EASA AD CF-2021-20
SUPERSEDED BY TCCA AD CF-2021-37
Summary
The Canadian Airworthiness Directive CF-2021-20 mandates inspection and cleaning of the air bleed shutoff valves (BOV) on Pratt & Whitney Canada PT6E-67XP engines, serial number HP0138 and earlier. This directive addresses a failure of the BOV to fully close at high power settings due to contamination from glass beads used in the gas generator case manufacturing process. The directive aims to ensure engines produce required power during high-demand maneuvers.
What Changed
CF-2021-20 introduces mandatory compliance with Pratt & Whitney Canada's Service Bulletin A75018R2, requiring inspection and cleaning of the BOV to prevent internal leaks caused by contaminants. It establishes inspection intervals and corrective actions if contamination or anomalies are found. This is a new directive addressing a specific safety risk identified through multiple incidents.
Why It Matters
This directive is critical for operators and maintenance organizations to prevent engine power loss during high power demands, which poses a safety risk during go-around maneuvers. Compliance ensures continued airworthiness and operational safety of affected PT6E-67XP engines. It also helps maintenance teams identify and mitigate contamination issues in the BOV before they lead to engine performance degradation.
What To Do
Operators must inspect the BOV within 50 flight hours from the directive's effective date, following the procedures in P&WC Service Bulletin A75018R2. If contamination or anomalies are detected, inspections must be repeated every 40 to 60 flight hours until the issue is resolved. All inspections must comply with the latest approved revision of the service bulletin.
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