AD/B737/119 Amdt 3 Fuel Boost Pump Wiring (Cth)
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/B737/119 Amdt 2 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/B737/119 Amdt 3 | Fuel Boost Pump Wiring | 13/2006 |
Applicability: | All model 737-100 -200, -300, -400 and -500 series aeroplanes. |
Requirement: | 1. For all aeroplanes that have accumulated 50,000 or more hours total time in service as of the effective date of this Directive - Remove the fuel boost pump wiring from the in-tank conduit for the aft boost pumps in main tanks numbers 1 and 2 and perform a detailed visual inspection to detect damage of the wiring, in accordance with the procedures specified in Boeing Alert Service Bulletin (ASB) 737-28A1120 dated 24 April 1998, as revised by Notices of Status Change (NSC) 01 dated 7 May 1998, NSC 02 dated 8 May 1998 and NSC 03 dated |
| 2. For all aeroplanes that have accumulated less than 50,000 hours total time in service as of the effective date of this Directive - Remove the fuel boost pump wiring from the in-tank conduit for the aft boost pumps in main tanks numbers 1 and 2 and perform a detailed visual inspection to detect damage to the wiring, in accordance with the procedures specified in Boeing ASB 737-28A1120 dated | |
| 3. For all aeroplanes - Remove the fuel boost pump wiring from the in-tank conduit for the centre tank left and right boost pumps and perform a detailed visual inspection to detect damage to the wiring, in accordance with the procedures specified in Boeing ASB 737-28A1120 dated 24 April 1998, as revised by NSC 01 dated 7 May 1998, NSC 02 dated 8 May 1998 and NSC 03 dated 9 May 1998; ASB 737-28A1120 Revision 1 dated 28 May1998 or Revision 2 dated | |
| 4. For all aeroplanes - Remove the fuel boost pump wiring from the in-tank conduit for the aft boost pumps in main tanks numbers 1 and 2 and the centre tank left and right boost pumps and perform a detailed visual inspection to detect damage to the wiring, in accordance with the procedures specified in Boeing ASB |
| 5. If red, yellow, blue or green wire insulation cannot be seen through the outer jacket of the electrical cable during the Requirement 1, 2, 3 or 4 inspections, accomplish the following actions in accordance with the procedures specified in Boeing ASB 737-28A1120 dated 24 April 1998, as revised by NSC 01 dated |
| a. Install Teflon sleeving over the electrical cable and reinstall the cable, or |
| b. Reinstall the electrical cable without Teflon sleeving over the cable, or |
| c. Replace the electrical cable with new cable without Teflon sleeving. |
| 6. If Requirement 5.b is applied, repeat the Requirement 1, 2, 3 or 4 inspection, as applicable, and then install Teflon sleeving over the cable. |
| 7. If Requirement 5.c is applied, repeat the Requirement 1, 2, 3 or 4 inspection, as applicable, and then install Teflon sleeving over the cable. |
| 8. If red, yellow, blue or green wire insulation can be seen through the outer jacket of the electrical cable during the Requirement 1, 2, 3 or 4 inspections, but no evidence of electrical arcing is found, accomplish the following actions in accordance with the procedures specified in Boeing ASB 737-28A1120 dated 24 April 1998, as revised by NSC 01 dated 7 May 1998, NSC 02 dated |
| a. Replace the electrical cable with a new cable, install Teflon sleeving over the cable and reinstall the cable, or |
| b. Replace the electrical cable with a new cable without Teflon sleeving. |
| 9. If Requirement 8.b is applied, repeat the Requirement 1, 2, 3 or 4 inspection, as applicable, and then install Teflon sleeving over the cable. |
| 10. If any evidence of electrical arcing but no evidence of fuel leakage is found on the removed cable during the Requirement 1, 2, 3 or 4 inspections, accomplish the following actions in accordance with the procedures specified in Boeing ASB 737-28A1120 dated 24 April 1998, as revised by NSC 01 dated 7 May 1998, NSC 02 dated 8 May 1998 and NSC 03 dated 9 May 1998; ASB 737-28A1120 Revision 1 dated 28 May1998 or Revision 2 dated 26 November 1998: |
| a. Verify the integrity of the conduit in accordance with the instructions contained in either NSC 03; ASB 737-28A1120 Revision 1 or Revision 2 to the ASB, and |
| b. Accomplish either of the following actions: |
| (i) Replace the damaged electrical cable with a new cable, install Teflon sleeving over the cable and reinstall the cable, or |
| (ii) Replace the electrical cable with a new cable without Teflon sleeving. |
| 11. If Requirement 10.b.(ii) is applied, repeat the Requirement 1, 2, 3 or 4 inspection, as applicable, and then install Teflon sleeving over the cable. |
| 12. If any evidence of fuel is found on the removed cable during the Requirement 1, 2, 3 or 4 inspections, accomplish the following actions in accordance with the procedures specified in Boeing ASB 737-28A1120 dated 24 April 1998, as revised by NSC 01 dated 7 May 1998, NSC 02 dated 8 May 1998 and NSC 03 dated 9 May 1998; ASB 737-28A1120 Revision 1 dated 28 May1998 or Revision 2 dated 26 November 1998: |
| a. Replace the conduit section where the arcing was found, and |
| b. Accomplish either of the following actions: |
| (i) Replace the damaged electrical cable with a new cable, install Teflon sleeving over the cable and reinstall the cable, or |
| (ii) Replace the electrical cable with a new cable without Teflon sleeving. |
| 13. If Requirement 12.b.(ii) is applied, repeat the Requirement 1, 2, 3 or 4 inspection, as applicable, and then install Teflon sleeving over the cable. |
| 14. For Groups 1 and 2 aeroplanes, as identified in Boeing ASB 737-28A1120 dated 24 April 1998, replace the case ground wire with a new wire in accordance with Boeing ASB 737-28A1120 dated 24 April 1998, as revised by NSC 01 dated |
| 15. Deleted. |
| Later revisions of the above SBs, approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 99-21-15, are considered acceptable for compliance with the equivalent Requirements of this Directive. |
| Note: FAA AD 99-21-15 Amdt 39-11360 refers. |
Compliance: | For Requirement 1 - Remains unchanged as ‘Prior to further flight after the effective date of the original issue of this Directive’. |
| For Requirement 2 - Remains unchanged as ‘Prior to the accumulation of 40,000 hours total time in service or within 14 days from the effective date of the original issue of this Directive, whichever is later’. | |
| For Requirement 3: | |
| a. Model 737-300, 400 and 500 series aeroplanes - Remains unchanged as ‘Prior to the accumulation of 40,000 hours total time in service or within 14 days from the effective date of Amendment 1 of this Directive, whichever is later’. | |
| b. Model 737-100 and 200 series aeroplanes - Remains unchanged as ‘Prior to the accumulation of 40,000 hours total time in service or within 10 days from the effective date of Amendment 1 of this Directive, whichever is later’. | |
| c. All model aeroplanes - Remains unchanged as ‘Prior to the accumulation of 50,000 hours total time in service or within 5 days from the effective date of Amendment 1 of this Directive, whichever is later’. | |
| For Requirement 4 - Remains unchanged as ‘Prior to the accumulation of 30,000 hours total time in service or within 45 days from the effective date of Amendment 1 of this Directive, whichever is later and then at intervals not to exceed 30,000 hours time in service from the initial accomplishment of the inspection’. | |
| For Requirement 5 - Prior to further flight, immediately following the Requirement 1, 2, 3 or 4 inspection. | |
| For Requirement 6 - Within 500 hours time in service after the cable reinstallation. | |
| For Requirement 7 - Within 18 months or 6,000 hours time in service, which ever occurs first, after the cable replacement. | |
| For Requirement 8 - Prior to further flight, immediately following the Requirement 1, 2, 3 or 4 inspection. | |
| For Requirement 9 - Within 18 months or 6,000 hours time in service, which ever occurs first, after the cable replacement. | |
| For Requirement 10 - Prior to further flight, immediately following the Requirement 1, 2, 3 or 4 inspection. | |
| For Requirement 11 - Within 18 months or 6,000 hours time in service, which ever occurs first, after the cable replacement. |
| For Requirement 12 - Prior to further flight, immediately following the Requirement 1, 2, 3 or 4 inspection. | |
| For Requirement 13 - Within 18 months or 6,000 hours time in service, which ever occurs first, after the cable replacement. | |
| For Requirement 14 - Prior to further flight, immediately following the Requirement 1, 2, 3 or 4 inspection. | |
| This Amendment becomes effective on21 December 2006. | |
| Background | This amendment allows compliance in accordance with later revisions of certain service bulletins. |
| Amendment 2 introduced minor formatting changes, made the Requirement 4 inspection repetitive, which removed the optional Teflon sleeving terminating action, deleted Requirement 15 and added ASB Revisions to the requirement statements. | |
| Amendment 1 increased the range of affected aeroplanes and reduced some compliance times due to information obtained by the FAA since the issue of original telegraphic directives T98-10-51 and T98-11-51. | |
| The FAA received reports of severe wear of fuel boost pump wiring on two model 737-200 aeroplanes that had accumulated 54,000 and 67,000 hours total time in service. The cause of this wear was attributed to chafing between the in-tank fuel boost pump wiring and the surrounding conduit inside the fuel tank. If the outer sleeving and the insulation is worn off the 115 volt alternating current conductor wiring, electrical arcing between the conductor and conduit could occur resulting in puncture of the conduit. Electrical arcing could also provide an ignition source inside the fuel tanks. Puncture of the conduit may also provide a path for fuel to leak from the fuel tank. | |
| Actions required by this Directive are designed to detect and correct chafing between the fuel boost pump wiring and the surrounding conduit, therefore decreasing the likelihood of electrical arcing and consequent fire or explosion of the fuel tank. | |
| This Directive is considered interim action, additional inspections may be required beyond those specified in this directive, especially if inspections required by the FAA AD reveal damage in low hour aircraft. | |
| The original issue of this Directive became effective on 14 May 1998. | |
| Amendment 1 to this Directive became effective on 19 May 1998. |
| Amendment 2 to this Directive became effective on 23 March 2000. |
James Coyne
Delegate of the Civil Aviation Safety Authority
9 November 2006
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