HOW HUMS SYSTEMS HAVE THE POTENTIAL OF SIGNIFICANTLY REDUCING THE DIRECT OPERATING COST FOR MODERN HELICOPTERS THROUGH MONITORING

Commercial applications of Health and Usage Monitoring Systems (HUMS) are developing rapidly in response to commercial regulatory requirements for improved helicopter drive train monitoring. By monitoring the on-board system and extending technologies for failure prediction through the application of advanced software and hardware, HUMS offers the most effective means of significantly reducing the direct operating cost for rotary-wing aircraft. It does this by concentrating the new technology on the zero-redundancy transmission system and load path of the aircraft. FDR/HUMS systems are now operational and being installed on medium and large helicopters worldwide. The Teledyne Controls/Stewart Hughes system was the first certified FDR/HUMS and has today been operational for almost five years. Typically, the cost of helicopter ownership can be broken down into five major categories of cost with 36% allocated to depreciation, 29% to insurance, 24% to maintenance, 6% to the flight crew and 5% to fuel. More than half of the cost can thus be attributed to maintenance and insurance. Operators with HUMS installations therefore expect to have HUMS provide reduced operating costs through reduced maintenance and insurance. Based on the successful operational experience of HUMS systems, several potential operational cost savings are expected in the areas of reduced scheduled and unscheduled engine, rotor and gearbox removals. A reduced number of spare units used for unscheduled component removals and increased time between overhaul provides further cost savings. A built-in rotor tracker which is part of HUMS reduces or eliminates costly test flights required for rotor track and balance adjustments. Helicopter operators therefore look for potential benefits that can be derived from monitoring life limited components. However, the involvement of the helicopter manufacturer is necessary, to achieve the full potential benefits of HUMS. Operators also expect to use HUMS to assist them with planning maintenance actions, thereby making these actions manageable, rather than surprises or “emotional events”. With the additional safety improvements provided by HUMS, a reduction in insurance premiums will eventually also be provided to helicopter operators using the system. The advantages of employing HUMS are already being recognized by the insurance community as the loss ratios decline for helicopter operators which have deployed HUMS in aircraft which operate in the North Sea. Insurance rates are thus expected to reflect this lower cost experience. Also to he expected from HUMS is improved productivity and efficiency through more accurate cost tracking, which will permit the operators to develop more accurate charging for services provided to their customers. These cost savings and our experience with HUMS operation are summarized in this paper.