AIRCRAFT MAINTENANCE MANUAL
DFE-AMM-AR1
Rev. 1 – 07/24/2014
10-2
10.2.2. Repair guidelines
Repairs must be performed only by qualified persons – see Section 0 Paragraph 0.12.
Dents, cracks and loose rivets are the most frequent problems encountered during the operation of
an all-metal airplane.
The following guidelines should be considered during repair:
1. The Strength in any cross-section of a repaired area/part should at a minimum be the
same as the strength of the original undamaged area or part. The repaired area is not
considered as a whole, but is considered as:
• an original assembly unit
• a stiffener or a patch
If the cross-section of a repaired area is (in all directions), at a minimum, the same
as the one on the original part, or if a stiffener or a patch shape and design is similar,
and the same materials are used, then there is no risk that the airframe will be
weakened.
2. The load has to be transferred by a stiffener or a patch from one side of a repaired area
to another. In some cases, the load transmission should be carried out at another
structural member and then back to an undamaged part of the original structure.
3. The length of overlapping between a reinforcement (stiffener or patch) and the
undamaged part of the original structure should be enough to assure a good joint. The
length of overlapping is very important to assure no load concentration.
10.2.3. Damage classification
Various types of damage may occur during aircraft operation. It is important to correctly classify
damage according to its character, size and especially, which part of the airplane has been damaged.
The important parts are the engine, engine mount, propeller, wing spar, wing box in the fuselage,
elevator, control system, and landing gear.
Any damage must be repaired only by person/repair station qualified in accordance with Section
0,12 Qualification requirements. The damaged parts may be replaced in their entity by new ones supplied by
the aircraft manufacturer.
Any damage and its repair should be recorded in the Log Book.
