Applicability: AS 355 helicopters, versions E, F, F1, F2 and N, fitted with tail rotor hub pitch-change plate bearings, all part numbers.

Effective date: April 22, 1999

Compliance : Required as indicated in DGAC AD 1999-084-057(A)

Remarks: Where applicable, the requirements of this AD must be integrated into the Aircraft´s Logbook(s). Address inquiries concerning this AD to: Civil Aviation Authority, Airworthiness Division, Ruzyne Airport, 160 08 Prague 6, Czech Republic, tel: 420 2 324086, fax: 420 2 364112.

DGAC 1999-084-057(A)
February 24, 1999

This Airworthiness Directive is issued subsequent to some cases of deterioration of the tail rotor hub pitch-change plate bearing, which can lead to seizure of the bearing and loss of control of the aircraft.

3.1.Within 50 flying hours following the effective date of this Airworthiness Directive, check the rotational torque of the bearing once, in accordance with the instructions described in paragraph 2B(1) of EUROCOPTER AS 355 Service Bulletin No. 05.00.30 referenced below.

3.2. Every 100 flying hours, following the effective date of this Airworthiness Directive, carry out the axial play, friction point and brinelling check in accordance with the instructions described in paragraph 2B(2) of the Service Bulletin referenced below.

3.3. Before installing a pitch-change plate assembly or a tail rotor gear box assembly, held as spare, on an aircraft, check the rotational torque of the bearing in accordance with the instructions described in paragraph 2B(1.b) of the Service Bulletin referenced below.

3.4. Interpretation of results : 3.4.1. If the measured rotational load is greater than 300 grams, remove the pitch-change plate assembly from the aircraft, or do not install the pitch-change plate assembly or tail rotor gear box assembly, held as spare, on the aircraft.

3.4.2. If the rotational load is less than 300 grams, and if the measured axial play is greater than or equal to 0.4 mm, and/or friction points or brinelling are detected:

- Check the condition of the parts (excluding the pitch-change plate bearing) and replace them according to the criteria defined in paragraph 2B (3.b) of the Service Bulletin referenced below.

- Replace the pitch-change plate bearing with a bearing in airworthy condition.

Reference: EUROCOPTER AS 355 Service Bulletin No. 05.00.30