AD/B747/121 Amdt 1 - Inspection of APU and Cargo Compartment Fire Extinguisher Bottle Cartridges

Overview

The Civil Aviation Regulations 1998, established by the Commonwealth of Australia, were enacted to regulate civil aviation safety, particularly through the issuance of airworthiness directives to address specific safety concerns. One such directive, AD/B747/121 Amdt 1, focuses on the inspection of Auxiliary Power Unit (APU) and cargo compartment fire extinguisher bottle cartridges for Boeing 747 Series aeroplanes, particularly model 747-400 aircraft. This directive responds to incidents where bent pins in discharge cartridge cartridges and damaged electrical connectors went undetected by operational tests, posing a risk in fire scenarios. The directive mandates a visual inspection of the discharge cartridges and electrical connectors as outlined in Boeing Alert Service Bulletin 747-26A2210 dated 29 October 1992, with the policy objective to ensure the proper function of fire extinguisher systems, thereby enhancing aircraft safety. Compliance with this directive is required unless the inspection has already been performed.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, pertains to the Civil Aviation Safety Authority's (CASA) Schedule of Airworthiness Directives, which apply to the safety and operational standards of aircraft in Australia. This particular legislative instrument, AD/B747/121 Amendment 1, focuses on Boeing 747 Series aeroplanes and mandates a visual inspection of the discharge cartridges and electrical connectors installed on each fire extinguisher bottle in the auxiliary power unit, as well as the lower and main deck cargo fire extinguishing systems. This requirement applies to all model 747-400 aircraft identified in Boeing Alert Service Bulletin 747-26A2210 dated 29 October 1992. The directive is designed to ensure the proper discharge of fire extinguisher bottles in the event of a fire, following reports of bent pins in discharge cartridge cartridges and damaged electrical connectors. Compliance with this directive must be achieved by 30 November 1993 unless already completed. The directive extends its reach through the inclusion of detailed instructions from the referenced Boeing Service Bulletin and FAA AD 93-09-01 Amendment 39-8568.

Key Provisions

The Civil Aviation Regulations 1998, specifically in Part 39 - 105, under the Civil Aviation Safety Authority Schedule of Airworthiness Directives, contain crucial provisions concerning the safety and operational standards of aircraft. In relation to Boeing 747 Series aeroplanes, AD/B747/121 Amendment 1 mandates the inspection of Auxiliary Power Unit (APU) and cargo compartment fire extinguisher bottle cartridges (Section 1). This applies to all model 747-400 aircraft identified in Boeing Alert Service Bulletin 747-26A2210 dated 29 October 1992. The directive requires a visual inspection of the discharge cartridges (squibs) and electrical connectors installed on each fire extinguisher bottle in the APU, lower cargo, and main deck cargo fire extinguishing systems. Notably, the operational tests of the discharge cartridges need not be performed prior to the visual inspection. However, if any damage is detected during the inspection, it is imperative to replace the damaged item and conduct an operational test of the fire bottle discharge cartridge circuit before further flights. The obligations imposed by this directive are clear and precise, mandating that all specified Boeing 747-400 aircraft must undergo the aforementioned inspections unless they have already been completed. The inspections are intended to ensure that the fire extinguisher bottles will discharge properly in the event of a fire, thus enhancing the safety of the aircraft and its occupants. Additionally, the directive clarifies that cross-wiring end-to-end functional checks, as required by AD/B747/68 Amendment 1, are not obligatory if the inspection is conducted one discharge cartridge at a time. This directive was issued in response to reports of bent pins in discharge cartridge cartridges and damaged electrical connectors, conditions that can prevent the fire bottle from discharging yet remain undetected by the operational test. Failure to comply with the requirements set forth in AD/B747/121 Amendment 1 can lead to significant consequences. The directive specifies that compliance must be achieved by 30 November 1993, unless the inspection has already been conducted. Non-compliance could potentially result in the aircraft being deemed unfit for operation, which could lead to civil or criminal penalties. While the specific penalties are not detailed in the directive, under general aviation safety regulations, breaches can result in hefty fines, enforcement actions, or even prosecution. Such consequences underscore the importance of adhering to the stipulated inspection requirements to maintain the safety and airworthiness of the aircraft.