Thanks to all my well wishers regarding this accident.
Here's the report that I submitted to the FAA verbatim:
While practicing autorotations on the grass runway 35 at Chambers County (T00), during the third landing, I experienced a sudden loss of lift during the flare due to a possible strong wind shear, resulting in a vertical drop of about four feet. I immediately attempted recovery with full power, but was unable to prevent a hard landing during the go-round which caused the propeller to strike the bottom keel. The aircraft bounced to the left initially, the rotors impacted the ground, and the detachable mast sheared at the junction and twisted off, held in place with the control rods. The aircraft came to rest on the mast junction on its right side, and I evacuated the aircraft immediately and called for help.
Major damage caused was to the three propeller blades which sheared at the hub, mast sheared/bent at the detachable junction, and both rotor blades gouged and bent.
It is interesting to note how someone has posted that the gyro ran out of energy high off the runway. This is pure speculation, and that is the reason I am not seen on this forum anymore. What does one tell the pilot that crashes during a microburst, caught on the wrong side of the shear, pilot error????
As you may note in my report, the sink was quite sudden and unexpected and full power was applied, but it did not prevent the hard touch down.
I have even experienced unexpected tail winds occasionally at Anahuac when the wind direction changes suddenly. For those that feel this cannot happen, please go through some of the old threads and posts by Birdy, where he explains some interesting and unexpected phenomena regarding wind shear at low altitudes.
I hope this answers the queries, and I am thankful and blessed to have walked away from this one. Moral of the story is that one should always be prepared for the unexpected.
As an instructor, what I teach students is that it is not so much as the situation itself, but how one deals with a situation. In this situation, all that I could do was open full power to try and arrest the sink. Sometimes, it just may not be enough power under the circumstances. But any landing you can walk away from is a good one, as the saying goes.
Happy landings and Merry Christmas!