AD/DHC-8/113 Fuel & Hydraulic Tubes Chafing (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.

Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes

AD/DHC-8/113 Fuel & Hydraulic Tubes Chafing 4/2006

Applicability:

Bombardier Inc. DHC-8 Series 400 aircraft serial numbers 4003 through 4089.

Requirement:

1.    For aircraft without Bombardier Systems Drawings SYD 84-28-002, Issue 1, or later approved revisions, and SYD 84-29-006, Issue 1, or later approved revisions incorporated; or

For aircraft without Modsum 4-184079 and Modsum 4-184081 incorporated:

Install Bombardier Modsum 4-113438 (modified fairlead plate assemblies). Bombardier Service Bulletin (SB) 84-54-09, dated 23 January 2004, or later revisions approved by Transport Canada.

2.    For aircraft with Bombardier Systems Drawings SYD 84-28-002, Issue 1, or later approved revisions, and SYD 84-29-006, Issue 1, or later approved revisions incorporated; or

For aircraft with Modsum 4-184079 and Modsum 4-184081 incorporated;

Install Bombardier Modsum 4-113438 (modified fairlead plate assemblies).  Bombardier (SB) 84-54-09, or later revisions approved by Transport Canada.

Note:  Transport Canada AD CF-2004-07 refers.

Compliance:

1.    Within 500 hours time in service after the effective date of this directive.

2.    Within 4,000 hours time in service  after the effective date of this directive:

This Airworthiness Directive becomes effective on 13 April 2006.

Background:

Service difficulty reports indicate there is a potential for chafing of fuel and hydraulic tubes with the fairlead plate where the tubes pass through the firewall.  Titanium plates attached to the fairleads have close tolerance holes to provide isolation between fire zones.  If the tubes are not centred in the fairlead plate, nacelle flexing can cause a fouling condition, which may cause chafing of the tubes, leading to leakage of fluid creating an unsafe condition.

Bombardier Inc. has issued System Drawings SYD 84-28-002 (for the fuel tubes), and SYD 84 29 006 (for the hydraulic tubes), to provide temporary rework instructions (to enlarge the tolerance holes) for the fairlead plates, in order to avoid chafing with the tubes which pass through the fairlead plates.  Production rework Modsum 4-184079 (for the hydraulic tubes) and Modsum 4-184081 (for the fuel tubes) were issued to introduce the intent of SYDs 84-28-002 and 84-29-006 for production aircraft.  In addition, Bombardier Inc. Service Bulletin (SB) 84-54-09 was issued to introduce modified fairlead plate assemblies to rectify the fuel and hydraulic tubes chafing problem.

Jayaprakashan Ambali
Delegate of the Civil Aviation Safety Authority

21 February 2006