Comment from British Antarctic Survey

Background: Although operating UK Overseas Territories registered aircraft (x4 DHC-6 and x1 DHC-7, regulated by UK ASSI and of Canadian type/design, the BAS (British Antarctic Survey) aircraft currently complies with received FAA AD’s to accord with previous (but recently narrowed in scope) UK ASSI AD compliance requirements. This due to the aircraft having US type design propellors, adopting several US originated STC’s, the common US/Canadian AD reciprocity, the transiting of BAS aircraft through US airspace, as current BAS policy, and also as best aviation practice. As such BAS has received and is in process of actioning FAA 2026-13-02, as per current BAS policy, and in the expectation of a reciprocal TCCA AD being issued. Comments:- Regarding FAA AD 2026-13-02 Docket No. FAA-2026-4659; Project identifier MCAI-2025-00826-A,T), British Antarctic Survey would like to comment as follows. 1-For AD 2026-13-02 para (c): ‘This AD applies to all transport and commuter category airplanes equipped with a radio altimeter’ Although the BAS aircraft types are commuter/transport type by design, they are not operated by BAS for commuter/commercial transport air operator/hire or reward purposes, and not under CFR 14 part 121. The aircraft are not equipped for the use of the landing aids/systems which Figure 3 to paragraph (h) restricts, however, the AD makes an AFM change necessary ‘to all transport and commuter category airplanes equipped with a radio altimeter’ whether the landing aids restricted in the AD are present on the aircraft or not. BAS considers that the applicability may benefit from clarification, if it still meets the FAA intent, possibly revised to applicable to ‘all transport and commuter category airplanes being operated commercially as passenger transport and equipped with the landing aids/systems defined in Figure 3 of paragraph (h) of the AD, and/or operating under CFR 14 part 121’. Appreciating that the size of the aircraft may be considered more relevant to the risk than the operating useage, which may be why the wider capture exists as it is now, and also that the intent may be to fully capture the possibility of an aircraft being inadvertently later modified to adopt the restricted landing aids. 2-For AD 2026-13-02 para (h): ‘This may be done by inserting a copy of figure 3 to paragraph (h) of this AD into the existing AFM’. BAS considers that an AFM change is not a method ordinarily open to an operator, being within the domain of a TCH, STC/LSTC holder, or through an approved design change that results in an AFM change or supplement. As such (as advised to FAA for previous similar AD’s), BAS is resorting to advising of the AD restrictions to crew by publishing a (NTA) Notice To Aircrew. This being an internal document that is readily and immediately actionable by BAS, is formal, controlled, and crew facing in nature. While the AD does state AD compliance ‘may’ be achieved by insertion in to AFM, BAS considers that the AD would benefit from further defining the possible compliance method(s), especially with many AFM’s being in electronic format, from ‘This may be done by inserting a copy of figure 3 to paragraph (h) of this AD into the existing AFM’ to ‘This may be done by inserting a copy of figure 3 to paragraph (h) of this AD into the existing AFM, or by operator publishing the limitations stated in AD Figure 3 to paragraph (h) by issuing Notice To Aircrew or using operators usual formally issued, controlled and distributed crew advisory process.’