Over the life of an aircraft it will experience damage from a variety of reasons such as accidental impact, lightening strikes or bird strikes, corrosion or exposure to elements, and many other examples.
The damage will be found and evaluated by maintenance persons and recorded accordingly. Note that not all damage will require a physical repair, it is possible that the “repair” is an approved evaluation, and the damage is permitted to remain.
It is also not always possible to see damage on an aircraft, it might be hidden from sight (for example floor beam repairs) or it could be a composite fuselage repair (for example the Boeing 787) and you can walk past it without externally noting it.
Often a physical inspection can take place during a paint input as this is when the paint is removed, and the bare metal is exposed or composite as applicable. This is referred to as a BMI – Bare Metal Inspection and you can see multiple repairs and damages you cannot normally see.
For most repairs, we will refer to a structural manual, such as the structural repair manual (SRM) which covers multiple smaller or common repairs on an aircraft.
When damage exceeds the limits noted in a structural manual then repair and evaluation
instructions may come from various sources such as a Part 21 authorised organisation or the OEM (original equipment manufacturer).
The next consideration would be the records for the repairs; on board, the aircraft will be a document noting damage and detailing a summary of the damage. To accompany this there shall also be a “repair file” which is all the supporting paperwork and documents to accompany each repair where the repair is certified and documented.
The damage we see and the recorded details for the repair should be accurate, and dimensions / location recorded along with damage in the near vicinity are very important considerations during a
review as these can determine repairs being appropriate or not.
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