History of Flight
The aircraft, a Beechcraft King Air 200 (registration ZS-ACS), departed from Runway 29 at Wonderboom Aerodrome for a local training flight in the General Flying Area. During exercises, the right main landing gear failed to extend. The flight crew performed emergency checklist actions from the Aircraft Flight Manual, including attempts with the normal electrical system and the manual system, but the gear could not be extended. The crew returned to Wonderboom Aerodrome, notified Air Traffic Control (ATC) of the situation, and proceeded to orbit at 5500 ft AGL to burn off fuel while continuing emergency procedures. The pilot executed an emergency landing on Runway 11 with the right main landing gear retracted. After touchdown on the left main and nose landing gear, the aircraft departed the runway to the left.
Injuries to Persons
No injuries were sustained by the two pilots and one passenger on board.
Damage to Aircraft
The aircraft sustained substantial damage, including damage to the right hand inboard and outboard flaps during the ground impact sequence. Other damage was limited to skid markings on the runway surface.
Personnel Information
The instructor pilot, aged 52, held an Airline Transport Pilot Licence with type endorsement for the King Air 200, and had 10,723 total flying hours, including 862.30 hours on type. The student pilot, aged 26, held a Commercial Pilot Licence with instrument and night ratings, and had 540 total flying hours, including 2.00 hours on type.
Aircraft Information
The aircraft was a Beechcraft King Air 200 (B200), serial number BB-961, manufactured in 1982. At the time of the incident, total airframe hours were 11,788.7. The last maintenance inspection was on 06 October 2011 at 11,778.0 hours, with 10.7 hours since then. The Certificate of Airworthiness was valid until 27 October 2012. Both engines were Pratt & Whitney PT6A-42 models, and propellers were Hartzell HCB3TN-36G. The aircraft was equipped with a mechanical landing gear system.
Meteorological Information
Surface wind was 320° at 5 knots, visibility 10 km, temperature 27°C, dew point 5°C, cloud cover CAVOK.
Tests and Research
Post-incident testing revealed that the right hand main landing gear actuator had failed internally. Metallurgical examination showed extensive wear on the teeth of both bevel gears in the actuator, with some teeth missing. Additionally, three sections of the support structure were found to be worn.
Probable Cause
The probable cause was that the aircraft landed with the right main landing gear retracted. The contributory factor was a mechanical failure.