Flight Controls - Horizontal Stabilizer Trim Actuator (HSTA) - Rubber Bull Gear (RBG) Wheel Abnormal Wear
- Published
- Effective
- Deadline
AI-generated summary of the official EASA document. Verify against the PDF before acting.
What to do
Operators must verify the HSTA serial numbers within 4000 flight cycles from the AD effective date against the applicable MHIRJ Service Bulletin SB 670BA-27-077. If affected, the RBG wheels must be removed and replaced within the same 4000 flight cycle limit. Installation of affected HSTA units is prohibited unless they bear the suffix 'D' on the identification plate. Compliance must be completed by 12 July 2024 plus 4000 flight cycles on the HSTA.
Summary
The Canadian Airworthiness Directive CF-2024-25 addresses abnormal wear of the Rubber Bull Gear (RBG) wheel in the Horizontal Stabilizer Trim Actuator (HSTA) on Mitsubishi Heavy Industries RJ Aviation ULC model CL-600 series aircraft, including CL-600-2C10, CL-600-2C11, CL-600-2D15, CL-600-2D24, and CL-600-2E25. This directive mandates inspection and replacement of affected RBG wheels to prevent failure of the horizontal stabilizer trim system. The AD applies to all serial numbers of the specified aircraft models.
What changed
CF-2024-25 introduces a new mandatory inspection and replacement requirement for HSTA RBG wheels showing abnormal wear due to machining and surface treatment quality issues. It requires verification of HSTA serial numbers against a specified service bulletin and prohibits installation of affected components unless marked with a specific suffix. This is a new regulation addressing a recently identified unsafe condition.
Why it matters
This AD is critical for aviation professionals to prevent potential failure of the horizontal stabilizer trim system, which could compromise flight safety. Operators and maintenance organizations must ensure compliance to avoid grounding aircraft or facing regulatory penalties. The directive helps maintain airworthiness by addressing a specific component wear issue that could lead to in-flight warnings and system malfunctions.
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