Federal Aviation Administration March 9, 2007 – Federal Register Recent Federal Regulation Documents

The FAA proposes to supersede an existing airworthiness directive (AD) for certain Turbomeca Arriel 1B, 1D, 1D1, and 1S1 turboshaft engines. That AD currently requires initial and repetitive position checks of the gas generator 2nd stage turbine blades on all Turbomeca Arriel 1B, 1D, 1D1, and 1S1 turboshaft engines. That AD also currently requires initial and repetitive replacements of 2nd stage turbines on 1B, 1D, and 1D1 engines only. This proposed AD would require adding a 3,000 hour life limit to Arriel 1B 2nd Stage Turbine Blades. This proposed AD results from reports of failures of second stage blades. We are proposing this AD to prevent failures of the 2nd stage turbine blades, which could result in uncommanded in-flight engine shutdown, and subsequent forced autorotation landing or accident.

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as: