TOKYO, Feb. 6 (Xinhua) -- Japan's Ministry of Defense said Tuesday it is investigating the cause of a fatal crash of a Ground Self-Defense Force (GSDF) attack helicopter in southwestern Japan a day earlier that killed the two crew members aboard.
The ministry is investigating eyewitness accounts that the main rotor detached midair causing the chopper to nosedive into a residential house in Kanzaki City, Saga Prefecture, with the ensuing fire rapidly gutting the house.
According to Japan's Defense Minister Itsunori Onodera, the AH-64D helicopter was on a test flight after having its main rotor head replaced.
The rotors on AH-64D attack choppers need their main rotor heads, which connect the four blades, replacing after 1,7150 hours of flight time, Onodera said.
The four-blade, twin-turboshaft attack chopper had also undergone a routine 150-hour inspection.
The chopper took off from the the GSDF's Metabaru Camp located about 4 km from the crash site at 4:35 p.m. local time on Monday and is believed to have crashed into the house during its flight from east to west at 4:43 p.m.
All four residents in the two-story house that was hit by the chopper have been confirmed safe, although an an 11-year-old girl sustained minor injuries when she fled from her home.
Japanese Prime Minister Shinzo Abe in a parliamentary committee on Tuesday was quoted as apologizing for the fatal crash which "threatened the safety of the residents and caused huge damage."
All of the GSDF's 12 other AH-64 helicopters have been grounded pending emergency inspections and checkups will be carried out on all SDF helicopters, the defense ministry said.