EASA SIB CASA-2025-08
Low Torque on Transmission Mounted Bellcranks
Summary
The Transport Canada Civil Aviation Safety Alert (CASA) titled 'Low Torque on Transmission Mounted Bellcranks' (CASA 2025-08) addresses a potential issue affecting Bell Model 429 helicopters with specific serial numbers. It highlights the risk of accelerated wear and fatigue cracking due to under-torqued transmission bellcrank assembly joints. The alert provides guidance on inspection and corrective actions to ensure proper torque application and hardware replacement.
What Changed
This new safety alert introduces awareness of incorrect torque values used during assembly of transmission-mounted bellcranks on Bell 429 helicopters, which may lead to increased bolt fatigue and damage. It references Bell Alert Service Bulletin 429-22-58 Rev A and updates the 2-year flight controls inspection procedure to include checks of these bellcranks and their supports. The alert mandates inspections, part replacements, and correct torque application to mitigate the identified risks.
Why It Matters
For aviation professionals, this alert is critical because improper torque can cause premature wear and potential failure of key flight control components, impacting helicopter safety and reliability. Operators, maintainers, and compliance teams must address this issue to prevent costly repairs and ensure continued airworthiness. Timely inspections and adherence to updated maintenance procedures help maintain operational safety and regulatory compliance.
What To Do
Owners, operators, and maintainers of Bell Model 429 helicopters with serial numbers 57001 to 57335, 57338, 57343, and 57346 should perform inspections and replace affected parts as outlined in Bell ASB 429-22-58 Rev A. They must also apply the correct torque values during assembly and incorporate the updated 2-year flight controls inspection procedure. These actions should be completed in accordance with the latest maintenance manual revisions to ensure compliance and safety.