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PostPosted: Mon Mar 18, 2013 16:44 
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Am afraid to see the price! :)


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PostPosted: Mon Mar 18, 2013 22:36 
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I know, Joe,

Presently, you get 15(!) GE 4537s ($15.40 each at Skygeek) for a single LED ($229 at Spruce), but this ratio will certainly improve constantly, with more and more LEDs being marketed. And then, how do you calculate the hassle for exchanging a lamp, every now and then and for taking-off and landing without a working light at a busy little airport like the one I am flying from? :? Of course, this is only my personal opinion and I admit to have been flying a Cub for nearly 20 years that had no lights at all. But what is the use of landing and taxi lights, when they don't work, during take-off, approach, landing and taxi?

Matt

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PostPosted: Thu May 02, 2013 12:27 
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After more discussion with and inspection by the mechanic and an avionics specialist, we agreed that the short life of my GE lamps must have been caused by vibrations (landings and taxiing with new bungees & engine vibrations) and that mounting them with the glow wires positioned vertically, would only marginally increase their life span.

I bit the bullet and ordered two Whelen PAR46 LEDs. The PMA list that comes with each LED does explicitly mention the Sedan. The installation is as simple as that of the GEs, the hardest part being the mounting of the landing light lens with the rubber profiles. These LEDs truly are a drop-in replacement, except for two little aspects. One: For some reason their ground and plus connector positions are switched. But unless your wiring inside the wing is very short, this does not present a problem. And two: The LEDs cross section is flatter than that of the GE, so there is more space behind the lamp, requiring a little tiny bit more plus wire, but this is really negligible.

The LED appearance is space-age and really does not belong into the wing of a 1940's/1950's airplane. If this modification was not reversible, I probably would not have dared to take this step, but decided to try and see, if I can get used to it. The emitted light is sensational, though: Very white and bright and at only about half the consumption of the incandescent lamps!

But see for yourself...

Matt

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PostPosted: Thu May 02, 2013 17:46 
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Matt,

They look great and thanks for your observations regarding their installation. It was hard to imagine the short life-span you were having with the incandescent lamps. I hope these are the solution.

Richard

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Last edited by hangerash on Mon Apr 14, 2014 03:45, edited 1 time in total.

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PostPosted: Fri May 03, 2013 06:35 
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Thanks, Richard,

My mechanic did mention that, according to his own experience, every now and then, a series of the GE lamps seems to be of minor quality.
Maybe the good stuff is reserved for you guys in the US. :wink:

Matt

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PostPosted: Fri May 03, 2013 08:23 
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Matt,

Agree with the look but truthfully for the safety would probably make the switch... when I can afford it! :)

Joe A


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PostPosted: Sun Apr 13, 2014 16:02 
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I am reporting back on my experience with the Whelen PAR46 LED landing and taxi lights, during the past year: First of all and most important, they have been working dependably. And they do use half the Amps that the incandescent bulbs did. So, I am not hesitating to switch them on, whenever the lighting conditions are marginal or on those grey-in-grey misty days.

Unfortunately, a problem has arisen, during the winter months and in cold air temperatures: Whenever a light had been on for at least five minutes or so, condensation droplets were visible inside the lamps (see first picture below). I observed this effect, after several flights in both lamps and assume, the condensation formed only, after I had switched the respective light off, after landing. Whelen's reply to my report was:
Quote:
Condensation is a normal occurrence for all lighting fitting those types of application. It has to do with the air temperature both inside and outside the lighthead assembly.
Personally, I just don't like the idea of liquid humidity inside a lamp housing. When asked, an avionics shop here in Switzerland mentioned that they had installed LED position lights (brand not known to me) into our Air Force Super Puma helicopters and that they also produced condensation which damaged the LED elements and caused the lamps to prematurely fail in several cases. I also searched the internet for similar observations to mine by other pilots and was surprised to quickly find several posts in various message boards (see below). Somehow this just doesn't seem right to me and I would not expect something like this in a $250 lamp. Shouldn't there be a vacuum inside the lamp preventing condensation?

Matt

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PostPosted: Sun Apr 13, 2014 17:55 
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Matt,

Great info! I had thought about switching over to the LED lights on the Sedan but this report sure is not helping any....

I would not be happy about it either!

Joe A


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PostPosted: Sun Apr 13, 2014 21:21 
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It would be interesting to know, if other brand LED landing lights show the same condensation effects.

By the way, I forgot to mention: The last flights were done in a higher OAT of about 53 °F (12 °C) and there was no condensation at all.

Matt

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PostPosted: Mon Apr 14, 2014 03:52 
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I presume the only reason for the lens (cover) in front of the LEDs is to isolate them from touch or foreign object damage. Since there is neither vacuum nor pressurization to be concerned with, why not place three or four #40 holes near the perimeter to permit the heated air to escape?

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PostPosted: Mon Apr 14, 2014 05:56 
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Hi Richard

Thanks for your constructive input!

Drilling holes was one of my first thoughts, too – right after :evil: :!:. One small hole at the bottom and another one at the top should be enough to solve the issue. But I am hesitating, since what goes inside – spiders, flies, mosquitos, dust, etc. – must not necessarily come out again. (Remember, I bought these to never have to remove the landing light lens, again.)

I agree, the lamp's front clear "lens" is only for physical protection from objects. But the 18 LED elements, each positioned behind its own, specifically shaped little lens, don't seem to be hermetically separated from the rest of the atmosphere inside the lamp. So, they are always exposed to the observed, sometimes visible (when condensed), sometimes invisible humidity. And from what I learned from the avionics folks, this does not help a long lamp life.

Someone in another forum suggested to remove two of the four screws along the lamp's rim, while it is switched on, let it run for a while to allow the humidity to dissipate, then insert the screws, again, while the lamp is still on. Sounds like a plausible solution and I might try this out, before drilling holes. In general, though, I would expect a manufacturer to test things out and to come up with proper measures, before going into serial production.

By the way, Aircraft Spruce now asks $298,95 for this specific LED type, compared to the $229, a year ago! Anyone with condensation issues in other types and/or brands of LED landing lights?

Matt

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PostPosted: Tue Apr 15, 2014 14:42 
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I nearly suggested removing a screw or two instead of drilling the holes. I had forgotten how creative spiders can be at seeking a space. You are correct that holes would possibly solve the problem only to create another. It is indeed a shame the manufacturer doesn't take ownership of their problem.

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PostPosted: Tue Apr 15, 2014 15:45 
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It seems to me the problem is the moisture content of the air trapped inside the lens. The moisture is simply changing states and will not go away. If holes are drilled into the lens, the problem MIGHT get better during extremely dry conditions but conversely get worse with high humidity. Not to mention the bug issue.

A solution might be to seal the lamp with an inert gas, like standard "sealed" incandescent lamps. At $250 a pop, you would think that this would not be an issue.

Dennis


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PostPosted: Thu Apr 17, 2014 21:57 
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Thanks, Dennis,

I believe, you are right about the holes/humidity.
I'll try to find out, if LEDs from other manufacturers have the same problem.
Will report back, when I know more.

Matt

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PostPosted: Thu Sep 25, 2014 09:55 
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A few of my C-170 pals are running this inexpensive LED light. Look around and you can find it for around $100:

Grote Trilliant® 36 LED Whitelight Work Lamp 63821-5

Here is a link to a PDF from Grote which on the second page shows some actual picture comparisons of the same light from an incandescent vs the Grote LED replacement.

http://www.grote.com/prodcat/attachment ... racket.pdf

Unfortunately, that pdf file only claims comparison with certain PAR36 lamps...such as the 4461 which is a 60-watt lamp...not a 100-watt such as the 4509.

There is no requirement that the incandescent lamps meet TSO or PMA. They are "standard" parts. They are also subject to AC 23-27. They are a similar situation as your rudder nav light... a common automotive lamp.

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