EASA AD CF-2021-19
Navigation System — Uncommanded Heading Change from Magnetic to True
Summary
Canadian Airworthiness Directive CF-2021-19 addresses an issue with uncommanded heading changes from magnetic to true on MHI RJ Aviation ULC aircraft, including Bombardier models CL-600-2B19, CL-600-2C10, CL-600-2C11, CL-600-2D15, CL-600-2D24, and CL-600-2E25 equipped with specific inertial reference system part numbers. The directive mandates updates to the Airplane Flight Manual to include revised abnormal procedures related to instrument systems. This AD aims to enhance flight safety by mitigating misleading heading information on primary flight and multi-function displays.
What Changed
This new Airworthiness Directive introduces a mandatory update to the Airplane Flight Manual's Chapter 05 – Abnormal Procedures – Instrument Systems for affected aircraft models. It addresses reports of uncommanded heading changes from magnetic to true, which can cause misleading navigation information. The AD requires operators to incorporate specific AFM revisions approved by Transport Canada and inform flight crews accordingly.
Why It Matters
Uncommanded heading changes can lead to significant navigation errors, potentially causing aircraft to operate outside protected terrain and obstacle clearance areas. For operators and maintenance teams, compliance with this AD is critical to maintain operational safety margins and ensure accurate heading information is displayed. Flight crews must be aware of the updated abnormal procedures to respond effectively to such events.
What To Do
Operators of affected MHI RJ Aviation ULC aircraft must update their Airplane Flight Manuals by incorporating the specified revisions to the abnormal procedures chapter within 30 days of the effective date, May 27, 2021. After updating the manuals, all flight crews must be briefed on the changes and operate the aircraft in accordance with the revised procedures. Compliance with CAR 605.84 regarding ADs must be ensured before conducting any take-off.
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