Helicopter two-stage tactile warning system

Keywords: Rotor, Aircraft

In GB Patent 2353773 Safe Flight Instrument Corporation describes a rotary wing aircraft such as a helicopter. It has a two-stage alarm in the form of a shaker mechanism comprising a moveable mass or weight which operates on a collective control arm. The shaker may be of a reciprocating type or a rotating eccentric mass driven by a DC motor. The shaker is controlled in response to sensed operating parmneters. If comparators detect any parmneter exceeding first reference values, the shaker vibrates at a first frequency or amplitude as a warning. If comparators detect any parameter exceeding second reference values, the shaker vibrates at a greater second frequency or amplitude, warning of a more imminent or serious condition. More than two reference values may be utilised. Operating parameters may include output shaft or rotor speeds, engine torque or exhaust gas or turbine inlet temperatures.