AD/AS 355/49 - Single-Pole Circuit Breakers
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
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Eurocopter AS 355 (Twin Ecureuil) Series Helicopters
AD/AS 355/49 Single-Pole Circuit Breakers 3/99
Applicability: Model AS 355 helicopters, versions E, F, F1, F2 and N equipped with the following single-pole circuit breakers manufactured by Crouzet:
| Location | Rating | Part Number |
|---|---|---|
| Emergency Flotation Gear Optional Installation | 5 Amp | 84 400 032 |
| 10 Amp | 84 400 034 | |
| Other Optional Installations | 1 Amp | 84 400 028 |
| 3 Amp | 84 400 031 | |
| 7.5 Amp | 84 400 033 | |
| 15 Amp | 84 400 035 | |
| 20 Amp | 84 400 036 |
Two types of Crouzet circuit breakers may have been delivered under Eurocopter Part Number (P/N) 704A36-6120-XXX (X indicates any digit). These circuit breakers are either P/N 84 400 XXX or SP4696-XX. This Directive is only applicable to P/N 84 400 XXX circuit breakers.
Note 1: The circuit breakers are known to be installed on helicopters delivered between 24 April 1995 and 31 August 1996. The circuit breakers may also be installed on helicopters delivered prior to 24 April 1995 or after 31 August 1996 if circuit breakers have been replaced on optional installations since 24 April 1995 or if an optional installation was fitted between 24 April 1995 and 31 August 1996.
Requirement: 1. Check the functioning of all circuit breakers, listed in the above table, that are fitted to installations listed in paragraph 1D1 of Eurocopter AS 355 Mandatory Service Bulletin (SB) 01.00.44 date code 98-47.
2. Apply the procedures detailed in paragraph 2B of the SB to all the circuit breakers for the remaining installations.
3. Test each circuit breaker held as spares that has a part number listed in this airworthiness directive by applying a torque load and checking the circuit breaker in accordance with the directions given in paragraphs 2B(1) and 2B(2) of the SB.
4. The use of circuit breakers bearing the part numbers listed in this Airworthiness Directive is prohibited.
Note: DCAG AD 98-510-055(A) refers.
Compliance: 1. Within 200 hours time in service but no later than 26 June 1999.
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
2. Prior to 1 January 2000.
3. Prior to installation.
4. From 31 December 1999.
This Airworthiness Directive becomes effective on 25 March 1999.
Background: This AD is issued to check for any loss of electrical continuity for single-pole circuit breakers bearing the part numbers listed. During testing by the OEM a loss of electrical continuity was discovered between the terminals of the circuit breaker in the engaged position. This loss was found to be due to deterioration of the circuit breaker operation brought about by excessive torque loading during installation.