AD/CESSNA 170/56 - Instrument Panel Light Dimming Rheostat

Overview

The Civil Aviation Regulations 1998, as amended, were enacted to provide a comprehensive framework for the regulation of civil aviation within Australia. The Regulations aim to ensure the safety and efficiency of air travel, including the establishment of standards for aircraft airworthiness and operational procedures. One of the key legislative instruments under these Regulations is the Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives, which addresses specific safety concerns and mandates corrective actions for aircraft types and models. This includes AD/CESSNA 170/56, an Airworthiness Directive issued by CASA in 1994, which was introduced in response to an inflight fire incident reported by the Federal Aviation Administration (FAA) in a Cessna Model 172. The fire was attributed to a short in the electrical wiring controlled by the instrument panel light dimming rheostat. The policy objective of this directive is to mitigate the risk of inflight fires by requiring the replacement of the existing rheostat with an improved version that is both current-limiting and heat-protected, thereby decreasing the likelihood of a fire caused by a defective rheostat. The Civil Aviation (Safety) Regulations 1998 were enacted by the Parliament of Australia and are administered by CASA, which is the regulatory body responsible for enforcing these regulations. The specific Airworthiness Directive AD/CESSNA 170/56 targets certain Cessna aircraft models, including the 172E, 172F, 172G, 172H, 172I, 172K, F172E, F172F, F172G, F172H, FR172E, FR172F, FR172G, R172E, R172G, and R172H series. The directive mandates the replacement of the instrument panel light dimming rheostat to address a known safety hazard and ensure compliance with international safety standards. The directive was issued to ensure that affected aircraft are equipped with the necessary safety improvements to prevent inflight fires, thereby enhancing the overall safety of air travel within Australia.

Scope and Application

The Civil Aviation Regulations 1998, specifically under PART 39 - 105, governs the airworthiness of various aircraft models, with the Airworthiness Directives (AD) providing detailed requirements for maintenance and modifications. In this context, AD/CESSNA 170/56 pertains to specific models within the Cessna 170, 172, F172, FR172, and 175 series, targeting a critical safety issue related to the instrument panel light dimming rheostat. The directive applies to particular serial numbers of these models, including 172E, 172F, 172G, 172H, 172I, 172K (T-41A), F172E, F172F, F172G, F172H, FR172E, FR172F, FR172G, R172E, R172G, and R172H (T-41B, T-41C, and T-41D), each identified by their respective serial number ranges. This requirement is aimed at ensuring the safety of these aircraft by mitigating the risk of in-flight fires caused by electrical faults in the instrument panel light dimming rheostat. Compliance with this directive is mandatory, necessitating the replacement of the existing rheostat with an improved version that is both current-limiting and heat-protected. The directive must be complied with prior to 3 October 1994, as mandated by the Federal Aviation Administration (FAA) AD 93-24-15 Amdt 39-8764, reflecting a coordinated effort between Australian and international aviation authorities to address this safety concern.

Key Provisions

The Civil Aviation Regulations 1998, specifically under Part 39 - 105, mandate that certain Cessna aircraft models, including the 170, 172, F172, FR172, and 175 series, comply with Airworthiness Directives (AD) to maintain their airworthiness. AD/CESSNA 170/56, dated 3 March 1994, focuses on the requirement to replace the instrument panel light dimming rheostat in specified models and serial number ranges (section 17250573 through 17259223, F172-0019 through F17200754, FR17200001 through FR17200225, and R172-0001 through R172-0452). The directive necessitates replacing the existing rheostat with an improved version that is both current-limiting and heat-protected, as outlined in Cessna Single Engine Service Bulletin SEB92-33 Revision 2 dated 10 September 1993. This action is crucial to mitigate the risk of inflight fires caused by electrical faults in the rheostat. The obligations under these regulations require aircraft owners, operators, and maintenance personnel to ensure that the specified Cessna models are fitted with the upgraded rheostat as per the given compliance date of 3 October 1994. This involves verifying the serial number of the aircraft to determine applicability and conducting the necessary replacement of the rheostat, possibly including the fitting of a doubler, in accordance with the provided instructions. Additionally, the compliance must be documented and maintained in the aircraft’s maintenance records to demonstrate adherence to the AD. Failure to comply with these Airworthiness Directives can lead to serious consequences. The Civil Aviation Safety Authority (CASA) may take enforcement actions against non-compliance, which could include the grounding of the affected aircraft until the required modifications are made. For individuals or entities found in breach of these regulations, there may be civil penalties, including fines, and in more severe cases, criminal charges. The maximum penalties can vary, but they are designed to ensure the highest standards of aviation safety are maintained. Non-compliance not only poses a risk to the safety of the flight but can also result in significant legal and financial repercussions for the responsible parties.