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  #1  
Old 07-09-2012, 08:05 AM
LettersFromFlyoverCountry's Avatar
LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
 
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Location: St. Paul, MN.
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Default Melted lens

Gah.



I'm guessing the 100 degree temps last week and the plane parked in the sun at Red Wing -- unpainted, possibly redirecting sunlight into a death ray of some sort -- did this (I don't use the nav light). Is there any supplier that anyone is aware of of a harder plastic than this soft stuff?

Latest flight testing details, btw, are on the blog.
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Bob Collins
St. Paul, MN.
Blog: Letters From Flyover Country
RV-12iS Powerplant kit
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  #2  
Old 07-09-2012, 08:09 AM
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Mel Mel is offline
 
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Default

Bob, It is very unlikely that the sun melted your lens. Do you run with your nav lights on? Are they incandescent?
It is very common for the heat of incandescent bulbs to melt these lenses.
The only practical solution is to convert to LED type bulbs.

If you don't use the nav lights, I can't explain it. The melted area is directly over the nav light bulb.
I've NEVER seen lenses melted by sunlight!
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Last edited by Mel : 07-09-2012 at 08:12 AM.
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  #3  
Old 07-09-2012, 08:17 AM
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Phil Phil is offline
 
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Location: Waco, Texas
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Default Interesting.

Quote:
Originally Posted by Mel View Post
I've NEVER seen lenses melted by sunlight!
Maybe the shape of the bulb focused the light like a magnifying glass?
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  #4  
Old 07-09-2012, 08:26 AM
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LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
 
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Location: St. Paul, MN.
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Default

Quote:
Originally Posted by Mel View Post
Bob, It is very unlikely that the sun melted your lens. Do you run with your nav lights on? Are they incandescent?
It is very common for the heat of incandescent bulbs to melt these lenses.
The only practical solution is to convert to LED type bulbs.

If you don't use the nav lights, I can't explain it. The melted area is directly over the nav light bulb.
I've NEVER seen lenses melted by sunlight!
I don't use the nav lights at all.
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Bob Collins
St. Paul, MN.
Blog: Letters From Flyover Country
RV-12iS Powerplant kit
N612EF Builder log (EAA Builder log)
Last article: "Gonna Finish This Sucker" (Kitplanes)
Waiting for the avionics kit (backordered: chip shortage)
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  #5  
Old 07-09-2012, 08:27 AM
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LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
 
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Quote:
Originally Posted by Phil View Post
Maybe the shape of the bulb focused the light like a magnifying glass?
I was thinking the metal frame of the light assembly redirected the sunlight. This plastic is so soft, I don't think it takes much to melt.

I suppose, around here, it also could've been a collision with a mosquito.
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Bob Collins
St. Paul, MN.
Blog: Letters From Flyover Country
RV-12iS Powerplant kit
N612EF Builder log (EAA Builder log)
Last article: "Gonna Finish This Sucker" (Kitplanes)
Waiting for the avionics kit (backordered: chip shortage)
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  #6  
Old 07-09-2012, 08:49 AM
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Ironflight Ironflight is offline
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Wow - that looks very similar to mine (the melting) - I know mine melted due to the lights being on (did it the first time I sat with the lights on while on the ground). Ever since then I have made it a procedure to (try to) ONLY have the Nav lights on when I have air moving past the lenses.
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  #7  
Old 07-09-2012, 10:00 AM
Captain Avgas Captain Avgas is offline
 
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Location: Melbourne, Australia
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Default

Bob, that nav light looks to be very close to the lens. I'm sure most builders set their nav/strobe lights further back to avoid the problem of the generated heat deforming the lens. You say that you do not use the nav light, but is it possible that this occured when you were stationary and testing the lights and you did not notice the deformation at the time. The nav light can generate quite a lot of heat in a small time frame.

That lens is now cactus so it might be an idea to switch on the nav light for a while and see if the lens deforms further. That might tell you something either way.

Construction phase finished. Maintenance, repair and reinstatement phase underway.
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Last edited by Captain Avgas : 07-09-2012 at 10:03 AM.
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  #8  
Old 07-09-2012, 10:26 AM
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N8RV N8RV is offline
 
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I had the same thing happen, Bob, when I first tested my nav lights in the hangar. Honked me off.

I replaced the incandescent bulbs with LED replacements, but then had radio noise. Sounded like the squelch on the radio. I tried a couple of things to eliminate the noise, but it remained. So, I went back to the stock bulbs and, like you, just don't use the lights. Yet.
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  #9  
Old 07-09-2012, 10:53 AM
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LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
 
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Quote:
Originally Posted by Captain Avgas View Post
That lens is now cactus so it might be an idea to switch on the nav light for a while and see if the lens deforms further. That might tell you something either way.

Construction phase finished. Maintenance, repair and reinstatement phase underway.
Or it'd melt the other side. :*)
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Bob Collins
St. Paul, MN.
Blog: Letters From Flyover Country
RV-12iS Powerplant kit
N612EF Builder log (EAA Builder log)
Last article: "Gonna Finish This Sucker" (Kitplanes)
Waiting for the avionics kit (backordered: chip shortage)
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  #10  
Old 07-09-2012, 11:27 AM
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erich weaver erich weaver is offline
 
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Location: santa barbara, CA
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I had the same problem - I would bet my next pay check your light was turned on at some point after installation of the lens - it only takes a minute to do the damage. If I had mounted the light a 1/4 inch further back it wouldnt have happened. Pain in the butt to fix the root problem now too. I took the easy way out and replaced the lens while making a mental note to not turn on the nav lights longer than it takes to verify that they work - about 10 secs.

erich
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