Foggy/muted wing taxi/landing lights lenses

[PeterRus]

The taxi/landing lights lenses are "foggy" or "muted" on both wings -- due to the age, methinks. The lights are LEDs, and I'd like to replace the lenses with new ones -- they are available. However, it sounds like the new lenses will need trimming and/or drilling the screw holes. Some sellers offer trimming service if I mail the old lenses.

While removing and installing seems to be (a) legal if I do it myself and (b) straightforward I am not sure I have the tools/experience to trim the lenses and drill the holes. I am sure people have done this -- any comments or advice?

[EricJ]

Drilling polycarbonate or acrylic needs to be done carefully to prevent cracking the piece, but there are some methods that work well to mitigate that risk.   YT vids are your friend for this.   Trimming can be a little tricky, too.    The techniques are not difficult or hard to learn, though.   IMHO it is something you can do yourself, but talk to your A&P/IA first since they sign off your annual.   

 

[Marc_B]

The one benefit of having your A&P do it is that if they crack it, it’s their expense.  If you crack it it’s yours.  But with right tools and technique it shouldn’t be that difficult. 

If you can send in your lens, you might reach out to GLAP and that might be a good middle ground. 

[M20F-1968]

2 hours ago, PeterRus said:

The taxi/landing lights lenses are "foggy" or "muted" on both wings -- due to the age, methinks. The lights are LEDs, and I'd like to replace the lenses with new ones -- they are available. However, it sounds like the new lenses will need trimming and/or drilling the screw holes. Some sellers offer trimming service if I mail the old lenses.

While removing and installing seems to be (a) legal if I do it myself and (b) straightforward I am not sure I have the tools/experience to trim the lenses and drill the holes. I am sure people have done this -- any comments or advice?

Allow about 8 hours to fit both lenses (sounds like yours are wing-mounted lights).

You will need a combination disk/belt sander bench-mounted machine - The Harbor Freight version will work.

Also get countersinks from Aircraft Tools Co. They have fluteless countersinks that have a single hole in the side.  The cutting edge is the single hole.  They do not chatter and will safely cut without cracking.  Work slowly with the sander to fit the lens in place, with sufficient play.  It should not fit tightly.  The holes for the screws will also be oversized.  The screw heads will use couner-sinked washers.  Do not use the aluminum frame.

John Breda

[Utah20Gflyer]

Have you tried polishing the old ones?  Normally you can get them to almost new condition with a relatively small amount of work.  Maybe an hour or two.  I’d at least try before going through the time and expense of replacing them. 

[M20F-1968]

Also, when done, leave all screws 1 turn loose.

Work very slowly with the sander to fit the lenses.  The hardest part is to see that the lenses fit the curvature in all aspects of the compound curves without any stresses when fitted in place.

John Breda

[GeeBee]

1 hour ago, M20F-1968 said:

Allow about 8 hours to fit both lenses (sounds like yours are wing-mounted lights).

You will need a combination disk/belt sander bench-mounted machine - The Harbor Freight version will work.

Also get countersinks from Aircraft Tools Co. They have fluteless countersinks that have a single hole in the side.  The cutting edge is the single hole.  They do not chatter and will safely cut without cracking.  Work slowly with the sander to fit the lens in place, with sufficient play.  It should not fit tightly.  The holes for the screws will also be oversized.  The screw heads will use couner-sinked washers.  Do not use the aluminum frame.

John Breda

That's it. The proper tools make all the difference. Do not use standard drill bit or counter sinks. Get the right ones for acrylic.

[Schllc]

2 hours ago, Utah20Gflyer said:

Have you tried polishing the old ones?  Normally you can get them to almost new condition with a relatively small amount of work.  Maybe an hour or two.  I’d at least try before going through the time and expense of replacing them. 

You can buy a $35 kit from auto zone, take them off the plane and stuff a towel inside the curve to support the plexiglass and use a buffer or drill. If you wan to super glue some cracks do it before polishing. It only took me about an hour and they looked brand new. 

[PeterRus]

Great idea to polish the old ones! Thanks.

[gevertex]

3 hours ago, Utah20Gflyer said:

Have you tried polishing the old ones?  Normally you can get them to almost new condition with a relatively small amount of work.  Maybe an hour or two.  I’d at least try before going through the time and expense of replacing them. 

+1 to this. I used headlight lens restorer on mine and it got 80% of the yellowing out.

[LANCECASPER]

7 hours ago, PeterRus said:

The taxi/landing lights lenses are "foggy" or "muted" on both wings -- due to the age, methinks. The lights are LEDs, and I'd like to replace the lenses with new ones -- they are available. However, it sounds like the new lenses will need trimming and/or drilling the screw holes. Some sellers offer trimming service if I mail the old lenses.

While removing and installing seems to be (a) legal if I do it myself and (b) straightforward I am not sure I have the tools/experience to trim the lenses and drill the holes. I am sure people have done this -- any comments or advice?

Great Lakes Aero will trim, as you mentioned, and sell you the correct drill bit. I also highly recommend using tinnerman washers.

Also on newer Mooneys they eliminated the metal pieces that go on top of the acrylic. It looks much better without them when the lenses are trimmed nicely.

[Utah20Gflyer]

I have used premade kits to refinish plexiglass/polycarbonate and they work fine, but you can also do it with 1000 grit wet sand paper, then wet 2000 grit, then polishing compound like you’d use are a car.   Don’t do swirls, straight lines.  Lots of water when sanding.  
 

The good thing about a landing light lense is that it doesn’t have to be perfect like a windshield.  You just want maximum light transmission and for it to look good from a couple feet away.  

[PT20J]

I replaced mine. Great Lakes Aero made them for Mooney. They are polycarbonate (aka Lexan), not acrylic. Polycarbonate is softer and more impact and crack resistant but I find it harder to work with than acrylic. Because it is soft, it doesn't polish out as well as acrylic, but you cannot hurt anything by trying. I trimmed mine and it was a lot of work. If I were to do it again, I'd send the originals to Great Lakes and have them trim and drill them. If you drill them yourself, a step drill works best. I deleted the trim piece on mine as the later models. If you do this, drill the holes oversize and use countersink washers. No need to countersink the plastic.

[dkkim73]

7 hours ago, Schllc said:

You can buy a $35 kit from auto zone, take them off the plane and stuff a towel inside the curve to support the plexiglass and use a buffer or drill. If you wan to super glue some cracks do it before polishing. It only took me about an hour and they looked brand new. 

Did you use the rotary pads the same way as with car or other applications? Circular polishing and moving it around? I'm thinking of the admonition to polish linearly when doing things by hand like windshields. I got the Novus kit and was going to try doing the ice light (with masking) but thinking the landing light as well (or instead).

[Schllc]

3 hours ago, dkkim73 said:

Did you use the rotary pads the same way as with car or other applications? Circular polishing and moving it around? I'm thinking of the admonition to polish linearly when doing things by hand like windshields. I got the Novus kit and was going to try doing the ice light (with masking) but thinking the landing light as well (or instead).

I used a drill and the provided pads for all but the final step. I used a variable speed buffer for that step. They came out great. I was able to get the yellow out completely. They looked new from 5’ away. There were a few spider cracks around the screws they I glued but you could t hide. The ice light was a little harder bc it was recessed lower than the skins and I didn’t want damage the finish on the lip of the painted skin so I taped and did that by hand. That one was t as clear, but I got the yellow out and you couldn’t tell because the light refractor is directly below the lens so you couldn’t tell. 

[Utah20Gflyer]

12 hours ago, dkkim73 said:

Did you use the rotary pads the same way as with car or other applications? Circular polishing and moving it around? I'm thinking of the admonition to polish linearly when doing things by hand like windshields. I got the Novus kit and was going to try doing the ice light (with masking) but thinking the landing light as well (or instead).

If you are just using the buffing compound then it probably doesn’t matter whether you use straight lines or swirls, but wet sanding with sandpaper I’d recommend straight lines because it reduces the likelihood of swirls being visible later in the process (ie it reduces the total amount of work)

The upside of sandpaper is it removes material faster, downside is it removes more material.   In my estimation the plexiglass or polycarbonate will need to be replaced because of cracking before I run into an issue with material thickness.   If the damage is minor I would probably just use buffing compound, more serious I think the sandpaper makes sense.