Summary
We propose to adopt a new airworthiness directive (AD) for Agusta S.p.A. (Agusta) Model A109S helicopters, which would require modifying the electrical power distribution system to carry a higher electrical load. This proposed AD is prompted by an electrical failure on an Agusta Model A109E helicopter that resulted from ``inadequate functioning of the 35 amperes (amps) BATT BUS circuit breaker.'' The proposed actions are intended to require modifying the electrical power distribution system to prevent failure of the circuit breaker, loss of electrical power to instruments powered by the ``BATT BUS'' system, and subsequent loss of control of the helicopter.