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Poll - Have you Cracked your Canopy?

Has your canopy cracked?

  • No. I'm at the building stage and it did not crack during build.

    Votes: 77 18.1%
  • No. I've been flying less than 200 hours and it has not cracked.

    Votes: 67 15.8%
  • No. I've been flying more than 200 hours and it has not cracked.

    Votes: 116 27.3%
  • Yes. It cracked while building.

    Votes: 73 17.2%
  • Yes. It cracked during the first 200 hours.

    Votes: 40 9.4%
  • Yes. It cracked after the first 200 hours.

    Votes: 52 12.2%

  • Total voters
    425

alpinelakespilot2000

Well Known Member
Having just finished the canopy while reading all the terrible posts about canopy cracking, I'm wondering how long before my canopy is going to crack! :eek: (Yes, that's a joke... I hope! I am aware that builder technique has a lot to do with it.) That said, I am curious to get a feel for how many people have actually ended up with cracked canopies. My guess is that cracking canopies has been blown out of proportion a little, but maybe I'm wrong. I hope not!
 
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no but

i know two others that have. one i was doing the glasswork and noticed it before we got started. 1/2 inc. the other was a freind who is as anal as you get using all the right tools and 90+ temps..cracked the last hole. i know when/if mine cracks it will be the right front most hole. the bubble was really distorted. if i knew then what i know now i wouldnt even drill that hole. but then it may not have pulled down. who knows we'll see.
 
I am as ham-handed as anyone but the only canopy incident occured when I made the big cut and failed to properly support the soon-to-be two pieces. When the cut was almost complete, the windscreen part broke away leaving a crack that I was able to just cover with the fiberglass at the roll bar. Other factors in my favor could be the warm Georgia temps, plexi drills, and dumb luck.
 
Did I just jinx myself?

After choosing "No,I havent cracked it" I had a bad thought go racing through my mind. Did I just jinx myself...???
 
Very interesting. With only 29 votes to this point, it appears that a little over 1 in 4 have cracking at some point. However, if one makes it through the build process, that number drops to only 6.9%. Obviously more specific questions would lead to more accurate conclusions, but interesting nonetheless. I'm curious to see whether more votes corroborate the early trend.
 
I was replacing the struts on my tip-up & had one off & one on. For some reason, I decided to close the canopy, so I pulled down on the side without a strut. All was fine until it hit the canopy rail. Thankfully, I drilled it out & it hasn't grown any.
 
Mine cracked after 6 years and 1000 hours one night during a cold front when the temp got down to 5 deg. in the hangar.
 
cracked by weak struts

After about 150 hrs in just over a year in my RV7 tip-up, my struts were getting weak and a gust of wind blew my canopy down and broke off a corner of my canopy! I have fixed the canopy and I now have struts rated at 30 pounds of force instead of the stock 20 pounds. :eek:
 
Cracked Canopy

I have not worked on a RV canopy yet, however, if the instructions call out for rivets...you should consider rivnuts. With rivets you have no control over the compression force. If you have plexiglass riveted to a metal or alloy substraight, you will more than likely get a stress crack in a hot or cold environment. That is due to differences in the thermal expansion rates of the two materials. plastics tend to have twice the thermal expansion rate as say aluminum...therefore, if the plexiglass is tightly riveted to the alloy and the sun is hitting it, that is a recipe for a crack.
Just my two cents worth pulled from an A&P class.
Dan B
 
Cracked Canopies

I have built several RV's and I have had one canopy for an RV-4 crack in multiple places, nearly every hole spiderwebbing out. I also had an RV-7A canopy crack on the first hole drilled into it. There must have been a lot of stress in that part, because when it cracked, it left a gap over 1/4" at the bottom of the canopy. It also made a **** of a crack sound when it happened.
I have talked to several manufacturers of canopies, who gave me the same reason why most of them crack, which is that they are not properly heated while being formed. Therefore, it leaves a lot of stress (tension) in the part. I happen to fully agree with that after looking at what happened to me. Just my FYI.
 
It seems there are 2 kinds of builders. Those who have cracked the canopy, and those who are about to. I didn't vote yet because I'm not finished with it. I do plan to Sikaflex it though. Haven't decided whether to use a few fasteners also.

Clear skies,
 
Have been out of town since I created the poll. Interesting to see the results now that I'm back. It looks like if we make it through the cutting, drilling, and fitting stage, that only 1 in 9 (~ 12% of 136 votes) will have a problem with cracking thereafter. Any more voters out there?
 
<SNIP>

I have talked to several manufacturers of canopies, who gave me the same reason why most of them crack, which is that they are not properly heated while being formed. Therefore, it leaves a lot of stress (tension) in the part. I happen to fully agree with that after looking at what happened to me. Just my FYI.

That's interesting. I wonder if it would be possible to "stress-relieve" plexiglas by a controlled high-temperature soak, as is done with metal alloys.
 
mine cracked at 4 years

and 760 hours, during an ordinary joyride with OAT +35F... a near perfect paintjob:rolleyes: made ugly by a canopy crack
 
Ummmmmm

No, until up to 1/2 hour ago, then a 2 incher beside the front seat on the right side of my 8 canopy. And I could cry. Hope that doesn't happen to many more times. There are only so many EAA stickers that should be put on a canopy.
 
I don't think so!

It seems there are 2 kinds of builders. Those who have cracked the canopy, and those who are about to.
There are literally thousands of RVs flying and I doubt very seriously that most of them are cracked.
 
Mine RV-8 Cracked at 7 years and 1225+ hours

Mine RV-8 Cracked at 7 years and 1225+ hours. An ugly 10" crack behind the passenger seat. The crack started at a rivet hole where it is fastened to the frame. It was parked overnight at PAE in Washington, not overly cold or hot. Guess all those hours can cause stress.
 
Guys,
I've reported this before, but maybe this will help those that missed the last discussion. After 800 hours, my canopy cracked on a very, very cold February day in heavy turbulence. The crack started from the second rivet aft of the canopy bow on the left side of my 8. I had intended to fill the gap between the glass and the round canopy frame tube with Sikaflex, had purchased the product, but just hadn't got to it. Rats!

After removing the original canopy, I realized that I had not cut the sharp edge of the drilled holes with the deburring tool leaving an increased chance for crack to start. Prior to replacing the glass, I prepared the glass and canopy frame as if I was going to bond the glass on with Sikaflex. I riveted it on per plans, and then after masking off the glass, I inserted Sikaflex in the gap on both sides of the canopy frame bonding the tube to the glass. I believe this will relieve the stress on any single rivet yet retain the full strength of the rivets holding the glass on.

I recommend that all builders do this before, or after the first flight, but unlike me, before any cracks.
 
Another Canopy Crack on RV 8

My rear canopy developed a 9" crack on the aft section, starboard side, about 13" from the rear. The crack occured about one hour into my flight on a cold ( Surface 32 degree F ) but calm day on Xmas Eve... Merry Xmas to me ! The crack announced itself with a loud THUMP. My in flight diagnoses was a bird strike but this did not prove correct.

I installed my canopy per Van's instructions with the exception of using # 4 screws in lieu of Al. pop rivits. I reasoned that I could control the stress on the canopy much better with screws than with pulled rivits. It was an "anal installation ", edges polished, etc. The crack occured @ about 160 hours.

Ken, at Van's, advises that canopy cracks on the RV 8 are very rare and he could recall two instances of cracking.... Perhaps Ken should check the forums at VAF. I've ordered a replacement canopy from Van's and will install using the Sikaflex method.

Dick Jordan
RV 8A, N888BZ
Sticky Stuff
 
canopy cracked 8a during first two hundred fhrs

canopy cracked during first two hundred hrs of flight. When we drilled the holes in the plexi we did not know to oversize the holes when temp dropped to -#, in ny the canopy contracteh more than the rivets.

cyril
 
After 20 years and 1800 hours my main canopy cracked across the top. Temp was -10F or so and it happened a half hour after takeoff in smooth air. I'd flown in those temps 15-20 times with no ill effects but I suppose the canopy gets brittle with age. Anyway, I provided myself with some work (and expense).
 
Put the plane on the ramp one frigid winter day to clean the heated hangar. (-35 C). A few minutes after pulling the plane back in, heard a “tick”, found a 3” crack from front skirt fastener. Drill stopped, clear RTV on resulting hole, ok since then
Jay
 
18 years in service (not all my doing) and after getting the plane back to where I intended to keep it coming from a warm climate to a cold climate my 8 canopy cracked about 5cm long eminatig from a rivet left side just behind the rear canopy bow. Didn't even notice it till I went to clean it......grrrrrr stop drilled, filled hole with silicone and 3 years later hasn't propergated any further!
 
My RV-9A slider was built in Atlanta, lived there for 4 years, then lived in St. Louis for 5 years..TT of about 420 Hobbs hours. As of about 6 months ago it lives in Minnesota in an unheated T-hangar...it was -20°F a few days ago and this week we’re looking at daytime highs of 0°F. This the furthest north it’s ever been. Currently, it’s in an insulated hangar for a little avionics project but I turn the heat off when I’m not there and back on when I arrive. Thus, that airplane can have as much as 60-80 degree temperature swings several times a week. I’ve been closely watching that canopy for cracks and thus far, it’s good.
 
My RV-9A slider was built in Atlanta, lived there for 4 years, then lived in St. Louis for 5 years..TT of about 420 Hobbs hours. As of about 6 months ago it lives in Minnesota in an unheated T-hangar...it was -20°F a few days ago and this week we’re looking at daytime highs of 0°F. This the furthest north it’s ever been. Currently, it’s in an insulated hangar for a little avionics project but I turn the heat off when I’m not there and back on when I arrive. Thus, that airplane can have as much as 60-80 degree temperature swings several times a week. I’ve been closely watching that canopy for cracks and thus far, it’s good.

Anecdotally, from this and other threads, it’s the rapid temperature changes that are hardest on the canopy, e.g. going from a warm hangar to below zero outside in a matter of seconds or minutes. Gradual temperature swings generally not nearly as much of an issue. One of the (only) benefits of having an unheated hangar!
 
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-15f last week and now I have 2 4" cracks in the rear window. Yuk. What size drill is recommended for stop. Are you leaving hole as is or inserting a filler? I have read that some used Weldon3 for the crack. Any final repair pictures would be helpful.
 
For you RV-4 guys out there.

Here's a story from way back in 1992, when I was but a wee lad, with no money to buy a second canopy bubble.

I caused a crack near the #7 bulkhead. There was a small welding bump on the canopy frame. When I installed a Cleco nearby.... CRACK! So, the lesson is that no bumps are allowed beneath the Plexi, not even small ones.

I fixed it as seen in the photos below. It worked great. In fact, I'd consider simply cutting off the canopy ducktail right away if I ever built another RV-4.

Actually, the crack was somewhat beneficial. The main canopy is lighter and easier to handle. I had it off just recently during the condition inspection.

And the fixed aft portion allows me to toss a ball cap, rag, etc. under the Plexi. Hey, every bit of storage is VALUABLE in a relatively small RV-4!

The aft portion doesn't leak air to any noticeable degree, probably less than the standard ducktail... but who knows?

And it added at least 5 knots. :p

IMG_20200830_164838964_HDR.jpg


canopy.jpg


IMG_20200607_122842051.jpg
 
1997 RV-6 tip-up cracked in the aft right corner a few years ago. Crack emanated from a screw. Stop drilled the crack. A few months ago the crack completed its journey to edge and I now have a small triangle of canopy. I haven't bothered to try and fix it yet.
 
Cracked while building

When installing the outer handle, I did not first round-off the square end.
Error...
While turning the handle to check operation, the square butt caught the canopy, I didn't notice and continued turning.
I heard CLAC !! then said a few umprintable words...
Hairline crack, 1 centimeter long.
Stop-drilled and filled with Epoxy glue.
No worsening yet with only 10 hours of flight.(winter flying that is, down to -15C)
I don't expect it to change.
 
canopy cracking

Why don't the canopy manufacturers use Lexan polycarbonate instead of acrylic? Lexan is very forgiving for hole drilling and trimming. So many stories of cracking-WTF ???? Can/will anyone answer this question?
 
Sikaflex

I glued the canopy in with Sikaflex, Careful preparation and rivet after the Sikaflex sets up.

But you get a perfect seal and no cracks in over 500hrs.

It would be an interesting pole to see how many of the no cracks used Sikaflex?
 
Sikaflex

Also, during my prep, I drilled and cleco-ed the canoy to make sure of fit. Removed the canopy, Spread the Sikaflex, re-cleco-ed in place and riveted after the Sikaflex set.
 
Sikaflex

I'm just about to start the -14 Sikaflex cannopy installation in the next week or two. From my research I'm finding that 295 UV Black for the adhesive, 209D Primer and 205 Activator is what's being used. It would be great to see the differences in the crack data with rivet or adhesive installations.
 
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