AD/B737/321 Fuel Systems Airworthiness Limitations & Motor Operated valves (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 737 Series Aeroplanes

AD/B737/321 Fuel Systems Airworthiness Limitations & Motor Operated valves 6/2008

Applicability:

Model 737-600, -700, -700C, -800 and -900 series aeroplanes, as identified in Boeing Alert Service Bulletin (ASB) 737-28A1207, dated 15 February 2007.

Requirement:

1.    Inspect the following three motor-operated valves (MOVs) to determine whether an MOV with the affected part number, identified in the Accomplishment Instructions of ASB 737-28A1207, is installed:

a.     Left engine fuel shutoff (spar) valve,

b.    Right engine fuel shutoff (spar) valve, and

c.     Fuel crossfeed valve.

A review of aeroplane’s maintenance records is acceptable in lieu of this inspection if the part number of the part can be conclusively determined from that review.

2.    Accomplish all applicable related investigative and corrective actions in accordance with the Accomplishment Instructions of ASB 737-28A1207.

3. Revise the airworthiness limitations (AWL) section of the Instructions for Continued Airworthiness for the aeroplane by incorporating the information specified in Section F, ''AIRWORTHINESS LIMITATIONS–FUEL SYSTEM AWLs,'' of Boeing 737-600/700/700C/700IGW/800/900 MPD Document D626A001-CMR, Section 9, Revision November 2006 R1, into the Maintenance Planning Data (MPD) to incorporate AWL No 28-AWL-21 No. 28-AWL-22 and No. 28-AWL-24.

Accomplishing the revision in accordance with a later revision of the MPD document is an acceptable method of compliance if the revision is approved by the Manager, Seattle Aircraft Certification Office (ACO), United States Federal Aviation Administration (FAA).

Later revisions of the ASB 737-28A1207, approved by the FAA as an Alternate Method of Compliance (AMOC) to FAA AD 2008-06-03, are considered acceptable for compliance with the equivalent Requirements of this Directive.

Note:  FAA AD 2008-06-03 Amdt 39-15415 refers.
Compliance:	For Requirement 1 - Within 60 months after the effective date of this Directive.
For Requirement 2 - Before further flight after the Requirement 1 inspection/determination.
For Requirement 3 - Concurrent with Requirement 1.
This Airworthiness Directive becomes effective on 5 June 2008.
Background:	This Directive requires inspecting to determine if certain motor-operated shutoff valve actuators for the fuel tanks are installed together with related investigative and corrective actions as necessary.  The Directive also requires revising the AWL section of the Instructions for Continued Airworthiness.
The Directive results from a design review of the fuel tank systems and is issued to prevent electrical energy from lightning, hot shorts or fault current from entering the fuel tank through the MOV actuator shaft, which could result in fuel tank explosions and consequent loss of the aeroplane.

James Coyne
Delegate of the Civil Aviation Safety Authority

21 April 2008