Introduction
On September 5, 2009, at approximately 11:30 Japan Standard Time, a Robinson R44 helicopter, registered JA33TH, experienced a hard landing on rough terrain at the Miho Temporary Operation Site in Shimizu-ku, Shizuoka City, Shizuoka Prefecture. The helicopter, operated by a private pilot on a solo familiarization flight, sustained substantial damage to its left-hand lower frame and the lower half of its vertical stabilizer. The pilot was not injured.
Flight History
According to the pilot's statement, the helicopter had taken off from the same site earlier at 09:54 with three friends, landed at 10:21, and then the pilot decided to conduct a solo familiarization flight. The accident flight departed from Runway 15 at about 11:22. No flight plan was filed as the flight remained within 9 km of the site. The pilot flew the traffic pattern and approached Runway 33. After transitioning to a hover above the landing point, the helicopter moved via air-taxi towards an intended parking spot.
Accident Sequence
During the hover at approximately 3 ft above ground, the pilot reported crosswinds with fitful gusts. While attempting to stabilize the helicopter at about 1 ft prior to touchdown, a sudden pitch-up movement occurred. The pilot estimated the pitch angle as one-half to one-third of a typical "quick stop" control input. Concerned about possible tail rotor contact, the pilot raised the collective to increase height. After regaining a stable hover, the pilot, feeling urgency to land, lowered the collective while keeping the cyclic forward, resulting in a hard touchdown on the grass beside the runway from a height of about 5 ft.
Aircraft Damage
The aircraft sustained substantial damage: the left-hand lower frame was deformed, and the lower half of the vertical stabilizer was deformed. Examination of the engine and control systems revealed no abnormalities; the engine was operational, and no binding was found in the controls. The helicopter's estimated weight and center of gravity at the time of the accident were within allowable limits.
Personnel and Aircraft Information
The pilot, a 44-year-old male, held a private pilot certificate for rotorcraft, issued on July 23, 2009, with a total flight time of 59 hours 17 minutes, of which 13 hours 58 minutes were on the Robinson R44. The aircraft, serial number 1130, was manufactured on November 14, 2001, and had a total flight time of 743 hours 48 minutes. Its certificate of airworthiness was valid until January 27, 2010.
Meteorological Conditions
Wind data from the Shimizu Automated Meteorological Data Acquisition System, located about 4 km north of the site, showed average wind speeds of 6 kt from the east-northeast at 10:30 and 11:00, and from the northeast at 11:30. Maximum instantaneous wind speeds recorded were 10 kt, 11 kt, and 11 kt at those times, respectively.