Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to BHTC Model 407 helicopters. This proposal would require replacing certain cockpit warning horns. This proposal is prompted by reports that pilots have had difficulty in distinguishing between the FADEC Fail horn, the Engine Out horn, and the Low Rotor RPM horn. The actions specified by the proposed AD are intended to assist the pilot in properly identifying a specific cockpit warning horn (horn) and prevent an inappropriate pilot response to a horn, which could cause an engine overspeed and subsequent uncommanded reduction to flight-idle engine power.