CESSNA 170B — Airworthiness Directives

This document is an Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority of Australia, specifically addressing the Cessna 170, 172, and 175 series aeroplanes. The directive focuses on the crankcase breather tube and oil seal, aiming to mitigate the risk of rapid engine oil loss due to ice obstruction. It outlines inspection and modification requirements for affected aircraft models fitted with Lycoming O-320 or O-360 series engines. Compliance is mandated within a specified timeframe, ensuring that all relevant aircraft maintain airworthiness and operational safety.

• All Cessna 170, 172, and 175 series aircraft with Lycoming O-320 or O-360 engines are affected.
• Inspect the engine crankcase breather for an alternate air outlet as per Figure 1.
• If no alternate outlet exists, inspect and secure the crankcase to crankshaft seal.
• Drill the breather tube to include an alternate air outlet if necessary.
• Compliance is required within 100 hours of service after June 30, 1982.