This topic has done the rounds of the SAR crewrooms and raised some interesting questions - the crew involved justified their actions stating that they exceeded Vmax by an amount less than the manufacturers 10% allowance.
The terms Vmax, Vne and Vno are not defined anywhere in military documentation although it is widely taken that Vmax is the speed at which you have no more power left to accelerate the aircraft in level flight, Vne is the absolute maximum speed permissible in the aircraft (only achievable in a dive) and Vno (not used in the military) is actually the maximum figure one should fly at based on AUM and DA (ie what we actually term Vmax in the Sea King world).
What certification requirements do rotary wing manufacturers have to abide by? John Farley has stated the case for fixed wing on the other thread but what about helos?
The biggest threat on a Sea King at high speed is retreating blade stall which is why we have a cruise guide indicator fitted (a sensor in the stbd lateral jack) to assess in flight vibration ie proximity to RBS.
I would like to know where the RN crew got their information regarding a 'manufacturers 10% allowance' which may or may not exist. I just hope they applied a factor for ASI inaccuracies (a hot topic since the sandfilter box was fitted).
Any thoughts from the TP community? Or Westlands?