AD/B737/150 - Fuel Quantity Indicating System - No. 2 Tank Wiring Harness

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Boeing 737 Series Aeroplanes

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 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.

AD/B737/150 Fuel Quantity Indicating System - No. 2

Tank Wiring Harness

Applicability: All Model 737-300, -400 and -500 series aeroplanes.

4/2001

Requirement: 1. Except as provided by Requirement 6 of this Directive, perform a one-time detailed visual inspection of the Fuel Quantity Indication System (FQIS) wiring and fuel tubing on the inboard side of the right wing rib wing buttock line (WBL) 227 and on the aft side of stringer No 13 to determine if clearance of 9.5mm (3/8 inch) or greater exists between the FQIS wire harness and the refuel tube and tube coupling, and to detect any loose or broken refuel tube clamp or bracket, or chafing of the FQIS wire harness, in accordance with Boeing Alert Service Bulletin (ASB) 737-28A1168, Revision 1, dated 11 January 2001.

Note 1: 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, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required."

2. If, during the Requirement 1 inspection, the clearance between the FQIS wire harness and the refuel tube is found to be less than 9.5mm (3/8 inch) readjust the refuel tube and relocate the bonding jumper or, if necessary, lockwire away from the wiring in accordance with the ASB.

3. If, during the Requirement 1 inspection, any loose or broken refuel tube clamp or bracket is found, replace the broken clamp with a new clamp; repair the broken bracket or replace the broken bracket with a new bracket; and secure the loose clamp or bracket; as applicable; in accordance with the ASB.

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

4. If any chafing of the FQIS wiring harness is found, replace the wire harness with a new wire harness or accomplish the applicable action(s) specified below, in accordance with the ASB.

For jacket damage only that is less than 25.4mm (1 inch) in length with no sign of abrasion to the wire insulation - Install a Teflon sleeve over the wiring.

b. For jacket damage or a harness with an exposed shield or conductor and the insulation of the other wire is not damaged (there can be no broken shield strands if the shield wire is damaged or no broken wire strands if the unshielded wire is damaged) - Install a Teflon sleeve over the wiring terminal and along the wire to the damaged area.

5. For wiring that was repaired in accordance with Requirement 4.a., repair the wire harness or replace the wire harness with a new wire harness.

6. For aeroplanes on which the modification per FAA AD 99-03-04, Amdt 39-11018 has been accomplished prior to the effective date of this Directive - Perform the actions specified in Requirement 1, and in Requirements 2 or 3 of this Directive.

Note 2: Repairs accomplished by splicing the wires in accordance with the procedure included in Boeing ASB 737-28A1168, dated 26 September 2000, prior to the effective date of this Directive, are considered acceptable for compliance with Requirements 1, 2 and 3 of this Directive.

7. Submit a report of inspection findings to Service Bulletin Engineering, Boeing Commercial Airplane Group, PO Box 3707, Mail Stop 2H-37, Seattle, Washington 98124-2207, USA, as follows:

For aeroplanes on which the Requirement 1 inspection is accomplished after the effective date of this Directive.

b. For aeroplanes on which the Requirement 1 inspection has been accomplished prior to the effective date of this Directive.

Note 3: FAA AD 2001-01-13 requires submission to the FAA of a compliance plan for this work. CASA does not require submission of such a plan. However, operator planning should note: the amount of work involved. the relatively short compliance period, and the difficulty to satisfy the requirements of an exclusion under CAR (1998) 39.4.

Note 4: FAA AD 2001-01-13 Amdt 39-12084 refers.

Compliance: For Requirement 1 - Within 6 months after the effective date of this Directive.

For Requirement 2 - Before further flight. For Requirement 3 - Before further flight. For Requirement 4 - Before further flight.

For Requirement 5 - At the next scheduled "C" Check, but no later than 15 months after the effective of this Directive.

For Requirement 6 - Within 18 months after the effective date of this Directive. For Requirement 7.a. - Within 10 days after performing the inspection.

For Requirement 7.b. - Within 10 days after the effective date of this Directive. This Airworthiness Directive becomes effective on 19 April 2001.

Background: This Directive requires, among other actions, a one-time detailed visual inspection of the FQIS wiring and fuel tubing to determine if clearance exists between the FQIS wire harness and the refuel tube and tube coupling, and to detect any loose or broken refuel tube clamp or bracket or chafing of the FQIS wire harness.

These actions are necessary to detect and correct chafing and to prevent electrical contact between the FQIS wiring and the surrounding structure, which, in conjunction with another wiring failure outside the fuel tank, could result in fire or explosion of the fuel tank.

Eugene Paul Holzapfel

Delegate of the Civil Aviation Safety Authority 8 March 2001

The above AD is notified in the Commonwealth of Australia Gazette on 21 March 2001.

Overview

The Boeing 737 Series Aeroplanes Airworthiness Directive 2001 (AD/B737/150) was enacted in 2001 under the Civil Aviation Regulations 1998 (CAR 1998) by the Civil Aviation Safety Authority (CASA). This Airworthiness Directive was introduced to address safety concerns related to the fuel quantity indicating system (FQIS) wiring and fuel tubing in Boeing 737-300, -400, and -500 series aeroplanes. The problem the directive aimed to address was the potential for chafing and electrical contact between the FQIS wiring and the surrounding structure, which could, in conjunction with other wiring failures outside the fuel tank, result in a fire or explosion of the fuel tank. The policy objective of this directive was to ensure the safe operation of these aeroplanes by mandating specific inspections and corrective actions on the FQIS wiring and fuel tubing to mitigate any potential hazards.

Scope and Application

The Boeing 737 Series Aeroplanes Airworthiness Directive (AD) applies specifically to all Model 737-300, -400, and -500 series aeroplanes. This directive is issued under subregulation 39.1 (1) of the Civil Aviation Regulations 1998 by the Civil Aviation Safety Authority (CASA) and mandates certain actions to address identified safety issues related to the Fuel Quantity Indicating System (FQIS) wiring and fuel tubing. The directive requires operators of these aircraft to perform a one-time detailed visual inspection of the FQIS wiring and fuel tubing to ensure proper clearance and detect any defects. Additionally, it mandates specific actions such as readjusting the refuel tube, replacing or repairing clamps or brackets, and replacing the wire harness if necessary. Compliance with these requirements is time-bound, with different deadlines for various actions, ranging from within 6 months of the directive's effective date to within 15 months for scheduled maintenance checks. Operators must also submit inspection reports to Boeing Commercial Airplane Group within specific timeframes. This directive does not require a compliance plan submission to CASA, but operators are advised to consider the workload and compliance period when planning. The directive is applicable nationally within the Commonwealth of Australia and is published in the Commonwealth of Australia Gazette.

Key Provisions

The Airworthiness Directive (AD) issued under the Civil Aviation Regulations 1998 (CAR 1998) pertains specifically to Boeing 737-300, -400, and -500 series aeroplanes. The directive mandates a one-time detailed visual inspection of the Fuel Quantity Indication System (FQIS) wiring and fuel tubing to ensure there is at least 9.5mm (3/8 inch) clearance between the FQIS wire harness and the refuel tube and tube coupling. This inspection is designed to detect any loose or broken refuel tube clamps or brackets and any chafing of the FQIS wire harness. The inspection must be carried out in accordance with Boeing Alert Service Bulletin (ASB) 737-28A1168, Revision 1, dated 11 January 2001. If the clearance is found to be less than 9.5mm, the refuel tube must be readjusted, and the bonding jumper or lockwire must be relocated away from the wiring. If loose or broken clamps or brackets are found, they must be replaced or repaired, and any chafing of the FQIS wiring harness must be addressed by installing a Teflon sleeve over the wiring or replacing the harness. Operators of Boeing 737-300, -400, and -500 series aeroplanes must comply with the inspection and corrective actions outlined in the AD. Specifically, the detailed visual inspection must be completed within six months of the effective date of the directive. Any adjustments or repairs identified during the inspection must be completed before further flight. For wiring that has been repaired in accordance with Requirement 4.a., the repair or replacement of the wire harness must be completed at the next scheduled "C" Check but no later than 15 months after the effective date of the directive. Operators must also submit a report of the inspection findings to Boeing Commercial Airplane Group within 10 days of the inspection if performed after the effective date of the directive or within 10 days of the effective date if the inspection was performed prior to the directive's effective date. Failure to comply with the requirements of this Airworthiness Directive may result in various civil and criminal consequences. Civil Aviation Safety Regulations 1998 (CAR) outline that non-compliance with an AD can lead to penalties under the Civil Aviation Act 1988. Such penalties can include fines of up to $126,000 for individuals and $630,000 for corporations. Additionally, continued operation of an aircraft that does not comply with an AD may result in the grounding of the aircraft by the Civil Aviation Safety Authority (CASA), which can have significant operational and financial repercussions for the operator.

Area of Law: Aviation Law
Instrument: Legislative Instrument
Concepts: Definitions & Interpretation; Offence Provisions; Compliance Obligations; Enforcement Powers

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Sourced from the Federal Register of Legislation at 26 August 2026. For the latest information on Australian Government law please go to https://www.legislation.gov.au.

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