Airworthiness Directive 97-26-03
one-timeAirworthiness Directives; Eurocopter Deutschland GmbH (ECD) (Eurocopter Deutschland) Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters
What this AD requires
This amendment adopts a new airworthiness directive (AD) that is applicable to Eurocopter Deutschland Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 helicopters. This action requires visual inspections for cracks in the ribbed area of the main rotor mast flange (flange). This amendment is prompted by one report of cracks in a flange. The actions specified in this AD are intended to detect cracks in the flange, which, if not detected, could result in failure of the flange and subsequent loss of control of the helicopter.
Which aircraft AD 97-26-03 applies to
Requires visual inspection (5-power or higher magnification) of the main rotor mast flange ribbed area for cracks, before further flight and thereafter at intervals not exceeding 100 hours TIS, per Eurocopter Deutschland ASB-MBB-BK117-10-114 dated Aug 27, 1997; cracked masts replaced with an airworthy main rotor mast. Special flight permits will not be issued.
Whether AD 97-26-03 actually applies to your aircraft (by serial and installed parts) and whether it’s already complied with comes from that aircraft’s records.
How AD compliance is recorded
A valid compliance record (14 CFR 43.9) states:
Tailplate reads a tail number’s logbooks and matches every applicable AD — including this one — to its compliance evidence, with recurring next-due dates computed.
Look up a tail number →Read the full directive (Federal Register)Applicability is derived from the FAA directive corpus and is advisory, not a legal airworthiness determination. Compliance is established only from an aircraft’s actual records.