AD/HS 125/176 Cockpit Ventilation and Avionics Cooling System Blowers (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 125/176 Cockpit Ventilation and Avionics
Cooling System Blowers 10/2005

Applicability:	Raytheon Model HS.125 series 700A aeroplanes, BAe.125 series 800A aeroplanes, and Model Hawker 800 and Hawker 800XP aeroplanes, equipped with Brailsford TBL-2.5 blowers, as identified in Raytheon Service Bulletin SB 24-3272, Revision 1, dated October 2000.
Requirement:	1.    If not accomplished previously, inspect the aeroplane in accordance with the Accomplishment Instructions of Raytheon SB 24-3272, Revision 1 to determine the current rating of the circuit breakers of certain cockpit ventilation and avionics cooling system blowers.
2.    If, as a result of the Requirement 1 inspection, incorrect circuit breakers are found to be installed replace the circuit breakers and modify the blower wiring, as applicable, in accordance with the Accomplishment Instructions of Raytheon SB 24-3272, Revision 1.
Note:  FAA AD 2005-16-02 Amdt 39-14207 refers.
Compliance:	For Requirement 1 - Within 600 hours time in service or six months after the effective date of this Directive, whichever occurs first.
For Requirement 2 - Before further flight, after completing the Requirement 1 inspection.
This Airworthiness Directive becomes effective on 29 September 2005.
Background:	This Directive requires an inspection to determine the current rating of the circuit breakers of certain cockpit ventilation and avionics cooling system blowers and, if necessary, the replacement of the circuit breakers and modification of the blower wiring, as applicable.

Actions required by this Directive are intended to prevent smoke and fumes in the cockpit in the event that a blower motor seizes and overheats due to excessive current draw.

James Coyne
Delegate of the Civil Aviation Safety Authority

18 August 2005