Biomedical subjects

D F Shanahan

Publications and source records attributed to D F Shanahan.

6 recordsLinked to original sources

PubMed1993

Fatal mishap report: first SPH-4B flight helmet recovered from a U.S. Army helicopter mishap.

The most common cause of death in helicopter accidents is head injury. Flight helmets can be designed to distribute and attenuate crash forces to the head. Experience derived from crashes using the U.S. Army SPH-4 flight helmet has led to modifications to improve protection. Within the past year, the Army has introduced the SPH-4B flight helmet which includes several new features to reduce injury in future mishaps. The first SPH-4B flight helmet recovered from a fatal mishap is described and correlated with the injuries to the wearer. The new shell and liner reduced the impact forces to the head. There were no side impacts to determine the performance of the crushable earcups in the helmet. The new SPH-4B flight helmet has several new and distinctive features that should improve survival in future helicopter crashes. Careful study of life support equipment retrieved from crashes is important to understand how the equipment performs in the crash environment.

Accidents, Aviation↗

PubMed1989

Injury in U.S. Army helicopter crashes October 1979-September 1985.

All U.S. Army class A and B mishaps of four types of helicopters occurring from 1 October 1979 through 30 September 1985 were reviewed. During this 6-year period, there were 298 crashes involving 303 aircraft. There were 1,060 individuals aboard the crashed aircraft and 611 were injured, 136 fatally. The most common cause of injury was the "secondary impact" caused by collapse of structure into occupied areas, by inadequate restraint of the occupants which allowed them to flail into structure, or by a combination of both mechanisms. Injury solely related to acceleration occurred infrequently. The most frequently injured body regions in survivable crashes were the head (28%) and extremities (43%). Injury patterns are compared for different helicopter types and related to differences in design. Basic principles of crash injury protection, including individual protection by helmets, seatbelts, and airbags, and structural modifications to minimize injury potential, as well as crashworthy fuel systems, are reviewed, and recommendations are made to increase the crashworthiness of helicopters, such as adapting designs and standards on the basis of active field investigations.

Accidents, Aviation↗

PubMed1989

Kinematics of U.S. Army helicopter crashes: 1979-85.

All records of U.S. Army Class A and B mishaps of four types of helicopters occurring from Oct. 1, 1979, through Sept. 30, 1985, were reviewed for terrain impact kinematic parameters. During this 6-year period, there were 298 mishaps involving 303 aircraft. Approximately 88% of these crashes were considered survivable. Mean and 95th percentile vertical velocity changes at the most severe terrain impact were similar for all aircraft types except the UH-60, which experienced significantly higher impact velocities (p less than 0.001). Overall 95th percentile vertical and horizontal velocity changes at the most severe terrain impact were 11.2 m.s-1 and 25.5 m.s-1, respectively. Both these values are substantially different from values cited in current design standards. Roll, pitch, and yaw attitudes at impact were similar for all aircraft and agreed with the values in current design standards, except that the distribution of roll angles was considerably wider. The importance of using current kinematic parameters for crashworthiness design standards and crash injury prevention is stressed. Recommendations are made to improve crashworthiness design standards.

Accidents, Aviation↗

PubMed1984

Helicopter pilot back pain: a preliminary study.

Because of the high prevalence of back pain experienced by U.S. Army helicopter pilots, a study was conducted to ascertain the feasibility of reproducing these symptoms in the laboratory. A mock-up of a UH-1H seat and control configuration was mounted to a multi-axis vibration simulator (MAVS). Eleven subjects were tested on the apparatus for two 120-min periods. During one period, the MAVS was programmed to reproduce vibrations recorded from a UH-1H in cruise flight. The subjects received no vibration during the other test period. All subjects reported back pain which they described as identical to the pain they experience during flight, during one or more of their test periods. There was no statistical difference between the vibration and nonvibration test conditions (p greater than 0.05) in terms of time of onset of pain or intensity of pain as measured by a visual analog scale. It appears the vibration at the frequencies and amplitudes tested plays little or no role in the etiology of the back symptoms reported by these pilots. It is proposed that the primary etiological factor for these symptoms is the poor posture pilots are obliged to assume for extended periods while operating helicopters.

Adult↗

PubMed1984

Spinal injury in a U.S. Army light observation helicopter.

All accident reports involving U.S. Army OH-58 series helicopters were analyzed to determine vertical and horizontal velocity change at impact and the relationship of this kinematic data to the production of spinal injury. This analysis determined that spinal injury is related primarily to vertical velocity change at impact and is relatively independent of horizontal velocity change. The dramatic increase in the rate of spinal injury occurring just above the design sink speed of the aircraft landing gear (3.7 m/s) suggests that the fuselage and seat provide little additional impact attenuation capability above that of the gear alone. It is concluded that if this aircraft were modified to provide protection to the occupants for impacts up to 9.1 m/s (30 ft/s), approximately 80% of all spinal injury incurred in survivable accidents could be substantially mitigated. The incorporation of energy absorbing seats is recommended.

Acceleration↗

PubMed1983

Basilar skull fracture in U.S. Army aircraft accidents.

Of the 222 flight helmets retrieved from Army aircraft accidents during 1971-79 under the Aviation Life Support Equipment Retrieval Programs, 175 were SPH-4 helmets that were analyzed for physical damage and for the relationship of damage to injury sustained by the wearer. This analysis showed that lateral impacts resulted in a significantly higher rate of serious injury (AIS greater than or equal to 4) than impacts to other regions (68% versus 46%, p less than 0.001) Lateral impacts yielded a higher rate of basilar skull fracture than impacts to other areas of the helmet (46% versus 18%, p less than 0.001). It is concluded that lack of energy-absorbing material in the lateral portions of the helmet causes the high rate of basilar skull fracture and the increased prevalence of severe injury associated with lateral impacts. The incorporation of an energy-absorbing earcup design is recommended to reduce the high rate of severe injuries associated with lateral impacts.

Accidents, Aviation↗