Summary
We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) issued 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:
Cycle life limit value for ARRIUS 1A balancing piston Part Number (P/N) 0 319 20 152 0, initially set at 40 000 cycles, has been reduced to 16 000 cycles, following the discovery of a calculation error during a recent review of the ARRIUS 1 engine family files.
We are proposing this AD to prevent failure of the balancing piston, which could result in an engine in-flight-shutdown and the release of high-energy debris and damage to the helicopter.