Airworthiness Directive · Amendment 39-17558 · Main rotor control
Eurocopter Deutschland GmbH (ECD) Helicopters
This AD applies to Model MBB-BK 117 C-2 helicopters, certificated in any category.
We are adopting a new airworthiness directive (AD) for ECD Model MBB-BK 117 C-2 helicopters. This AD requires inspecting the rigging of the power-boosted control system and, if there is a nonparallel gap between the rigging wedges and the inner sleeves, performing a rigging procedure. This AD was prompted by the discovery, during rigging of the main rotor controls, of movement of the longitudinal main rotor actuator piston after shut-down of the external pump drive. Such movement could cause incorrect rigging results. The actions of this AD are intended to prevent incorrect rigging results, which could impair freedom of movement of the upper controls and subsequent reduced control of the helicopter.
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.
Within 300 hours time-in-service:
(1) Inspect the rigging of the power-boosted control system, referencing Figure 1 of Eurocopter Alert Service Bulletin ASB MBB BK117 C-2-67A-012, Revision 0, dated September 20, 2010 (ASB). Ensure the piston of the longitudinal actuator (right-hand side) is held in the fully extended position and the piston of the lateral actuator (left-hand side) is held in the fully retracted position against the mechanical stop. Also, ensure the gauge block is clamped between the sliding sleeve and the support tube.
(2) Insert the rigging wedges with the 25.4 degree (item 8 of Figure 1 of the ASB) and 19.5 degree (item 7 of Figure 1 of the ASB) markings in the “A” side of the guide grooves of the rigging device (item 3 of Figure 1 of the ASB).
(3) If the gap between the rigging wedges (items 7 and 8 of Figure 1 of the ASB) and the inner sleeves (item 9 of Figure 1 of the ASB) is closed, the rigging is correct.
(4) If there is a nonparallel gap between the rigging wedges (items 7 and 8 of Figure 1 of the ASB) and the inner sleeves (item 9 of Figure 1 of the ASB), the rigging is not correct. Perform a rigging procedure.
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.
