N101-026 TITLE: Multi-Axis Vibration Mitigation and Habitability Improvement for Seated Occupants

TECHNOLOGY AREAS: Materials/Processes, Human Systems

ACQUISITION PROGRAM: PMA-231, E-2 Hawkeye Program Office; FNC - Force Health Protection

OBJECTIVE: Develop innovative solutions for reducing high-frequency vibratory input to seated occupants performing missions on board propeller driven aircraft.

DESCRIPTION: The E-2C Hawkeye is the Navy’s all-weather airborne early warning and command and control aircraft for carrier battle groups. The E-2C also conducts missions that include surface surveillance coordination, strike and interceptor control, search and rescue guidance and communications relay functions. As the aircraft capability has been upgraded and mission lengths extended, there have been increasing complaints of annoyance, fatigue, and musculoskeletal pain during prolonged exposures to propulsion-generated vibration in this propeller-driven aircraft. Air Force studies have indicated that the introduction of a cushion alone may be insufficient to mitigate the full range of vibration felt by E-2C and other propeller-driven aircraft occupants.

Acute pain and discomfort amongst E-2C aircrew are most likely attributable to several factors such as poor posture, seating ergonomics, vibration of the aircraft during flight, and total number of flight hours. However, the work sought here centers around design concepts for reducing multi-axis whole-body vibratory input to seated occupants and for enhancements to seat that improve the aviators/operators ability to conduct long missions without developing numbness and pain in the back and legs.

Proposed concepts should:
• not cause a substantial increase in weight of the seating system;
• be retrofittable into the airframe without aircraft modifications;
• enhance crash performance and occupant protection;
• incorporate or develop materials that eliminate or reduce pressure points on the legs and impingements on the back;
• be compatible with aviator/operator body-borne mission equipment.

The E-2C has crew stations that are both parallel to the longitudinal axis of the aircraft (pilot/copilot) and perpendicular to the aircraft’s longitudinal axis (Naval Flight Officers). All seating stations are floor-mounted to tracks and have the capability to adjust vertically and fore/aft. Acceptable design concepts must take each of these seating orientations into account.

Concepts must demonstrate a reasonable likelihood of reducing total vibratory input delivered to the seated occupant and of increasing overall habitability for extended missions lasting up to 7 hours. Candidate system weight, complexity, reliability, maintainability, and effectiveness will be very important factors in selecting a candidate system.

PHASE I: Demonstrate feasibility of proposed cocept to reduce high-frequency vibratory input transmitted to seated occupants on board the E-2C and of improve seat habitability by reducing "hot spots" on the seat bottom and back cushion.

PHASE II: Develop and demonstrate prototype system. Based on the outcome of laboratory testing, perform refinements to the prototype system aimed at improving system performance.

PHASE III: Fabricate production representative seating systems or integrate the recommended solutions onto the existing seat depending on the design concept. Support qualification and flight demonstration testing.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: There is a need for implementation of vibration mitigating seating systems for civil aircraft. Military development of seating systems that significantly reduce whole-body vibration transmitted to seated occupants will likely result in an acceleration of implementation of these systems into civil aircraft.

REFERENCES:
1. Smith, S.D., Smith, J.A., (2005). Multi-axis vibration mitigation properties of seat cushions during military propeller aircraft operational exposures. AFRL/WS-05-2250.

2. Loomis, T.A., Hodgon, J.A., Hervig, L., and Prusaczyck, W.K. (1999). Neck and back pain in E-2C Hawkeye aircrew. Technical Report 99-12, Naval Health Center.

3. Testerman, R., Howell, H., Rudy, M., (2006). Final report for seating study completed on E-2C Aircraft (Unpublished).
Note: Reference #3 has not been released for public distribution. However, you can submit a request to Naval Air Systems Command, 47123 Buse Road, Patuxent River, MD 20670-1547.

4. International Standard 2631-1, 1997-07-15, Mechanical vibration and shock -Evaluation of human exposure to whole-body vibration - Part 1: General requirements.

5. E2 Seat Photo (uploaded in SITIS 12/7/09).

6. Drawing, PSE dimensions, uploaded in SITIS 12/08/09.

KEYWORDS: whole-body vibration; aircrew seating; fatigue; back pain; numbness; vibration mitigation

** TOPIC AUTHOR (TPOC) **

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