Flight Sequence
On June 22, 2000, at 17:35 local time, a pilot departed from Kaunas Darius and Girėnas Aerodrome in a Yakovlev Yak-52 (registration LY-AHT) for an aerobatic training flight in the piloting zone above the aerodrome under normal weather conditions. After switching radio frequency to contact Karmėlava ATC, the pilot climbed to 4,000 feet. About 15 minutes into aerobatic maneuvers, while repeatedly starting a maneuver, the pilot felt restricted elevator control column movement aft. The control column stopped at approximately one-quarter of its travel from neutral toward the dive position. Aileron inputs did not resolve the restriction. The pilot rolled the aircraft inverted and recovered from the dive into a climb. While climbing, the pilot rolled the aircraft from inverted flight and attempted to maintain level flight using engine power and elevator trim. During these attempts, the aircraft repeatedly entered dives. An attempt to report the emergency to the flight controller failed because the connection between the pilot's headset and the aircraft radio had separated and could not be reconnected. The pilot again rolled inverted, turned away from the city, and climbed while flying southwest. At approximately 700 meters, the engine stopped (the engine can operate in inverted flight for only about two minutes due to the limited capacity of the inverted flight fuel tank). The pilot opened the canopy, released the seat belts, and bailed out with a parachute. The aircraft crashed and caught fire near the Kaunas bypass road, between Garliava and the Kaunas–Klaipėda highway, near Tirkliškiai village, 50 meters from a gasoline station. The pilot landed successfully by parachute.
Injuries and Damage
Neither the pilot nor any people at the accident site were injured. No third-party property damage occurred. The aircraft was destroyed and partially burned.
Crew Information
The pilot, a 26-year-old Lithuanian citizen, held a BESS license that had expired on September 9, 1996. He had received Jak-52 commander qualification on August 27, 1994, and aerobatic qualification on July 17, 1992. His total flight time was 336 hours, with 4 hours 55 minutes in the last 90 days. Total time on the Jak-52 was 75 hours 7 minutes, with 4 hours 55 minutes in the last 90 days. A Class 2 medical certificate was valid until May 18, 2002. The pilot was flying under a license renewal program.
Aircraft Information
The Yak-52 (LY-AHT, serial number 833804) was manufactured in Romania on October 20, 1983. Total time in service was 770 hours 59 minutes, with 3,359 landings. It had undergone one overhaul at a plant in Shakhty, Russia, on July 28, 1989. Since that overhaul, it had accumulated 320 hours 2 minutes and 1,231 landings. The last periodic maintenance (100-hour check) was performed on June 2, 2000, after which it flew 4 hours 58 minutes. The airworthiness certificate (No. 00261) was valid until April 18, 2001.
Meteorology
Weather at Kaunas AMS at the time was suitable for flight and did not influence the accident. METAR reports: SA EYKA 221450Z VRB04KT CAVOK 29/13 01011 NOSIG; SA EYKA 221550Z VRB04KT CAVOK 29/13 01011 NOSIG.
Communication Equipment
During the aerobatic flight, the headset-to-radio connector separated. The pilot could not reconnect it, preventing both transmission and reception.
Accident Site and Wreckage
The accident occurred outside the aerodrome. The aircraft struck the ground (road embankment) in an inverted attitude, with the nose (engine) and right wing first. It rotated northwest approximately parallel to the road and caught fire. Both cockpits were crushed, the rear fuselage deformed, the elevator separated from its stabilizer attachment, the right side of the stabilizer deformed, the fin broken off, the rudder crushed and separated, both wings and ailerons deformed, a section of the right wing separated, and the Pitot tube detached.
Fire
After impact, the aircraft ignited. The engine, nose gear, and both cockpits were almost completely burned. The left aileron fabric and main gear tires also burned. The fire was extinguished by gas station personnel and a fire engine crew.
Safety Factors
In the emergency, the pilot left the aircraft in flight with a parachute. The canopy and seat belt release operated normally; the parachute deployed in time.
Additional Information
In late May/early June 2000, a smoke system was installed on LY-AHT in place of the barograph. The installation was performed privately by an engineer-constructor working for UAB "Helisota," who did not hold a CAI engineer license. After the accident, examination of the wreckage revealed a barograph mounting bracket jammed in the elevator trim tab counterweight guides. The bracket had been removed in late May and handed over to the smoke system installer. The installer stated he did not use it and placed it on the grass near the command post; he did not know how it entered the aircraft. Before a test flight, the aeroclub engineer and pilot inspected the aircraft interior but did not notice the bracket. The pilot reported no unusual noises or control restrictions on that flight. Between the test flight and the accident (June 16–22), 20 flights (mostly aerobatic) were made with the aircraft, but the bracket was not detected.
Analysis
The barograph mounting bracket was removed in late May. It was handed over to the smoke system installer but not used. The bracket was left misplaced and forgotten (the interval between removal and smoke system installation was longer than 16 days). Since the bracket was not needed for the smoke system and was not stored with spare parts or disposed of, it could have entered the aircraft at any time during that period. Once inside, it could have lodged in a location (e.g., under the second seat) not detectable by routine inspection. No entries about the barograph removal or smoke system installation were made in the aircraft logbooks. It is presumed that during the smoke system installation, the bracket was intended for use but was not needed and was forgotten inside the aircraft.
Conclusions
The accident occurred due to the elevator jamming in the dive position after a barograph mounting bracket entered the aircraft fuselage and became wedged between the elevator trim tab counterweight and its guide.