History of the Flight
The pilot arranged a two-hour flight from Cambridge Airport to the Southwold area. After an external inspection, he called for taxi clearance at 0848 hrs and was cleared for takeoff from Runway 23 at 0858 hrs. Weather conditions were good, with surface wind 180°/8 kt and CAVOK reported at Cambridge at 0920 hrs. The forecast wind at 2,000 feet was 190°/17 kt.
The tower controller observed the takeoff but could not hear the engine due to soundproofing; no other witnesses commented on engine sound. Shortly after departure, the pilot contacted approach control and advised he was leaving the circuit. Radar showed the aircraft turned left and tracked directly toward Southwold.
A witness at Walsham Le Willows, about 30 nm east of Cambridge, heard the aircraft pass overhead making an unusual rasping noise "as if the exhaust was detached or broken." The engine was not misfiring but was described as noisy for that size of aircraft. The witness estimated altitude between 2,000 and 3,000 feet.
At 0928 hrs, the Cambridge approach controller received a distress call: "PAN PAN PAN GOLF ALPHA VICTOR LIMA ROMEO LOSING POWER FIVE MILES WEST OF SOUTHWOLD." The controller acknowledged and another aircraft monitored. A minute later, the pilot responded: "LIMA ROMEO, LOOKING AT HALESWORTH AS A LANDING SITE." Halesworth is a disused airfield 2.5 nm northeast of the town. The main runway has agricultural buildings on its west side, and straight metalled taxiways of sufficient length for a forced landing exist. A large flat open area lies between two taxiways in an arc from 190°T to 250°T.
The controller made two further calls but received no acknowledgement; a short unintelligible transmission possibly originated from the aircraft. Around this time, a witness in Halesworth, 7.5 nm west of Southwold, heard the engine run "roughly and then stop."
Occupants of a farmhouse 300 metres from the accident site heard and then saw the aircraft approaching from the south, wings level, at an estimated 300 feet. The engine made an irregular "put putting" noise as it passed overhead. Radar indicated ground speed was approximately 75 kt.
A nurse witness saw the aircraft execute a left turn at low angle of bank, yawed and skidding, still at about 300 feet agl. After turning left through approximately 90° onto a westerly heading, the aircraft descended with wings level, under control but making a forced landing. It was lost from sight behind trees. Between the aircraft and the disused airfield perimeter after the turn were two fields of standing peas about one metre high, each 100 metres long in the direction of travel and 200 metres wide, separated by a row of trees and bushes 12 to 14 feet high. The aircraft was estimated at 200 feet as it crossed the eastern edge of the first field.
Concerned witnesses set off in cars to find the aircraft. The farmer located it first and approached the wreckage. The nurse and an off-duty policeman arrived and rendered medical assistance until paramedics arrived by air ambulance. A Search and Rescue Sea-King helicopter evacuated the pilot to Ipswich Hospital.
Medical Aspects
Evidence indicated the pilot's lap and diagonal restraint harness was properly secured before he was released. However, during impact he slipped sideways to the right, out of the upper body restraint, and struck his head on the instrument panel, receiving a fatal injury. Post-mortem examination found no pre-existing medical condition that might have caused or contributed to the accident.
Engineering Investigation
The aircraft came to rest upright in the base of a 14–15 feet high hedge, resting on its left wing which had separated at the root and inverted. The left wing had broken structurally at the inboard end of the aileron cut-out. Evidence suggested the aircraft struck the hedge top first with its upper surfaces before falling back. The rear fuselage and tail were bent to the right and downwards; the engine frame crushed rearwards, but the cabin section was not severely distorted.
The aircraft approached on a track of about 300°M over gently falling ground that became level over the last 50 metres. The left wingtip first contacted the ground, cutting a widening swath for about 8 metres through the crop. Ground marks indicated the left outer wing failed structurally at about 2/3 semi-span, separated at the root, and the nose landing gear and engine struck the ground. The nose gear broke off, but no marks showed the main gear or right wing struck the ground. There was no evidence of sliding between engine contact and the hedge.
Propeller condition showed no evidence of significant power at impact. Engine examination in situ revealed no obvious mechanical failure; no significant oil spillage in the engine bay or along the ground path, but an oily patina existed along the underside of the fuselage and tailplane.
The accident site characteristics were consistent with the aircraft stalling and dropping its left wing while flying close to the ground, then pitching nose-down and yawing left, striking the ground before bouncing into the hedge nose-down at about 45°.
Detailed examination at the AAIB showed the aircraft was in a clean configuration, controls serviceable, elevator trim at mid-range. No evidence suggested any airframe malfunction or failure before impact. The pilot's harness was sound; neither lap strap nor diagonal belt showed evidence of high loading.
Engine examination revealed a massive internal mechanical failure consistent with very rapid loss of oil contents or pressure. The big ends of No. 1 and 2 connecting rods failed in tensile rupture, having become so hot that strength was insufficient to sustain inertial forces. Their crankpins were heavily scored. No. 3 big end showed severe heat distress and heavy scoring; No. 4 showed some distress and light scoring. All crankshaft main bearings and other lubricated surfaces were in good condition. No debris penetrated the crankcase. Examination of oil lubrication system ancillary equipment found no pre-impact failure or misassembly that could cause significant oil loss. Engine compartment showed no significant oil wetting of cowling interior or firewall, only light oil mist near top of nose gear leg and light oil wetting underside of fuselage. No evidence of oil leakage through failed casings or seals; only evidence of oil escape was from the crankcase breather, and no logical explanation could be found.
Maintenance
The aircraft's records indicated it was properly certificated and regularly maintained. The last maintenance was a Star Annual inspection for Certificate of Airworthiness renewal, during which cylinders No. 1 and 3 were removed for overhaul and refitted with new piston rings correctly installed. After reassembly, the engine was filled with 8 quarts of appropriate oil. Oil consumption after maintenance was normal; one litre was added after 24 hours flying to bring to full, and no further oil was added in the next 6 hours. The pilot who flew the aircraft for 35 minutes before the accident flight stated the sump appeared full when dipstick checked.
Discussion
Following loss of engine power, the pilot declared intention to land at Halesworth. He positioned the aircraft downwind for a left-hand circuit, but which area he intended to land on is not known.