Andrzej Jeziorski/SINGAPORE

Mitsubishi Heavy Industries (MHI) has recalled its production standard MH2000 helicopters after a defect was discovered in the production of the engine cover surrounding the high pressure turbine. The incident comes a year after Japan's first indigenous rotary wing aircraft was granted Japanese Civil Aviation Bureau certification.

The 4.5t maximum take-off weight helicopter is powered by two 597kW (800 shp) Mitsubishi MG5-100 turboshafts. MHI says the helicopters recalled include all three of those delivered to customers so far and one of the two demonstrator aircraft owned by the Tokyo-based manufacturer. The other flight test aircraft is unaffected, it adds.

It is understood that the affected engine covers were not properly strengthened during production, and might not have been able to contain a high pressure turbine blade failure. The flaw was discovered in August during a review of the manufacture of the helicopter.

Sales of the MH2000 have been slow in the first year of production, with MHI recording a backlog of only one machine, currently in production. The aircraft is being targeted at VIP, police aviation, emergency medical services and news gathering markets. An Instrument Flight Rules variant is also being developed, with certification planned for next year.

MHI is working on reducing the aircraft's internal and external noise and vibration levels. It admits cabin noise levels at 100% rotor speed reach 88dB, while the design target is 82-83dB. External noise levels reach 90.7dB at 490ft (150m) altitude, nearly 6dB above target.

The company is attempting to further reduce aerodynamic interference between the main rotor and fuselage and optimising the design of the tail rotor by adjusting blade spacing to suppress noise.

Source: Flight International