R44 inflight breakup story - TV NZ

[fdr]

The subject accident of this thread, ZH-IPY has a couple of oddities to it;

1. the conditions at the time were unlikely to be conducive to severe turbulence at all,
2. if the winds aloft were strong, then the resultant GS suggests the CAS was not that high, which is not conducive to a low g event from environmental causes,
3. the IP was an experienced pilot with multiple RHC safety courses completed,
4. the red blade exhibited a fracture near the chord extension, however this was not in the region where fatigue has previously occurred, and the TAIC assessed the failure to be overload which does appear to be appropriate.

low g occurred almost certainly, however turbulence was unlikely to be the cause in this case, either the winds were light, and NZL is not known for thermals (other than really good gliders), orographic effects etc may occur but then the GS suggests there is a trade between the wind or CAS/TAS, take your pick, the low g due environmental is not likely.

I made comment before reading the latest version of SN-32; RHC makes appropriate note on the potential for motion of the pilots arm, and that is a factor worthy of awareness.

There is no doubt that the divergence occurred, and the pitch links have failed under overload which is consequential to not due to divergence. The divergence is unlikely to have occurred from environmental conditions. Divergence to the front and left side is not likely to come from a left pedal input, there is a fair authority at cruise speed, but the damping from the tail is fairly high then too. About the only thong that would be conclusive is a video of the cockpit at the time of the event, it is somewhat more like the Concorde event than most of the other known low g/turbulence cases.

There are some benefits from having zero hinge moment rotor systems, there are also some definite drawbacks.

NZL certainly is oversubscribed with bad days with the RHC, from 275 odd copters a 5% in flight break up rate would upset the Sqn in 1943... Time for a full time local RHC safety course maybe...