VG-21 Maintenance Item # 23 7 December, 1996

A Canopy Glass Replacement Experience.

Rosemary DeAngelo's canopy was damaged when it came unlatched in flight while someone else was flying it. Two new side windows were installed and the left side hinge was replaced when it was fixed but the door has been difficult to open and close since the repair work was done. She suspected that the canopy may have been bent and that the wrong type of hinge was used in the repair because the door didn't fit right when it was closed.

Since she was about to replace the windshield Rosemary asked if I had any advice about what could cause the problems with her canopy. I suggested that the best time to check and repair the canopy was while the glass was removed. I offered to help out and although I've installed and replaced Varga windows several times, I don't have an A&P license so I asked Keith Small, a young free-lance mechanic here at Falcon Field if he would do it with my help. He agreed, so I order a 6 ft. length of MS20257-P2 hinge and 200 CR3213-4-1 Cherry Max rivets for the hinge and Rosemary had the glass shipped to me. She flew in on a Saturday afternoon with the expectation that she would leave her airplane and return the following Saturday afternoon to pick it up. Keith had an empty hanger so I put Rosemary's airplane in my hanger where the tools were and I put my plane in Keith's empty hanger.

On Sunday I met Keith at my hanger and we removed the canopy door and top, found that the hinge was OK but that the canopy top and windshield frames were twisted. The right hand hinge was also bent a little at both ends and had some loose rivets. The rear window frame also appeared to have been bent but Rosemary wasn't planning to replace the rear window. Keith had done other window replacements but hadn't done a Varga so I told him how to remove the windows and windshield and left to get 200 CR3243-4-2 Cherry Max rivets for the window retainers, some DAP window caulk and to borrow an arbor press to straighten the canopy top frame.

I returned on Monday with the press and parts and saw that Keith had removed the windshield and had started to clean up the retainers for reinstallation. On Tuesday I made some form blocks for the press to help straighten the canopy top and saw that Keith hadn't done any more work. By Thursday at noon Keith still hadn't done much more so I decided to take the rest of the Thursday and Friday off from work to finish the job and hope that I could get Keith to sign the log book when I was done. After spending a couple of hours disassembling the canopy door, Keith showed up to say that he'd just finished another job that he had committed to at the same time he said he would do Rosemary's plane and that I could go back to work and he'd have the Varga finished by noon on Saturday. I went back on Friday at noon and Keith hadn't made any visible progress so I again decided not to go back to work and to try and finish the airplane before Rosemary got there the next day. A few minutes later, Keith came by and promised to finish the airplane on time. I went back to work and when I stopped by the hanger after work, Keith was still there and had made significant progress. The work he'd done looked good and he said he could finish up in a few hours and didn't need my help so I went home with my fingers crossed.

When I got back to the airport on Saturday morning, the airplane was finished and parked on the ramp in front of Keith's hanger. I opened and closed the canopy door several times to see if its operation had improved and found that it did except it hung up slightly at the bottom of its travel and sometimes had to be pushed down to its latch point. Further examination showed that there wasn't enough clearance between the canopy top and the rear window canopy bow at one point. I filed down the high spot on the canopy as much as I could but still couldn't get enough clearance to avoid occasional hang ups. The canopy door didn't stick up at the front any more and did work better than before but as Rosemary said when I showed her the problem "It's not perfect?". In hind sight, I shouldn't have let Keith wait so long to finish the job that I didn't have time to take care of any problems. After the fact, it was obvious that even though Rosemary wasn't replacing the rear window, it should have been removed to straighten the rear window frame and then reinstalled. Unfortunately, this would have also added four or five hours to the job. I feel bad that I didn't give myself the time to fix it better but hopefully you can learn from the error of my ways.

A problem that added labor time to this job was the type of sealant used on previous window replacements. Someone had used ProSeal fuel tank sealant that made it difficult to remove the window retainers and was hard and time consuming to scrape off. The original DAP sealant probably didn't seal as well but was much easier to remove and clean up.

Drilling out Cherry rivets isn't too hard if you punch in the mandrel and have gained the skill to drill through the center of the rivet without slipping off the rivet head but it is time consuming. The better you are at removing rivets, the fewer over-size rivets will be required for you and the next guy that has to do the same job.

Another problem unrelated to the window but that added time to the job was that the right hand side panel had been glued in place with RTV sealant by a previous mechanic and had to be removed carefully with a knife and scraped off before it could be reinstalled.

Rosemary's invoice from Aircraft Windshield Co. for one windshield ($286.37) two left side windows ($38.12) and one right side window ($42.37) plus 7.75% tax ($31.39) and shipping ($25.00) totaled $461.37. Keith's labor bill at $27/hr x 27.7 hours came to $747.00. I also bought $10.00 worth (40') of Ace Hardware pIn 57625 1/8" x 3/8" self adhesive closed cell rubber weather strip and about $8.00 worth (two tubes) of DAP sealant. Again, rivets were about 40 cents each and we used about 160 (160 x .40 = $64). Aircraft Spruce has some rubber P-strip seal that also works well and I recently found a similar type of 1/4" x 3/8" P-strip at a local hardware store. It is Macklanburg-Duncan pIn 02576 and cost about $5 for a 17' strip.

Another problem unrelated to the window but that added time to the job was that the right hand side panel had been glued in place with RTV sealant by a previous mechanic and had to be removed carefully with a knife and scraped off before it could be reinstalled.

Rosemary's invoice from Aircraft Windshield Co. for one windshield ($286.37) two left side windows ($38.12) and one right side window ($42.37) plus 7.75% tax ($31.39) and shipping ($25.00) totaled $461.37. Keith's labor bill at $27/hr x 27.7 hours came to $747.00. I also bought $10.00 worth (40') of Ace Hardware pIn 57625 1/8" x 3/8" self adhesive closed cell rubber weather strip and about $8.00 worth (two tubes) of DAP sealant. Again, rivets were about 40 cents each and we used about 160 (160 x.40 = $64). Aircraft Spruce has some rubber P-strip seal that also works well and I recently found a similar type of 1/4" x 3/8" P-strip at a local hardware store. It is Macklanburg-Duncan pIn 02576 and cost about $5 for a 17' strip.

If you have to repeat this experience with your airplane and have someone do it for you, I think you can expect to spend between $1500 and $2000 for parts and labor depending on the labor rate you're stuck with. If you decide to do it yourself, and add a rear window to the above parts list you might be able to do it for less than $1000.

Another problem that Rosemary asked me to look at was her cabin heat. The valve didn't seem to close completely and she had a severe heat leak that felt like it was going to cook her radios. I disconnected the cable at the cabin heat box bell crank and found that the wire had been cut off too short and that the valve would only close about half way. Fortunately I had just replaced my mixture control and had an extra wire that was longer than her cabin heat cable. All I had to do is exchange my red knob for her black one, slide the old mixture wire into her cabin heat cable housing and cut the wire to the correct length. Normally the wire attached to the valve bell crank is bent 90 degrees down to provide proper travel and a little spring force when the valve is closed but her bell crank had been modified and I couldn't do that. If you're having heat leaks, you might want to check your cable travel to make sure it's closing all the way.

After she left Falcon Field, Rosemary went to a paint shop in Tucson. She had gotten a quote from Arizona Aeropainting in Eloy, AZ (the original factory paint shop) of over $8000. Aircraft Color Design in Tucson was willing to do her blue and yellow military paint scheme for about $5500 so she took it there.

If you have had any experiences related to the repair or maintenance of your Varga, I suspect it would be helpful to other Varga to hear about them. Just send your story to me and I will reprint it in a future newsletter.