To: Helo Teacher
Point 1) the certification requirements dictate that a stick plotting board is used to determine that the helicopter will move in the same sense as cyclic stick displacement. The certification standards indicate that the displacement of the helicopter could be up to 2-degrees from cyclic stick displacement and could be attributed to pitch coupling. It is not intended to be up to the pilot to determine if the stick displacement is objectionable or not. It states that under ideal conditions if you moved the cyclic forward from the rigged neutral position the helicopter would fly straightforward. If it deviates from that sense of movement the difference can be no greater than +/- 2-Degrees.
Point 2) The certification requirements dictate that the helicopter demonstrate sideslip at .6 VNE by pushing hard to the stops on the pedals. First one pedal and returning to neutral and then on the other pedal. The helicopter must comply with this requirement as well as to demonstrate flying out of trim. Now you have to think on two planes at once. 1) The restrictions were placed on the sideslipping and out of trim flight because it was determined that in doing so you could induce severe flapping loads to the point of causing mast bumping and loss of the rotor. 2) If it was determined that these two actions would result in mast bumping then what happened when these same actions were demonstrated in order to gain certification. My premise about the Robinson not being certifiable stems from the facts above. If the Helicopters were presented for certification with the restrictions against sideslipping and out of trim flight they could not pass the certification requirement requiring demonstration of these flight maneuvers. It is not to say that they could not do these maneuvers because the OZ pilots do it all the time. However the fact remains that if you do these maneuvers and something happens it is your fault because the AD and the POH tell you not to do them.
Regarding the crosswind component on the Bell 206 this limitation was established during the sideslip demonstration during the certification trials. The test sets the maximum outer limits that can be obtained by the specific design. On the Bell it just happened that because of the test it was determined that the restriction be put in place for certification. I am assuming this because of what you said in your post.
Regarding what you said about lateral cyclic having to be used to counter the propeller effect of the tail rotor, I was under the Impression that there is a left tilt of 2-degrees on the mast to counter this effect. Regarding the report, if I had it to do all over again I would have made some changes. These changes would have been prompted by what I have learned from the postings of others including your self which caused me to look deeper into the subject. The most illuminating of all of those changes of mind occurred when I reread the rigging procedures and I found out the following.
http://pprune.homestead.com/files/rigging.jpg
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The Cat