AD/BAe 146/63 - Pitot-Static System - True Airspeed Computer No.1 (Cth)

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 146/63 Pitot-Static System - True Airspeed Computer No.1

10/96

Applicability: This Directive is applicable to BAe 146 Series 100, 100A, 200, 200A, 300 and 300A aeroplanes equipped with a True Airspeed (TAS) Computer No 1 installed in accordance with BAe Avro modification HCM40159B (SB.34-69-40159B) or HCM40297G and where a Dual Mode `S' Transponder has been installed in accordance with BAe Avro modification HCM30118B (SB.34-90-30118B) or HCM40277A (SB.34-91-40277A).

Note: The requirements of this Directive were incorporated prior to delivery on the following constructors number aeroplanes, if the modifications referenced above were also incorporated:

Series 100 and 100A - E1199 and subsequent.

Series 200 and 200A - E1270, E2178, E2188, E2196 and subsequent.

Series 300 and 300A - E3118, E3163, E3165, E3169, E3181, E3185, E3187, E3189, E3191 and subsequent.

Requirement: Install new pitot and static lines between the TAS 1 unit and the drain valve in accordance with either British Aerospace (Commercial Aircraft) Limited, Modification Service Bulletin SB.34-131-46041A dated 24 June 1991 or British Aerospace, Regional Aircraft Limited, Avro International Division, Modification Service Bulletin SB.34-131-46041A Revision 2 dated 2 July 1996.

Note: Both Service Bulletins have been classified as mandatory by the CAA(UK).

Compliance: Unless previously accomplished, then prior to 31 December 1996.

This directive becomes effective on 12 September 1996.

Background: The introduction of the Mode `S' transponder resulted in the TAS 1 unit being moved from its position on the avionics rack. This resulted in the pitot and static flexible hoses between the TAS 1 unit and the drain valve forming an unacceptable water trap. This Directive introduces new shorter flexible hoses designed to minimise the likelihood of water being trapped.