Date:	Thursday 30 April 1959
Time:	day
Type:	Westland Whirlwind HAS.7 (S-55T)
Owner/operator:	Westland Helicopters Ltd
Registration:	XK941
MSN:	WA/168
Fatalities:	Fatalities: 0 / Occupants: 2
Aircraft damage:	Destroyed
Location:	Yeovil Aerodrome, Yeovil, Somerset -   United Kingdom
Phase:	Approach
Nature:	Test
Departure airport:	Yeovil Aerodrome, Yeovil, Somerset (EGHG)
Destination airport:	Yeovil Aerodrome, Yeovil, Somerset (EGHG)
Confidence Rating:	Information is only available from news, social media or unofficial sources

Narrative:
Westland Whirlwind HAS.7, First flown: 27 August 1957. Delivered to Royal Navy Fleet Air Arm as XK941, 21 September 1957. Returned to Westland Helicopters for trials and tests, 1958

Written off (damaged beyond repair) 30 April 1959 on a post-overhaul test flight: control was lost while in a hover at Yeovil, Somerset, due to fatigue failure of the starboard lateral control rod. The main rotors struck the ground after the aircraft rolled to port. It came to rest on its port side and caught fire. The two crew escaped without injury

According to the following published eyewitness report from one of the crew (see link #8):

"A day in the life of a Flight Test Observer
By Bob Klitz
Aircraft: Westland Whirlwind Mk 2 XK941
Pilot: Lt Brigham RN
Date: 30 April 1959
We had been conducting Clutch Endurance trials following failures in service of transmission between engine and main rotor, calling for the immediate adoption of flare-out landing drill utilising just residual rotor speed/inertia to cushion the landing under collective control. The lower the altitude at which the failure occurred, the lower the chance of preserving the airframe.

One of our company test pilots would demonstrate how he could drop his helicopter safely on the pad by cutting the power at a hundred feet and pulling it off with inches to spare. The object of the endurance trial was to accumulate airframe hours by repeated cycles of ten minutes hovering at ten feet followed by a minute in the circuit at around a thousand feet and the next ten back in the hover at ten feet. This cycle would be continued for around one and a half hours during which readings were recorded, followed by crack detection inspection of suspected components.

After returning from the completion of the fourth circuit around Yeovil we were into the first couple of minutes of the fourth hover at about ten feet over the airfield when all control of the cyclic pitch was lost suddenly! The Whirlwind dropped rapidly onto it’s port side, the rotor blades striking the ground and paddling the fuselage round some fifty degrees to starboard before coming to a standstill. Being in the port seat, I could not move anywhere to escape until the pilot, of heavy build, eventually got out above me.

I think he was still counting our lucky stars that the control loss hadn’t occurred five minutes earlier...After we got clear, Avgas, leaking from the ventral tank ignited and the wreck soon became somewhat engulfed. Not the clutch, but the far more serious cyclic control linkage failure was shown to be the cause in this instance. A defect of much wider significance but which shed no light on the RN failures".

1. Halley, James (1999) Broken Wings – Post-War Royal Air Force Accidents Tunbridge Wells: Air-Britain (Historians) Ltd. p.199 ISBN 0-85130-290-4.
2. Royal Air Force Aircraft XA100-XZ999 (James J Halley, Air Britain, 2001 p 53)
3. Wings Over Somerset: Aircraft Crashes since the End of World War II By Peter Forrester
4. National Archives (PRO Kew) File AVIA 5/40/S3009: https://discovery.nationalarchives.gov.uk/details/r/C6578789
5. National Archives (PRO Kew) File BT233/410: https://discovery.nationalarchives.gov.uk/details/r/C424531 (Note: File mis-recorded as "Whirlwind XK951" [sic] = XK951 was a Canberra)
6. National Archives (PRO Kew) File AVIA 5/38/S2938: https://discovery.nationalarchives.gov.uk/details/r/C6578718
7. http://www.ukserials.com/results.php?serial=XK
8. https://www.helis.com/database/cn/26627/
9. http://www.ukserials.com/losses-1959.htm
10. https://www.faasquadron.org.uk/Portals/33/docs/Buzz%2064%20Apr%202013.pdf

Date/time	Contributor	Updates
23-Jan-2013 16:29	Dr. John Smith	Added
27-Jan-2020 15:51	Dr. John Smith	Updated [Time, Location, Departure airport, Destination airport, Source, Narrative]
27-Jan-2020 15:52	Dr. John Smith	Updated [Narrative]
27-Jan-2020 15:53	Dr. John Smith	Updated [Source]
02-Dec-2020 23:32	Dr. John Smith	Updated [Source]