Interior Plastic Door Cracked on my Mooney

[RonM]

Friends:  I have the Mooney 1991 MSE / 1997 Missile Conversion.  The other day I was in my airplane. I pushed down on the front passenger side arm-rest and the plastic about maybe 4 or 5 inches below the arm-rest cracked.  A nice 7 or 8 inch crack in the plastic.  (I assume the interior door trim is plastic?)  Anyhow - any suggestions for repair?  Can it be "plastered up" some-how? What would be the solution to that issue?  Sure, it is purely cosmetic, but appearance is important.  We all take pride in the appearance of our airplanes, I think. I am the original owner of the airplane, so this fall I will have owned it 30 years.  Much thanks for any commentary.    RonM

[ArtVandelay]

For small repairs:

[RonM]

Thank U Art!  Much appreciated!

  Best - RonM

[A64Pilot]

You may choose to remove the panel and effect the repair to the backside, and sometimes reinforcing it with some fiberglass cloth tape isn’t a bad idea.

[1980Mooney]

59 minutes ago, A64Pilot said:

You may choose to remove the panel and effect the repair to the backside, and sometimes reinforcing it with some fiberglass cloth tape isn’t a bad idea.

Definitely remove the panel and glue it from the backside. Done carefully the crack will barely be visible from inside the plane – you will probably be the only one that notices it. 
 

And with a long crack like that A strip of fiberglass cloth tap pressed onto the glue as suggested will give it more strength. Every year my panels gain epoxy. 

[RonM]

Thank U A64Pilot and 1980Mooney!  Much appreciated!   RonM

[Greg Ellis]

These two videos may help out as well….

 

This one isn’t great but may give you pointers on what not to do….

 

[A64Pilot]

While the store 5 min epoxies may be fine, I’ve found West Systems Epoxy to be a better quality adhesive, for something like this which may be best repaired by wetting out a strip of fiberglass tape and applying it and covering with epoxy resin, this product I’ve found hard to beat. it’s self mixing and applied from a standard caulk gun, buy several nozzles as they are only good for one use, but it can be used without a nozzle just mixed after it’s dispensed, being a thickened product it won’t run as bad as most epoxies, but if needed it can be worked into a thinner consistency, like for wetting out for instance.

Buy some acetone to clean for prep and I use isopropanol alcohol to clean up. but have heard vinegar works, but I haven’t tried it.

https://www.westsystem.com/specialty-epoxies/six10-thickened-epoxy-adhesive/

 

Oh, and wet the cloth out on wax paper of course and take a sharpie and make a mark across the plug and tube of the six ten,  that way you can reinstall it the same way and won’t put the resin side on the hardener having it possibly glue itself in.

Although if the panel flexes a lot, maybe West systems G-flex may be better

https://www.westsystem.com/specialty-epoxies/gflex-650-toughened-epoxy/

Edited June 5, 2021 by A64Pilot

[laytonl]

I use fiberglass cloth and plumbers pvc pipe glue.  It melts the fiberglass into the plastic and results in a strong bond.  Anytime I have a panel off and it has cracks or screw hole issues I use this technique.  Being doing it for over 30 yeArs on various airplanes.  Lee

[PT20J]

The plastic is ABS. The best thing I've found to repair ABS is more ABS. Two to three layers of glass cloth embedded with ABS cement on the back will do the trick. You can use the black ABS cement from the plumbing section of the hardware store. Put on just enough to saturate the cloth -- you don't want big puddles as it will soften the underlaying plastic. If you have a flat surface that needs reinforcement, you can get some ABS sheet from a plastic supplier and cut it and glue it with the same glue on the backside.  The Permatex plastic welder shown above works well if you need to fill a void or hole. I found it difficult to get it perfectly smooth, so after sanding you can fill in any voids with auto body spot putty and sand smooth. SEM makes plastic paint that will do wonders for covering repairs and making old yellow plastic look like new. I used Phantom White.

Skip

[RJBrown]

Epoxy gets hard and brittle and will eventually lose its grip with plastic. When ABS flexes old brittle epoxy let’s go. I would not use it. I would use the methods listed above. I used Acetone and fiberglass to fix the interior pictured back in the early 90s but ABS glue sounds better. I used the lightweight fiberglass cloth that is used in the R/C hobby industry. I brushed the fiberglass cloth into the backside of the plastic with the plastic solvent. I used powdered ABS mixed into the acetone to make filler putty for big holes/cracks. Acetone is very thin and watery and can be hard to work with. I’ve not used it but ABS plumbers glue has more body and might work better. 
I did use SEM paints. They come from auto detail supply stores. SEM has a whole line of products to repair and repaint the interiors of cars.

[PT20J]

I've tried melting Legos in MEK, and melting ABS chips I purchased online in MEK, and ABS cement (which according to the label is ABS resin mixed with MEK and Acetone). They all worked the same. The advantage to the Legos is that you can make whatever color you want which can be useful if you are not going to paint.

I needed to fix a cracked and warped glare shield and afterwards the top side looked pretty rough -- kind of like a bondo'ed fender before painting. SEM makes a spray texture and I used that and painted it with SEM Satin Black and it looks like new.

If you have a warped piece, you can do some minor reshaping with a heat gun, but be very careful as the temperature where ABS gets soft is not too much lower than the temperature where it melts, and the plastic panels are pretty thin and heat quickly.

Skip

[67 m20F chump]

I did it like A64pilot using west system epoxy.  However I did replace the door plastic with a new one because of how broken up it was.  

[A64Pilot]

If you can get the ABS glue to work for you it may be better if the panels are ABS. Place I worked at we vacuumed formed Royalite to make plastic parts. I’m not sure what Royalite is but it’s a lot like our panels. We used glue to attach different pieces together to make apart at times and it wasn’t epoxy.

‘For those that want to use epoxy if they are having a problem with it popping loose from being too hard, they need to use the G-flex or other flexible epoxy.

‘For any Epoxy use West Systems is a high grade often used in boat building and repair.

[PilotX]

I used the repair kit from Plane Plastics. I repaired the area around O2 gauge with a sheet of black ABS of Amazon, heated and molded into place, they coated liberally with the goo like in the PP video. Good luck. I broke some parts putting them back in, it was quite frustrating. 

[PT20J]

Royalite is a trade name for ABS. The problem with ABS is that it gets brittle with age. It doesn’t help that Mooney used such thin sheets to begin with which gets thinner in places where it is stretched during the vacuum forming process. 

[RonM]

Thanks all for the Videos, and the helpful commentary on this topic.  So much appreciated!     Regards - RonM

[carusoam]

When using glues and plastics...

It is really helpful to match the chemistries...

Our plastic interior parts are most often ABS... until the Long Bodies came out...

Acrylonitrile

Butadiene

Styrene

All three of these chemical groups are found in ABS molecules...

The styrene is known for its browning with age...

The butadiene is known for its rubbery impact resistance...

Adding fiberglass cloth to the backside, improves its strength...

PP thoughts only, not a chemist...

Best regards,

-a-

[RJBrown]

Epoxy sticks to the surface only. It does not bond chemically to the ABS. Epoxy eventually hardens becomes brittle and lets go. 
Great Planes sell 1/2 oz fiberglass cloth. That is 1/2 ounce per square yard. Very light material. I used acetone to melt the fiberglass cloth into the ABS panel. Lay the cloth where you want it dry. Using a soft paint brush apply acetone sparingly. Repeat. Cracks around screw heads can be filled with powdered ABS and solvent. 
Remember when we were kids we could get real model airplane cement. The stuff some people sniffed to get high. It chemically melted the plastic material the kits were made out of. The pieces were chemically welded together. Then we graduated to flying models and used tightbond glue. It soaked into the wood and glued it together like Elmers glue but better. Wood glues didn’t work on plastic models. That’s the kind of joint you get with epoxy. Purely a surface adhesion joint.

Epoxy is a BAD idea for ABS. There is a reason plumbers use a glue that chemically melts into the plastic to make a pressure proof joint. If a plumber glued your sprinkler system together with epoxy it would pop apart. Use the right “tool” for the job. 
A very thin, slow setting, ABS plumbing glue would be my choice to try going forward. Clear, not black and not the fast setting types or wet types.

Edited June 7, 2021 by RJBrown

[Vance Harral]

5 hours ago, RJBrown said:

Epoxy sticks to the surface only. It does not bond chemically to the ABS.

Agreed, but you can improve the bond by roughing up the surface of the plastic prior to using the epoxy.  I've had success with this method, but also failures where I didn't sufficiently roughen the surface of the plastic first.

The acetone solution sounds superior when done correctly, but also less forgiving of mistakes.

[DCarlton]

8 hours ago, RJBrown said:

Epoxy sticks to the surface only. It does not bond chemically to the ABS. Epoxy eventually hardens becomes brittle and lets go. 
Great Planes sell 1/2 oz fiberglass cloth. That is 1/2 ounce per square yard. Very light material. I used acetone to melt the fiberglass cloth into the ABS panel. Lay the cloth where you want it dry. Using a soft paint brush apply acetone sparingly. Repeat. Cracks around screw heads can be filled with powdered ABS and solvent. 
Remember when we were kids we could get real model airplane cement. The stuff some people sniffed to get high. It chemically melted the plastic material the kits were made out of. The pieces were chemically welded together. Then we graduated to flying models and used tightbond glue. It soaked into the wood and glued it together like Elmers glue but better. Wood glues didn’t work on plastic models. That’s the kind of joint you get with epoxy. Purely a surface adhesion joint.

Epoxy is a BAD idea for ABS. There is a reason plumbers use a glue that chemically melts into the plastic to make a pressure proof joint. If a plumber glued your sprinkler system together with epoxy it would pop apart. Use the right “tool” for the job. 
A very thin, slow setting, ABS plumbing glue would be my choice to try going forward. Clear, not black and not the fast setting types or wet types.

I deleted all of my previous comments to avoid steering folks astray.  I used the term epoxy loosely in one of my previous posts.  I've been using JB Weld Plastic Bonder.  It's a two part adhesive that's apparently urethane based.  It's bad ass like most urethane adhesives.  I couldn't get it off the plastic if I tried, particularly if I prep properly.  If it pops off it'll probably be long after I'm dead (we'll see).  Plus it seems to bond plastic to sheet AL fairly well if both surfaces are roughed up.  One thing about Mooney owners is they're typically ALL a bunch of smart people.  I've got a MSME and 35 years experience and I've taken classes in adhesives.  I get all the arguments for bonding ABS with ABS and using fiberglass sheet (and don't disagree) but if you're not willing to use something like Plastic Bonder on a non-structural piece of thin cosmetic plastic, I'm wondering when anyone would ever use it.  I've used it because it's convenient and it fills well and can be sanded and drilled easily.  I will report back if it ever pops off.  Here's the description...  

PlasticBonder™ is a quick-setting, two-part, urethane adhesive system that provides strong and lasting repairs and works on thermoset, carbon fiber composites, thermoplastics, coated metals, concrete & more. PlasticBonder™ has a 1:1 mixing ratio, sets in 15 minutes and can be sanded after 30 minutes. With a tensile strength of 3770 PSI, PlasticBonder™ sets to a tan color and cures to a hard, permanent bond.

Edited June 7, 2021 by DCarlton

[PT20J]

41 minutes ago, DCarlton said:

I deleted all of my previous comments to avoid steering folks astray.  I used the term epoxy loosely in one of my previous posts.  I've been using JB Weld Plastic Bonder.  It's a two part adhesive that's apparently urethane based.  It's bad ass like most urethane adhesives.  I couldn't get it off the plastic if I tried, particularly if I prep properly.  If it pops off it'll probably be long after I'm dead (we'll see).  Plus it seems to bond plastic to sheet AL fairly well if both surfaces are roughed up.  One thing about Mooney owners is they're typically ALL a bunch of smart people.  I've got a MSME and 35 years experience and I've taken classes in adhesives.  I get all the arguments for bonding ABS with ABS and using fiberglass sheet (and don't disagree) but if you're not willing to use something like Plastic Bonder on a non-structural piece of thin cosmetic plastic, I'm wondering when anyone would ever use it.  I've used it because it's convenient and it fills well and can be sanded and drilled easily.  I will report back if it ever pops off.  Here's the description...  

PlasticBonder™ is a quick-setting, two-part, urethane adhesive system that provides strong and lasting repairs and works on thermoset, carbon fiber composites, thermoplastics, coated metals, concrete & more. PlasticBonder™ has a 1:1 mixing ratio, sets in 15 minutes and can be sanded after 30 minutes. With a tensile strength of 3770 PSI, PlasticBonder™ sets to a tan color and cures to a hard, permanent bond.

I think this is likely equivalent to the Permatex product that I used for a filler. It sticks like hell as you said, has enough body to fill voids and is easily sand-able. It also flexes without cracking which was important when I was repairing a glareshield. The ABS cement/glass cloth works well when you need to make a thin repair and the part has a complex shape. I found it especially good for reinforcing screw holes which tend to propagate cracks. 

One thing to be careful about is that once ABS has been melted in solvent, it seems to be less hard and have a lower softening temperature than the original material. Perhaps a chemist among us can explain the effect. I did tests with ABS cement and MEK-melted Legos with the same results: Once it hardens you can easily poke depressions in it with an awl and it softens with a heat gun long before ABS sheet. So, it’s not as good a choice for filling voids or anything where thickness is required. The PlasticBonder is much better for that application.

Skip

[carusoam]

The plastic bonder describes sticking to everything...

Expect that it’s method of doing that is improved by having a rough surface... and be really good at getting in and holding onto the tiny crevices....

 

For skip’s discussion on why ABS loses the rigidity after being dissolved in a solvent.... there are a couple of reasons working together on that... 

If you don’t get all of the solvent out... it has a tendency to lubricate things and allow movement at the molecular level...  ‘rubberized’

If you get all the solvent out, and the properties still aren’t right...   there is a lot of entanglements among the polymer molecules that provide strength... dissolving them in solvent has a tendency to mess with the entanglements as well...

Often injection molded parts like legos... don’t have much strength compared to sheet like materials... this is because the processes used for both are different...  extruded strong thin sheet materials use high molecular weight polymers...  injection molded parts need low molecular weight materials to flow into the fine mold cavities...

Strength of the repair may benefit from a high molecular weight material...

See if you can find some ABS sheet as a raw material...

At this level of discussion... you can probably purchase some ABS pellets from a plastics supplier... and select the properties you want to have...  and skip all of the extra heat history of extrusion and molding... 

PP thoughts only, not a plastics repair guy... or chemist...

Best regards,

-a-