AD FAA-2010-1253

We are adopting a new airworthiness directive (AD) for the Kaman Model K-1200 helicopters. This AD requires revising the Limitations section of the Instructions for Continued Airworthiness (ICA) by establishing a life limit of 8,000 hours time-in-service (TIS) for each main rotor blade (blade) set. Also, this AD requires removing each blade set from service if it has accumulated 8,000 or more hours time-in-service (TIS). This AD also requires replacing certain blade sets with airworthy blade sets at specified intervals based on the blade set serial number (S/N). This AD was prompted by an accident and the subsequent discovery of cracks in multiple blade spars. We are issuing this AD to prevent blade failure and subsequent loss of control of the helicopter.