COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Cessna 170, 172, F172, FR172 and 175 Series Aeroplanes
AD/CESSNA 170/48 Exhaust Muffler/Shroud 9/83
Applicability: Model 172RG with S/Nos 172RG0001 to 172RG1134.
Requirement: 1. Modify the muffler shroud in accordance with Cessna SL No SE83-13. In addition, visually inspect the flanges on the outer diameter of the ends of the muffler for cracks prior to reinstallation of the muffler shroud. Repair or replace any cracked components.
2. Visually inspect the muffler shroud for security and proper location and the flanges on the outer diameter of the ends of the muffler for cracks. Repair or replace any cracked components before further flight. Removal of the muffler shroud for this inspection is not required.
3. Reinspect any repaired components.
Note: As an alternative to comply with paragraphs 1, 2 and 3 of the requirement, deactivate the cabin heat system by removing the cabin heat control cable from the control arm on the cabin heat located on the firewall at the right upper side of the engine compartment. Ensure that the valve spring mechanism is functioning and that the cabin heat valve is spring loaded to the closed position and wire locked in the closed position. FAA AD 83-14-04 Amdt 39-4684 refers.
Compliance: Para 1 - Within 25 hours time in service after 31 August 1983.
Para 2 - Within 50 hours time in service after the modification detailed in para 1 of the requirement has been embodied and repeated thereafter at intervals of 50 hours time in service.
Para 3 - Within 25 hours time in service after the repair.
Background: An overseas Authority and the manufacturer, require modification and repeated inspections to the exhaust muffler/shroud assembly in order to prevent the possibility of carbon monoxide contamination. This action supersedes that taken in cancelled AD/CESSNA 170/41.
Overview
The Civil Aviation Regulations 1998, enacted by the Australian Government, aim to ensure the safety and reliability of civil aviation. Specifically, Part 39 - 105 Civil Aviation Safety Authority Schedule of Airworthiness Directives addresses various safety concerns and compliance requirements for different aircraft models, including the Cessna 170, 172, F172, FR172, and 175 series aeroplanes. This legislation was introduced to mitigate potential safety risks associated with the exhaust muffler/shroud assembly, specifically to prevent carbon monoxide contamination. The policy objective is to ensure that aircraft meet the required safety standards to protect passengers and crew. The Civil Aviation Safety Authority enforces these regulations to maintain the highest standards of airworthiness across the aviation industry in Australia.
Scope and Application
The Civil Aviation Regulations 1998, specifically Part 39 - 105, pertain to the Civil Aviation Safety Authority's Airworthiness Directives, including AD/CESSNA 170/48 which mandates modifications and inspections for the exhaust muffler/shroud assembly on certain Cessna 172RG series aeroplanes with specific serial numbers. This regulation applies to the identified model and serial number range of Cessna 172RG aircraft, targeting the critical issue of potential carbon monoxide contamination. The directive requires modifications to the muffler shroud, visual inspections for cracks in the flanges, and subsequent repairs or replacements. Additionally, there is an alternative compliance option involving deactivation of the cabin heat system, ensuring the cabin heat valve is correctly positioned and secured. The specified timeframes for compliance are within 25 hours of time in service after the relevant dates, and the directive mandates reinspection after repairs and repeated inspections every 50 hours of time in service following the initial modification. This regulation extends its application nationally, affecting all operators and owners of the specified aircraft within Australian jurisdiction. The scope of the directive does not include any stated exclusions or exemptions, and compliance is mandatory for the specified aircraft within the defined parameters.
Key Provisions
The Civil Aviation Regulations 1998 (the Regulations) mandate specific maintenance and inspection requirements for certain models of Cessna aeroplanes. Specifically, AD/CESSNA 170/48 pertains to the exhaust muffler/shroud of the Model 172RG with serial numbers ranging from 172RG0001 to 172RG1134. This directive outlines several key requirements for the modification and inspection of the exhaust muffler/shroud (section 1). Firstly, the muffler shroud must be modified in accordance with Cessna Service Letter SE83-13, and the flanges at the ends of the muffler must be visually inspected for cracks before reinstallation, with any cracked components to be repaired or replaced (section 1(1)). Secondly, the muffler shroud must be visually inspected for security and proper location, and the flanges for cracks, with any cracked components to be repaired or replaced before further flight (section 1(2)). Lastly, any repaired components must be reinspected within 25 hours of time in service after the repair (section 1(3)). Alternatively, the cabin heat system can be deactivated by removing the cabin heat control cable and ensuring the valve spring mechanism is functioning correctly and the cabin heat valve is closed and locked (section 1, Note). Compliance deadlines are set for these requirements, with the initial modification and inspection to occur within 25 hours of time in service after 31 August 1983, followed by repeated inspections every 50 hours of time in service after the initial modification (section Compliance).
The Regulations impose clear obligations on the operators and maintainers of the affected Cessna aeroplanes. Operators must ensure that the exhaust muffler/shroud modifications and inspections are carried out as specified in AD/CESSNA 170/48 (section 1). This includes modifying the muffler shroud according to the specified service letter and inspecting the flanges for cracks, with any necessary repairs or replacements carried out promptly. Additionally, operators must ensure that any repaired components are reinspected within the prescribed timeframe (section 1(3)). The alternative method of deactivating the cabin heat system must also be performed correctly to comply with the directive (section 1, Note). Failure to comply with these requirements can result in the aeroplane being deemed unairworthy, posing significant safety risks.
Failure to comply with the requirements of AD/CESSNA 170/48 can result in serious consequences. The Civil Aviation Safety Authority (CASA) can take enforcement action against operators and maintainers who do not adhere to these safety directives. Possible penalties include fines, suspension or revocation of aircraft operating certificates, and potential criminal charges for serious breaches that result in unsafe conditions. The specific penalties are determined based on the severity and circumstances of the non-compliance, but the overarching goal is to ensure that all affected aircraft meet the necessary safety standards to prevent potential hazards such as carbon monoxide contamination.