Airworthiness Directives; Pratt & Whitney Canada Corp. (P&WC) PW305A and PW305B Turboprop Engines

摘要

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) issued 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: As a result of a change in the low-cycle fatigue lifing methodology for the IMI 834 material, the recommended service life of certain PW305A and PW305B Impellers has been reduced, as published in the Airworthiness Limitations (AWL) section of Engine Maintenance Manual (EMM). The in-service life of impellers P/N 30B2185, 30B2486 and 30B2858-01 has been reduced from 12,000 to 7,000 cycles; and of P/N 30B4565-01 from 8,500 to 7,000 cycles. We are proposing this AD to prevent failure of the impeller, which could result in an uncontained event and possible damage to the airplane.