Originally Posted by
wrench1
The nodal arms have up and down stops that limit the travel. In Post 127 just below the break in the lift link, you will see one of the up stops. Once the nodal arms hits those stops that result is directly transmitted to the airframe which you will feel in the aircraft. For example, if the minimum blade angle or autorotation RPM is not set properly, the nodal beams will bounce against the down stops and produce a noticeable "knock" in the cockpit with the collective full down. The common "fix" is to simply pull a bit of collective to pull the beams off the stops, however, the correct fix is to adjust the min blade angle or auto rpm.
wrench1: Thanks for explaining. Are those stops the same as the "restraint dampers" referred to in the 206L-4 flight manual available on the web?
It is difficult to find clear images of the Nodamatic suspension on-line, but to give others an impression of what it consists of, following gives an overall view of the system on an unrelated 206L wreck:
In some of the grainy footage shown on the web, it does seem possible that a portion of the cabin top was pulled away with the main rotor (as was suggested in an earlier post) given the size and shape of what is seen hanging from the mast as this portion falls.
Additional to the link with footage of the break-up from ABC News shared by Flexible Response at #139, the ABC also showed somewhat zoomed in and slowed down versions of the same footage from 0:54 in this update:
In #184, Dick Smith asked re status of rotor recovery. The Wikipedia entry for this accident indicates search is underway using a side scan sonar to identify wreckage. However wiki notes that parts already recovered as of April 11 include the forward portion of the tail boom (assuming this doesn't mean the remnants of boom still connected to the main fuselage?), horizontal stabiliser finlets and vertical fin.