Repairing Taxiway Light Damage to Underside of Wing - Aug 2008

Any scratch is serious that would allow moisture to get past the gelcoat  and
into the fiberglass skin.  If the scratch is deeper than the gelcoat  (i.e.
into the fiberglass skin itself) it needs repaired for structural reasons,  as
well.

=====================================================

Date:         Sun, 17 Aug 2008 20:33:31 -0400
Reply-To:     "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
Sender:       "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
From:         Bruce SCHIMMEL <bruce@SCHIMMEL.COM>
Subject:      Repairing taxiway light damage to underside of wing
Comments: cc: Luiz Castilho <luiz.castilho@aeromot.com.br>
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Greetings --

I recently scrapped the underside of a wing with the top of a runway 
light.

The runway light left a shallow dent on the leading third of the 
wing's chord.

1. When does a shallow dent become serious? How deep, wide or long?

2. What are my repair options?

thanks, Bruce
=========================================================================
Date:         Sun, 17 Aug 2008 21:07:53 EDT
Reply-To:     "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
Sender:       "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
From:         Chuck Cheeseman <XimangoUSA@AOL.COM>
Subject:      Re: Repairing taxiway light damage to underside of wing
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Bruce,
 
Any scratch is serious that would allow moisture to get past the gelcoat  and
into the fiberglass skin.  If the scratch is deeper than the gelcoat  (i.e.
into the fiberglass skin itself) it needs repaired for structural reasons,  as
well.  If you need details on the layup (layers and orientation) in the  area
of the damage, let me know.
 
Chuck Cheeseman
Ximango USA
 
 
In a message dated 8/17/2008 8:34:08 P.M. Eastern Daylight Time, 
bruce@SCHIMMEL.COM writes:

Greetings --

I recently scrapped the underside of a wing with  the top of a runway 
light.

The runway light left a shallow  dent on the leading third of the 
wing's chord.

1. When does a  shallow dent become serious? How deep, wide or long?

2. What are my  repair options?

thanks,  Bruce





**************Looking for a car that's sporty, fun and fits in your budget?
Read reviews on AOL Autos.     
(http://autos.aol.com/cars-Volkswagen-Jetta-2009/expert-review?ncid=aolaut00030000000007 )
=========================================================================
Date:         Sun, 17 Aug 2008 21:22:29 -0400
Reply-To:     "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
Sender:       "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
From:         Bruce SCHIMMEL <bruce@SCHIMMEL.COM>
Subject:      Re: Repairing taxiway light damage to underside of wing
In-Reply-To:  <be7.347ecea5.35da2569@aol.com>
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Fortunately, no. It dimpled the gelcoat, but didn't penetrate it.

It seems more a need for a putty of sorts.

yrs, Bruce


On Aug 17, 2008, at 9:07 PM, Chuck Cheeseman wrote:

Bruce,

Any scratch is serious that would allow moisture to get past the 
gelcoat  and
into the fiberglass skin.  If the scratch is deeper than the gelcoat  
(i.e.
into the fiberglass skin itself) it needs repaired for structural 
reasons,  as
well.  If you need details on the layup (layers and orientation) in 
the  area
of the damage, let me know.

Chuck Cheeseman
Ximango USA


In a message dated 8/17/2008 8:34:08 P.M. Eastern Daylight Time,
bruce@SCHIMMEL.COM writes:

Greetings --

I recently scrapped the underside of a wing with  the top of a runway
light.

The runway light left a shallow  dent on the leading third of the
wing's chord.

1. When does a  shallow dent become serious? How deep, wide or long?

2. What are my  repair options?

thanks,  Bruce





**************Looking for a car that's sporty, fun and fits in your 
budget?
Read reviews on AOL Autos.
(http://autos.aol.com/cars-Volkswagen-Jetta-2009/expert-review?
ncid=aolaut00030000000007 )
=========================================================================
Date:         Mon, 18 Aug 2008 07:49:52 EDT
Reply-To:     "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
Sender:       "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
From:         John Lawton <Thrmlseekr@AOL.COM>
Subject:      Re: Repairing taxiway light damage to underside of wing
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
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In a message dated 8/17/2008 9:22:48 P.M. Eastern Daylight Time, 
bruce@SCHIMMEL.COM writes:

Fortunately, no. It dimpled the gelcoat, but didn't penetrate  it.
Hey Bruce,
 
Here's a way to check it for underlying damage. Take a nickle and tap an 
area of the wing skin that is away from the scratch, i.e., an area not  damaged.
Listen to how that sounds. It should be a fairly sharp "click" when you  tap
it. Next, tap the scratched area and see if it sounds the same. What you are 
trying to do here is see if the skin has become detached from the foam just 
below the outer wing skin. You should hear the same sharp "click" when you  tap
the scratched area. If you hear more of a "thud", you've delaminated the  skin
from the foam and that will require a repair to the outer skin. Chances are 
you didn't delaminate the skin, but if you did it will require a skin  repair.
If you're not familiar with composites, a skin repair is probably  best left
to a pro.
 
Otherwise, if it's just a dent, you might try gently heating the  scratched
area with a heat gun to coax the skin back to normal. The key  here is gently.
Chances are, unless the scratch is really deep, it will return  to about 80%
of normal, maybe more, with just heat. Be very careful doing  this, though. You
have to sneak up on it s-l-o-w-l-y.
 
Sometimes shallow dents can be filled with just gel coat or urethane, 
depending on what your bird is finished with. You will need to lightly scuff the 
scratched area with 320 grit to remove any shine. Do all the sanding  with your
sand paper on a sanding block to keep the surface flat. Mix your gel  coat as
directed with MEKP or MEK. You can spray gel coat or  urethane with an
airbrush, slowly building up layer upon layer  until you have 6-10 thin coats,
filling the scratched area. Let the  gel coat kick, about 24 hours at 80F, longer if
it's cooler, then sand it flat  with 600, 800, then 1200, keeping the surface
wet with a sponge. Be sure to  change your water and wash out the sponge
between grits. Once you've  sanded with 1200, it should be ready for buffing.
 
Otherwise, if you try heat and that doesn't pull the dent back out to  your
satisfaction and the dent is too deep for filling with urethane paint or  gel
coat, microballons (micro) is the filler of choice. Scuff the area of the 
scratch with 80 grit until the shine is dull. There should be no shine in the 
immediate area of the dent, but don't go too far out around the scratch or 
you'll just make it a bigger job than it needs to be. Mix the  micro with a small
amount of expoxy resin (Aeropoxy, West Systems,  MGS, etc) to about the
consistency of whipped cream. It should hold a peak  like whipped cream or merangue.
I would not use 5 minute epoxy for this.
 
This mixture is called "dry micro." Using a throw away brush, apply  a very
light layer of epoxy resin to the scratched/dented area. Then,  using a plastic
bondo knife, (available at any auto parts  store) spread a thin layer of the
dry micro as evenly and as flatly as  possible over the scratch. Any excess
you might get on the non-sanded parts  of the skin can be removed while it's wet
with denatured alcohol or acetone.  It's better to get any excess off while
it's wet, otherwise you'll  have to sand it off later after it's kicked. The
smoother you get it  now over the scratched area, the less sanding later.
Neatness counts.
 
 Let the micro cure about 24 hours at 80F or above. Longer if it's  cooler.
Sand the area again with 180 grit, then 320. At this point it's ready to 
paint. Shoot gel coat or urethane with an airbrush, slowly building up  thin
layers. It should take about 5-8 thin coats to cover. Once the  gel coat or urethane
has fully kicked, sand with 600, 800 and 1200, keeping  the surface wet with
a sponge. Between each sanding be sure you wash  out your sponge and change
your water so you don't get the larger grit scratches  when you are on the
higher grits. After you've got the area sanded with 1200  it's ready for a buff.
 
Aircraft Spruce has the epoxy and micro. If you don't want to tackle this 
yourself, contact John Murray at Eastern Sailplane, or Monty at M&H and  they'll
be happy to fix it for you. We can fix it for you, too, but it's a bit  of a
haul to come all the way to our shop from your location for such a minor 
repair.
 
 Then again, we're dry as a bone here and the soaring is excellent. 
Yesterday was 9000' cloudbase with 8+ knotters. I did a 300K with ease  yesterday.
Probably could have done a 500k if I'd have gotten an earlier  start.
 
Anyway, hope it helps!
 
John  Lawton
Whitwell, TN (TN89)
Ximango  #135



**************Looking for a car that's sporty, fun and fits in your budget?
Read reviews on AOL Autos.     
(http://autos.aol.com/cars-Volkswagen-Jetta-2009/expert-review?ncid=aolaut00030000000007 )
=========================================================================
Date:         Mon, 18 Aug 2008 08:53:30 -0400
Reply-To:     "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
Sender:       "Ximango Owners Group (XOG)" <XIMANGO@HOME.EASE.LSOFT.COM>
From:         Bruce SCHIMMEL <bruce@SCHIMMEL.COM>
Subject:      Re: Repairing taxiway light damage to underside of wing
In-Reply-To:  <bf8.378ffaeb.35dabbe0@aol.com>
Mime-Version: 1.0 (Apple Message framework v753.1)
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John,

Many thanks for this detailed description. I really appreciate it, 
and I'm sure others do, also.

yrs, Bruce


On Aug 18, 2008, at 7:49 AM, John Lawton wrote:

In a message dated 8/17/2008 9:22:48 P.M. Eastern Daylight Time,
bruce@SCHIMMEL.COM writes:

Fortunately, no. It dimpled the gelcoat, but didn't penetrate  it.
Hey Bruce,

Here's a way to check it for underlying damage. Take a nickle and tap an
area of the wing skin that is away from the scratch, i.e., an area 
not  damaged.
Listen to how that sounds. It should be a fairly sharp "click" when 
you  tap
it. Next, tap the scratched area and see if it sounds the same. What 
you are
trying to do here is see if the skin has become detached from the 
foam just
below the outer wing skin. You should hear the same sharp "click" 
when you  tap
the scratched area. If you hear more of a "thud", you've delaminated 
the  skin
from the foam and that will require a repair to the outer skin. 
Chances are
you didn't delaminate the skin, but if you did it will require a 
skin  repair.
If you're not familiar with composites, a skin repair is probably  
best left
to a pro.

Otherwise, if it's just a dent, you might try gently heating the  
scratched
area with a heat gun to coax the skin back to normal. The key  here 
is gently.
Chances are, unless the scratch is really deep, it will return  to 
about 80%
of normal, maybe more, with just heat. Be very careful doing  this, 
though. You
have to sneak up on it s-l-o-w-l-y.

Sometimes shallow dents can be filled with just gel coat or urethane,
depending on what your bird is finished with. You will need to 
lightly scuff the
scratched area with 320 grit to remove any shine. Do all the sanding  
with your
sand paper on a sanding block to keep the surface flat. Mix your gel  
coat as
directed with MEKP or MEK. You can spray gel coat or  urethane with an
airbrush, slowly building up layer upon layer  until you have 6-10 
thin coats,
filling the scratched area. Let the  gel coat kick, about 24 hours at 
80F, longer if
it's cooler, then sand it flat  with 600, 800, then 1200, keeping the 
surface
wet with a sponge. Be sure to  change your water and wash out the sponge
between grits. Once you've  sanded with 1200, it should be ready for 
buffing.

Otherwise, if you try heat and that doesn't pull the dent back out 
to  your
satisfaction and the dent is too deep for filling with urethane paint 
or  gel
coat, microballons (micro) is the filler of choice. Scuff the area of 
the
scratch with 80 grit until the shine is dull. There should be no 
shine in the
immediate area of the dent, but don't go too far out around the 
scratch or
you'll just make it a bigger job than it needs to be. Mix the  micro 
with a small
amount of expoxy resin (Aeropoxy, West Systems,  MGS, etc) to about the
consistency of whipped cream. It should hold a peak  like whipped 
cream or merangue.
I would not use 5 minute epoxy for this.

This mixture is called "dry micro." Using a throw away brush, apply  
a very
light layer of epoxy resin to the scratched/dented area. Then,  using 
a plastic
bondo knife, (available at any auto parts  store) spread a thin layer 
of the
dry micro as evenly and as flatly as  possible over the scratch. Any 
excess
you might get on the non-sanded parts  of the skin can be removed 
while it's wet
with denatured alcohol or acetone.  It's better to get any excess off 
while
it's wet, otherwise you'll  have to sand it off later after it's 
kicked. The
smoother you get it  now over the scratched area, the less sanding 
later.
Neatness counts.

  Let the micro cure about 24 hours at 80F or above. Longer if it's  
cooler.
Sand the area again with 180 grit, then 320. At this point it's ready to
paint. Shoot gel coat or urethane with an airbrush, slowly building 
up  thin
layers. It should take about 5-8 thin coats to cover. Once the  gel 
coat or urethane
has fully kicked, sand with 600, 800 and 1200, keeping  the surface 
wet with
a sponge. Between each sanding be sure you wash  out your sponge and 
change
your water so you don't get the larger grit scratches  when you are 
on the
higher grits. After you've got the area sanded with 1200  it's ready 
for a buff.

Aircraft Spruce has the epoxy and micro. If you don't want to tackle 
this
yourself, contact John Murray at Eastern Sailplane, or Monty at M&H 
and  they'll
be happy to fix it for you. We can fix it for you, too, but it's a 
bit  of a
haul to come all the way to our shop from your location for such a minor
repair.

  Then again, we're dry as a bone here and the soaring is excellent.
Yesterday was 9000' cloudbase with 8+ knotters. I did a 300K with 
ease  yesterday.
Probably could have done a 500k if I'd have gotten an earlier  start.

Anyway, hope it helps!

John  Lawton
Whitwell, TN (TN89)
Ximango  #135