Originally Posted by
Less Hair
His statement sounded like it was about a lost tail rotor before the loss of control and the boom being hit.
can you point to who/where the comment on the TR comes from please?
One of the eyewitnesses indicates the helicopter was in a hover (OGE...) and then there was a pop....
If the RPM is normal, in the OGE hover the fact that the head is a semi-rigid design, (hybridized from a teetering head to a teetering + coning hinge for root load relief) is basically immaterial. Cyclic inputs on a Robbie like any civil helicopter should be smooth and coordinated, but the hover is not a point that modest cyclic inputs will compromise TPP/tail boom clearance. High speed, very different story. A TR drive failure will get out of sorts in a high hover quite quickly and will result in reduced TPP/tail boom clearance unless the throttle is closed, but there is a few seconds before it gets wild from the inertial moments on the fuselage feeding back into the control system. The video indicates that the NR was likely maintained for the early parts of the event, the blades had not suffered an underspeed event resulting in blade stall (the SN "LOW RPM STALL") the rotors only appear to come out of plane after the pitch over and presumably the engine stoppage from fuel pickup point catching air. This doesn't say one way or the other if the pilot had closed the throttle and entered autorotation, it is probable the event wasn't from an engine failure, however. So, the rotor control head itself is unlikely to have been bad, no pitch link failure, no coning hinge failure, an accidental forward whack on the cyclic is very uncomfortable in the hover but doesn't normally result in a tail strike (there is a neat video somewhere of that being done at a low hover, and stuff happens but the tail didn't get cut off). The same forward whack at 115KIAS is pretty much deadly.
The losses in the RHC are a mixed bag of causes, the fact that it has become the universal training helicopter with the minimal production of any other entry-level chopper other than the Colibri (which has a pretty neat head design) and a smattering of others. The rotor head needs operational care by the pilot, as it did on the B206 and UH1B/H etc... or 2 blade AH1s. They are not forgiving of bad habits, but then, the guys & girls who train the pilots in them take remarkable care to cover those matters, as does the Manufacturer. The RHC Safety Course is a worthwhile course for any person flying them, CoViD notwithstanding.
Sad day for all concerned, fortuitous location of the incident.