AD/CESSNA 150/44 - Instrument Panel Light Dimming Rheostat

Overview

The Civil Aviation Regulations 1998, enacted by the Parliament of Australia, address various aspects of civil aviation safety within the country. Among these, Part 39 - 105 focuses on the Civil Aviation Safety Authority's Schedule of Airworthiness Directives, which includes specific requirements for maintaining the airworthiness of various aircraft models. One such directive pertains to the Cessna 150, F150, 152, and F152 series aeroplanes, with AD/CESSNA 150/44 focusing on the instrument panel light dimming rheostat. This directive was introduced to address the safety issue of potential inflight fires caused by electrical faults in the instrument panel light dimming rheostat. The policy objective is to enhance aircraft safety by requiring the replacement of the rheostat with an improved, current-limiting, and heat-protected version, thereby reducing the risk of inflight fires.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105 under the Civil Aviation Safety Authority Schedule of Airworthiness Directives, applies to certain Cessna 150, F150, 152, and F152 series aeroplanes. The regulation mandates that these aircraft, identified by specific model and serial numbers, must undergo a replacement of the existing instrument panel light dimming rheostat. This requirement also necessitates, in some installations, the fitting of a doubler. The directive is to be carried out in accordance with the Accomplishment Instructions outlined in Cessna Single Engine Service Bulletin SEB92-33 Revision 2 dated 10 September 1993. Compliance with this directive is mandated before 3 October 1994, following a report of an inflight fire in a Cessna Model 172, which was attributed to a short in the electrical wiring controlled by the rheostat. The replacement aims to mitigate the risk of inflight fires by installing a current-limiting and heat-protected rheostat. The directive is part of the broader Australian regulatory framework and is closely aligned with corresponding Federal Aviation Administration directives, indicating a collaborative approach to aviation safety between Australia and other jurisdictions.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, details the Civil Aviation Safety Authority’s (CASA) Schedule of Airworthiness Directives for certain Cessna aircraft models, including the 150, F150, 152, and F152 series aeroplanes. One such directive, AD/CESSNA 150/44, pertains to the instrument panel light dimming rheostat (section 3/94). This directive applies to specific serial numbers of Cessna 150 and F150 models, namely 15061533 through 15071128 and F150-0001 through F150-0529 (section Applicability). The directive mandates that unless already done, the existing instrument panel light dimming rheostat must be replaced, with some installations also requiring a doubler, as per the Accomplishment Instructions of Cessna Single Engine Service Bulletin SEB92-33 Revision 2 dated 10 September 1993 (section Requirement). Compliance with this directive is crucial for the specified Cessna aircraft models. Operators and owners must ensure that the required modifications are completed prior to 3 October 1994 (section Compliance). This directive is grounded in safety concerns, following a report of an inflight fire in a Cessna Model 172, which was traced to a short in the electrical wiring controlled by the instrument panel light dimming rheostat. The directive aims to mitigate this risk by replacing the rheostat with an improved version that is both current-limiting and heat-protected, thereby reducing the likelihood of an inflight fire (section Background). Entities governed by this Act, primarily aircraft operators and owners, are obligated to undertake the specified modifications within the stipulated timeframe. These obligations include sourcing the necessary parts, ensuring that the modifications are carried out by qualified personnel, and maintaining accurate records of compliance. Failure to adhere to these directives can result in serious safety hazards, potentially leading to catastrophic outcomes. The directive references FAA AD 93-24-15 Amdt 39-8764 for further context and guidance on the required modifications. Failure to comply with the airworthiness directive can result in severe consequences. The Act does not specify particular offences or penalties in this instance, but non-compliance could lead to the grounding of the aircraft until the required modifications are made. In more serious cases, where non-compliance has led to an incident or accident, the penalties can be substantial, including fines and potential criminal charges. These measures underscore the importance of adhering to airworthiness directives to ensure the safety of all passengers and crew on board.