DAVID LEARMOUNT / LONDON
Successful system tests in C-130H will lead to 10 months of human factors assessment
An active noise control system (ANCS) tested in a US Air National Guard (ANG) Lockheed Martin C-130H Hercules cockpit has completed the first part of its test programme successfully, says UK-based Ultra Electronics Controls.
Launched before last year's Iraq war, the programme has yet to be completed, having been delayed when the test aircraft was deployed to the Gulf. Ultra marketing manager Rob McDonald says there will be 10 months of human factors testing from the ANG base at Martinsburg, West Virginia using the same aircraft. Reports from the ANG say the technology "will make a significant difference to our flying crew".
The ANCS has shown it can reduce cockpit noise from a punishing 112dB to 96.2dB at the co-pilot's position - the worst location - which represents a reduction of about 90% in noise power, according to Ultra. This improves communications and reduces crew fatigue and hearing damage, it says.
The system works by measuring fuselage vibration caused by propeller-generated noise energy at a number of points, then carefully positioned loudspeakers produce "anti-noise" - noise energy with a phase opposite to that caused by the propellers. In addition, the system's embedded propeller balance monitoring system (PBMS) detects propeller imbalance precisely, and even calculates where ground engineers should place counterbalance weights. This can reduce maintenance time for the task from one day to roughly 1h, says Ultra. Reduced propeller vibration also means a longer life for avionics and less fatigue to structural components.
McDonald hopes that if the potential human factors benefits are insufficient to woo the US military into paying about $200,000 per airframe for the ANCS, the maintenance savings created by the PBMS may attract it.
Ultra says the EU law on health and safety at work will, by 2006, apply to civil and military flightcrews. It also hopes to see European military interest in the ANCS.
Source: Flight International
