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: Upon receipt

Compliance : Required as indicated in DGAC AD T 1999-084-057(A)R1

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 33320922, fax: 420 2 20562270.

SUBJECT : Tail rotor hub pitch-change plate bearing.

Helicopters models :

-AS 355 E, F, F1, F2 and N (TAD 1999-084-057(A) R1)

fitted with tail rotor hub pitch-change plate bearing all part numbers

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 10 flying hours following the effective date of this Airworthiness Directive Revision 1,

check the rotation torque of the bearing, in accordance with the instructions described in

paragraph 2B(1) of the Service Bulletin referenced below, except if already carried out.

3.2. 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 :

3.2.l.within 10 flying hours (without exceeding 2 weeks) following the effective date of this

Airworthiness Directive Revision 1 :

a) for bearings which have not been controlled so far,

b) for bearings which were controlled 40 flying hours or 6 months ago, or more,

3.2.2. every 50 flying hours (without exceeding 6 months).

3.3. Before installing a pitch-change plate assembly or a tail rotor gear box assembly, held as spare,

on an aircraft, check the rotation torque and carry out the axial play, friction point and brinelling

check in accordance with the instructions described in paragraph 2B(1b) and 2B(2) of the ServiceBulletin 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.

4. REFERENCES : EUROCOPTER AS 350 Service Bulletin No 05-00-29 AS 355 Service Bulletin No 05-00-30Note : The instructions described in the Service Bulletins AS 350 No 05-00-29 and AS 355 No 05.00.30 will not be modified by their revisions 1 which will take into account the new deadlines.

5. EFFECTIVE DATE :

Original AD : MARCH 6,1999