EASA SIB CASA-2025-02
Collective Pitch Transducers Part Number 412-074-101-103/-107 causing Engine Parameter Oscillations and Full Authority Digital Engine Control (FADEC) Faults
Summary
The Transport Canada Civil Aviation Safety Alert (CASA) titled "Collective Pitch Transducers Part Number 412-074-101-103/-107 causing Engine Parameter Oscillations and Full Authority Digital Engine Control (FADEC) Faults" addresses issues affecting Bell Textron Canada Limited (BTCL) Model 407 helicopters. The alert informs owners, operators, and maintainers about engine parameter oscillations and FADEC faults linked to specific collective pitch transducers (CPT) part numbers 412-074-101-103 and 412-074-101-107 installed on these helicopters.
What Changed
This CASA announces the release of BTCL Technical Bulletin 407-23-140, which provides installation instructions for a redesigned CPT with part number 412-074-101-105. This new transducer incorporates design improvements to resolve the engine parameter oscillations and FADEC faults that persisted despite previous replacements with part number 412-074-101-107. The alert supersedes earlier corrective actions by introducing a fully redesigned CPT assembly validated through flight testing.
Why It Matters
The issues addressed by this alert can cause engine parameter oscillations, rotor speed droop and lag, FADEC faults, and reduced maximum power capacity during flight, which pose safety risks and operational disruptions. Aviation professionals, including operators and maintenance personnel, need to be aware of these risks to ensure continued airworthiness and safe operation of the affected Bell 407 helicopters. Timely compliance helps prevent in-flight engine control anomalies and potential power loss.
What To Do
Owners, operators, and maintainers of BTCL Model 407 helicopters are recommended to replace the older CPTs with part numbers 412-074-101-103 and 412-074-101-107 with the new redesigned CPT part number 412-074-101-105 as soon as possible. The installation should follow the instructions provided in BTCL Technical Bulletin 407-23-140. For further information, stakeholders are advised to contact Transport Canada or the designated continuing airworthiness office.