Synopsis
The aircraft was observed cruising at about 2,500 ft before it pitched nose-up and entered a steep spinning descent, striking the ground. The left wing folded rearwards during the descent, attributed to a structural failure near the wing root caused by upward bending beyond design limits. No pre-existing material defect or significant design issue was found in the wing structure. The failure most likely occurred during an attempted recovery from an inadvertent manoeuvre inducing a structural overload, but the cause of the manoeuvre could not be identified. One Safety Recommendation was made regarding the EV-97 Eurostar pitch trim mechanism.
History of the Flight
The pilot planned a flight from Arclid Airfield, Cheshire, to Swansea Airport, expecting a duration of about 1 hour 20 minutes. On the morning of the accident, he arrived at the airfield, likely refuelled the aircraft using jerry cans, and was seen in good spirits. He was accompanied by a passenger, a friend of his son.
The aircraft took off from Runway 20 at Arclid at about 0946 hrs, heading south-west. Radar data showed a gradual climb to 3,300 ft, with altitude varying but remaining above 2,000 ft. At 0955 hrs the pilot contacted London Flight Information Service, reporting his route at 2,500 ft and requesting a Basic Service. At 1010 hrs, London Information requested confirmation of routing and ETA; the pilot stated he was routing directly to Swansea with an ETA of 1145 local time (1045 UTC), though this was likely an error.
The aircraft continued on track until 1015 hrs, when near Shrewsbury it turned left and flew parallel to the original track. At 1045 hrs, after a period of straight and level flight, it began a descent, followed by climbing and turning manoeuvres. Further manoeuvring occurred at 1053 hrs, including descents and climbs, with a final climb from 2,550 ft to 2,975 ft over 40 seconds.
Witnesses on a track half a mile east of the accident site reported seeing the aircraft fly over in a normal level or slightly climbing attitude. After turning around, one witness noticed the aircraft in a vertical climbing attitude, then nose-down and rotating in a spiralling descent; the left wing appeared to have turned and pointed toward the tail. Other witnesses heard unusual engine noise and saw the aircraft plummeting and spinning, with a wing folded back.
Accident Site
The wreckage was found in a field near Builth Wells, about 360 m from the last radar return, in an initial impact crater indicating high vertical speed and low forward speed. The left wing was folded forward with significant impact damage near the root; the right wing had leading-edge compression along its entire length. A section of left wing belly fairing was found about 50 m behind the tail. No other parts were scattered between that point and the main wreckage.
Recorded Information
Radar data from Manchester and Clee Hill provided position and Mode S altitude every 8 seconds. The final stage showed the aircraft flying level for 40 seconds at an estimated groundspeed of 87 mph, equating to an airspeed of about 97 mph. A climb at 1,314 ft/min was followed by a descent of 2,440 ft/min between the last two radar returns. The final recorded radar return at 1056:23 hrs placed the aircraft at 2,625 ft (about 2,100 ft above ground), nearly overhead the accident site. No other traffic was recorded within 10 minutes of the accident.
Flight Planning and Navigation App
The pilot used SkyDemon on a mobile device, which can provide warnings when approaching a Danger Area. Danger Area EGD203, extending from the surface to 23,000 ft, was located 3.5 nm from the end of the radar track. With default settings, a warning would have been received around the end of the recording. Three mobile devices were recovered from the wreckage but were too damaged to extract data.
Meteorology
Weather conditions were fine with light winds and occasional cloud. A Met Office aftercast estimated wind at 2,000 ft as 240° at 10 kt. A motor glider pilot flying through the area 20 minutes after the accident reported cloud above 2,500 ft and fine conditions with light thermal activity.
Pilot Information
The pilot, aged 55, held a National Private Pilot's Licence (Microlight) and had 316 hours of flying experience, all on type, with 58 hours in the last 90 days and 22 hours in the last 28 days. He started training in October 2014 and qualified in June 2015 after 73 hours.