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ASN Wikibase Occurrence # 191015
Last updated: 16 September 2021
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Time:09:45 LT
Type:Westland Wasp HAS1
Registration: G-KAXT
MSN: F9669
Fatalities:Fatalities: 0 / Occupants: 2
Other fatalities:0
Aircraft damage: Substantial
Location:Bishopstone, near Salisbury, Wiltshire -   United Kingdom
Phase: En route
Departure airport:AAC Middle Wallop (EGVP)
Destination airport:RNAS Yeovilton (EGDY)
Investigating agency: AAIB
Damaged during a precautionary landing. Civilian owned and operated, although marked as XT787 (its former Royal Navy markings).

With the helicopter straight and level at approximately 1,150 ft, the pilot felt vibration through the collective lever. The vibration ceased after two or three seconds.

Approaching higher ground, the pilot pulled up on the collective lever but the helicopter did not respond. He lowered the lever and again, there was no response. Faced with a loss of collective pitch control, the pilot made a precautionary landing, but was unable to control the flare. The tail rotor struck the ground but the helicopter remained upright. The pilot and his passenger were uninjured.

The investigation established that the collective pitch control rod in the main rotor gearbox had broken. The control rod failure was secondary to a universal joint failure that had occurred in the cyclic control circuit due to lack of lubrication and a build-up of corrosion deposits. The pilot had reported vibration in the preceding months but despite diagnostic efforts, the cause had not been identified.

The Civil Aviation Authority (CAA) issued Emergency Mandatory Permit Directive No 2017-002-E on 20 Feb 2017 applicable to UK-registered Westland Wasp and Scout helicopters, to perform a visual check of the condition of the universal joint and introduce periodic lubrication of the joint.

One Safety Recommendation has been made to the CAA to review the maintenance requirements for ex-military aircraft.


2. CAA:
6. (MPD)
7. AAIB final report :

Accident investigation:
Investigating agency: AAIB
Status: Investigation completed
Download report: Final report
Safety recommendations:

Safety recommendation 2017-012 issued 9 June 2017 by AAIB to CAA



Photo of G-KAXT courtesy

High Wycombe - Wycombe Air Park / Booker (EGTB / HYC)
14 June 2018; (c) Mick Bajcar

Revision history:

31-Oct-2016 16:00 Aerossurance Added
02-Nov-2016 18:23 Dr.John Smith Updated [Time, Total occupants, Location, Phase, Nature, Departure airport, Destination airport, Source, Embed code, Damage, Narrative]
02-Nov-2016 18:38 Dr.John Smith Updated [Embed code, Narrative]
20-Feb-2017 13:41 Aerossurance Updated [Time, Location, Source, Narrative]
09-Jun-2017 20:07 Iceman 29 Updated [Source, Embed code, Narrative]
27-Dec-2017 12:58 Aerossurance Updated [Time, Departure airport, Destination airport, Source, Embed code, Narrative]
28-Jan-2018 09:51 Aerossurance Updated [Source]

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