1-1. PURPOSE. This order prescribes how the Federal Aviation Administration (FAA) certifies restricted category aircraft. It applies to Aircraft Certification Service (AIR) personnel, Flight Standards Service personnel, anyone designated by the Administrator, and organizations associated with the certification process. This order details the responsibilities and procedures for certification of restricted category aircraft under Title 14 of the Code of Federal Regulations (14 CFR) § 21.25. It supplements Order 8110.4, Type Certification; Order 8120.2, Production Approvals and Certificate Management Procedures; and Order 8130.2, Airworthiness Certification of Aircraft and Related Products.
a. When the FAA certifies military-derived aircraft, the aircraft includes the airframe, engines, and propellers. The FAA does not award military engines and propellers stand-alone engine or propeller TCs.
4-12. LIFE-LIMITED PARTS. The applicant must determine and include all life limits and mandatory inspections in the airworthiness limitations section of the maintenance manuals. The FAA must approve the life limits and mandatory inspections. The existing limitations associated with the military usage can be applied to the special purpose, if the applicant shows such operation is equivalent to the military design specifications and how the military used the aircraft. The applicant must justify how the new special purpose usage conforms to the military loads and fatigue design objectives.
a. If the aircraft or engine load and fatigue spectra in the special purpose operating environment is not the same as that in the military, the applicant must develop the required data to substantiate and set appropriate airworthiness limitations. This would likely require the applicant to develop a fatigue or damage tolerance methodology.
b. The applicant should account for previous service history in terms of accumulated fatigue damage for each individual life-limited component, when determining fatigue lives, inspection requirements, or any other limitation for the special purpose operation.
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Inquiries were made of the major manufacturers, those whose products are routinely used
for fire suppression missions. The manufacturers were asked, did or does the fire fighting
mission, in and of itself have a significant influence in determining the fatigue lives of the
flight critical parts and/or components on your products? The following responses have
been paraphrased
Sikorsky’s engineering test pilot, with responsibility for their S-70 “Firehawk”
program, also stated that no special allowances had to be made relative to
the “fire fighting mission”.