Operational Airworthiness
Paint and Sealant Removal Process
Purpose
The purpose of this notice is to advise you that Transport Canada (TC) has received reports from the Federal Aviation Administration (FAA) that some commercial transport category airplanes from differing States of Registry have been damaged in the process of being repainted in the mid-1990s.
The extent of this damage has rendered some of these aircraft beyond economical repair.
Description
Damage has been reported along fuselage skin lap joints, butt joints, and other areas of several aircraft. This damage appears to have been caused by the use of sharp tools used during paint and sealant removal (possibly make of metal, certain woods, micarda or hard plastic material) for removal of the pliable fillet seals at the structural joints in the skin during the repainting process. This use of sharp instruments can result in lines scribed in the fuselage skin. This damage has also been associated with the trimming of large external decals during their installation.
Lines scribed in the pressurized skin, if undetected, can result in cracks and possibly lead to widespread fatigue damage.
Affected Aircraft/Engine Model and Series
Multiple scribed lines have been found on some Boeing 737, 747, 757 and 767 airplanes. Any airplane model where sealant has been removed from fuselage joints, or on which large decals have been applied and trimmed on the fuselage since original delivery, may be similarly affected.
Recommendation:
To ensure that sharp instruments or other tools that can damage the skin panel are not used to remove sealant or trim decals, TC recommends that manufacturers, operators and maintenance organizations, including refinishing shops:
- Review sealant removal and paint stripping practices, procedures, and tools used;
- Review training provided to affected personnel to ensure that they adhere to standard practices and manufactures instruction for stripping of paint, cleaning sealants, and general care of fuselage pressure boundaries; and
- During fuselage inspections, pay particular attention to any structure that has been subject to refinishing, for evidence of scribed lines.
Standard practices for the removal of various coating can be found in the Aircraft maintenance and Structural Repair manuals. FAA Advisory Circulars AC 65-15A and AC 43.205 also address the paint removal process.