Avid Speedwing (Modified), G-FOLD, 22 August 2002

1 Avid Speedwing (Modified), G-FOLD AAIB Bulletin No: 8/2003 Ref: EW/C2002/08/02 Category: 1.3 Aircraft Type and Registration: Avid Speedwing (Modified), G- FOLD No & Type of Engines: 1 Rotax 582 piston engine Year of Manufacture: 1994 Date & Time (UTC): 22 August 2002 at 1630 hrs Location: Otherton Airfield, Staffordshire Type of Flight: Private Persons on Board: Crew -1 Passengers - None Injuries: Crew - 1 (Serious) Passengers - N/A Nature of Damage: Damaged beyond economic repair Commander's Licence: Private Pilot's Licence Commander's Age: 46 years Commander's Flying Experience: 414 hours (of which none were on type) Last 90 days - 93 hours Last 28 days - 28 hours Information Source: AAIB Field Investigation History of the flight On the day prior to the accident, the aircraft had been flight tested by a PFA inspector following a wing span extension modification. The inspector completed the test flight and was satisfied with the aircraft's performance. This type of aircraft requires a Permit to Fly to be issued by the CAA, on the recommendation of the Popular Flying Association (PFA), before any other flight may be conducted. However, at the time of this accident, the Permit to Fly had not yet been issued, but there was no reason to suggest that it would not have been issued in due course. As the owners were not qualified pilots, they intended to let a member of the local flying club familiarise himself with the aircraft before flying with them. This pilot had not flown the Avid Speedwing before but owned and regularly flew a Kitfox aircraft, which is similar. The day following the test flight, the pilot visually checked the aircraft and made several high-speed taxi runs. With the owner's assistance, the aircraft was refuelled and the pilot commenced his solo familiarisation flight. During his pre take-off checks, the pilot verified that the controls were moving freely and in the correct sense. As he accelerated down the grass Runway 34, he felt a 'bump' and heard a distinct 'crack' at approximately 65 mph. The takeoff was continued and, as the aircraft became airborne, there began an uncommanded gentle roll to the left. A witness on the ground observed a short period of level flight before the roll commenced. Application of right roll demand failed to correct the roll and the pilot reported that the left bank increased as he applied right stick input, but at no time did he feel any restriction to movement of the control stick. Document title 2 At approximately 100 feet agl and 85 mph, the aircraft began to descend with an increasing angle of bank. The pilot reduced power momentarily, which increased the nose down attitude. Full power and full up elevator were applied. Just prior to impact, the pilot applied full left rudder in order that the right side of the aircraft would take the full force of the impact. A witness stated that the aircraft appeared to be turning back towards the airfield as if to make an emergency landing. Further witness and pilot reports suggested that the aircraft struck the ground initially with the left wing or landing gear and rapidly rolled onto the right wing, with the aircraft slewing through 90° to the left before coming to a halt. The pilot was able to extricate himself from the wreckage without assistance, but subsequently required hospital treatment. Aircraft Description The Avid Speedwing is a high wing kit plane, with a maximum take-off weight of 463 kg. It has a side-by-side two seat configuration. The aircraft can be 'trailered' for transport by road and has folding wings that rotate backwards about the aft spar pickup. The fuselage is constructed from a steel tube rigid joint truss structure. The fuselage and wings are covered in dope sealed Dacron fabric. The standard wing has a span of 24 feet, although the accident aircraft had been recently modified to increase the wing span to 30 feet. The kit can be built in either a tailwheel or a tricycle gear configuration. The accident aircraft originally had a tricycle gear configuration, but in May 2000 it was converted to a tailwheel configuration. The aircraft had a flaps-up stall speed of 50 mph at maximum take-off weight. The Avid's lateral control system is unusual in that it consists of two full span flaperons. The flaperons can be deflected symmetrically downwards to act as flaps and can also be deflected asymmetrically via the control stick to act as ailerons to control bank angle. The flaperon is actuated via a vertical control rod attached to the inboard leading edge of the flaperon. The vertical control rod is connected to a mechanical mixer behind the pilot's seat that takes flap input from the flap lever and lateral control input from the control stick. Wreckage and Impact Examination The impact marks in the ploughed field indicated that the aircraft had struck the ground in a left wing low attitude, with approximately 20 to 30 degree left bank. The aircraft had then yawed to the left and impacted travelling sideways. The sideways motion caused the right wheel to collapse underneath the fuselage and it had formed a track in the field along the direction of travel (see Figure 1). The direction of travel of the right wheel track was 151°M. The aircraft is estimated to have impacted at a speed of between 50 kt to 70 kt and travelled a distance of 25 metres along the ground. The right wing appeared to have dug into the soil, collapsing the wing tip, and absorbing some of the impact energy. Fortunately, the vertical impact was not sufficient to cause any spinal injury to the pilot. The tailwheel had bent to the left and dragged through the soil producing another track. The left wing was undamaged apart from slight rub and soil marks where the left wing tip had grazed the soil. The left wing aft lift strut threaded rod attachment had fractured. The left wing struts had also buckled forwards. The left flaperon had detached from the wing, but was still attached to its control rod - it was probably torn off when the left wing tip touched the ground. The right flaperon had detached and was buckled. It had separated from its control rod as the right wing had dug into the ground. Document title 3 Flight Control System Examination The control stick was free to move in both axes. The elevator control rod had been bent, but forceful application of full fore and aft stick caused the elevator to move to its full up and down travel. No evidence of any pre-impact damage to the rudder control system was found. The rudder was operated by cables that connected the rudder directly to the rudder pedals - these cables were intact. Sideways movement of the control stick moved a bell crank that was connected to a rod that operated the flaperon mixer mechanism behind the pilot's seat. The bell crank was bent and the connecting rod was also slightly bent. The stick moved the vertical flaperon control rods freely but the bent bell crank restricted the degree of down left flaperon available. When the bell crank was disconnected from the rod, the flaperon control rods operated to their full travel in both directions. It was possible to jam aft movement of the 'mixer to bell crank' connecting rod by rotating the pilot's left seat belt attachment plate downwards. However, with the seat belt secured, as it was in this accident, the plate would not have been able to jam the control rod. Older versions of the Avid had a flaperon control rod that passed directly underneath the seat - a design that enabled a collapsed seat to jam the control rod. The Avid in this accident was equipped with a modified control rod that passed along the left side of the fuselage, clear of the seat base. Airframe Examination The most extensive damage to the fuselage structure was to the landing gear truss as shown in Figure 2. The upper cross tube had fractured as a result of the sideways l

Accidents Database

Avid Speedwing (Modified), G-FOLD, 22 August 2002

Report Overview

Avid Speedwing (Modified), G-FOLD

Download report:

Official Documents

Document Content Preview

dft-avsafety-pdf-023415.pdf

Change History

Related Entities