Proposed rule · 2026-23213

Airworthiness Directives; Airbus Helicopters Deutschland GmbH (AHD) Helicopters

The FAA proposes to adopt a new airworthiness directive (AD) for all Airbus Helicopters Deutschland GmbH (AHD) Model MBB-BK 117 C-1 and MBB-BK 117 C-2 helicopters with a certain air conditioning system installed in accordance with FAA Supplemental Type Certificate (STC) No. SR00601DE. This proposed AD was prompted by reports of corrosion on the condenser inlet duct, which caused the internal support wire helix to impinge the tail rotor (TR) drive shaft. This proposed AD would require repetitively inspecting the TR drive shaft; repetitively inspecting the exterior of the Air Comm Corporation (ACC) condenser duct assembly (duct assembly); repetitively inspecting (using a borescope) the interior of the ACC duct assembly; and depending on the results of these inspections, replacing certain parts. The FAA is proposing this AD to address the unsafe condition on these products.