Date:	Friday 23 September 2016
Time:	09:45 LT
Type:	Westland Wasp HAS1
Owner/operator:	Private
Registration:	G-KAXT
MSN:	F9669
Year of manufacture:	1967
Engine model:	Rolls-Royce Nimbus MK 10301
Fatalities:	Fatalities: 0 / Occupants: 2
Aircraft damage:	Substantial
Category:	Accident
Location:	Bishopstone, near Salisbury, Wiltshire -   United Kingdom
Phase:	En route
Nature:	Private
Departure airport:	Middle Wallop Airport (EGVP)
Destination airport:	Yeovilton Royal Naval Air Station (YEO/EGDY)
Investigating agency:	AAIB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
Westland Wasp HAS1 G-KAXT suffered a loss of collective pitch control resulting in a forced landing, at Bishopstone, near Salisbury, Wiltshire.

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.

=Nature of Damage=
Per the AAIB report "Broken universal joint and collective pitch control rod, damaged tail rotor and driveshaft,
structural damage"

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

=Safety Recommendation 2017-012=
It is recommended that, for ex-military aircraft on the UK civil register, the Civil Aviation Authority requires maintenance and overhaul tasks to be reviewed in the light of the expected aircraft utilisation and calendar-based time limits introduced where appropriate. Where such calendar-based time limits already exist, these should be reviewed to ensure that they are appropriate for the aircraft utilisation"

Bishopstone is a village and civil parish in Wiltshire, England, in the Ebble valley about 5.5 miles south-west of Salisbury. The parish is on the county boundary with Hampshire and includes the small village of Croucheston and the hamlet of The Pitts

1 AAIB final report: https://assets.publishing.service.gov.uk/media/591c30aaed915d20f800001c/Westland_Wasp_HAS1_G-KAXT_06-17.pdf2.
2. http://www.salisburyjournal.co.uk/news/14761108.Helicopter__comes_down_with_a_bump__in_turnip_field/
3. https://www.spirefm.co.uk/news/local-news/2103586/navy-helicopter-makes-controlled-landing-in-bishopstone/
4. http://www.bishopstone-salisbury.co.uk/helicopter-crash.html
5. http://aerossurance.com/helicopters/wasp-stung-lack-lubrication/
6. https://navywings.org.uk/portfolio/westland-wasp-2/
7. http://www.adf-serials.com.au/nz-serials/nzwasp.htm
8. https://rnzaf.proboards.com/thread/10030/westland-wasp
9. https://www.facebook.com/navyrotors/posts/airshow-and-event-organisers-wishing-to-contact-us-about-a-booking-for-the-2016-/894841540593684/
10. https://en.wikipedia.org/wiki/Bishopstone,_Salisbury

XT787 c/n F9669 was built as part of Royal Navy contract KK/N/93/CB25(a) at the Fairey division of Westland Helicopters Hayes on 10th January 1967 and made her first flight on 19th January 1967. In her Royal Navy career, XT787 (as \'476\') operated on frigates HMS Leander and HMS Rhyl as part of 829 NAS and also later with 703 Sqn (Portland).

After being retired in 1981, the Royal Navy\'s Wasp helicopters were reinstated into service during the Falklands campaign when RN Wasps were brought out of storage for deployment on Leander, Tribal and Rothesay class frigates which were too small to carry the Lynx helicopter which replaced the Wasps on the newer ships of the fleet.

However, in October 1982, not long after the cessation of hostilities in the Falkland Islands, XT787 was struck off charge from the Royal Navy and, because of her excellent condition and low hours (679:40 total flying hours in RN) she was transferred to New Zealand where, until 1997, she served as part of the RNZAF but in service with RNZN as NZ3905. On 24 March 1985, and against all the rules, the Wasp landed the right front wheel on the top of Mount Cook, at 12,350 Feet. No other Westland Wasp had ever done this, but why unrepeatable? Well, a few years later, about 70 million tons fell off the top and it\'s now 32 feet shorter!

On being withdrawn from RNZN service in March 2002, (after accumulating a total of 2,661 hours on the airframe) NZ3905 was sold back to Westlands and was subsequently bought by Kennet Aviation and registered as G-KAXT. With MoD approval, G-KAXT was again marked as XT787, and repainted in the South Atlantic camouflage scheme of HMS Endurance’s Wasp XS527 which took part in the attack of the \'Santa Fe\'.

Latest: AAIB current field investigations page updated https://t.co/DJlvISgzRX pic.twitter.com/Aezjv0Dnwx

— AAIB (@aaibgovuk) October 20, 2016

Westland Wasp G-KAXT (in former markings as XT787) landing at Shuttleworth Collection Airfield, Old Warden, Bedfordshire September 24 2011

Collective pitch control rod failure to Westland Wasp, 23 Sep 16 https://t.co/ubfoosqCeq pic.twitter.com/GuhbCIcNEX

— AAIB (@aaibgovuk) 9 juin 2017

Date/time	Contributor	Updates
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]
06-Apr-2024 06:37	Dr. John Smith	Updated [Departure airport, Destination airport, Source, Embed code, Narrative, Category]
06-Apr-2024 06:38	ASN	Updated [[Departure airport, Destination airport, Source, Embed code, Narrative, Category]]
06-Apr-2024 06:39	ASN	Updated [Narrative]
06-Apr-2024 06:39	ASN	Updated [[Narrative]]