How can I repair ABS plastic parts, such as the throttle quadrant cover? What about window molding repairs?
(Search strings: ABS cement, ABS repair, plastic repair, Royalite repair, fairing repair, repair fairings, wingtip repair, repair my wingtips, window trim)
CREDITS: This information has been extracted from an activity reported by Tim Olsen, using techniques recommended by Bob Steward.
Well I gotta hand it to the guy, he knows his sh-tuff! I’m taking the Sundowner on an 1100 mile X/C in a couple days, and got irritated by all of the cracks in my throttle quadrant cover. It was split in at least 5 or 6 areas, and ALL 4 screws had the plastic completely cracked around them. It was just hanging there. An in one spot, when I pulled it off, there was even a hole, where a piece had chipped OUT of a corner.
I took Bob’s advice from this post below from 7/12/2003 about proper plastic repairs using MEK and ABS chips.
My first question is “where the heck am I going to find ABS”? Sure, lots of things are made of it, but try shopping around a store looking for items labeled “ABS” so you can chop them up…hard to find. I did find PVC/CPVC/ABS cement at one store, but am glad I never opened it. It did say it was for all of those types of “pipe”.
I called our local Home store, (Menards, in my case, maybe Home Depot or Lowes or whatever in yours) and just asked if they had ABS pipe, and sure as shinola they did! 10′ of 1-1/2″ pipe for less than $3, and they had actual ABS Cement in BLACK for maybe less than $2 also.
I used the ABS cement first, to open up the cracks and put it on, then hold the parts together.
Then, I took the pipe and put it on my mitre saw and made about 50 cuts really quick with a carbide blade, cutting 1/4″ off at a time, and letting the collection bag (I used a plastic bag) catch all of the shavings. Then, I put them in a baby food jar with enough MEK to dissolve them and make a nice goopy paste. From the inside of the quadrant, I brushed that over all of the cracks, fairly thick. After a short time, it flowed nice and smooth and looked REALLY nice inside, and outside it looked good too.
Then for the harder parts. Where the 4 screws were, those pieces were chipped out. One chip was smaller, so I stuffed it in with the cement. The other 3, I put tape over the top side, and filled it with the slurry from behind, and built it up a ways so it was again one continuous edge. After that got a little stiff, I pulled the tape off the top and spread another layer on the outside of the flange to build it up.
If I would have had more time before my trip, I could have worked slower and probably not filled it from the top side, and from all appearances it would have looked nearly perfect. But, I wanted it really strong, and soon, so I thickened up that flange. Then, I cut a couple of 1/4″ aluminum strips to overlay the flange and use as a big backing (from the front side) plate to distribute the pressure a bit. I primed it in black to match.
Tomorrow I just have to drill my 4 holes out again, drill the holes in the aluminum strips, and then screw it all back on again. It’ll be stronger than it has been since I bought the thing, and it looks pretty darn good. Much better price at less than $5 than paying the $260 or so that Beech gets for this $20 part.
Please read Beech Service Letter SL-63-13 dated November 4, 1963, on Royalite plastic repairs. This SL may also be referenced in logbook entries documenting legitimate repairs like this.
Many people are making these ABS plastic repairs with materials that stick to ABS/”Royalite” much like tape. They seem to have a good bond when applied, but really don’t. Anyone with any experience on these parts has had to deal with repairs that peel right off within a few years. I was helping out a Grumman owner with the same issue less than a week ago.
The ABS plastic cement will bond just like a weld does in steel. You can use it with the hobby shop thin fiberglass to create parts and fill missing areas. You can use the cloth to reinforce a crack repair if you want to, but the ABS weld will be as strong as the parent material. The key is to build it up in thin layers, letting each layer dry. Don’t try to over-work it when applied, as it just makes the surface rough. Give it several days to harden up; it hardens slowly when any thickness is applied. Once hard, it can be sanded and finished like the base part.
Be sure to use proper stripper, flexible primer, and flexible finish paint on the plastic parts. You need quality products from an auto refinishing supply, not Pep Boys stuff.
CRITICAL ADDED INFORMATION:
The black plastic interior parts such as the older spar cover, quadrant cover, etc. are indeed Royalite R20 (ABS). So are the exterior fairings and Wingtips-Stab tips. However, Beech Technical Support has stated that all the interior plastic door and window trim panels are made of something called ‘Kydel hair cell 100’. He doesn’t yet know whether the SI covering ABS plastic repairs will work on it. The name sounds suspicious to me, as though it may be misspelled. A quick Google search didn’t turn up any useful info. The few times I have tried repairs on side panels it has seemed more like hard vinyl. I have not yet tried to use ABS repair on the window moldings; only the smaller interior plastic parts and exterior fairings. The window panels may require plastic welding with a compatible rod, or bonded repairs using a compatible epoxy that works with the Kydel. If any members can add technical information regarding the Kydel plastic, that would be very helpful.
Beech recommends the use of powdered cleansers (like Ajax) and a soft rag for surface refurbishment on the light-colored interior trim. This will also help remove crystallized surface plastic. If you do any strong cleaning, DO NOT use any solvents other than isopropyl (rubbing) alcohol. Westley’s makes a whitewall cleaner called ‘Bleche-White’ that at one time was heavily promoted and packaged as a cleaner for interior vinyl. The stuff is pretty harsh on hands, but it works better on vinyl than anything else I have ever used, and is available at most auto parts stores. I have used it very successfully on window trim. If you will just be cleaning and reinstalling, the cleaner can be followed by a water rinse and dry. The parts can be reinstalled after an overnight soaking in Armor-all (a very heavy dripping coat). If you will be doing repairs and a re-paint with a plastic paint like the Molecubond, I would stick with the powdered cleanser and water. That way nothing will interfere with the paint bond. You can coat the back side with Armor-All before reinstallation.
If you just do routine interior cleaning, make sure you restore some plasticizers by applying a heavy coating of a product like Armor-All, and letting it soak in overnight. Don’t just wipe on a very thin and shiny layer, like most folks tend to do.