Summary
We propose to adopt a new airworthiness directive (AD) for MD Helicopters Inc. (MDHI) Model 369A, 369D, 369E, 369FF, 369HE, 369HM, 369HS, 500N, and 600N helicopters with a certain part-numbered main rotor blade attach pin (pin) installed. This proposed AD would require ensuring the life limit of the pin as listed in the Airworthiness Limitations section of aircraft maintenance records and Instructions for Continued Airworthiness (ICA). If the hours time-in-service (TIS) of a pin is unknown, or if a pin has exceeded its life limit, this proposed AD would require removing the affected pin from service. This proposed AD is prompted by a report from an operator who purchased pins that did not have life limit documentation. The proposed actions are intended to document the life limit to prevent a pin remaining in service beyond its fatigue life, which could result in failure of a pin, failure of a main rotor blade, and subsequent loss of control of the helicopter.