AD/J4100/25 Fuel Tank Bonding Leads and Fuel Pipe Clearances (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.

BAe Systems (Operations) Jetstream 4100 Series Aeroplanes

AD/J4100/25 Fuel Tank Bonding Leads and
Fuel Pipe Clearances 5/2008 DM

Applicability:	Jetstream 4100 series aeroplanes, all models, all serial numbers.
Requirement:	1.    Inspect the bonding leads between ribs 1 and 9, and between ribs 16 and 19, in the left (LH) and right (RH) wings in accordance with paragraph 2B(2) of BAE Systems (Operations) Ltd Service Bulletin (SB) J41-28-013 Revision 1 dated 10 January 2008.
2.    If, as a result of the Requirement 1 inspection, any defective bonding leads are found, replace the bonding leads with airworthy parts.
3.    Examine all fuel system pipe runs inside the LH and RH wings in accordance with paragraph 2B(3) of SB J41-28-013 Revision 1.
4.    If, as a result of the Requirement 3 examination, incorrect clearances are found, adjust the clearances to meet the requirements of the SB.
5.    Install additional electrical bonding of components within the LH and RH wings in accordance with paragraphs 2B(4) to 2B(15) of SB J41-28-013 Revision 1.
Later revisions of SB J41-28-013, approved by the European Aviation Safety Agency (EASA), are acceptable for compliance with the Requirements of this Directive.
Note:  EASA AD 2008-0040 refers.
Compliance:	For Requirements 1, 3 and 5 - At the next major inspection or wing tank access, or within 24 months after the effective date of this Directive, whichever occurs first.
For Requirements 2 and 4 - Before the next flight after the applicable inspection/examination.
This Airworthiness Directive becomes effective on 14 March 2008.

Background:

Following the assessment of fuel tank wiring installations required by SFAR 88 and equivalent JAA/EASA policy, BAE Systems identified two features in the Jetstream 4100 where the need for design changes was apparent.  One of these is addressed by SB J41-28-013 which introduces additional bonding leads between pipes, structure and various components to improve the electrical bond paths within the fuel tank areas.  This design change is identified by modification number JM41659.  Additionally, SB J41-28-013 provides instructions to inspect the existing bonding leads, to replace any defective leads and to examine all fuel system pipe runs in the wings to ensure appropriate clearances are maintained.

Insufficient or defective bonding in the fuel tank area, if not corrected, could lead to ignition of fuel vapours and subsequent fuel tank explosion.

For the reason stated above, this Directive requires the installation of additional bonding leads, inspection of existing bonding leads and all fuel system pipe runs in the wings together with follow-on corrective actions, as necessary.

David Punshon
Delegate of the Civil Aviation Safety Authority

5 March 2008