AD/B737/15 Amdt 3 - Fuel Boost Pump Bypass Valve

Overview

The Civil Aviation Regulations 1998, as amended, were enacted by the Parliament of Australia to ensure the safe and efficient operation of civil aviation within the country. Part 39, in particular, outlines the regulations concerning the airworthiness of aircraft, including the issuance of airworthiness directives. The problem or gap addressed by this specific legislative instrument is the need to address safety concerns identified in Boeing 737 series aeroplanes, particularly regarding the Fuel Boost Pump Bypass Valve. This directive, AD/B737/15 Amendment 3, was introduced to mitigate the risk of engine flame-out during cruise conditions caused by water accumulation and freezing in the bypass valve, which could prevent fuel flow to the engine. The objective is to ensure compliance with safety standards set forth by the Civil Aviation Safety Authority, enhancing the overall safety of air travel within Australia.

Scope and Application

The Civil Aviation Regulations 1998, specifically under Part 39 - 105 and the Civil Aviation Safety Authority Schedule of Airworthiness Directives, address the safety and maintenance requirements for Boeing 737 series aeroplanes with respect to the Fuel Boost Pump Bypass Valve. This legislation applies to all Boeing 737 series aeroplanes that are listed in Boeing Service Bulletin 737-28A1072 Revision 4. The primary requirement outlined in this directive is for aircraft owners and operators to undertake specific actions to mitigate the risk of engine flame out during cruise conditions, which was identified as a consequence of water freezing within the Fuel Boost Pump Bypass Valve and obstructing fuel flow. Operators must comply with the actions specified in Part I of Boeing Service Bulletin 737-28A1072 Revision 4 and, if not already modified under previous revisions of the Service Bulletin, they must also comply with Part II of the same bulletin. Additionally, for aircraft that previously exhibited bracket preload when modified under earlier revisions, an inspection of the suction feed bypass system for preloading is mandated. Compliance with these directives is expected at each maintenance interval coinciding with approximately 300 hours of time in service until improved bypass valves are installed, and certain actions must be completed prior to 31 March 1992. This legislation applies nationally, as it is a Commonwealth regulation, and it extends its reach to all relevant aircraft operating within Australian airspace.

Key Provisions

The Civil Aviation Regulations 1998, under Part 39, section 105, specifically address airworthiness directives for Boeing 737 series aeroplanes, including AD/B737/15 Amendment 3, which pertains to the fuel boost pump bypass valve. This directive (section 105) is applicable to Boeing 737 series aeroplanes listed in Boeing Service Bulletin 737-28A1072 Revision 4 (section 11/90). The requirement outlined in section 1 of the directive necessitates actions in accordance with Part I of Boeing Service Bulletin 737-28A1072 Revision 4. For aircraft not previously modified under Part II of Boeing Service Bulletin 737-28A1072 Revision 2 or 3, additional action as specified in Part II of the same bulletin, Revision 4, is required. Furthermore, for those aircraft that had exhibited bracket preload when previously modified in accordance with Revision 2 or 3 of the bulletin, an inspection of the suction feed bypass system for preloading must be conducted in line with Boeing Service Bulletin 737-28A1072 Revision 4. This is to ensure that any preloading issues are identified and rectified, thereby preventing future incidents of engine flame out during cruise conditions. Operators and maintenance personnel governed by this airworthiness directive must adhere to the specified actions and requirements. The directive mandates compliance at each maintenance interval coinciding with approximately 300 hours of time in service until improved bypass valves are installed as per Requirement 2. Additionally, all modifications and inspections must be completed before 31 March 1992. Failure to comply with these mandates can lead to significant safety risks, including engine flame out, which could endanger passengers and crew. Failure to comply with the provisions of this airworthiness directive can result in severe consequences. The Civil Aviation Regulations 1998 impose both civil and criminal penalties for non-compliance with airworthiness directives. Civil penalties can include fines and other sanctions, while criminal penalties may include imprisonment. The exact penalties are determined by the specific regulations and the severity of the non-compliance. Furthermore, non-compliance can lead to the grounding of the aircraft, which can have substantial financial and operational repercussions for the operator. The overarching aim of these provisions is to ensure the highest standards of safety in civil aviation.