Overview

The Airworthiness Directive AD/BAe 146/109, issued in 2004, addresses a specific safety concern identified in the British Aerospace BAe 146 Series aeroplanes, particularly those fitted with Thales Avionics Distance Bearing Indicators (DBI) with certain part and serial numbers. This legislative instrument was enacted by the Civil Aviation Safety Authority (CASA), which is the regulatory body responsible for ensuring air safety in Australia. The primary objective of this directive is to mitigate the risk of a manufacturing fault in the DBI PSU transformer, which could potentially propagate the aircraft's 115VAC input power supply through the instrument, causing a loss of all primary navigation instruments. The directive mandates that affected DBIs be removed and replaced with modified versions or DBIs with unlisted serial numbers, in accordance with specified service bulletins, within a four-month compliance period.

Scope and Application

The Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA) under subregulation 39.1 (1) of the Civil Aviation Safety Regulations 1998 applies specifically to British Aerospace BAe 146 Series Aeroplanes, more precisely to the Avro 146-RJ Series RJ70, RJ85, and RJ100 models fitted with Thales Avionics Distance Bearing Indicator (DBI) parts with specified serial numbers. The AD mandates that the identified DBIs be removed and replaced with modified versions to mitigate the risk of a manufacturing fault that could propagate the aircraft’s 115VAC input power supply through the instrument, leading to potential loss of primary navigation instruments. This requirement must be carried out within four calendar months of the AD's effective date, which is 13 May 2004. The AD does not explicitly exclude any entities or industries from its scope, and it applies across the Commonwealth of Australia. The AD extends its application through reference to subordinate instruments, such as BAE Systems (Operations) Service Bulletin SB 34-371-70671A, which provides detailed instructions on the replacement process.

Key Provisions

The Airworthiness Directive (AD) AD/BAe 146/109 (sections 1-3) applies specifically to the British Aerospace BAe 146 Series aeroplanes with certain serial numbers, specifically those equipped with a Thales Avionics Distance Bearing Indicator (DBI) with particular part and serial numbers (section 1). The directive mandates that the relevant DBI units be identified and, if they fall within the specified serial numbers, they must be removed and replaced with a modified version of the DBI, either P/N 63543-280-2 or an unlisted serial number P/N 63543-280-1, following the instructions in BAE Systems (Operations) Service Bulletin SB 34-371-70671A dated 19 September 2003 (section 2). Compliance with this directive is required within four calendar months from the effective date, which is 13 May 2004 (section 3). The AD imposes clear obligations on the operators of the affected aeroplanes. Operators must determine the part number and serial number of the DBI on their aeroplanes as per the instructions in the referenced service bulletin. If the DBI matches the serial numbers listed in the applicability section, it must be removed and replaced with an approved version. This action is necessary to mitigate the risk of a manufacturing fault that could result in the propagation of the aircraft's 115VAC input power supply, potentially leading to a loss of primary navigation instruments (section 2). The directive provides a specific timeframe for compliance, requiring the action to be completed within four months of the directive's effective date. Failure to comply with the requirements of this AD can result in significant consequences. Although the specific penalties are not detailed in the AD itself, non-compliance with airworthiness directives generally falls under the Civil Aviation Safety Authority's (CASA) regulatory framework. Potential penalties may include fines and the possibility of grounding the affected aircraft until compliance is achieved. The severity of the penalty would depend on the extent of non-compliance and any resultant safety risks. Operators are advised to adhere strictly to the directive to avoid these potential repercussions.