Document ID: chunk:federal_register_of_legislation:F2011L01843:body:0:p1
Version: federal_register_of_legislation:F2011L01843
Segment Type: other
Provision Reference: 
Character Range: 0–2951

AIRWORTHINESS DIRECTIVE
On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/B737/152 and issues the following 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/B737/152 Amdt 1  Centre Fuel Tank - Limitations  18/2011

Applicability:  All Model 737 series aeroplanes.
Requirement:    Revise the Limitations Section of the Aircraft Flight Manual (AFM) to include the information detailed in FAA AD 2001-08-24 Amdt 39-12201.
Compliance:     Date remains unchanged to that detailed in the original issue of this Directive.

                Despite the new AD/B737/152 Amdt 1, an exclusion or an alternate method of compliance that was in force before the coming into effect of AD/B737/152 Amdt 1 continues to be in force.
                This Airworthiness Directive becomes effective on 30 September 2011.
Background:     On 3 March 2001, a Boeing Model 737-400 series airplane caught fire and burned while parked at a bay at the Don Muang International Airport, Bangkok, Thailand.  Although the accident investigation is ongoing and the probable cause of the accident has not been identified, the Government of Thailand, in conjunction with the United States National Transportation Safety Board, has determined that the centre tank exploded shortly after the main fuel tanks of the airplane were refuelled.  It appears that the centre tank fuel pumps were operating dry (no fuel passing through them) at the time of the explosion.

                This accident is similar to a 1990 centre tank explosion on a Boeing Model 737-300 airplane.  The ignition source of that explosion was never identified.  The centre tank fuel pumps were operating dry at the time of that explosion.

                Extended dry operation of the centre tank fuel pumps, which occurred prior to both incidents, is contrary to the manufacturer's procedures for safe operation of the fuel pumps.  Extended dry pump operation can result in overheating and excessive wear of the pump bearings and consequent contact between rotating and nonrotating parts of the pumps.  Both overheating of the bearings and contact between rotating and nonrotating parts have the potential to create an ignition source in the form of hot surfaces or sparks.  In addition, during dry operation of the pumps, ignition of vapour in a fuel pump can create a flame front that can