Attention:
Owners, operators and maintainers of Airbus Canada Limited Partnership (ACLP) aeroplanes model BD‑500‑1A10 and BD‑500‑1A11
| File Classification No.: | Z 5000-35 |
|---|---|
| RDIMS No.: | 21245949 |
| Document No.: | CASA 2026-03 |
| Issue No.: | 01 |
| Effective Date: | 2026-03-10 |
Purpose:
The purpose of this Civil Aviation Safety Alert is to raise awareness of unexpected localizer signal disturbances on ACLP model BD-500-1A10 and BD-500-1A11 aeroplanes, and to recommend relevant corrective actions to mitigate the issue.
Background:
In-service events involving unexpected localizer signal disturbances have been reported. These occurrences were identified during Instrument Landing System approaches at various altitudes, including during the rollout phase, and might have resulted in deviations from the normal flight path or ground tracking. In some situations, the approach capability was degraded; in others, the disturbance was subtle enough that it went unnoticed by the flight crew and did not trigger an excessive deviation alert.
Localizer signal disturbances can generate lateral autopilot commands, which may require flight crew intervention by disconnecting autopilot during approach and/or rollout.
To address these concerns, ACLP issued Flight Operations Transmission (FOT) A220‑FOT‑34‑50‑001 to raise awareness and provide operational recommendations. Subsequently, ACLP’s investigation identified improper radome rigging and potentially inadequate electrical bonding as suspected root causes. Consequently, ACLP issued Service Bulletin (SB), BD500-538013 to modify the radome assembly and frame to improve conductivity on applicable aeroplanes.
Recommended action:
Transport Canada (TC) recommends that owners, operators and maintainers of ACLP model BD‑500‑1A10 and BD‑500‑1A11 applicable aeroplanes incorporate the modifications as described in SB BD500‑538013 Issue 001, dated 30 October 2025, or later revisions, to improve conductivity.
For aeroplanes where these recommended modifications have not been incorporated, owners and operators should ensure that all flight crews are aware of and apply the recommended operational procedures and guidelines provided by ACLP FOT A220‑FOT‑34‑50-001 Revision E, dated 04 November 2025, or later revisions.
Within Canada, in accordance with the reporting requirement of Part V, subpart 21 (521) of the Canadian Aviation Regulations, owners, operators and maintainers should submit a Service Difficulty Report (SDR) to TC for the discovery of each reportable service difficulty. (Please note: if any localizer signal disturbance occurs that is noticed and/or affects flight or ground tracking, an SDR should be submitted). Outside Canada, report any such occurrence in accordance with local reporting requirements.
ACLP continues to assess this issue. TC may recommend or mandate additional corrective actions as necessary.
Contact office:
For more information concerning this issue, contact a Transport Canada Centre; or contact João Falcão, Continuing Airworthiness in Ottawa, by telephone at 1-888-663-3639, or by e-mail at TC.CAWWEBFEEDBACK-retroactionWebMDLN.TC@tc.gc.ca.
Original signed by
Jenny Young
Chief, Continuing Airworthiness
National Aircraft Certification
Localizer signal deviation disturbances
(PDF, 246 KB)
The Transport Canada Civil Aviation Safety Alert (CASA) is used to convey important safety information and contains recommended action items. The CASA strives to assist the aviation industry's efforts to provide a service with the highest possible degree of safety. The information contained herein is often critical and must be conveyed to the appropriate office in a timely manner. The CASA may be changed or amended should new information become available.