What is the FAA regulation regarding exterior graphics for aircraft?

The FAA has issued a policy memoin the Small Airplane Issues List (ID# A-0101) on the subject: Vinyl Covering Shrink Wraps on Exterior of Part 23 Airplanes, Gliders, and Airships

Applicants should be aware that the FAA has issued a memo stating there are safety issues with the installation of vinyl covering shrink wraps on the exterior of airplanes, gliders, and airships that are not present with other exteriors such as paint and deicing boots. These issues include hazards that are major to catastrophic, so the installation by FAA Field Approval is not acceptable.

Only Federal Aviation Administration (FAA) Type Certificate (TC), Amended Type Certificate (ATC), and Supplemental Type Certificate (STC) are acceptable for this installation.

This memorandum is not applicable to vinyl decals or logos that are placed on limited areas of the
fuselage or empennage. The following are safety concerns with the installation of vinyl shrink wrap coverings that must be evaluated by the applicant for any TC/ ATC/STC application:

1. Without proper engineering evaluation and/or tests, vinyl shrink wrap cannot be placed on any control surface or control surface tab: a. without consideration of the effect on the flutter characteristics (whether the surface is mass balanced or not) and b. where that installation would change the existing clearance between adjacent surfaces with and without loading.
2. Scoring the skin of aircraft when cutting the vinyl sheets to fit, which can start cracks, particularly in pressurized aircraft.
3. Blocking of fuel vents, static ports, hinges, drain holes etc., making them inoperative or changing the airflow over static ports.
4. Use of an open flame from a blowtorch to apply the material. This is a concern around fuel tanks and vents, sensitive antennas, and especially on composite parts, which have cure temperatures well below the temperature of a blowtorch.
5. Covering required exterior aircraft markings and emergency exits.
6. Vinyl sheets losing adhesion on the surface or on rotating parts and jamming control surfaces or compromising engines.
7. Static build-up causing electrical discharges in or around fuel tanks and causing radio/navigation interference.
8. Tinting of windows and windshields with transparent vinyl, which compromises the view of pilots.
9. The impact on removal of ice build-up on critical surfaces.
10. Flammability of the material, including lightning strikes, and especially near engine exhausts and around engine nacelles. Flammability test specimens should be built up from the cowling/nacelle with the vinyl shrink wrap applied.
11. Peeling of the wrap from rain or hail.
12. Masking of cracks and corrosion in structure and skin.
13. Lifetime of a vinyl shrink w/Tap installation. How long before mandatory removal.
14. Effects of de-icing fluids on the film.