FAA Counsel: Only Airworthiness Limitations Section and ADs Are Mandatory in Manufacturer Maintenance Manuals for Part 91 Aircraft
Why It MattersOperators and maintenance providers working under Part 91 must separate the binding ALS and Airworthiness Directive items from accepted manual content, which shapes how maintenance programs and compliance records are built.
Under 14 CFR 21.50(b), the holder of a type certificate or supplemental type certificate for an aircraft, engine or propeller applied for after 28 January 1981 must furnish at least one complete set of Instructions for Continued Airworthiness (ICA) to the owner on delivery, or when the first standard airworthiness certificate is issued, whichever is later. The manufacturer writes the instructions and the FAA reviews them. Section 25.1529 requires transport-aircraft ICA to be prepared in accordance with Appendix H to Part 25 and to be acceptable to the FAA Administrator.
The binding portion is the Airworthiness Limitations Section (ALS), which paragraph H25.4 requires to be segregated and clearly distinguishable. For transport aeroplanes it lists mandatory replacement times, structural inspection intervals, fuel tank system limitations, wiring component replacement times, lightning protection limitations, certification maintenance requirements and a limit of validity. Section 21.31(c) makes the ALS part of the type design, 14 CFR 43.16 requires work to follow it, and 91.403(c) prohibits operating an aircraft unless its mandatory replacement times and inspection intervals are met.
The rest of the ICA is accepted rather than approved. In a 22 April 2011 legal interpretation concerning a Beech Baron, the FAA Office of the Chief Counsel stated that, as a general proposition, manufacturers' maintenance manuals, service bulletins and inspection programs are not FAA-approved and not mandatory for small aircraft under Part 91; Airworthiness Directives and the ALS are the exceptions. Section 43.13(a) nonetheless still requires maintenance to follow the current manufacturer's manual or other methods acceptable to the FAA.
