AD/SF340/78 - Landing Gear Electrical Circuit Breaker (Cth)

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES

SAAB SF340 Series Aeroplanes

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 39.1 (1) of CAR 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.

AD/SF340/78 Landing Gear Electrical Circuit Breaker 5/2000

Applicability: Model SF340A aeroplanes, serial numbers (S/N) 004 through 159 inclusive and Model 340B aeroplanes, S/N 160 through 459 inclusive, except 342, 379, 395, 409, 431 and 455.

Requirement: Install a new electrical circuit breaker and related wiring in accordance with SAAB Aircraft AB Mandatory Service Bulletin SAAB 340-32-120 dated 25 February 2000.

Note: LFV AD 1-155 refers.

Compliance: Within six months from the effective date of this Directive.

This Airworthiness Directive becomes effective on 18 May 2000.

Background: The Swedish Civil Aviation Administration advised that a number of occurrences have been reported of emergency extension of the landing gears being necessary due to a popped circuit breaker which it was not possible to reset. This circuit breaker is also common to the 'Weight on Wheels' and 'Landing Gear Locked Down' signals to other systems such 'Nose Wheel Steering' and 'Flight Idle Stop'. Not being able to reset the circuit breaker therefore causes failure of the Nose Wheel Steering system which results in reduced capability to steer the aircraft on the ground.