AD/HS 125/177 Hydraulic Over-Temperature Switch Fuse (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 125/177 Hydraulic Over-Temperature Switch Fuse 4/2006 DM

Applicability:	Raytheon Model Hawker 800XP aeroplanes, serial numbers 258541, 258556, and 258567 through 258713 inclusive.
Requirement:	1.    If not previously accomplished, carry out a general visual inspection to determine if a 20-amp fuse is installed in the hydraulic over-temperature switch electrical circuit on panel ZK in the rear equipment bay in accordance with the Accomplishment Instructions of Raytheon Service Bulletin SB 24-3724, dated May 2005.
2.    If, as a result of Requirement 1 inspection, a 20-amp fuse is installed, replace it with a 3-amp fuse in accordance with the Accomplishment Instructions of the SB 24-3724.
3.    If signs of damage are found contact the Raytheon Aircraft Company for applicable repair actions and carry out the specified repairs.
Note:  FAA AD 2006-02-03 Amdt 39-14455 refers.
Compliance:	For Requirement 1 - Within 50 flight hours or 30 days after the effective date of this Directive, whichever occurs first.
For Requirement 2 and 3 - Before further flight after the Requirement 1 inspection.
This Airworthiness Directive becomes effective on 24 February 2006.

Background: This Directive requires an inspection to determine if the correct fuse is installed in the hydraulic over-temperature switch electrical circuit on panel ZK in the rear equipment bay and, if necessary, the replacement of the existing fuse and the repair of any damage.  The Directive follows advice from the United Sates Federal Aviation Administration (FAA) regarding a report of the installation of an incorrect fuse in the over- temperature switch electrical circuit during aeroplane maintenance.  The Directive is issued to prevent possible heat damage to associated wiring and surrounding equipment, which could result in smoke or fire on the aeroplane, when the incorrectly rated fuse fails to blow.

James Coyne
Delegate of the Civil Aviation Safety Authority

6 February 2006