AAIB investigation to Westland Wasp HAS1, G-CMBE

Loss of control during pre-flight checks, Marston Doles, Warwickshire, 15 March 2025

From:
Air Accidents Investigation Branch
Published
14 August 2025
Category:
General aviation - rotorcraft
Report type:
Bulletin - Correspondence investigation
Date of occurrence:
15 March 2025
Aircraft type:
Westland Wasp HAS1
Location:
Marston Doles, Warwickshire
Registration:
G-CMBE

An instructor and student pilot were carrying out pre-flight checks. One of the checks required the deselection of the hydraulic system to ensure mechanical flying control continuity and freedom of operation in the correct sense. As the instructor selected the hydraulic system off, the collective lever 鈥榡umped鈥� upwards and the aircraft lifted into the air. The instructor was unable to regain control and the helicopter struck the ground and rolled over. The cause of the abnormal collective movement could not be positively determined but a transient system malfunction could not be ruled out.

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Published 14 August 2025