The US Federal Aviation Administration has followed the recommendations of the German airworthiness authority and issued emergency airworthiness directives (ADs) grounding Eurocopter BK117 and BO105 helicopters until tension-torsion (TT) straps contained in the main rotor head are inspected and replaced as required.
The US aviation agency says that 130 US-registered BK 117s are affected by the AD, but that only about 60, many of which are used for emergency medical services (EMS) and air ambulance duties, remain grounded pending replacement of the main rotor component.
The twin-turboshaft rotorcraft were taken out of service following the crash on 17 July of a BK117 operated by Houston's Hermann Hospital. A main rotor blade separated, killing three crew.
The FAA says BK117s, BO105CB-5s and BO105CBS-5s that have straps more than 15 years old (or have made 25,000 or more flights) must undergo the replacement. Further ADs on the BO105 are expected in the coming weeks.
Rocky Mountain Helicopters of Provo, Utah, one of the largest US operators of Eurocopter machines, with 33 BK117s and five BO105s, has grounded 16 BK117s, and says that six more machines will be affected by the AD.
Source: Flight International
