COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Boeing 737 Series Aeroplanes
AD/B737/139 Wire Bundle Chafing - Electric Motor
Driven Hydraulic Pump
3/2000
Applicability: Model 737-300, -400, and -500 series aeroplanes, as listed in Boeing Alert Service (ASB) Bulletin 737-29A1076, Revision 1, dated 21 October 1999; and Model 737- 600, -700, and -800 series aeroplanes, as listed in Boeing ASB 737-29A1077, Revision 1, dated 21 October 1999.
Requirement: 1. For Model 737-300, -400, and -500 series aeroplanes:
- Without Boeing ASB 737-29A1076 dated 2 April 1998 accomplished - Perform a one-time detailed visual inspection of wire bundle W0334 and the hydraulic case drain and pressure hoses for the electric motor driven pump (EMDP) for hydraulic system "B" to detect any discrepancy (e.g. damage or chafing of wire bundle W0334 and the hydraulic case drain and pressure hoses; and incorrect separation between those components), in accordance with Part 1 of the Accomplishment Instructions of Boeing ASB 737-29A1076, Revision 1, dated 21 October 1999.
b. With Boeing ASB 737-29A1076 dated 2 April 1998 accomplished - Perform a one-time detailed visual inspection of wire bundle W0334 and the hydraulic case drain and pressure hoses for the EMDP for hydraulic system "B" to detect any discrepancy (e.g. damage or chafing of wire bundle W0334 and the hydraulic case drain and pressure hoses; and incorrect separation between those components), in accordance with Part 2 of the Accomplishment Instructions of Boeing 737-29A1076, Revision 1, dated 21 October 1999.
2. If any discrepancy is found, during the Requirement 1.a. inspection, perform corrective actions in accordance with Part 1 of the Accomplishment Instructions of ASB 737-29A1076, Revision 1.
3. If any discrepancy is found, during the Requirement 1.b. inspection, perform corrective actions in accordance with Part 2 of the Accomplishment Instructions of ASB 737-29A1076, Revision 1.
4. For Model 737-600, -700, and -800 series aeroplanes:
- Without Boeing ASB 737-29A1077 dated 4 March 1999 accomplished - Perform a one-time detailed visual inspection of wire bundle W5230 and the hydraulic case drain and pressure hoses for the EMDP for hydraulic system "B" to detect any discrepancy (e.g. damage or chafing of the W5230 wire bundle and the hydraulic case drain and pressure hoses; and incorrect separation between those components) in accordance with Part 1 of the Accomplishment Instructions of Boeing ASB 737-29A1077, Revision 1, dated 21 October 1999.
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
b. With Boeing ASB 737-29A1077, dated 4 March 1999 accomplished - Perform a one-time detailed visual inspection of wire bundle W5230 and the case drain and pressure hoses for the EMDP for hydraulic system "B" to detect any discrepancy (e.g. damage or chafing of the W5230 wire bundles and the hydraulic case drain and pressure hoses; and incorrect separation between those components), in accordance with Part 2 of Boeing ASB 737-29A1077, Revision 1, dated 21 October 1999.
5. If any discrepancy is found during the Requirement 4.a. inspection, perform corrective actions in accordance with Part 1 of the Accomplishment Instructions of the ASB 737-29A1077, Revision 1.
6. If any discrepancy is found during the Requirement 4.b. inspection, perform corrective actions in accordance with Part 2 of the Accomplishment Instructions of ASB 737-29A1077, Revision 1.
Note 1: For the purposes of this Directive, a detailed visual inspection is defined as: "An intensive examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate by the inspector. Inspection aids such as mirrors, magnifying lenses, etc. may be used. Surface cleaning and elaborate access procedures may be required."
Note 2: FAA AD 99-26-21 Amdt 39-11480 refers.
Compliance: For Requirement 1 - Within 90 days of the effective date of this Directive.
For Requirement 2 - Prior to further flight. For Requirement 3 - Prior to further flight.
For Requirement 4 - Within 90 days of the effective date of this Directive. For Requirement 5 - Prior to further flight.
For Requirement 6 - Prior to further flight.
This Airworthiness Directive becomes effective on 23 March 2000.
Background: The aircraft manufacturer has received report of the wire bundle to the Hydraulic System “B” EMDP being chafed. This Directive requires a one time inspection to detect discrepancies and, if necessary, correct the discrepancies. These actions are intended to prevent electrical arcing, with the subsequent risk of fire, being caused by chafing of the wire bundle.