Airworthiness Directive · Amendment 39-21680 · Main gearbox
Airbus Helicopters Deutschland GmbH (AHD) Helicopters
This AD applies to Airbus Helicopters Deutschland GmbH (AHD) Model MBB-BK 117 D-2 helicopters, certificated in any category, with an affected main gearbox or affected rotor mast nut as identified in Note 1 of European Aviation Safety Agency (now European Union Aviation Safety Agency) (EASA) AD 2017-0037, dated February 22, 2017 (EASA AD 2017-0037) installed.
The FAA is adopting a new airworthiness directive (AD) for Airbus Helicopters Deutschland GmbH (AHD) Model MBB-BK 117 D-2 helicopters. This AD was prompted by the discovery that certain parts that are approved for installation on multiple helicopter models are life limited parts when installed on Model MBB-BK 117 D-2 helicopters and some helicopter delivery documents excluded the life limit information. This AD requires determining the total hours time-in- service (TIS) of a certain part-numbered rotor mast nut and re- identifying a certain part-numbered rotor mast nut. This AD also requires establishing a life limit for a certain part-numbered rotor mast nut and helical gear support, and removing each part from service before reaching its life limit. Additionally, this AD requires replacing a certain part-numbered main gearbox (MGB) with a not affected MGB as specified in a European Aviation Safety Agency (now European Union Aviation Safety Agency) (EASA) AD, which is incorporated by reference (IBR). The FAA is issuing this AD to address the unsafe condition on these products.
Except as specified in paragraph (h) of this AD: Comply with all required actions and compliance times specified in, and in accordance with, EASA AD 2017-0037.
(1) Where EASA AD 2017-0037 refers to its effective date, this AD requires using the effective date of this AD.
(2) Where EASA AD 2017-0037 refers to flight hours (FH), this AD requires using hours time-in-service (TIS).
(3) Where paragraph (1) of EASA AD 2017-0037 requires determining the FH (total hours TIS) accumulated by the affected rotor mast nut since first installation on a helicopter, this AD requires removing the rotor mast nut from service before further flight if the total hours TIS cannot be determined.
(4) Where the service information referenced in Note 3 of EASA AD 2017-0037 specifies to use a vibrograph to mark the new part number, this AD requires using a vibro etch.
(5) Where paragraph (4) of EASA AD 2017-0037 requires replacing each affected rotor mast nut with a not affected rotor mast nut before exceeding 3,708 FH (total hours TIS) since first installation on a helicopter, this AD requires removing each affected rotor mast nut from service before accumulating 3,708 total hours TIS.
(6) Where paragraph (6) of EASA AD 2017-0037 requires replacing each part as identified in Table 2 of EASA AD 2017-0037 before exceeding the FH (total hours TIS) limit, this AD requires removing each part from service before exceeding the total hours TIS limit.
(7) Paragraph (7) of EASA AD 2017-0037 does not apply to this AD.
(8) The “Remarks” section of EASA AD 2017-0037 does not apply to this AD.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
