The repainting process is different for composites than for aluminum, at least in a couple of critical areas. All of those areas could be summed up in the words “manufacturers specifications.” That is, each manufacturer has its own dos and don’ts when it comes to stripping off old paint and putting on new stuff. The short answer for how to get the job done right is to find a shop that has done that make of aircraft and has happy customers. Unfortunately, many competent paint shops havent had to do a full repaint of a Cirrus or a Diamond yet. Is it worth trekking hundreds of miles to a shop that has a few under their belt, or working with a local gang with a good reputation knowing they will be learning on your aircraft? We think that depends on the attitude and other relevant experience of the shop. The big issue is in how they prep the aircraft before painting.
The Striptease
Depending on which aircraft youre talking about and what parts are composite, chemical paint strippers are either forbidden or just “not recommended.” All of the shops we spoke with stripped old paint off composites by sanding. Thats mostly hand sanding, too, as bead blasting can raise the temperature of some parts high enough to compromise the composite substrate itself. If the shop you talk to mentions putting chemicals on your composite aircraft, we recommend you head for the exit right then.
As an aside, the Grumman Yankee/Cheetah/Tiger line has a similar issue. They are bonded aluminum and some unlucky owners found out that chemical strippers would degrade the glue that bonded the skins to the ribs and formers.
Sanding means effort and time, and time usually cranks up the cost. The odd part of our research was that shops seemed split on how much more time it took to prep a composite aircraft. Some shops said the net time was about equal to an aluminum airplane on prep. They figured the extra time in sanding was balanced by less time spent masking and dealing with the chemicals. Other shops said it was 20- to 30-percent more