(a)Clarification of the terms ‘Major/Minor’ In line with the definitions given in point 21L.A.203, a new repair is classified as ‘major’ if the result on the aircraft, engine or propeller design has an appreciable effect on structural performance, weight, balance, systems, operational characteristics, declared noise or emissions levels or other characteristics affecting the airworthiness or the environmental compatibility of the product or part. In particular, a repair is classified as ‘major’ if it requires extensive static, fatigue and damage tolerance strength justification and/or testing in its own right, or if it requires methods, techniques or practices that are unusual (i.e. unusual material selection, heat treatment, material processes, jigging diagrams, etc.). Repairs that require a reassessment and re-evaluation of the original substantiation data to ensure that the aircraft continues to comply with all the relevant requirements should be considered ‘major’ repairs. Repairs whose effects are considered minor and require minimal or no assessment of the original substantiation data to ensure that the aircraft continues to comply with all the relevant requirements should be considered ‘minor’. It is understood that not all the substantiation data will be available to those persons/organisations classifying repairs. A qualitative judgement of the effects of the repair will, therefore, be acceptable for the initial classification. A subsequent review of the design of the repair may lead to it being reclassified, owing to early judgements being no longer valid.
(b)Airworthiness and environmental protection concerns for ‘Major/Minor’ classification The following should be considered for the magnitude of their effect when classifying repairs. Should the effect be considered significant, then the repair should be classified as ‘major’. The repair may be classified as ‘minor’ where the effect is known to be without appreciable consequence.
(1)Structural performance The structural performance of the product includes static strength, fatigue, damage tolerance, flutter and stiffness characteristics. Repairs to any element of the structure should be assessed for their effect upon the structural performance.
(2)Weight and balance The weight of the repair may have a greater effect upon smaller aircraft as opposed to larger aircraft. The effects to be considered are related to overall aircraft centre of gravity and aircraft load distribution. Control surfaces are particularly sensitive to the changes due to the effect upon the stiffness, mass distribution and surface profile which may have an effect upon flutter characteristics and controllability.
(3)Systems Repairs to any elements of a system should be assessed for the effect intended on the operation of the complete system and for the effect on system redundancy. The consequence of a structural repair on an adjacent or remote system should also be considered as above (for example, airframe repair in the area of a static port).
(4)Operational characteristics Changes may include: stall characteristics, handling, performance and drag, vibration.
(5)Other characteristics: changes to load path and load sharing, fire protection/resistance, characteristics affecting the environmental compatibility of the product are characteristics affecting the compliance of the product with the applicable environmental protection requirements Note: Considerations for classifying repairs as ‘Major/Minor’ should not be limited to those listed above.
(c)Examples of ‘major’ repairs
(1)A repair that requires a permanent additional inspection to the maintenance programme, necessary to ensure the continued airworthiness of the product. Temporary repairs for which specific inspections are required prior to installation of a permanent repair do not necessarily need to be classified as ‘major’. Also, inspections and changes to inspection frequencies not required to ensure continued airworthiness do not cause the classification of the associated repair as ‘major’.
(2)A repair to life-limited or critical parts.
(3)A repair that introduces a change to the aircraft flight manual (AFM).