COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES British Aerospace BAe 146 Series Aeroplanes AD/BAe 146/74 Powerplant Firewire Responder Units 4/99 DM Applicability: All BAe 146 100, 200, 300 Series aeroplanes and all Avro 146-RJ70, 85, 100 Series aeroplanes; without modification HCM01638A or British Aerospace Regional Aircraft BAe 146 Service Bulletin (SB) 26-44-01638A incorporated. Requirement: 1. Inspect fuel pipe Part Number (P/N) 2-193-940-02 for chafing caused by the engine firewire responder unit(s) in accordance with BAe 146 SB.26-44 dated 25 February 1999. Note: This Service Bulletin has been classified as mandatory by the CAA(UK). Compliance: 1. Prior to 1 April 1999 and thereafter at each aircraft 'C' check, until BAe 146 SB.26-44-01638A is incorporated. This Airworthiness Directive becomes effective on 17 March 1999. Background: Operators have reported incidences of damage to the fuel feed pipe P/N 2-193-940-02 caused by movement of the firewire responder unit(s) leading to contact between the responder connector backshell clamp and the adjacent fuel pipe. This Directive requires repetitive inspection of the area until optional terminating action is carried out.