Summary
We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
Some cases of failure of engine oil dipsticks, installed on Pratt & Whitney Canada (P&WC) PT6A66 and PT6A66B engines, were detected on P.180 aeroplanes; such failures, due to moisture penetration into the dipstick and subsequent corrosion, can cause incorrect reading of the engine oil low level on the Refuel/Ground Test Panel.
If left uncorrected, this situation could lead to in-flight engine failure(s). The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.