Aircraft SRM repairs

Structural repair manual repairs. 

In FAA rules, is it legal for Part-145 Repair Stations to do a  one-off certification of a component repaired per approved SRM when they do not have shop capability/approval for that component?

To be more specific... if an aircraft has acquired impact damage on an inlet cowl, later replaced with a serviceable one to continue revenue operations and the removed cowl "component" is then repaired per approved aircraft SRM by part 145 repair stations, with no aircraft structural component shop capability for the said cowl. Is it legal for part 145 repair stations to install the repaired cowl on the aircraft? Is there any legal

work required to have the component installed?...what are the FAA rules/solutions involving such cases?

EASA has separate repair shop approvals for structures, C4 aircraft Doors, C8 aircraft flight controls, C20 aircraft structures. There is something not very practical about this, as repairs differ less from what part is being repaired and more as to materials and methods.

Aircraft structural repair and analysing the Repair Area

The use of the aircraft SRM, the manufacturer's maintenance and parts manual is important in determining the extent of the damaged area. List the new or rebuilt parts needed. Determine if the damage is serious enough for complete replacement of a wing or control surface. For example, it may be more economical to replace a whole wing rather than pay for replacement parts and labour.

When planning repairs, consideration must be given to the speed of the aircraft. For example, a low-speed aircraft uses surface patches or common lap joints with universal head rivets, while high-speed aircraft use flush patches and countersunk rivets.

The cost of labour and parts must be estimated and the owner informed.

Damage that often appears on aircraft structures are things like oil canning, ruptures, cracking and gradual wear and tear. Oil canning is caused by the loosening of skins between two ribs or stringers. The metal pops back and forth until it becomes excessively coldworked and cracks. Ruptures are caused by the exertion of force on the structural skins of light, pressurized aircraft. Many aircraft will develop cracks near joints or seams. These cracks are usually caused by over coldworking the metal. Attrition is the failure of aircraft structures due to age and use. As an aircraft gets older, its ability to withstand the constant expansions and contractions caused by flying or landing is impaired.

In their earlier stages, many structural problems can be prevented by the addition of a stiffener in the area where the coldworking action is taking place. Excessive coldworking faults are commonly associated with light, thin-gauge aircraft skins. Larger aircraft are also affected, but over a longer period of time.