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New landing light lenses


PT20J

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  • 3 months later...
1 hour ago, Niko182 said:

What size drill size does one buy for the lenses? I know theres a special drill, but i dont know if its a 14, 17, or 18.

Thanks Nik

The landing light lenses are polycarbonate and don’t crack as easily as the acrylic wingtip lenses. Still, the unibit is the best bit for drilling all kinds of plastic.

 


IRWIN Unibit Step Drill Bit
 

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1 hour ago, Fly Boomer said:

How do you countersink the holes in the plastic lens?

With a countersink.

it is easier if you countersink them before you drill the final hole size. Drill a #30 hole and then countersink the hole, then drill the final hole size. You should drill and countersink a few holes in some scrap to get the correct countersink depth. You should countersink them deep enough that the washer doesn’t actually touch the countersink hole, so it will be kind of deep. Then drill the screw hole one size larger than the screw you are using. This will give the plastic a little room to expand and contract. 

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You don’t need to countersink the plastic. Just drill the holes large enough that the dimple in the washer fits down into the hole. This will put less stress on the plastic than if a countsunk hole and dimple do not perfectly match. The flat part of the washer provides plenty of surface area to hold the lens.

116361122_1000CskStainlessWashersAircraftSpruce.png.3c4283a3de8876cd9e7187f5dc17ce72.png

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On 5/19/2022 at 10:38 PM, LANCECASPER said:

I've replaced the lenses on Mooneys I've owned and it really improves the appearance. Countersunk washers help to avoid cracking the lens.

 

product_image

Most drill oversize holes and then use these countersunk washers.  However, in the case of Ovation wing mounted landing lights this leaves a very thin amount of acrylic between the hole and the edge of the lens.  This area always cracks.

To solve this problem, I drilled the lens through hole slightly oversize relative to the machine screw, not relative to the width of the countersink in the washer, and then countersunk that through hole somewhat oversize to accommodate the countersunk washer.  For countersinking in acrylic, Aircraft Tool supply has

"Zero flute countersinks" where the cutting edge is just one hole in the countersink, thus zero chatter in acrylics.  

I fitted my lenses this way (I have the Ovation landing lights in my F model) and left the screws snug but not tight, and there have been no cracks.

I did not install the frames.  It take forever to fit the lenses.  I used a bench sander (belt and disk sander combination). 

John Breda

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2 hours ago, PT20J said:

Agree fitting them is the hardest part. Especially since Lexan is so soft. They are made by Great Lakes Aero that advertises that it will trim them to match your originals. I wonder if anyone has tried that and can report on the results?

Skip

I sent Great Lakes Aero my lenses on the last Mooney I did (a Bravo a few years ago) and they did a great job. On the previous one (an Ovation) I had a local plastics company do the trimming for me with not-as-good results. After seeing what Great Lakes Aero did I would never attempt it myself.

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On 9/29/2022 at 5:08 PM, M20Doc said:

They should be #8-32 screws and dimpled washers.  If you can tolerate the additional drag, you can slip a small rubber washer under the dimpled washer to act as a cushion.

Which washers would you recommend?  Which, if any, of these?

https://www.aircraftspruce.com/catalog/hapages/nas549washers2.php?clickkey=3008341

Or these?

https://www.aircraftspruce.com/catalog/hapages/g8washers.php?clickkey=3008341

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@M20Doc SS vs Cadmium or Zinc plated?  Any reason to not go stainless for these screws?  Also, interestingly enough my IPC shows a grommet for the hole I guess...go figure, I've never seen anyone with the elastic grommets, but rather screw + countersunk washer.

image.png.f67e48849d31286a30ef309ca8b7a9c3.png

Marc.

EDIT the items above listed for the M20K wingtip lenses (but broadly applicable for J onwards I think). But the IPC doesn’t show washer for wing mounted lenses for landing/taxi lights and lists S3 (vs S4 screws wingtip). But I have washers on both wingtip as well as landing light lenses. 

933608B5-1671-458E-991E-1986EB0E792C.jpeg

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On 9/30/2022 at 12:00 PM, PT20J said:

Agree fitting them is the hardest part. Especially since Lexan is so soft. They are made by Great Lakes Aero that advertises that it will trim them to match your originals. I wonder if anyone has tried that and can report on the results?

Skip

I did that.  Worked great.  If there was any trimming left on my end it was minimal and minor sanding.  They do not drill the holes but that was super simple.  Just put them on the wing, marked the centers with a sharpie and drilled it out with the step bit, which they will also supply you along with a piece of scrap material to practice on.

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