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Old 03-29-2018, 02:56 PM
Pmoran's Avatar
Pmoran Pmoran is offline
Join Date: Apr 2015
Location: Onalaska, Wisconsin
Posts: 42
Default Crack in Windshield

I went to the hangar yesterday to take the RV-6A out after a cold winter's rest. After an extensive preflight, I pulled it out of the hangar and climbed in and started it up. As I was getting everything set up and slowly continuing through the checklist, I glanced up and notice a small crack in the windshield that I hadn't noticed before. I almost had a breakdown right then and there. The crack is about two (2) inches and it runs from the top left-center down and it is not noticeable while seated unless you intentionally search for it.

It just so happened that I ran into another RV owner on the airport that night that also experienced a crack in his canopy this cold winter; so I knew I wasn't the first person to experience the bad luck. Thankfully this website provides so much with regards to resources and information that the small donation requested is well worth the investment. I spent a lot of time researching to see if others may have experienced something similar and I wasn't disappointed.

I found a thread from 2014 from Gerry Julian who had a very similar experience. He drilled through his windshield with a 1/16 bit to stop the crack from continuing. Others suggested that one should use a drill bit exclusively for acrylic, however I could only locate a 1/8" bit from a local shop that develops plastic products. The person at the shop suggested that a 1/16 bit won’t grab enough to make a difference at that size.

My questions are: Should I use the 1/8 bit designed for this type of surface? This will create a little larger hole. Will the larger hole be significant enough to notice? Regardless of the size of the bit/hole, will this create a lot of noise and allow cold air to enter at a high rate of speed? Other than drilling a hole to stop the crack from spreading, is there anything else I should do and/or be aware of? Sorry for the big pictures. I'm still learning how to do this.
Any suggestions, advice or words of caution are welcome. Thanks in advance,
Pat Moran
(619) 994-3542

Last edited by Pmoran : 03-29-2018 at 03:38 PM. Reason: trying to add photos
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Old 03-29-2018, 03:03 PM
JimWoo50 JimWoo50 is offline
Join Date: Oct 2005
Location: Chicago sw suburbs
Posts: 411
Default I used a 1/16

Regular drill bit on a small hairline crack and it worked and it?s been 7 yrs or so.
Jim Woolard C56
N9855J RV-6 Donated 2020
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Old 03-29-2018, 04:13 PM
lr172 lr172 is offline
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 6,681

I initially used a regular #40 drill for all of my holes in the plexi and that should be all you need stop drill this.

N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019
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Old 03-29-2018, 04:33 PM
rockwoodrv9 rockwoodrv9 is offline
Join Date: Dec 2011
Location: Meridian ID, Aspen CO, Okemos MI
Posts: 2,856

Just to give another thought, a larger hole may make sure it stops. If you worry about air, fill it with some glue or silicone. Make sure the glue is compatible with your canopy.
Williamston MI
O-320 D2A
Flying N376E
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Old 03-29-2018, 07:18 PM
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Gash Gash is offline
Join Date: Aug 2009
Location: Goodyear, Arizona
Posts: 949

I'm getting ready to repair a similar canopy crack on my RV-7. I'm going to stop drill it with a #40 for acrylic. I don't think a 1/16" is big enough. That's a 1.59 mm diameter, and I don't think 0.80 mm is sufficient radius to relieve the crack stress.

After drilling, I'm going to fill the hole and the crack with Weld On #3. I bought a 1/4 pint can of Weld On 3 from Amazon for about $8. I also bought extra syringes with tiny little needles to help fill the crack and hole.

Good luck to as all!
Karl, Goodyear, Arizona (KGYR) ATP, CFII
Yak 50
=VAF= donor 2021

Last edited by Gash : 03-29-2018 at 07:26 PM.
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Old 03-29-2018, 09:03 PM
sibriggs sibriggs is offline
Join Date: Nov 2014
Location: Concord, NH
Posts: 230
Default High RPM

If you want to reduce the chance of more cracking or chipping when drilling. Put the bit in a High Speed Dremel. the bit will then melt the plexi as it drills and the hole is no bigger but the surface is sealed from the melted plexi.

Steve Briggs. RV9, G3x, G5, VPX, GTN625, PMags, A&P, IA, ATP-CFII
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Old 03-29-2018, 09:29 PM
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Mike S Mike S is offline
Senior Curmudgeon
Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 16,092

Take a look at this thread.
Mike Starkey
VAF 909

Rv-10, N210LM.

Flying as of 12/4/2010

Phase 1 done, 2/4/2011

Sold after 240+ wonderful hours of flight.

"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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Old 03-29-2018, 09:33 PM
RotaVR RotaVR is offline
Join Date: Aug 2011
Location: LaCrosse, WI
Posts: 49

I'll be taking my -4 to Pella tomorrow morning for the weekend. I have a new 1/8 acrylic bit you're welcome to use that I'll leave taped to my hanger door. Hanger A8. Compare the acrylic to the non-acrylic and you can see how the acrylic is designed to not grab. Keep it as long as you want. I'd leave it in my black truck but will be parking the truck in the hanger. Steve Schmitz
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Old 03-30-2018, 07:22 AM
Bob Milam Bob Milam is offline
Join Date: Jul 2014
Location: Chattanooga, Tn
Posts: 5

I had the best luck drilling holes in my canopy using a step drill bit with wide steps. A step drill has no tendency to draw the bit into the acrylic and you can keep the size of the hole to 1/8 inch.
Bob Milam
Chattanooga , Tennessee
RV6, 180hp, tip-up canopy
2018 Dues paid

Last edited by Bob Milam : 03-30-2018 at 07:25 AM.
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Old 03-30-2018, 07:34 AM
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AlexPeterson AlexPeterson is offline
Join Date: Sep 2005
Location: Ottertail, MN
Posts: 2,458

Please do not use a standard drill bit... Yes, many will report doing so without problems. A regular drill bit, just as it is starting to break through the far side, will "pull" itself through the rest of the way, making awful sounds. And, you may have much larger cracks to deal with. Someone offered the 1/8" plexi drill, good advice.
Alex Peterson
RV6A N66AP 1750+ hours
KADC, Wadena, MN
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