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.