EASA AD CF-2026-12
Levelling and Weighing — Aft Moveable Ballast Box Assembly Door Hinge Failure
Summary
The Levelling and Weighing — Aft Moveable Ballast Box Assembly Door Hinge Failure is an Emergency Airworthiness Directive CF-2026-12 issued by Transport Canada. It applies to Bell Textron Canada Limited model 505 helicopters, serial number 65011 and subsequent, equipped with ballast box assembly Part Numbers SLS-706-201-207 and SLS-706-201-207FM. The directive addresses a failure risk in the door hinge of the aft movable ballast box assembly that could lead to loss of helicopter control.
What Changed
This new Emergency Airworthiness Directive prohibits the use of ballast weights within the affected aft movable ballast box assemblies due to a discovered hinge failure. It introduces an immediate grounding of the ballast box use as an interim safety measure following a hinge failure found during post-flight inspection. This action follows a previous AD that mandated hinge replacement but now addresses a newly identified failure mode.
Why It Matters
This directive is critical for aviation professionals because failure of the ballast box door hinge can cause ballast weights to strike the tail rotor assembly, potentially resulting in severe vibrations and loss of helicopter control. Operators and maintenance teams must ensure compliance to prevent catastrophic tail rotor damage and ensure flight safety. The directive impacts operational readiness and maintenance planning for affected Bell 505 helicopters.
What To Do
Operators of Bell 505 helicopters with the specified ballast box assemblies must immediately cease using the ballast weights in the aft movable ballast box as of the effective date, March 4, 2026. Compliance is required before further flight. Stakeholders should monitor for further directives as this is an interim action and additional ADs may follow.