Based on his analysis, ARCCA’s expert was able to determine that the rotors required engine power in order to produce the amount of damage seen on the buildings. This analysis corroborated the public sector investigators’ previous testing and conclusions that there was no engine failure or no power transmission failure to the main rotors prior to the crash. Helicopters are typically powered by a single piston or turbine engine. The engine powers through a series of clutches and transmission to gear a primary lift rotor and a tail rotor. The controls may be a combination of mechanical, hydro-mechanical, or electro-hydro-mechanical. Cockpit sensor gauges, warning lights, and control switches are typically electronic or electro-mechanical, and event data recorders are increasingly common on more sophisticated helicopters. ARCCA engineers have the background, education, and experience to sort through the complex systems within a helicopter in order to root cause the cause of a helicopter crash. They also have the experience to analyze control logic and decipher event data recordings
, and the aerospace background and experience to evaluate hardware designs, control systems, and survivability.