During the ‘70s, we were occasionally asked to do an air test of some sort in the Puma HC1. Part of the test was to fly at VNE which was 167 knots which was only achievable in a dive. It was a white knuckle ride with the centre (plastic) windscreen panting. Seem to remember the ASI kissing 167 for just a fraction of a second before recovering to a more sensible flight regime.