AD/B747/212 - Modular Avionics Warning Electronic Assembly

Administered by Department of Infrastructure, Transport, Regional Development, Communications, Sport and the Arts

Legislation au F2006B03112 Not in force Legislative Instrument

Legislation content

 


Boeing 747 Series Aeroplanes

 

AD/B747/212 Modular Avionics Warning Electronic Assembly 11/99

TX

 

Applicability: Model 747-400 series aeroplanes, line numbers 1121 through 1177 inclusive, equipped with a modular avionics warning electronic assembly (MAWEA) power supply Part Number (P/N) 285T0035-201.

 

Requirement:  1. Check the status page of the engine indication and crew alerting system (EICAS) for any MAWEA failure; and perform the following system functional tests to detect loss of any visual, aural, or tactile alert:

 

Note 1: The following tests are an abbreviated version of Section 3, Work Instructions, of Boeing Service Bulletin (SB) 747-31-2288, dated 17 December 1998, and SB 747-31-2288 Revision 1, dated 28 January 1999.

 

  1. Perform a takeoff (T/O) configuration warning test to check the T/O configuration warning card, master monitors A and B, and left and right aural synthesizer cards.

 

(i)       Set the parking brake.

 

(ii)     Initiate the following central maintenance computer (CMC) ground test - 31 indication/recording: T/O warning.

 

(iii)  Verify that the left and right master warning lights (MWL) illuminate and the siren is heard from both the left and right speakers.

 

b.    Perform an altitude alert test to check the crew alert module.

 

(i)       Verify the parking brake is still set.

 

(ii)     Set the selected altitude on the mode control panel (MCP) to approximately 400 feet above the current altitude.

 

(iii)  Verify that the box around the current altitude on the altitude tape becomes bright white.

 

(iv)   Set the selected altitude on the MCP to 10,000 feet.

 

(v)     Verify the aural warning owl is not activated.

 

c.    Perform a stall warning test to check the left and right stall management module cards.

 

(i)       Ensure that the air data computers (ADC) are operational.

 

(ii)    Initiate the following CMC ground test – 27 stall warning: Left.

 

(iii)  Verify that both stick shakers activate.

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

SCHEDULE OF AIRWORTHINESS DIRECTIVES

 

(iv)   Initiate the following CMC ground test – 27 stall warning: Right.

 

(v)     Verify that both stick shakers activate.

 

d.    Perform an autopilot (A/P) disconnect test to check the left and right clacker wailer card.

 

(i)       Press and hold the A/P disconnect on either control wheel.

 

(ii)     Verify the wailer aural is heard over the left and right speakers and MWL’s.

 

(iii)  Release the A/P disconnect switch.

 

e.    Perform a MAWEA card light emitting diode (LED) test per Airplane Maintenance Manual (AMM) task 31-51-00-715-014, "MAWEA operational test," to verify that no red LED on the MAWEA circuit cards illuminate.

 

Note 2: The EICAS status page check and the system functional tests are maintenance functions that require an aircraft log book entry and maintenance release prior to flight.

 

2.    If any failure of the MAWEA, or the loss of any visual, aural, or tactile alert is detected during any Requirement 1 test, replace the power supply of the MAWEA with a new power supply, P/N 285T0035-202 Mod A, in accordance with either SB 747-31-2288 or SB 747-31-2288 Revision 1.

 

Note 3: Page 59 of SB 747-31-2288 Revision 1 incorrectly references the Boeing 767 AMM as the appropriate source of service information for accomplishment of the removal and replacement of the power supply. The correct reference is the Boeing 747 AMM.

 

3.    MAWEA power supply P/N 285T0035-201 may not be installed on any aeroplane as a replacement part.

 

Note 4: FAA AD 99-18-16 Amdt 39-11282 refers.

 

Compliance: 1. Before 1 October 1999 and thereafter before each flight.

 

Replacement of the MAWEA power supply P/N with P/N 285T0035-202 Mod A, in accordance with either SB 747-31-2288 or SB 747-31-2288 Revision 1 is terminating action for the Requirement 1 repetitive inspections.

 

2.    Before further flight.

 

3.    As of the effective date of this Directive.

 

This Airworthiness Directive becomes effective on 22 September 1999.

 

Background:  The Federal Aviation Administration has received a report advising that during a production test flight of a Model 747-400 series aeroplane the flight test crew noticed a power supply failure on the status page of the EICAS. Investigation revealed the automatic bench test procedure for the MAWEA overstressed the 5.7 volt over- voltage clamp circuit which resulted in the failure of the circuit to protect the warning cards in the MAWEA.

 

A slow failure of the MAWEA power supply could result in the gradual degradation of available visual, aural and tactile alerts which could result in flight crew not being aware of and not taking immediate or appropriate action in the event of an unsafe condition occurring.

 

This Directive requires repetitive checks to detect failures of the MAWEA power supply and if necessary, corrective action. The Directive also provides for an optional terminating action.

Overview

The Boeing 747 Series Aeroplanes Airworthiness Directive (AD) 2006B03112 was enacted to address potential failures in the Modular Avionics Warning Electronic Assembly (MAWEA) power supply of certain Boeing 747-400 series aeroplanes. This legislation was introduced by the Commonwealth of Australia under the Civil Aviation Regulations 1998, specifically Part 39 - 105, which is overseen by the Civil Aviation Safety Authority (CASA). The primary objective of this directive is to ensure the safety of flights by requiring repetitive inspections and corrective actions to address any detected failures in the MAWEA power supply. The AD mandates that before 1 October 1999, and subsequently before each flight, checks must be performed on the MAWEA power supply to detect any failures, and if necessary, the power supply must be replaced. Failure to comply with these directives could result in the gradual degradation of visual, aural, and tactile alerts, potentially leading to unsafe conditions during flight.

Scope and Application

The Airworthiness Directive (AD) AD/B747/212, issued under the Civil Aviation Regulations 1998, pertains specifically to Boeing 747-400 series aeroplanes with line numbers ranging from 1121 to 1177, equipped with a modular avionics warning electronic assembly (MAWEA) power supply Part Number 285T0035-201. This directive applies to the Commonwealth of Australia, overseen by the Civil Aviation Safety Authority (CASA). It mandates that before October 1, 1999, and subsequently before each flight, operators must check the EICAS status page for MAWEA failures and conduct a series of system functional tests to ensure the integrity of visual, aural, and tactile alerts. If any failures or loss of alerts are detected, the power supply must be replaced with a new one, P/N 285T0035-202 Mod A, in accordance with Boeing Service Bulletins 747-31-2288 or its revision dated January 28, 1999. Additionally, the old power supply, P/N 285T0035-201, is prohibited from being installed on any aeroplane as a replacement part. The directive became effective on September 22, 1999, addressing concerns identified during a production test flight that highlighted potential risks from a slow failure of the MAWEA power supply, which could lead to inadequate alerts for the flight crew.

Key Provisions

The legislative instrument F2006B03112 focuses on the maintenance and operational requirements for Boeing 747-400 series aeroplanes equipped with a specific Modular Avionics Warning Electronic Assembly (MAWEA) power supply. According to Section 1 of the directive, operators must check the status page of the engine indication and crew alerting system (EICAS) for any MAWEA failures and perform a series of functional tests to detect the loss of any visual, aural, or tactile alerts. These tests include a takeoff configuration warning test, an altitude alert test, a stall warning test, an autopilot disconnect test, and a MAWEA card light emitting diode (LED) test. Section 2 of the directive mandates that if any MAWEA failure or loss of alert is detected during these tests, the power supply must be replaced with a new one (P/N 285T0035-202 Mod A) in accordance with specified Boeing service bulletins. Operators of the affected Boeing 747-400 series aeroplanes are required to conduct these checks before 1 October 1999 and subsequently before each flight. Additionally, any detected MAWEA failures must be addressed before further flight, and the replacement of the MAWEA power supply must be completed as of the effective date of this directive, which is 22 September 1999. These requirements ensure that any issues with the MAWEA system are identified and rectified promptly to maintain the safety of the aircraft. Failure to comply with these provisions can result in serious safety risks. Specifically, a slow degradation of the MAWEA power supply could lead to insufficient alerts for the flight crew in case of an unsafe condition, potentially resulting in accidents. The directive does not explicitly outline specific penalties for non-compliance, but non-compliance with Civil Aviation Regulations could result in severe consequences, including fines and potential grounding of the aircraft until the issues are rectified. In summary, the key provisions of the legislative instrument F2006B03112 mandate thorough checks and corrective actions for the MAWEA power supply in Boeing 747-400 series aeroplanes to ensure the integrity of the warning systems, thereby enhancing flight safety. Non-compliance with these requirements could have severe safety implications and may attract penalties under the broader Civil Aviation Regulations.

Legal classification tags

Instrument
Legislative Instrument
Concepts
Definitions & Interpretation
Regulatory Standards
Enforcement Powers
Compliance Obligations

Interactions

Authorises

All Versions

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.