AD/B747/378 Airworthiness Limitations and Inspections Fuel 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/B747/378 Airworthiness Limitations
and Inspections - Fuel Systems 7/2008

Applicability:	Model 747-400, -400D and -400F series aeroplanes, with an original certificate of airworthiness or original export certificate of airworthiness issued before 12 April 2006.
Note 1:  Aeroplanes with a original certificate of airworthiness or original export certificate of airworthiness issued on or after 12 April 2006, must be already in compliance with the airworthiness limitations specified in this Directive because those limitations were applicable as part of the airworthiness certification of those aeroplanes.
Requirement:	1.    Revise the approved maintenance program by incorporating the information in the subsections specified below; except that the initial inspections specified in Table 1 of this Directive must be done at the compliance times specified in Table 1.
a.     Subsection B, "AIRWORTHINESS LIMITATIONS (AWLs)-FUEL SYSTEMS," of Revision March 2008 of the MPD.
Note 2:  The term "Revision March 2008 of the MPD," as used in this Directive, means Boeing Temporary Revision (TR) 09-010, dated March 2008.  Boeing TR 09-010 is published as Section 9 of the Boeing 747-400 Maintenance Planning Data (MPD) Document, D621U400-9, Revision March 2008.
b.    Subsection C, "PAGE FORMAT: FUEL SYSTEMS AIRWORTHINESS LIMITATIONS," of Revision March 2008 of the MPD.
c.     Subsection D, "AIRWORTHINESS LIMITATIONS-FUEL SYSTEMS," AWLs No. 28-AWL-01 through No. 28-AWL-23 inclusive, of Revision March 2008 of the MPD.  As an optional action, AWLs No. 28-AWL-24 through No. 28-AWL-29 inclusive, as identified in Subsection D of Revision March 2008 of the MPD, also may be incorporated into the approved maintenance program.

Accomplishing the revision in accordance with a later revision of the MPD 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 in accordance with Subsection D of Revision March 2008 of the MPD.
Note 3:  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 4:  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 specialized 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 or loose 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-10	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 the MPD 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.
4.    For Model 747-400 series aeroplanes equipped with an auxiliary fuel tank - Revise the approved maintenance program by incorporating AWLs No. 28-AWL-30, No. 28-AWL-31 and No. 28-AWL-32 of Subsection D of Revision March 2008 of the MPD.
Accomplishing the Requirement 4 revision in accordance with a later revision of the MPD 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 4 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 the MPD 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 2008-10-06.
Actions accomplished before the effective date of this Directive in accordance with any revision to Section 9 of the Boeing 747-400 MPD Document, D621U400-9, listed in Table 2 are acceptable for compliance against the corresponding elements of Requirements 1, 2 and 3.

Table 2
Revision 23, dated March 2006 Revision 24, dated June 2006 Revision November 2006	Revision December 2006 Revision December 2006 R1 Revision May 2007	Revision October 2007 Revision November 2007
Note 5:  FAA AD 2008-10-06 Amdt 39-15512 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.
For Requirement 4 - Before 16 December 2008.
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

22 May 2008