EASA SIB CASA-2022-05
Circuit Breaker Panels — Inadequate Torque on Mounting Hardware
Summary
Transport Canada Civil Aviation Safety Alert CASA 2022-05 is a safety alert addressing inadequate torque on mounting hardware of circuit breaker panels #1 and #2 in Mitsubishi Heavy Industries RJ Aviation CRJ 550/700/701/702/705/900/1000 aeroplanes. The alert highlights issues with improper assembly and torque values on circuit breaker bar connections and bus bar connections that have led to in-flight system failures and increased crew workload.
What Changed
CASA 2022-05 introduces new Aircraft Maintenance Manual (AMM) tasks specifying removal and installation procedures for circuit breakers and bus bars to correct improper installation practices. The alert also notes updates to torque values and installation techniques in the Electrical Standard Practice Manual (ESPM) and the issuance of a temporary AMM revision and Wingspan article to raise immediate awareness.
Why It Matters
This alert is critical for operators, maintainers, and compliance teams as improper torque and installation of circuit breaker hardware can cause electrical failures, system alerts, and degraded flight control responsiveness. Correct procedures reduce the risk of in-flight system malfunctions, improve safety, and help maintain regulatory compliance.
What To Do
Affected personnel must follow the revised AMM tasks and ESPM torque specifications when removing and installing circuit breakers and bus bars. Operators should review Service Bulletin 670BA-24-032 for additional guidance and ensure maintenance staff are trained on the updated procedures. The revised AMM with new tasks is scheduled for publication by December 2022.