and PREVIOUSLY standard airworthiness 304,
then part 43 would still apply to your glider **that had a previously
issued standard airworthiness**. The only reason someone would get an
experimental for a previouslt standard glider would be to get out of
the annual inspection by and IA requirement, but 43 still applies in
that case, so no joy.

So, your understanding of the rule is correct - we're just boring the
hell out of RAS with this academic discussion is all. This really is
academic because I've personally never seen this applied in the case
of a glider; I believe the rule exists only to keep the aircraft that
are temporarily in experimental R&D or Exp. Show Compliance under part
43 while they fly off the test flight requirements.

I'm not allowed to interpret the rules, so it's only my view, if you
want a real interpretation, you have to ask the professionals in DC,
you can find the link to ask FAA legal a question like this on www.faa.gov.
You can also read the FAA Order 8130.2, I think rev. G is now current
- but it's damned boring reading;-) and like I said before - it's
never really been an issue for any glider I've ever known, just those
crazy power pilots!!

Sorry if I mislead you earlier,

Jim