AD/B747/379 Airworthiness Limitations & Inspections Fuel Tank Systems (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.

Boeing 747 Series Aeroplanes

AD/B747/379 Airworthiness Limitations &
Inspections - Fuel Tank Systems 7/2008

Applicability:	Model 747-100, 747-100B, 747- 100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR and 747SP series aeroplanes.
Requirement:	1.    Revise the approved maintenance program by incorporating the information in Section D, "AIRWORTHINESS LIMITATIONS-SYSTEMS," AWLs No. 28-AWL-01 through No. 28-AWL-19 inclusive, of Revision March 2008 of Document D6- 13747-CMR; except that the Requirement 2 initial inspections specified in Table 1 of this Directive must be done at the compliance times specified in that Table.
As an optional action, AWLs No. 28-AWL-20 through No. 28-AWL-23 inclusive, as identified in Section D of Revision March 2008 of Document D6-13747-CMR, also may be incorporated into the approved maintenance program.
Note 1:  The term "Revision March 2008 of Document D6-13747-CMR," as used in this AD, means Boeing 747-100/200/300/SP Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs), D6-13747-CMR, Revision March 2008.  (For the purposes of Revision March 2008 of Document D6-13747-CMR, the Model 747SR series aeroplane is basically a Model 747-100 series aeroplane with certain modifications to improve fatigue life.)
Accomplishing the revision in accordance with a later revision of Document D6-13747-CMR is an acceptable method of compliance if the revision is approved by the Manager, Seattle Aircraft Certification Office (ACO) of the United States Federal Aviation Administration (FAA).
2.    Carry out the inspections specified in Table 1.
Note 2:  For the purposes of this Directive, a detailed inspection is: "An intensive examination of a specific item, installation or assembly to detect damage, failure or irregularity.  Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate.  Inspection aids such as mirror, magnifying lenses, etc., may be necessary.  Surface cleaning and elaborate procedures may be required."

Note 3:  For the purposes of this Directive, a special detailed inspection is: "An intensive examination of a specific item, installation or assembly to detect damage, failure or irregularity.  The examination is likely to make extensive use of specialised inspection techniques and/or equipment.  Intricate cleaning and substantial access or disassembly procedure may be required."
Table 1 - Initial Inspections
AWL Number	Description	Compliance Time (Whichever occurs later)
		Threshold	Grace Period
28-AWL-01	A detailed inspection of external wires over the centre fuel tank for damaged clamps, wire chafing and wire bundles in contact with the surface of the centre fuel tank	Within 144 months since the date of issue of the original certificate of airworthiness or the date of issue of the original export certificate of airworthiness	Within 72 months after the effective date of this Directive
28-AWL-03	A special detailed inspection of the lightning shield to ground termination on the out-of-tank fuel quantity indicating system to verify functional integrity	Within 144 months since the date of issue of the original certificate of airworthiness or the date of issue of the original export certificate of airworthiness	Within 24 months after the effective date of this Directive
28-AWL-13	A special detailed inspection of the fault current bond of the fuelling shutoff valve actuator of the centre wing tank to verify electrical bond	Within 144 months since the date of issue of the original certificate of airworthiness or the date of issue of the original export certificate of airworthiness	Within 60 months after the effective date of this Directive
Accomplishing the inspections identified in Table 1 in accordance with a later revision of Document D6-13747-CMR is an acceptable method of compliance if the revision is approved by the Manager, Seattle ACO.

Accomplishing the inspections identified in Table 1 as part of an approved maintenance program before the applicable compliance time specified in Table 1 constitutes compliance with Requirements 2.
3.    Repair any discrepancy found during any of the Requirement 2 inspections in accordance with Section D of Revision March 2008 of Document D6-13747-CMR.
Accomplishing the Requirement 3 repairs in accordance with a later revision of Document D6-13747-CMR is an acceptable method of compliance if the revision is approved by the Manager, Seattle ACO.
After accomplishing the applicable actions specified in Requirements 1 to 3 inclusive, no alternative inspections, inspection intervals or Critical Design Configuration Control Limitations (CDCCL) may be used unless the inspections, intervals or CDCCLs are part of a later revision of the Revision March 2008 of Document D6-13747-CMR that is approved by the Manager, Seattle ACO; or unless the inspections, intervals or CDCCLs are approved as an alternate method of compliance (AMOC) to FAA AD 2008-10-07.
Actions accomplished before the effective date of this Directive in accordance with any revision to Boeing 747-100/200/300/SP Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs), D6-13747- CMR, listed in Table 2 are acceptable for compliance against the corresponding elements of Requirements 1, 2 and 3.
Table 2
Revision March 2006 Revision May 2006	Revision December 2006 Revision January 2007	Revision September 2007 Revision January 2008
Note 4:  FAA AD 2008-10-07 Amdt 39-15513 refers.
Compliance:	For Requirement 1 - Before 16 December 2008.
For Requirement 2 - At the compliance time specified in Table 1.
For Requirement 3 - Before further flight after the Requirement 2 inspections.
This Airworthiness Directive becomes effective on 3 July 2008.

Background: This Directive results from a design review of the fuel tank systems.  The Directive is issued to prevent the potential for ignition sources inside fuel tanks caused by latent failures, alterations, repairs or maintenance actions, which, in combination with flammable fuel vapours, could result in a fuel tank explosion and consequent loss of the aeroplane.

James Coyne
Delegate of the Civil Aviation Safety Authority

23 May 2008