AD/HS 125/178 Air Conditioning Fan Venturi Motor (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.

British Aerospace BAe 125 Series Aeroplanes

AD/HS 125/178 Air Conditioning - Fan Venturi Motor 5/2006

Applicability:	Raytheon Model DH.125, HS.125 and BH.125 series aeroplanes; Model BAe.125 Series 800A (C-29A and U-125), 800B, 1000A and 1000B aeroplanes; Model Hawker 800 (including variant U-125A) and 1000 aeroplanes all identified in Raytheon Service Bulletin SB 21-3669, dated December 2004.
Requirement:	1.    If not previously accomplished, carry out either of the flowing actions in accordance with the Accomplishment Instructions of Raytheon Service Bulletin SB 21-3669:
a.     Modify the existing fan venturi part number (P/N) 132322-2-1 by installing an improved motor, P/N 207640-34.
b.    Replace the existing fan venturi P/N 132322-2-1 with a new fan venturi P/N 132322-3-1.
Note 1:  Raytheon Service Bulletin SB 21-3669 refers to Honeywell Service Bulletin 132322-21-4041, Revision 2, dated 20 August 2004, as an additional source of service information for doing the modification.  The Raytheon service bulletin includes the Honeywell service bulletin.
2.    Fan venturi, P/N 132322-2-1, may not be installed on any aeroplane as a replacement part unless the fan venturi has been modified in accordance with Requirement 1.a. or unless the fan venturi has a new P/N in accordance with Requirement 1.b.
Later revisions of the above Raytheon SB, approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 2006-01-04, are considered acceptable for compliance with the equivalent Requirements of this Directive.
Note 2:  FAA AD 2006-01-04 Amdt 39-14443 refers.
Compliance:	For Requirement 1 - Within 1,200 hours time in service or 24 months after the effective date of this Directive, whichever occurs first.
For Requirement 2 - As of the effective date of this Directive.
This Airworthiness Directive becomes effective on 11 May 2006.

Background:

This Directive supersedes AD/HS 125/141 which applied to Raytheon aeroplanes identified above.  That Directive required a visual inspection to determine whether adequate clearance exists between the fan venturi motor casing and the adjacent equipment together with any necessary adjustments.  The Directive also required a visual inspection to detect signs of overheating, degradation of insulating materials, and ingestion of debris into the motor together with the replacement of discrepant parts with serviceable parts.

This new Directive instead requires that operators replace the fan venturi with a new or modified part.  This results from advice from the United States Federal Aviation Administration that the fan venturi overheated and produced smoke while the aeroplane was on the ground.  This Directive is issued to prevent heat and fire damage to equipment adjacent to the fan venturi, which could result in smoke in the cabin and/or burning equipment.

James Coyne
Delegate of the Civil Aviation Safety Authority

28 March 2006