AD/CESSNA 170/16 Amdt 1 - Rear Spar

Overview

The Civil Aviation Regulations 1998, enacted by the Parliament of Australia, serve to regulate the safety and operational standards of civil aviation within the country. One of the significant concerns addressed by these regulations is the maintenance and airworthiness of aircraft, ensuring they meet stringent safety standards to protect passengers and crew. A specific legislative instrument, F2006B04951, targets the Cessna 170, 172, F172, FR172, and 175 Series aeroplanes, introducing mandatory inspections for these aircraft models to prevent potential structural failures. This directive requires regular visual inspections of the main plane rear spar web and upper flange at the outer end of the attachment fitting to detect fatigue cracks, particularly those originating beneath the attachment fittings. The aim is to maintain the integrity of these aircraft and prevent any safety risks that might arise from undetected structural damage. This legislative instrument is part of a broader effort to enforce safety directives as outlined in the Civil Aviation Regulations 1998, overseen by the Civil Aviation Safety Authority (CASA). The policy objective is to enhance aircraft safety by mandating regular inspections and repairs, ensuring that all aircraft meet the necessary safety standards before continued operation. By targeting specific models and areas prone to structural issues, the regulations aim to proactively address potential safety hazards, thereby safeguarding the public and maintaining the high safety standards of Australian civil aviation.

Scope and Application

The Civil Aviation Regulations 1998, specifically under Part 39, mandate the applicability of Airworthiness Directives for certain aircraft, including Cessna 170, 172, F172, FR172, and 175 series aeroplanes. The directive AD/CESSNA 170/16 Amendment 1 applies to all models prior to the M and F172M models, requiring specific inspections to ensure the safety and airworthiness of these aircraft. The directive mandates a visual inspection of the rear spar web at the root attachment area and the upper flange of the rear channel, focusing on detecting fatigue cracks originating beneath the attachment fittings. This inspection must be performed using a magnifying glass of at least 4X magnification or an approved alternative such as the "Syte Ade" device. If there is any doubt about the presence of cracks, the trailing edge root end rib must be removed to facilitate a more detailed inspection. The directive stipulates that such inspections should occur at intervals not exceeding 100 hours of time in service, ensuring ongoing compliance with safety standards. The directive's application extends to all relevant aircraft within its scope, ensuring that operators adhere to these safety requirements.

Key Provisions

The main sections of the Civil Aviation Regulations 1998 concerning the Cessna 170, 172, F172, FR172 and 175 Series Aeroplanes are detailed in AD/CESSNA 170/16 Amendment 1, focusing on the rear spar of the aircraft (AD/CESSNA 170/16 (1)). This directive mandates specific inspections to ensure the airworthiness of the affected aircraft models. Section 1 of the amendment requires a visual inspection of the main plane rear spar web at the root attachment area and the upper flange of the rear channel at the outer end of the attachment fitting, looking for fatigue cracks that originate in the radius beneath the attachment fittings (AD/CESSNA 170/16 (1)(2)). The inspection must be conducted using a magnifying glass of at least 4X magnification or an alternative device such as the “Syte Ade” (AD/CESSNA 170/16 (1)(3)). If there is any doubt about the presence of cracks due to the close fit of the trailing edge root end rib to the spar, the rib must be removed for a more detailed inspection (AD/CESSNA 170/16 (1)(4)). The obligations imposed by these regulations are specific and require adherence to a strict inspection protocol. Operators of affected aircraft models must ensure that the required inspections are conducted at intervals not exceeding 100 hours of time in service (AD/CESSNA 170/16 (1)). This means that each aircraft must undergo the specified inspection process every 100 hours of operation to maintain compliance with the safety directives. Additionally, the inspection must be thorough, utilising appropriate magnification tools or devices to detect any fatigue cracks accurately. The technical illustration provided in Rex Aviation Technical Memorandum No. 12 dated 10 May 1960, must also be referenced to identify the specific areas that require scrutiny (AD/CESSNA 170/16 (1)). Failure to comply with the airworthiness directives stipulated in AD/CESSNA 170/16 Amendment 1 can result in serious consequences. The regulations do not explicitly detail specific offences or penalties for non-compliance; however, operating an aircraft that does not meet the required safety standards can lead to significant civil or criminal liability. Non-compliance with airworthiness directives can result in the aircraft being grounded, which would prevent it from operating until the necessary inspections and repairs are completed. Furthermore, operating an aircraft that fails to meet these safety standards could potentially lead to accidents or incidents, which may result in legal actions against the operator for negligence or failure to adhere to regulatory requirements. In summary, the Civil Aviation Regulations 1998, specifically AD/CESSNA 170/16 Amendment 1, impose stringent inspection requirements on the rear spar of certain Cessna aircraft models to ensure their airworthiness. Operators must adhere to these requirements, conducting inspections at intervals not exceeding 100 hours of time in service and using appropriate tools and techniques. Failure to comply with these directives can result in significant civil or criminal liabilities, including the potential grounding of the aircraft and legal actions against the operator.