Airworthiness Directive · Amendment 39-14758 · Eurocopter Model AS350B, B1, B2, B3, BA, D, and AS355E Helicopters
Eurocopter Model AS350B, B1, B2, B3, BA, D, and AS355E Helicopters
Model AS350B, B1, B2, B3, BA, D, and AS355E helicopters, with a main servo control (MSC), all part numbers, installed, on which the tightening torque of the attachment nut that secures the upper ball end has been increased by following MOD 073191 or MET Work Card 67.30.00.402 since Revision 04-06 for the AS350 models and since Revision 04-08 for the AS355 models, but not modified per MOD 073343, certificated in any category.
This amendment adopts a new airworthiness directive (AD) for the specified Eurocopter helicopters. This action requires, within 10 hours time-in-service (TIS), inspecting the tapered housing of each main servo-control (MSC) for a crack. If no crack is found, this AD requires, before further flight, retorquing the upper ball-end attachment nut of the MSC. If a crack is found, this AD requires, before further flight, replacing the MSC with an airworthy MSC. This amendment is prompted by the discovery of cracks in the tapered housings of MSCs. The actions specified in this AD are intended to detect a crack in the MSC tapered housing and to prevent loss of the attachment of the MSC to the upper attachment yoke, loss of the main rotor control, and subsequent loss of control of the helicopter.
Required as indicated, unless accomplished previously.
To detect a crack in the MSC tapered housing and to prevent loss of the attachment of the MSC to the upper attachment yoke, loss of main rotor control, and subsequent loss of control of the helicopter, do the following:
(a) Within 10 hours time-in-service (TIS):
(1) Disconnect each MSC from the servo-control distributor and the upper attachment yoke.
(2) Cut the safety wire and remove it from the upper ball end of the attachment nut.
(3) Loosen attachment nut “a” shown in Figure 1 of this AD and lift the positioning lock washer under the attachment nut so the edge below the lock washer at the top of the tapered housing is visible around the entire periphery.
(4) Visually inspect each MSC tapered housing for a crack using a 10-power or higher magnifying glass paying particular attention to area “L” and to the edge of the tapered housing located under the lock washer under attachment nut “a” as depicted in Figure 1 of this AD.
(5) Do not modify the length of the visible section of the upper ball end of the MSC.
Note 1: MET Work Card 67.30.00.402, paragraph 5.2, provides information concerning the positioning of the upper ball end of the MSC.
(b) If you do not find a crack, before further flight:
(1) Adjust the tightening torque on the attachment nut that secures the upper ball end of the MSC to between 177-199 in-lbs (2-2.25 decanewton meters (daN·m)).
(2) Install safety wire and apply sealant to the upper ball end by running a sealant bead on the attachment per the applicable maintenance work card(s).
(3) Reattach the MSC to the servo control distributor and the upper attachment yoke.
(c) If you find any crack (oblique, horizontal, or vertical), before further flight, replace the MSC with an airworthy MSC and adjust the tightening torque of the attachment nut to between 177-199 in-lb (2-2.25 daN·m)).
Note 2: Eurocopter ASBs 05.00.51 and 05.00.48 dated February 27, 2006, pertain to the subject of this AD.
Note 3: This AD differs from the European ASBs and the EASA AD in that we do not permit flight with known cracks in the MSC tapered housing.
(d) Adjusting the tightening torque on the upper ball-end attachment nut of a non-cracked MSC or replacing a cracked MSC with an airworthy MSC with 177-199 in-lb (2-2.25 daN·m) tightening torque applied to the upper ball-end attachment nut is terminating action for the requirements of this AD.
(e) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Contact the Manager, Safety Management Group, Rotorcraft Directorate, FAA, ATTN: Uday Garadi, Aviation Safety Engineer, Regulations and Guidance Group, Fort Worth, Texas 76193-0110, telephone (817) 222-5123, fax (817) 222-5961, for information about previously approved alternative methods of compliance.
(f) Special flight permits will not be issued.
(g) This amendment becomes effective on September 27, 2006.
Note 4: The subject of this AD is addressed in European Aviation Safety Agency Emergency AD No. 2006-0055-E, dated March 1, 2006.
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.
Aircraft
