Vibration exposure of helicopter pilots

Status:

completed 06/2002

Aims:

Helicopter pilots often complain about low back pain as a result of several years of a long daily flying service. Some flying manoeuvres require especially unfavourable body postures - trunk bent forward - which even aggravate the backache. To lay the basis for a risk assessment, the pilot's and copilot's exposure to vibration is measured in different types of helicopters. The seats - in one case a trolley bed - are assessed in terms of vibration attenuation. The project was initiated by the institution for statutory accident insurance and prevention in the vehicle operating trades.

Activities/Methods:

The vibration measurements are conducted on the seat, at the seat mounting point and in one case on the trolley bed as well as at one of its points of support. Measurement directions are: back-breast, shoulder-shoulder, which are perpendicular, and the direction of the spine of the sitting pilot respectively of a lying person.

Results:

The vibration exposure was measured on ten different models of helicopter. Two examples of one particular model of helicopter were studied, and on a further helicopter, the change in exposure was measured following the fitting of other seats. In both cases, the setting of the engine, which represents the principal source of vibration, was shown to influence the incidence and magnitude of spectral components and the magnitude of the vibration exposure across the entire frequency range. More recent models of seats do not necessarily exhibit more favourable vibration transfer factors; improved body restraint and other ergonomic improvements such as adjustable supports for the lumber spine result in a more favourable subjective impression, however. Generally speaking, past measurements on older helicopter models were confirmed: a general assessment of the vibration impact based on these measurements in accordance with the criteria for occupational disease 2110 revealed that a danger to the spine was unlikely where flights were of the usual duration. More recent models of helicopter generally exhibit lower vibration impact levels.

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