AD/TB20/18 - Fuel System

Overview

The Civil Aviation Regulations 1998, administered by the Civil Aviation Safety Authority (CASA) under the Civil Aviation Act 1988, aim to ensure the safety and efficiency of civil aviation in Australia. A notable legislative instrument within this framework is F2006B07321, which pertains to Airworthiness Directives for specific aircraft models. This particular instrument, AD/TB20/18, addresses safety issues associated with Aerospatiale (Socata) TB20 (Trinidad) series aeroplanes, specifically focusing on their fuel systems. The directive was introduced to mitigate risks such as fuel siphoning and air ingestion in the fuel lines, which could potentially cause power interruptions or engine failure. The policy objective is to ensure that all affected aircraft comply with safety standards by implementing specific modifications, such as installing a check valve and replacing certain fuel system components, to prevent these risks. The directive applies to Aerospatiale (Socata) TB20 and TB21 models with serial numbers ranging from 1 to 730. It mandates the installation of a check valve into the fuel system to prevent fuel from siphoning back into the fuel tank and the replacement of certain fuel pumps with models that incorporate a solid rotor design, capable of displacing air within their operating parameters. Compliance with these directives is required before 31 October 1991, underscoring the urgency and importance of these safety measures. This legislative measure is part of CASA's broader efforts to maintain high safety standards in the aviation industry, ensuring that all aircraft operating within Australian airspace meet stringent safety criteria.

Scope and Application

The Civil Aviation Regulations 1998, under Part 39, specifically section 105, pertains to the Airworthiness Directives issued by the Civil Aviation Safety Authority (CASA). This particular directive, AD/TB20/18, applies to the Aerospatiale (Socata) TB20 (Trinidad) Series Aeroplanes, specifically the TB20 and TB21 models with serial numbers ranging from 1 through 730. The directive mandates that operators of these aircraft must install a check valve into the fuel system in compliance with Socata Service Bulletin number 47/1 and kit 9128 for model TB20. Additionally, both TB20 and TB21 models require the replacement of the Dukes pump with a Weldon pump, using specific part numbers and kits as outlined in the directive. This regulation is necessary to prevent issues such as power interruption or loss due to air being drawn into the fuel lines when the engine-driven fuel pump loses its prime. The directive references DGAC AD 89-183-(A)R1 and mandates compliance prior to 31 October 1991, ensuring that all affected aircraft are modified to maintain airworthiness standards.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, address the requirements for airworthiness directives, with the Aerospatiale (Socata) TB20 (Trinidad) Series Aeroplanes being a focal point in AD/TB20/18 (Section 10/90). This directive applies to model TB20 and TB21 aeroplanes with serial numbers ranging from 1 to 730. The primary requirement is the installation of a check valve in the fuel system for model TB20, in accordance with Socata Service Bulletin number 47/1 and kit 9128, and the replacement of the Dukes pump with a Weldon pump for both model TB20 and TB21. These changes must be made in accordance with kits 9132 and 9133, respectively. This is referenced in DGAC AD 89-183-(A)R1, which underscores the importance of these modifications. The obligations imposed by this directive require that the specified modifications be completed before 31 October 1991. The rationale behind these requirements is to address the potential for air to be drawn into the fuel lines if the engine-driven fuel pump loses its prime when the engine is stopped. This situation could cause a power interruption or loss. By installing a check valve, the directive ensures that fuel does not siphon back into the fuel tank when the engine is stopped and the fuel selector is not in the off position. Furthermore, the installation of an electric fuel boost pump with a solid rotor design ensures that air is displaced within the system's operating parameters, thereby maintaining operational safety. The consequences for non-compliance with these airworthiness directives are significant. Failure to adhere to the specified requirements and timelines may result in the aeroplane being deemed unairworthy, which could lead to serious safety hazards. In the event of an incident or accident resulting from non-compliance, there could be severe civil and criminal repercussions. While the specific penalties are not detailed within the text, non-compliance with airworthiness directives under the Civil Aviation Regulations 1998 can lead to penalties that include fines and imprisonment, reflecting the gravity of ensuring the safety of civil aviation.