## Evaluating Whole body vibration levels in military and civilian helicopters according to levels defined by EC (2002/44/EC).

Jan Anders Marheim
Sivilingeniør, akustikk og vibrasjon
Dir: +47 67 57 15 90 | Mob: +47 45 40 15 90
jan.anders.marheim@norconsult.com

Introduction:

Whole body vibration (WBV) is known to affect the muscular and skeletal system in the lower part of the spine. On the background of these effects The European Parliament and the Council of the European Union proposed a Directive in 2002 that stated the maximum levels of vibration exposure in a working environment. The action level was set to 0.5 m/s2. The limit level was set to 1.15 m/s2. In July 2005 the directive was implemented in the national labor inspection in every EU member countries. The national regulation makes the employers' responsible for examine possible WBV vulnerable work places. The Helicopter working environment is well known for substantial low frequency vibration. To be confident that different helicopter working environments were according to the regulation, we measured three military and three civilian helicopters.

Methods:

The following helicopters were measured: Bell 412, Westland Sea King MK43B, Westland Sea Lynx MK86, Sikorsky S92, Eurocopter EC135 T2 and Eurocopter Super Puma 332, L2.

All operationally relevant maneuvers were included in the test. The vibration levels were measured and recorded according to ISO 2631-1.

Results:

The Sikorsky S92 and Sea Lynx helicopter had the highest overall root-mean-square (RMS) acceleration values. EC135 T2 was the only helicopter with consistent levels below action value for all maneuvers and altogether the helicopter with the overall lowest vibration levels. There are several possible reasons for the rather large differences between helicopters, with implications for possible health effects for helicopter aircrew. Some reservations regarding the results must be made based on individual airframe differences and helicopter configurations.

Conclusion:

None of the helicopters measured passed the action level during an eight hour working day. We believe that the daily exposure level is lower in most of the helicopters since an eight hour flight time during a day is extraordinary.