COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Boeing 727 Series Aeroplanes
AD/B727/161
Amdt 1
Fuel Boost Pump Wiring Conduits 7/99 TX
Applicability: All Model 727 series aeroplanes.
Requirement: 1. Perform a boost pump dry bay inspection in accordance with steps 1 through 4 of Boeing All Operator Message (AOM) M-7200-99-04035 dated 21 May 1999.
2. If, during the Requirement 1 dry bay inspections, evidence of a fuel leak or a strong scent of fuel is detected proceed in accordance with step 5 of Boeing AOM M-7200-99-04035 dated 21 May 1999.
3. Verify correct operation of the boost pump electrical circuits by performing step 6 of Boeing AOM M-7200-99-04035 dated 21 May 1999.
Note 1: For aeroplanes on which the actions specified in step 5-E-<3> of the AOM were accomplished, ensure that the fuel tank in which the conduit was replaced is refuelled prior to accomplishing Requirement 3.
4. Perform a detailed visual inspection of the in-tank fuel boost pump wire bundles and install sleeving over the wire bundles. Both actions are to be accomplished in accordance with Boeing Alert Service Bulletin (ASB) 727-28A0126 dated
24 May 1999.
Note 2: For the purposes of this Directive, a detailed visual inspection is defined as an intensive visual examination of a specific structural area, system, installation or assembly to detect damage, failure fatigue or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the person performing the inspection. Inspection aids such as mirrors, magnifying lenses etc may be used. Surface cleaning and elaborate access procedures may be required.
Note 3: Installation of the sleeving over the wire bundles (Requirement 4) may be deferred for 18 months or 6 000 hours TIS, whichever occurs first, after accomplishment of the Requirement 4 visual inspection and any necessary rectification action under Requirement 5; provided that another detailed visual inspection and any necessary rectification is carried out immediately prior to installation of the sleeving.
5. If, during the requirement 4 inspection, any discrepancies or anomalies are found they are to be rectified in accordance with ASB 727-28A0126.
Note 4: FAA Telegraphic AD 99-12-52 refers.
Compliance: 1. For aeroplanes with:
- 50 000 or more total hours time in service (TIS) at the effective date of the original issue of this Directive - remains unchanged as ‘within five days after 26 May 1999’.
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
b. Less than 50 000 total hours TIS at the effective date of the original issue of this Directive - remains unchanged as ‘either, prior to the accumulation of 30 000 total hours TIS or within ten days after 26 May 1999, which ever occurs later’.
2. Prior to further flight after the Requirement 1 inspections.
3. Immediately following Requirement 1, if no fuel leakage was evident; or immediately following completion of Requirement 2, if fuel leakage was detected.
4. For aeroplanes with:
- 50 000 or more total hours TIS at the effective date of this amendment - within 20 days after the effective date of this amendment and thereafter at intervals not to exceed 30 000 hours TIS.
b. Less than 50 000 total hours TIS but more than 30 000 total hours TIS as of the effective date of this amendment - within 30 days after the effective date of this amendment and thereafter at intervals not to exceed 30 000 hours TIS.
c. 30 000 or less total hours TIS at the effective date of this amendment - within 90 days after the effective date of this amendment and thereafter at intervals not to exceed 30 000 hours TIS.
5. Prior to further flight after the Requirement 4 inspection. This Amendment becomes effective on 2 June 1999.
Background: The FAA received reports of severe wear of the in-tank fuel boost pump wiring and arc through of the surrounding conduit on two model 727 series aeroplanes that have accumulated in excess of 50 000 total hours TIS.
The wear and arc through have been attributed to chafing between the in-tank fuel boost pump wiring and the wall of the surrounding conduit, exposing the electrical conductor and placing it in contact with the aluminium wall of the conduit. This condition has resulted in arc through of the conduit wall and presents an ignition source inside the fuel tank. The resultant hole in the conduit can also provide a path for fuel to leak from the fuel tank.
The original issue of this Directive required an inspection for fuel leaks and, if necessary, replacement of the conduit. This amendment introduces an additional inspection and, if necessary, replacement of the boost pump wire bundles. The installation of protective sleeving over the wire bundles is also required.
The original issue of this Airworthiness Directive became effective on 26 May 1999.