AD/CESSNA 170/47 Amdt 1 - Crankcase Breather Tube and Oil Seal

Overview

The Civil Aviation Regulations 1998, enacted by the Parliament of Australia, were established to ensure the safety and regulation of civil aviation within the country. This legislation is integral to the operations of the Civil Aviation Safety Authority (CASA), which is tasked with enforcing aviation safety standards. One specific issue the regulations aim to address is the potential for rapid loss of engine oil in certain Cessna aircraft models due to ice obstructing the engine crankcase breather. To mitigate this risk, the Civil Aviation Safety Authority has issued Airworthiness Directives (AD), including AD/CESSNA 170/47, which mandates modifications to the crankcase breather tube and oil seal to ensure the safety of the aircraft. The policy objective behind these directives is to enhance the safety of flight operations by preventing engine failures that could be caused by ice obstructions. The AD/CESSNA 170/47, amended to ensure continued safety even after modifications to the exhaust system, requires specific actions to be taken on various Cessna models equipped with Lycoming 0-320 or 0-360 series engines. The directive mandates that the engine crankcase breather tube be visually inspected for any pre-existing alternate air outlets and that these be documented in the aircraft maintenance records if present. If no such outlets exist, the crankcase to crankshaft seal must be inspected and either reinstalled or replaced if not flush with the crankcase face. Additionally, an alternate air outlet must be drilled into the breather tube to prevent future obstructions. Compliance with these directives is required within 100 hours of time in service following the specified date. This directive underscores the importance of maintaining stringent safety standards to prevent potential hazards during flight operations.

Scope and Application

The Civil Aviation Regulations 1998, specifically under Part 39 - 105, apply to the maintenance and airworthiness of certain aircraft models, with a focus on the Cessna 170, 172, F172, FR172, and 175 series aeroplanes. This particular airworthiness directive (AD/CESSNA 170/47) pertains to all models 170A, 170B, 172, 172A to 172P, 175, 175A, 175B, 175C, R172D, and R172E that are fitted with Lycoming 0-320 series or 0-360 series engines. The directive aims to mitigate the risk of rapid loss of engine oil due to ice obstructing the engine crankcase breather by requiring inspections and modifications to the crankcase breather tube and oil seal. The requirement for compliance must be met within 100 hours of time in service following 30 June 1982, unless it has already been addressed. The regulation is binding across the Commonwealth of Australia and applies to all relevant aircraft and their operators within the jurisdiction of the Civil Aviation Safety Authority.

Key Provisions

The main operative sections of this legislative instrument (Civil Aviation Regulations 1998, Part 39 - 105) provide specific directives for the airworthiness of certain Cessna aeroplanes. Section 1 mandates a visual examination of the engine crankcase breather to check for an alternate air outlet that is drilled or cut in the tube, as shown in Figure 1. If such an outlet exists, an appropriate entry must be made in the aircraft maintenance records, and no further action is required. Section 2 outlines further actions to be taken if the specified hole or cutout is not present in the breather tube. It requires the inspection of the crankcase to crankshaft seal to ensure it is secure and flush with the forward face of the crankcase. If the seal is not in the correct position, it must be reinstalled or replaced. Additionally, the engine crankcase breather tube must be drilled to include an alternate air outlet as specified in Figure 1. These actions must be completed within 100 hours of time in service after 30 June 1982, unless they have already been accomplished. The obligations imposed by this legislative instrument are specific and technical. Operators and maintainers of the specified Cessna aeroplanes must visually inspect the engine crankcase breather to determine if it contains the specified alternate air outlet. If the outlet is present, they must record this in the aircraft maintenance records. If the outlet is absent, they must inspect the crankcase to crankshaft seal, ensuring it is secure and flush with the forward face of the crankcase. If the seal is not in the correct position, it must be reinstalled or replaced. Additionally, they must drill the engine crankcase breather tube to include the alternate air outlet as shown in Figure 1. These actions must be completed within the specified timeframe, unless already done. Failure to comply with the provisions of this legislative instrument can lead to significant consequences. While the text does not specify exact penalties, non-compliance with Civil Aviation Regulations can result in enforcement actions by the Civil Aviation Safety Authority (CASA). These actions may include fines, suspension or revocation of an airworthiness certificate, and potential criminal charges. The specific penalties can vary depending on the severity of the non-compliance and the specific regulations violated. Operators and maintainers must ensure strict adherence to the directives to avoid these potential consequences.