Document ID: chunk:federal_register_of_legislation:F2006B03178:body:0:p3
Version: federal_register_of_legislation:F2006B03178
Segment Type: other
Provision Reference: 
Character Range: 5928–8852

may be selected ON and all CWT fuel may be used.

                    If a centre wing tank pump fails with fuel in the centre tank, accomplish the FUEL OVRD CTR L, R non- normal procedure.

                If the main tanks are not full, the zero fuel gross weight of the aeroplane plus the weight of CWT tank fuel may exceed the maximum zero fuel gross weight by up to 7,000 pounds (3,200 kilograms) for takeoff, climb, cruise, descent, and landing, provided that the effects of balance (CG) have been considered.

                When defueling any fuel tanks, the Fuel Pump Low Pressure indication lights must be monitored and the fuel pumps positioned to OFF at the first indication of fuel pump low pressure. Defueling with passengers on board is prohibited.

           The limitations contained in this Directive supersede any conflicting basic Aircraft Flight Manual limitations.

           Accomplishment of Requirement 2 of AD/B747/280 is acceptable for compliance with the requirements this Directive. This Directive does not require that those actions be repeated unless the terminating actions specified in Requirements 4, 6 and 7 of AD/B747/280 have been accomplished.

           Accomplishment of the terminating actions specified in Requirement 4, 6 and 7 of AD/B747/280, does not allow removal of the AFM revisions required by this Directive.

           Note: FAA Emergency AD 2002-24-51 and AD2002-24-52 refer.

 Compliance: Before 29 November 2002.

           This Airworthiness Directive becomes effective on 26 November 2002.

           Background: The United States Federal Aviation Administration has received reports indicating that two fuel tank pumps from different Model 747 series aeroplanes showed evidence of extreme localized overheating of parts in the priming and vapour pump section of the fuel pump. The priming and vapour pump section of the pump is open to the fuel tank via the pump inlet line and the vapour vent of the pump. The cause of this overheating is believed to be friction between the pump parts; however, the specific cause of the friction is unknown at this time.

           Overheating of the parts in the priming and vapour pump section of the fuel pump provides an ignition source in the fuel tank during dry running of the pump, which could result in fire/explosion of the fuel tank.

           This Directive requires revision of the AFM to require the flight crew to maintain certain minimum fuel levels in the centre fuel tanks, together with a prohibition of the use of the horizontal stabilizer fuel tank (for Model 747-400 series aeroplanes) and certain centre auxiliary fuel tanks (on Model 747 series aeroplanes). These procedures specify crew monitoring of fuel levels and shutoff of centre fuel tank pumps at specified levels that ensure the pump inlet remains covered during pump operation. Covering the pump inlet prevents fuel vapours from coming