I had the privelege to visit some 'armed forces' in South East Asia to demonstrate the Helituner with Noel in the early eighties.
One particular air force presented a recently overhauled Sikorsky to be 'analyzed' by the Helituner.
Within 30 minutes, he identified a cracked battery support tray bracket as the source of the heavy 1: 1 vibration in the -supposedly- overhauled
helicopter.
He loved to sit in the back of a helicopter -after final adjustments were made- during a test flight, and show the pilots his Parker pen standing up straight on the Helituner key board panel.
However, he had the greatest fun watching the faces of the pilots when he exposed them to a intro movie showing the twisting of a MR Blade filmed from the top of the mast. Several pilots had white faces -as they had no idea that this was perfectly normal -,and I know of some that changed jobs afterwards and switched -back- to plank flying.....
My her rest ip peace.