If you have ever ridden in a military helicopter, you have felt the vibration that seems to shake your whole body during even a short trip. What happens to the aircrew and passengers who are exposed to prolonged and repeated whole-body vibration?
The U.S. Army Public Health Command Ergonomics Program studied this question when asked to collect vibration data on the UH--60 M Blackhawk and the UH--72A Lakota helicopters by the Vermont Army National Guard.
Coordinating the requirements to conduct the study took more than eight months and mountains of paperwork. While the data from the study hasn't been completely analyzed yet, it ultimately will allow researchers to assess whether there are health impacts to aircrews and how to reduce those impacts. As well, this project is attempting to jump-start a program that will ultimately collect vibration measurements from all military rotary wing aircraft that other researchers, laboratories and equipment designers can use, according to Steven Chervak, USAPHC ergonomist.
"The ability to collect whole-body vibration data on an aircraft has been an exercise in collaboration," said Chervak. "The cooperation among the Army, Air Force and Army National Guard to collect this data has been extraordinary. It was a real team effort."
Team members including the Program Executive Office Aviation, Utility Helicopter Division, Redstone Arsenal, Ala., the ARNG and the Air Force Research Laboratory at Wright-Patterson Air Force Base, Ohio, and Chervak worked together as they prepared to collect data.
"Before we could even begin collecting data, we had to demonstrate the air-worthiness of our equipment. We had to prove that the testing equipment would not adversely affect either the aircraft or the crew," said Chervak.
Team members demonstrated how the equipment would be attached to both the helicopter and the members of the aircrew to measure vibration at the seat and on the helmet without interfering with safety of the crew or passengers.
"Ken Forsythe, an industrial hygienist with the Maryland ARNG, wanted us to target musculoskeletal pain, including low back pain, and discomfort reported by members of aircrews," according to Chervak. "We installed equipment to measure vibration and flew on the helicopters to observe posture changes among crew members in flight. We also looked at how their postures changed during day and night missions because of flight conditions and additional equipment such as night vision goggles."
Concern about musculoskeletal pain and discomfort is not new among military flight crews. Navy aviation reports have indicated that back pain can even affect situational awareness in pilots and crew members.
Suzanne Smith, senior biomedical engineer with the Air Force Research Laboratory, directed the vibration data acquisition and will continue to work with USAPHC to share information and improve aircraft seat properties, explained Chervak.
"The number of hours pilots and aircrew are in the air has increased during deployments, and low back pain can interfere with mission accomplishment. Members of aircrews sit in one position for long periods, which can hinder blood flow, causing additional concerns," according to Chervak.
Vibration doesn't just affect the aircrews of helicopters. Many patients are transported by helicopter and subjected to vibration as well. Often, patients are not seated, but strapped on stretchers attached directly to the floor of a helicopter. Measuring the vibration they experience can provide information that will lead to better methods of transporting patients.
"The information we are collecting with the help of our partners will provide insight into occupational exposures and provide additional data for research," Chervak explained. "We are hoping to be able to perform additional testing on other types of helicopters and contribute to the redesign of seats and equipment to help eliminate or limit the occupational hazards of flying in helicopters.
"Information collected in our studies has the potential to affect not only military, but also civilian helicopters that transport patients to hospitals," he said. "This is a great opportunity to demonstrate the importance of ergonomics and to provide a real service in support of our Soldiers."