Airworthiness Directive · Amendment 39-18684 · Rotorcraft flight control
Airbus Helicopters Deutschland GmbH (Previously Eurocopter Deutschland GmbH) (Airbus Helicopters) Helicopters
This AD applies to Airbus Helicopters Model MBB-BK 117 C-2 helicopters with a lateral duplex trim actuator, part number (P/N) 418-00878-050 or P/N 418-00878-051, or a longitudinal duplex trim actuator, P/N 418-00878-000 or P/N 418-00878-001, installed, certificated in any category.
We are adopting a new airworthiness directive (AD) for Airbus Helicopters Model MBB-BK 117 C-2 helicopters with certain duplex trim actuators installed. This AD requires repetitively inspecting the lateral and longitudinal trim actuator output levers for correct torque of the nuts. This AD was prompted by a design review that indicated the attachment screws can become loose under certain circumstances. These actions are intended to prevent the loss of an attachment screw, which could result in movement of the output lever in an axial direction, contact of a bolt connecting the control rod to an output lever with the actuator housing, and subsequent loss of helicopter control.
You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.
(1) Within 300 hours time-in-service (TIS), apply a torque of 31.0 inch-pounds (3.5 Nm) to the self-locking nut (nut) on each lateral and longitudinal trim actuator output lever and apply a torque marking between the nut and the screw.
(2) Thereafter at intervals not to exceed 400 hours TIS, visually inspect each nut on each lateral and longitudinal trim actuator output lever to determine whether the torque is at 31.0 inch-pounds (3.5 Nm). If the torque is not at 31.0 inch-pounds, apply a torque of 31.0 inch-pounds (3.5 Nm), remove the previous torque marking, and apply a new torque marking between the nut and the screw.
(3) Do not install a lateral duplex trim actuator, part number (P/N) 418-00878-050 or P/N 418-00878-051, or a longitudinal duplex trim actuator, P/N 418-00878-000 or P/N 418-00878-001, on any helicopter unless each nut has been inspected for proper torque in accordance with the requirements of 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.
