EASA SIB CASA-2025-07
Py Lines and Fuel Control Unit Contamination
Summary
The Transport Canada Civil Aviation Safety Alert CASA-2025-07 addresses contamination issues in the Py lines and Fuel Control Unit (FCU) of Pratt & Whitney Canada Corp. PT6B-37A model engines. This alert informs owners, operators, and maintainers about reported contamination that can affect engine performance during critical phases such as takeoff and climb.
What Changed
CASA-2025-07 introduces awareness of sodium hydroxide contamination found in the rear Py line and FCU following engine overhaul cleaning procedures. It highlights the potential for slow acceleration, slow deceleration, power loss, or uncontrolled acceleration due to this contamination and recommends specific inspection and corrective actions.
Why It Matters
This alert is critical for aviation professionals because contamination in the Py lines and FCU can lead to unsafe engine behavior, impacting flight safety and engine reliability. Operators and maintenance teams must recognize these symptoms and take corrective measures to prevent in-flight engine performance issues and ensure regulatory compliance.
What To Do
Affected stakeholders should perform engine acceleration checks and apply corrective actions as outlined in Pratt & Whitney Canada Service Bulletin A39125 Revision 1 or later. Any discovery of contamination must be reported to Transport Canada via a Service Difficulty Report within Canada or to P&WC or local authorities outside Canada, following applicable reporting requirements.