Measuring Safety in Single- and Twin-strongenginestrong Helicopters.pdf

Measuring Safety in Single- and Twin-engine Helicopters Accurate measurement of helicopter safety is crucial to both the flying public and the operators of rotary-wing aircraft. The author questions the veracity of some safety statistics and he challenges recent ICAO amendments that would restrict operations in single-engine helicopters in favor of twin-engine helicopters. by Roy G. Fox Chief Safety Engineer Bell Helicopter Textron Inc. Safety has always been a paramount concern causes of accidents and injuries, not just me- in aviation. Safety is not an absolute; rather it chanical components such as engines or tail is a relative measure of the risk involved when rotor blades. flying in an aircraft. Several methods are used to measure safety, but some can be misleading Accident data from the United States (U.S.), and create a perception of a low level of safety the United Kingdom (U.K.), and Canada were in helicopters. Misconceptions about helicop- analyzed to determine the risk to occupants of ter safety can cause overly restrictive regula- single- and twin-engine helicopters. These three tions and prohibit the use of safe aircraft. Thus, nations account for about 82 percent of all realistic measurement of helicopter safety is known non-Soviet bloc civil helicopters. crucial to helicopter operators and the flying public. Why Measure Safety? There is a question of whether an occupant is safer in a single-engine or a