By Paul Seidenman & David J. Spanovich/Overhaul & Maintenance
Helicopter maintenance and safety could be significantly enhanced through greater use of health and usage monitoring systems (HUMS), experts say.
"Stepped up use of HUMS could reduce accidents," said Mark Liptak, an aviation safety engineer with the FAA's Safety Data and Analysis Services, as well as program director for the International Helicopter Safety Team (IHST)--an international body that wants to cut worldwide helicopter accidents by as much as 80% by 2016.
Citing a 2007 IHST study of 197 accidents in the U.S. in calendar year 2000, Liptak reported that maintenance and parts/systems together represented a significant cause of 20% of those accidents," said Liptak. "We found that in 47% of the accidents, HUMS might have minimized the chances of the accident due to parts/systems failures, since it could have predicted their impending failure."
HUMS, explained Liptak, can generate important information to maintenance technicians, such as a history of vibration characteristics, fluid temperatures, and engine over-torquing, which could minimize accidents. "I'm hearing elevated levels of discussion in the industry to place HUMS on legacy, as well as new production helicopters."
Along with safety, HUMS has shown itself to be a proven maintenance tool. "We have used Honeywell's VXP HUMS for rotor track and balance analysis," said Jim Brodbeck, a quality assurance staff member at Columbia Helicopters in Aurora, Ore. "It has reduced the amount of flight time required to do that by 50-60%."
Columbia Helicopters operates 21 twin-rotor aircraft, originally built by Boeing for the military, but now used in aerial firefighting, heavy lifting, and in oil and gas exploration. Brodbeck said that one 15-20 minute flight is now required to do a simultaneous analysis of both rotors. "Before VXP, we had to make one flight for each rotor analysis, at a cost of about $4,000 per flight hour."
While currently using the VXP as a carry-on, Columbia plans to install it as an airframe mounted system, incorporating sensors that will provide a complete analysis of all of the aircraft's rotating systems--the rotors, transmission and engines.
"The sensors will give us plenty of time to pull the parts for overhaul and reuse, instead of waiting until they are beyond any hope of repair," said Brodbeck.
Dave Downey, VP flight safety for Bell Helicopter Textron, reported that outside of the oil and gas industry, there has not been a widespread demand for HUMS. "The oil and gas firms generally require anyone bidding a helicopter service contract to have HUMS on any Part 29 helicopter, which is one with a max takeoff weight over 12,500 lbs.," he explained.
Still, Downey noted that offering "some type of lighter weight HUMS for retrofit or forward fit" within the next six to nine months is under consideration. "We are in technical discussions with companies that manufacture HUMS to find out what they offer, the kind of weight penalty involved, and if they are affordable by our customers. "We also want to see how the FAA will react to some just-issued NTSB recommendations having to do with flight data and cockpit voice recordings for helicopters. That will also factor into our decision."
Interest in HUMS may be driven by the current global economy. ýýýAs budgets are cut, more people want to repair, rather than replace," said Bill Lawler, sales director, condition based maintenance systems, Honeywell Aerospace Helicopter and Surface Systems Group, in San Diego, Calif. "They want to know when they can still fix something that is on the verge of failure. It has been demonstrated that these systems are saving time and money."
Honeywell's latest generation HUMS, available under the company's Zing product portfolio, includes the 1100 Series 1134--for light helicopter, fixed wing aircraft and turbine engine application--and the 1200 Series 1239 for medium to large helicopters and fixed wing airplanes. All are based on what Lawler reported are current trends in customer requirements.
"Based on customer input, there is a mandate for affordability and commonality between the new-production and older HUMS equipment, so that any upgrades don't require a complicated learning process, or a specially dedicated infrastructure to use it. They simply want to download the data to a computer, without having to depend on a dedicated staff of analysts to interpret it," he said.