Part Number MS20220-3 Pulleys with Corroded and Dislodged Bearings
- Published
AI-generated summary of the official EASA document. Verify against the PDF before acting.
What to do
Operators of DHC DASH 8 series 100/200/300/400 aircraft should incorporate the relevant De Havilland Canada Service Bulletins to replace eight affected pulleys in the center wing area with corrosion-resistant parts. Maintenance personnel must exercise maximum caution when servicing the flight control pulley systems. For further information, contact Transport Canada or Philip Lynch at the Continuing Airworthiness office.
Summary
Part Number MS20220-3 Pulleys with Corroded and Dislodged Bearings is a Transport Canada Civil Aviation Safety Alert (CASA 2025-11) addressing corrosion issues in flight control pulleys and pulley bearing assemblies installed on De Havilland Canada (DHC) DASH 8 series 100/200/300/400 aircraft. The alert highlights multiple service difficulty reports involving corroded and seized pulleys causing stiff roll control and autopilot disconnection. It targets operators and maintenance personnel responsible for the affected flight control systems.
What changed
This CASA introduces awareness of corrosion-related failures in P/N MS20220-3 pulleys used in the center wing flight control systems of DHC DASH 8 aircraft. It recommends replacing these pulleys with corrosion-resistant D1310001-03 pulleys using stainless steel bearings as specified in De Havilland Canada Service Bulletins SB 8-27-126 for series 100/200/300 and SB 84-27-76 for series 400. The alert consolidates recent incidents and advises enhanced maintenance vigilance.
Why it matters
The corrosion and failure of these pulleys can lead to increased control resistance and autopilot disconnection, posing safety risks during flight. For operators and maintenance organizations, recognizing and addressing this issue is critical to maintaining safe and reliable flight control operation. Compliance helps prevent in-flight control anomalies and potential incidents related to pulley seizure or bearing failure.
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