Aircraft are typically made of aluminium, although some may be made of composite materials.
Aluminium is a soft metal and thus easily damaged through rough handling, or by the perils of so-called “hangar rash”. In addition, aircraft are regularly damaged through accidents – from the mundane but expensive wheels-up landings, to more serious incidents such as runway excursions, which often result in the aircraft becoming inverted.
The aluminium panels used in aircraft manufacture often have compound curves which require specialist skills to manufacture or repair. For this reason complex parts such as cowlings may be made out of composite materials however, many surfaces such as wing leading edges and tail cones are a still made out of aluminium, which has to be formed and shaped and then accurately joined, most often with rivets.
Rivetted bonding has to be done to very accurate tolerances if the components are to align properly and to be joined accurately with the formers that give them shape. Again, as in all aircraft maintenance, the sheet metal engineering company must be certified and approved by the civil aviation authority and standards are regularly checked.
Fortunately, a skilled sheet metal repair should be indistinguishable from the original, even when multiple levels of damage have occurred such as from a wheels-up landing. However, it is still always essential that where parts are not possible to be replaced, such as fuselage stringers and formers, they be repaired to accurate tolerances without any cracks or splits being created by the repair process. For this reason, it is essential that only the most reputable aircraft maintenance organisations, with the necessary sheet metal repair credibility, are entrusted with aircraft repairs.