But beware the less experienced who right turn tail into wind and can't catch it quick enough when they run out of power. Certainly wakes the tourists up, a quick 360 degree view of the helipad. They are then placated by being told that he/she was just demonstrating the rapid manouvouerability of the machines, while the pilot unhooks from the seat cushion.
I take it you have also paid you time over the gorge sometime previously?
Quote:
As for wind.... most we get up here is about 35 knots, but whoever designed the pad put it facing the complete opposite direction to the prevailing wind, so always tail in to wind landings (note, not termination, just landing) to get the pax out with out walking in to the tail rotor. If one of the junior guys is struggling a bit, we get him to land on the lawn facing the other way.
Two quotes above do indicate a bit of confusion, the only lawn as far as I have been told is down in the park pad, so I guess you are referring to techniques of difficulty on both pads by junior drivers. Now I am not wanting to be too harsh but if I was involved with tourism in oz I think i would be fairly perlexed and making representation to somebody to get both operations sorted out to a much safer degree. Where in fact is each chief pilot? It is quite inexcusable to have war stories as such.
In short a jolly good crash at either location would put at risk ALL of your heli-tourism colleagues in OZ and probably very unfairlay have the pollies and public suggesting that the local FOI's were a tardy and slack mob as well.
Meanwhile - back to the thread. It seems there is a common point of fore and aft oscillations at 80 - 85 knots after the machines are strobed in the hover and smooth at high airspeed. Why not put the accelerometers back on the machine and just see what is happening.
We used to have what we called the death rattles on the lightweight blade 47's, which was nothing more than a blade going out of track, usually at the three oclock position, and it would become quite fierce if one was silly enough to let the vibe build up. It was an easy matter to cancel it by lowering lever slightly and turning slightly to the right then slowly resume preceeding direction and power.
It was always more prevalent in the texas equipped no bar machines.
It was accentuated by loose rod ends, worn out power cylinders, out of alignment power cylinders and control rods ( thus creating a bending and shortening moment) or worn or old sprag or lord mounts.
Some of the civil 3B1's had also an oil-canning effect in the firewall about the power cylinder attach points which allowed the rod ends to jump around. This was not evident in the Augusta models which had an extra gusset in the firewall construction.
I suggest that there may be a drag moment building up from the fuselage at 85 knots which is translating into creating a problem with the transmission mounts stiffness or tension at that drag component
This could mean that transmission is unable to be controlled properly in the fore and aft periods at that airspeed or the control rods are suffering adverse feedback which means that the blade is being forced into an out of track condition at that airspeed. Perhaps the transmission mounts could be wider spaced or made of a different grade of rubber. Perhaps some stiffening around the control rod and power cylinder attach points may help. At any rate all you're doing is guessing until you put the accelerometers on and start recording some data.
It may be that the fuselage flies in a different profile at 110 knots and does not create the same drag moments.