AD/B737/131 Amdt 4 - Electrical Power

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Legislation au F2006B02832 In force Legislative Instrument

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AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/B737/131 Amdt 3 and issues the following AD under subregulation 39.1 (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/B737/131

Amdt 4


Electrical Power 11/2004

 

 

Applicability: All Model 737-100, -200, -300, -400 and -500 series aeroplanes.

 

Requirement: 1. For Model 737-100 and -200 series aeroplanes equipped with battery charger Boeing Part Number (P/N) 10-60701-1:

  1. Replace the battery charger with a new or serviceable battery charger, Boeing P/N 10-60701-3, in accordance with Chapter 21-10-111 of the Boeing 737 Airplane Maintenance Manual (AMM), and
  2. Replace the battery with a new or reconditioned battery in accordance with Chapter 24-31-11 of the Boeing 737 AMM.

Incorporation of Boeing Alert Service Bulletin (ASB) 737-24A1136 dated 27 April 2000 or Revision 1 dated 24 January 2002 or Revision 2 dated 7 August 2003 is optional and allows the battery maintenance to be scheduled in accordance with the Boeing 737 Maintenance Planning Document (MPD).

2.        For Model 737-300, -400 and -500 series aeroplanes - Replace the battery with a new or reconditioned battery in accordance with Chapter 24-31-11 of the Boeing 737 AMM.

 

Incorporation of ASB 737-24A1136 or Revision 1 or Revision 2 is optional and allows the battery maintenance to be scheduled in accordance with the 737 MPD.

 

3.        For all Model 737-100, -200, -300, -400 and -500 series aeroplanes - Perform a test to determine the condition of the Generator Control Unit (GCU) diode CR910 in accordance with Boeing Telex Message M-7200-99-01528 dated 5 March 1999.

  1. If the diode fails the Requirement 3 test, replace the GCU with a new or serviceable GCU and the battery with a new or reconditioned battery. Repeat the Requirement 3 diode test until successful completion of the test is achieved.
  2. Once the Requirement 3 diode test has been successfully completed, repeat the diode test.

 

Incorporation of ASB 737-24A1136 or Revision 1 or Revision 2 is optional terminating action for the Requirement 3.b repetitive testing of the diodes.

 

4.        Battery chargers P/N 10-60701-1 may not be installed on any Model 737 series aeroplane as a replacement part.

 

5.        For Model 737-100 and -200 series aeroplanes equipped with battery charger Boeing P/N 10-60701-3 - Replace the aeroplane battery with a new or reconditioned aeroplane battery in accordance with Chapter 24-31-11 of the Boeing 737 AMM. Accomplishment of this replacement constitutes terminating action for Requirement 1.b.

 

Incorporation of ASB 737-24A1136 or Revision 1 or Revision 2 is optional and allows the battery maintenance to be scheduled in accordance with the 737 MPD.

 

6.        For all aeroplanes - Determine the condition of diode CR910 of the GCU, in accordance with the "Alternative Test of Diode CR910", as specified in Boeing Telex Message M-7200-99-01528, dated 5 March 1999. Accomplishment of this action constitutes terminating action for Requirement 3.

  1. If all diodes successfully pass "Alternative Test of Diode CR910", repeat the diode test.
  2. If any diode fails the "Alternative Test of Diode CR910" - Replace the GCU with a new or serviceable GCU, and the aeroplane battery with a new or reconditioned aeroplane battery, and repeat the "Alternative Test of Diode CR910" for the replaced GCU in accordance with the telex message until successful completion of the test is achieved.

Note 1: Any test performed, prior to the effective date of the original issue of this Directive, in accordance with Boeing Telex Message M-7200-99-01528 dated 19 February 1999 or 4 March 1999, is not acceptable for compliance with either Requirement 3 or 6.

 

Note 2: FAA AD 99-18-17 Amdt 39-1128 and FAA AD 99-24-08 Amdt 39-11432

together with FAA Alternate Method of Compliance (AMOC) letters 130S-00-257 dated 4 May 2000 and 130S-01-566 dated 4 October 2001 refer.

 

Compliance: For Requirement 1.a. - Remains unchanged as "Prior to 5 December 1999".

 

For Requirement 1.b. - Remains unchanged as "Prior to 5 December 1999 (unless already accomplished within the previous 750 hours time in service) and thereafter, at intervals not to exceed 750 hours time in service" unless ASB 737-24A1136 or Revision 1 or Revision 2 has been incorporated where replacement may be scheduled in accordance with the 737 MPD.

 

For Requirement 2 - Remains unchanged as "Prior to 5 December 1999 (unless already accomplished within the previous 750 hours time in service) and thereafter, at intervals not to exceed 750 hours time in service" unless ASB 737-24A1136 or Revision 1 or Revision 2 has been incorporated where replacement may be scheduled in accordance with the 737 MPD.

 

For Requirement 3 - Remains unchanged as "Prior to 5 December 1999". For Requirement 3.a. - Before further flight.

For Requirement 3.b. - At intervals not to exceed 600 hours time in service until Requirement 6 is accomplished or Boeing ASB 737-24A1136 or Revision 1 or Revision 2 is incorporated.

 

For Requirement 4 - Remains unchanged "As of the effective date of the original issue of this Directive".

 

For Requirement 5 - Within 90 days after the effective date of this Amendment, or within 750 hours time in service after the last battery replacement accomplished in accordance with Requirement 1.a., whichever occurs later. Thereafter, replace the aeroplane battery with a new or reconditioned aeroplane battery at intervals not to exceed 750 hours time in service unless ASB 737-24A1136 or Revision 1 or Revision 2 has been incorporated where replacement may be scheduled in accordance with the 737 MPD.

 

For Requirement 6 - Within 90 days after 20 April 2000 (the effective date for Amendment 2), or within 90 days after accomplishment of the test required by Requirement 3, whichever occurs later (unless the "Alternative Test of Diode CR910", as specified in Boeing Telex Message M-7200-99-01528, was accomplished as compliance for Requirement 3).

 

For Requirement 6.a. - At intervals not to exceed 600 hours time in service until Boeing ASB 737-24A1136 or Revision 1 or Revision 2 is incorporated.

 

For Requirement 6.b. - Before further flight and thereafter, repeat the diode test at intervals not to exceed 600 flight hours until Boeing ASB 737-24A1136 or Revision 1 or Revision 2 is incorporated.

 

This Amendment becomes effective on 28 October 2004.

 

Background: The United States Federal Aviation Administration (FAA) issued AD 99-18-17 following an incident during which all electrical power was lost due to a combination of a weak or depleted battery and failure of a diode in the GCU.

 

This Directive, whilst including the requirements of FAA AD 99-18-17, also includes the requirements of superseding FAA AD 99-24-08. The Directive requires repetitive replacement of the battery and, in certain cases, replacement of the GCU. The Directive also requires repetitive testing of a GCU diode. These actions are intended to prevent failure of all electrically powered systems in the aeroplane, which could result in an inability to continue safe flight and landing.

 

This Amendment introduces optional service bulletins, which are considered terminating action for the repetitive diode testing and allows battery maintenance to be scheduled in accordance with the MPD.

 

Amendment 3 clarified the requirements for use of the "Alternative Test of Diode CR910".

 

Amendment 2 contained some minor formatting changes, introduced new requirements for some aeroplanes fitted with P/N 10-60701-3 battery chargers and adds a requirement for diode testing, which constitutes terminating action for Requirement 3.

 

Amendment 1 contained some minor editorial corrections and provided relief for operators that already had batteries on a 750 hour time in service replacement cycle.

 

Amendment 3 became effective on 13 July 2000.

 

Amendment 2 became effective on 20 April 2000.

 

Amendment 1 became effective on 24 November 1999.

 

The original issue of this Airworthiness Directive became effective on 13 October 1999.


James Coyne

Delegate of the Civil Aviation Safety Authority 17 September 2004

 

 

 

 

 

 


The above AD is notified in the Commonwealth of Australia Gazette on 6 October 2004.

Overview

The Civil Aviation Safety Authority Amendment Instrument 2004 (F2006B02832) was enacted in 2004 as an amendment to address identified safety issues related to the electrical power systems in Boeing 737 series aeroplanes. This legislative instrument was issued by the Civil Aviation Safety Authority (CASA) under the Civil Aviation Act 1988. The primary aim of this amendment is to ensure the continued airworthiness of Boeing 737 aeroplanes by mandating specific actions to mitigate risks associated with battery and generator control unit failures. These measures are intended to prevent the total loss of electrical power, which could compromise the safety of flight operations. This amendment to the Airworthiness Directive AD/B737/131 Amdt 3 specifically targets the replacement and testing of critical electrical components, including battery chargers and generators, in various models of the Boeing 737 series. The directive applies to all Model 737-100, -200, -300, -400, and -500 series aeroplanes, and it incorporates optional service bulletins that provide flexibility in scheduling maintenance tasks. The overall objective is to enhance the reliability and safety of electrical systems in these aircraft by addressing potential points of failure and ensuring regular maintenance and testing protocols are followed.

Scope and Application

The Airworthiness Directive (AD) AD/B737/131 Amdt 4 pertains to all Boeing 737-100, -200, -300, -400, and -500 series aeroplanes. This directive applies to aircraft and aeronautical products that are subject to the Civil Aviation Safety Regulations 1998 (CASR 1998) and specifically targets the electrical power systems of these aircraft models. The directive mandates specific actions to address identified unsafe conditions, including the replacement of certain battery chargers and batteries, and the testing and potential replacement of the Generator Control Unit (GCU) diode CR910. It is enforced by the Civil Aviation Safety Authority (CASA) under its delegate's authority and is applicable across the Commonwealth of Australia. There are no specific exclusions mentioned in the AD; however, certain conditions allow for optional incorporation of Boeing Alert Service Bulletins (ASB), which can modify the frequency of battery maintenance and testing of the GCU diode. Compliance timelines are set for various actions, with some deadlines contingent on the aeroplane's service history and the incorporation of specified ASBs.

Key Provisions

This Airworthiness Directive (AD) revokes the previous AD AD/B737/131 Amdt 3 and issues new requirements for Boeing 737 series aeroplanes. The AD mandates specific actions to address an unsafe condition related to electrical power. The applicability section states that the AD applies to all Model 737-100, -200, -300, -400, and -500 series aeroplanes. The requirement section outlines the actions that need to be taken for different model series. For the Model 737-100 and -200 aeroplanes equipped with a specific battery charger, the battery charger must be replaced, and the battery must be replaced or reconditioned. The incorporation of certain Boeing Alert Service Bulletins (ASB) is optional, allowing for scheduled maintenance according to the Boeing 737 Maintenance Planning Document (MPD). For the Model 737-300, -400, and -500 aeroplanes, only the battery needs to be replaced or reconditioned, with the incorporation of ASB also being optional for scheduling maintenance. Additionally, for all model series, a test must be conducted on the Generator Control Unit (GCU) diode CR910, and if the diode fails the test, the GCU and battery must be replaced. Once the test is successfully completed, the test must be repeated. Battery chargers of a specific part number must not be installed on any Model 737 series aeroplane. For aeroplanes with a different battery charger, the battery must be replaced or reconditioned. The AD also requires an "Alternative Test of Diode CR910" for all aeroplanes. If the diodes pass this test, the test must be repeated. If any diode fails the test, the GCU and battery must be replaced, and the test must be repeated until successful. The AD imposes several obligations on the parties or entities it governs. Operators of Boeing 737 series aeroplanes must ensure that the specified actions are taken according to the requirements outlined in the AD. This includes replacing the battery charger and battery for certain model series, replacing the battery for other model series, and performing the required tests on the GCU diode CR910. Operators must also ensure that the battery chargers of a specific part number are not installed on any Model 737 series aeroplane. The AD provides optional incorporation of Boeing ASBs, allowing operators to schedule maintenance according to the Boeing 737 MPD. Compliance with the AD must be achieved within specified timeframes and intervals, as outlined in the compliance section. Failure to comply with the requirements of this AD may result in civil or criminal consequences. The AD does not explicitly state the penalties for non-compliance, but non-compliance with ADs can lead to enforcement actions by the Civil Aviation Safety Authority (CASA). Such actions may include fines, suspension or revocation of airworthiness certificates, and other regulatory measures. Additionally, non-compliance with ADs can result in the grounding of affected aircraft, which can have significant operational and financial implications for operators. It is essential for operators to adhere to the AD requirements to maintain the airworthiness of their Boeing 737 series aeroplanes and ensure the safety of their operations.

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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.