Evaluation of pilot whole-body vibration exposure levels on a CH-147F Chinook military helicopter

Flight testing has been performed on a Royal Canadian Air Force (RCAF) CH-147F Chinook helicopter to measure pilot whole-body vibration exposure levels during representative flight conditions. Vibration data have been analysed in accordance with the ISO2631-1:1997 standard. The results showed that the helicopter cabin vibration was mainly introduced by the aerodynamic loads at N/rev harmonics of the three-bladed tandem rotor speed. The pilot whole-body vibration levels varied significantly depending on flight conditions and aircraft load configurations. The highest vibration levels occurred during manoeuvres and high speed flight. Referencing to the guidelines in ISO 2631-1:1997, the pilot whole-body vibration exposure level in the tested flight profile were rated as \u201cuncomfortable\u201d, and the maximum duration of such a mission should be limited to 1.0 or 3.3 hours depending on the lower or upper limit of the Vibration Health Guideline Caution Zone respectively. The results of a subjective analysis, by the pilot, of the comfort levels during the flight did not provide good correlation with the level of discomfort indices measured during the tested flight profile.NRC publication: Ye