Stampe SV4C (Modified), G-BIMO, 10 July 2010

32 © Crown copyright 2011 AAIB Bulletin: 5/2011 G-BIMO EW/C2010/07/01 ACCIDENT Aircraft Type and Registration: Stampe SV4C (Modified), G-BIMO No & Type of Engines: 1 de Havilland Gipsy Major 10 Mk 2 piston engine Year of Manufacture: 1946 Date & Time (UTC): 10 July 2010 at 1640 hrs Location: Near Rotherfield Peppard, Oxfordshire Type of Flight: Private Persons on Board: Crew - 1 Passengers - 1 Injuries: Crew - 1 (Fatal) Passengers - 1 (Fatal) Nature of Damage: Aircraft destroyed Licence: Private Pilot’s Licence Age: 41 years Flying Experience: About 179 hours (of which 95 were on type) Last 90 days - at least 8.5 hours Last 28 days - Not known Information Source: AAIB Field Investigation Synopsis The aircraft entered an inverted spin during an unsuccessful attempt to perform a rolling aerobatic manoeuvre and impacted the ground, causing the two occupants to receive fatal injuries. No technical defects were found that could have contributed to the accident. History of the flight The aircraft departed White Waltham Airfield at about 1530 hrs for a local flight. The owner, who was PPL‑qualified, was seated in the front cockpit and a friend of his, also PPL-qualified, was seated in the rear. The majority of the flight and the entire accident sequence were recorded by a digital video camera mounted on the owner’s helmet. The history of the flight was reconstructed from a combination of the video evidence, eyewitness statements and recorded radar data. Despite the video evidence, it was not possible to determine who was flying the aircraft. The aircraft departed to the west of White Waltham, climbing steadily to a peak recorded altitude of 3,650 ft as indicated by the front cockpit altimeter. After making various gentle climbing turns, the aircraft tracked in a generally southerly direction. It then conducted a 180° level turn to track approximately north. Video evidence of the accident manoeuvre shows that the aircraft pitched nose-down and accelerated to 110 kt at 3,400 ft, before pitching nose-up. The attitude 33 © Crown copyright 2011 AAIB Bulletin: 5/2011 G-BIMO EW/C2010/07/01 was stabilised with the nose above the horizon. The aircraft then commenced a slow roll to the right, with the nose remaining above the horizon until the aircraft had rolled past the inverted. The roll continued, but the aircraft’s flight path then became ‘spooned’, resembling the helical profile of a barrel roll. The aircraft appears to have departed controlled flight during the roll, with the departure developing into an inverted spin which continued for eight turns until the aircraft entered the tree canopy, some 37 seconds after commencing the roll. Both occupants received fatal injuries in the ground impact. Several eyewitnesses observed the aircraft’s uncontrolled descent. Aircraft information The Stampe SV4C is a two-seat biplane of predominantly wooden construction which has been used extensively for aerobatics. G-BIMO was built in 1946 and was placed on the UK civil register in 1981. In 1995 it underwent a major modification involving replacement of the original Renault engine with a De Havilland Gipsy Major 10 Mk 2 engine and a Hoffmann wooden propeller. In addition to the two tandem pilots’ seats, the fuselage incorporated a locker, with a hinged forward door, positioned under the curved upper decking aft of the rear seat. Small items of loose equipment could be placed therein and were retained by the closed door. The fuel system incorporated a single tank positioned in the centre of the upper wing. This location is close to the empty longitudinal centre of gravity (CG) of the aircraft. G-BIMO utilised a ‘flop tube’ fuel pick-up arrangement to ensure that fuel could be drawn from the tank irrespective of aircraft’s attitude or direction of acceleration. Accident site The wreckage of the aircraft came to rest in woodland. The on-site evidence was consistent with the aircraft having struck the treetops at a very steep flight path angle, with its longitudinal axis orientated beyond the vertical. The aircraft was structurally complete at the initial impact with the trees. The extent of the damage sustained by the aircraft in its passage through the trees and the ground impact was consistent with a relatively low descent speed. The four wing surfaces were relatively lightly damaged and were geometrically disposed in approximately their correct relative positions. A considerable proportion of the wooden forward fuselage had been destroyed. Damage to the wooden propeller, and horizontal slash marks on a vertical tree trunk, indicated that the engine was turning at a low rpm, but was delivering some power during the impact sequence. Substantial quantities of loose items associated with the aircraft and items of clothing were recovered from the accident site. Detailed wreckage examination The aircraft wreckage was recovered to the AAIB facilities for detailed examination. The flying controls were found to be correctly connected, except where obvious impact damage had occurred. No evidence of control restriction was found. External examination of the fuel system and strip examination of the engine revealed no evidence of pre‑impact failure. The aviation-related items and clothing recovered from the vicinity of the site were collected and were found to be capable of all being securely stowed simultaneously within the fuselage locker on another aircraft of the same type. 34 © Crown copyright 2011 AAIB Bulletin: 5/2011 G-BIMO EW/C2010/07/01 There was no evidence available to allow the quantity of fuel on board the aircraft at the time of the accident to be established. Weight and balance A weight and balance calculation was performed by the AAIB using the empty weight and CG position established when the aircraft was weighed in 1995. The post-mortem occupant weights were used, together with the total mass of the loose items, all of which were assumed to have been placed in the locker behind the rear seat. As the fuel contents at the time of the accident were unknown, various possibilities were considered. In general, it appeared that with the tank more than approximately half-full, the CG would have been within specified limits, but the total weight would have exceeded the maximum aerobatic limit. With a low fuel load the CG would have been further aft and could have been close to, or just beyond, the specified aft limit. Pilot experience The owner and his friend had completed PPL courses at the same flying school during 2008. The flying school had retained their training records, which showed that they had made good progress throughout the course. Both had around 200 hours total flying experience. According to the owner’s flying logbook, he gained his PPL after approximately 73 hours. He then undertook differences training on the Stampe with a qualified flying instructor, who was approved to teach aerobatics. He completed his differences training after approximately 15 hours. According to the instructor, the owner undertook aerobatics training with him and had reached the stage where he was competent to perform aileron rolls and loops solo. The instructor had demonstrated stall turns, half-Cubans and barrel rolls to the owner, but the owner was reportedly not yet competent in performing these. In total, the owner’s logbook had 21 entries referring to some form of aerobatics, mainly loops and rolls and almost all with him recorded as pilot in command. Although the instructor had checked out the owner on flying the Stampe from the rear seat, the owner was legally permitted to fly the aircraft from either seat. Shortly after qualifying for his PPL, the owner’s friend purchased a share in a Jungmann. During his differences training, his instructor had demonstrated some basic aerobatic manoeuvres to him. It is believed that the owner’s friend had completed about 23 hours on the Jungmann; his most recent flight in it was August 2009. The

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Stampe SV4C (Modified), G-BIMO, 10 July 2010

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