EASA AD CF-2024-04
Turboprop Engine — Overspeed Governor Hydraulic Pump — Malfunction of Pressure Relief Valve
Summary
Canadian Airworthiness Directive CF-2024-04 addresses a malfunction in the overspeed governor hydraulic pump pressure relief valve on Pratt & Whitney Canada PW100 series turboprop engines, including models PW118 through PW124B. The directive mandates removal of affected pressure relief valves to prevent propeller pitch-lock conditions that can cause propeller overspeed and potential control difficulties. This AD applies to specific serial numbers of the pressure relief valves identified in the directive.
What Changed
CF-2024-04 introduces mandatory removal of affected overspeed governor hydraulic pump pressure relief valves with specific serial numbers due to contamination causing low regulating pressure. It prohibits having two affected valves installed simultaneously and bans reinstallation of these valves after the effective date. The directive references P&WC Service Bulletin PW100-72-21945 Revision 5 or later for corrective actions.
Why It Matters
This directive is critical for operators and maintenance organizations to prevent propeller overspeed events that can lead to thrust asymmetry and loss of aircraft control. Compliance ensures continued airworthiness and safety of aircraft powered by affected PW100 series engines. It also helps maintenance teams identify and remove contaminated components to avoid in-flight malfunctions.
What To Do
Operators must remove one affected pressure relief valve within 60 days if both engines have affected valves installed, and remove all affected valves within 360 days from the effective date of 14 March 2024. After removal, affected valves cannot be reinstalled. Compliance must follow the instructions in P&WC Service Bulletin PW100-72-21945 Revision 5 or later approved revisions.
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