AD/A109/63 Battery Bus Circuit Breaker (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Agusta A109 Series Helicopters

AD/A109/63 Battery Bus Circuit Breaker 9/2009 DM

Applicability:

A109E helicopters as follows:

-      all serial numbers (S/N) up to and including S/N 11077, if equipped with a kit part number (P/N) 109-0812-04-101, -103, -107 or -109, and

-      S/N 11078 to S/N 11758 inclusive, except S/N 11741, 11754 and 11757.

Requirement:

Modify the fuselage electrical installation P/N 109-0741-49 and the overhead panel electrical installation P/N 109-0741-55, installing the BATT BUS circuit breaker modification kit P/N 109-0824-73-101, in accordance with the instructions of Agusta Bollettino Tecnico 109EP-98 dated 22 June 2009 or later revision approved by the European Aviation Safety Agency (EASA).

Note:  EASA AD 2009-0137 refers.

Compliance:

Within 50 hours time in service after the effective date of this Directive but no later than 31 December 2009, whichever occurs first.

This Airworthiness Directive becomes effective on 7 July 2009.

Background:

Following a report of an electrical failure on one A109E helicopter, the investigations done by the Type Certificate holder have identified the inadequate functioning of the 35 Amperes (Amps) BATT BUS circuit breaker as the reason for the electrical failure.

To prevent this unsafe condition, Agusta has developed a BATT BUS circuit breaker modification kit, for the replacement of the 35 Amps circuit breaker with a 50 Amps circuit breaker and the replacement of the wires with oversized ones.

James Coyne
Delegate of the Civil Aviation Safety Authority

30 June 2009