Windsor, VA, USA
N388BA
LET Blanik L 33 Solo
The pilot completed a preflight inspection of the glider, including the cockpit area. After a tow release at 3,000 feet msl, the pilot flew for about 1 hour. To descend, the pilot completed a spin to the right. He then induced a spin to the left, and heard a loud bang when an object struck the inside of the canopy. Then pilot then saw the object float forward and settle into the area where the rudder pedals were located. As he tried to apply opposite rudder, he felt a binding in the pedals. He had sufficient rudder authority to stop the spin's rotation; however, the airplane's dive angle and airspeed had increased significantly. The pilot "pulled back fairly hard" on the control stick, and as the airspeed climbed to 100-110 knots, he recovered the glider. The object that became entangled in the rudder pedals was subsequently identified as a transformer used for charging the glider's battery. The transformer was not normally used in the glider for recharging. It had been borrowed from another club member, and "someone" had used it to charge the battery via a long extension cord. The battery would have normally been disconnected, and put on a small transformer/charger in the club office.
On October 3, 2001, about 1315 eastern daylight time, a LET Blanik L 33 Solo glider, N388BA, operated by Tidewater Soaring Society, was substantially damaged during a descent into Garner Airport (3VA8), Windsor, Virginia. The certificated private pilot was not injured. Visual meteorological conditions prevailed at the time of the accident. No flight plan was on file for the local flight, conducted under 14 CFR Part 91. The Society's board of directors established an internal committee to investigate the accident. The resulting report became part of the information submitted to the Safety Board. According to the report, the pilot completed a thorough preflight inspection, including the cockpit area. After a tow release at 3,000 feet msl, the pilot flew the glider for about 1 hour, and was at 4,300 feet when he decided to descend using stalls and spins. After several stalls, he induced a spin to the right at approximately 4,000 feet. He completed the spin about 3,500 feet, never exceeding 85 knots. He then induced a spin to the left, and heard a loud bang when an object struck the inside of the canopy. The pilot then saw the object float forward and settle into the area where the rudder pedals were located. As he tried to apply opposite rudder, the pilot felt a binding of the pedals. He had sufficient rudder authority to stop the spin's rotation; however, the airplane's dive angle and airspeed had increased significantly. The pilot then "pulled back fairly hard" on the control stick, and as the airspeed climbed to 100-110 knots, he recovered the glider about 3,000 feet. The object that became entangled in the rudder pedals was subsequently identified as a transformer used for charging the glider's battery. The transformer was not normally used in the glider for recharging. It had been borrowed from another club member, and "someone" had used it to charge the battery via a long extension cord. Normally, the battery would have been disconnected and put on a small transformer/charger in the club office. The glider flew 14 times since the accident flight by various pilots, including the accident pilot. Pilots noted their flights as routine with no high g-loading, or abnormal or aerobatic maneuvers performed. Another pilot, who flew the glider immediately after the accident flight, observed the accident pilot's spins, approach and landing. He did not consider the second spin recovery to be abrupt, but he did think the glider's wing tips hit the ground "very firmly" during the landing rollout as the glider crossed a drainage depression in the runway. During his preflight inspection, the second pilot noted cosmetic damage to the spoiler caps, but no further damage to the wing, including the wing roots. Statements by subsequent pilots indicated that wing root damage began to appear as working rivets. Some noted that the condition of the wings was similar to the that found in other club gliders, including surface waviness, minor dents and cracked paint. On October 14, 2001, the club's operations officer grounded the glider when rivets on the bottom side of the wing root had progressed from "working rivets" to displaced rivets. A detailed examination revealed permanent plastic deflection of both wings, increased waviness of wing surfaces, and numerous bent rivets at both wing roots. The wing dihedral was measured, and found to have increased from the manufacturer's standard, by 34 mm on the left wing and 31 mm on the right wing. Later, at an authorized repair facility, the wings were determined to be "destroyed." According to the glider's Sailplane Flight Manual, at 110 knots indicated airspeed, the g-limit was approximately 4.6 g's at maximum gross weight. A technical consultant, who held a doctorate in aerospace engineering and who also authored the club's investigative report, determined that the sailplane sustained a g-load of 8 g's based on the extent of damage and the accident pilot's recollection of the flight conditions. The glider had been acquired new, earlier in the year, and had flown approximately 106 hours and 130 flights. The accident pilot subsequently presented a safety paper to club members regarding his experiences with the flight and the hazards of FOD (foreign object damage). He discussed the chain of events that led up to the accident, including "1) FOD left in the aircraft, 2) failure to discover FOD during preflight, 3) unusual attitude maneuver dislodging FOD, and 4) Murphy's Law in full effect when FOD lodged in rudder mechanism."
The pilot's inadequate preflight inspection, which resulted in a loose battery charger becoming entangled in the rudder pedals during a spin recovery, and a subsequent overstress of the glider. Factors included the loose battery charger, and the non-standard battery charging procedure.
Source: NTSB Aviation Accident Database
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