Originally Posted by
KG86
On a couple of occasions, I had US Army pilots in the other seat of my RAF Chinook. Invariably, when I lifted to the hover, they would say that the vibration was so severe, to them, that in the US they would land back on and give it to the maintainers to fix. As I recall, the US Army changed whole (balanced) rotor blade sets, rather than one blade at a time in the UK. So the US comments about excessive vibration could probably be taken with a small pinch of salt. It could be SOP for us!
Vne for a US Chinook was 170 kts. RAF limited it to 160 kts. Flight at that speed tested the security of one's teeth fillings.
Spot on! The RAF also changed the lubricants used by Boeing which was reputed to change the vibration characteristics. I'm sure the experts will say that the RAF rotirtuning regime works in terms of reducing vibration induced stresses on the aircraft, but the frames do seem to crack very frequently.