What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
(-23) Upon returning to "jmar" the Yuma station, the pilot was flying normally @ 500' (AGL) then flared to a hover @ 50' (AGL). A loud "humming" noise could be heard as reported by the pilot, then a loud "bang". The pilot auto-rotated as best he could which resulted in a non-eventful landing other than the hi-speed shaft puncturing the firewall. The (lone) pilot was uninjured and there was no post-event fire.
As the FAA filed it
(-23) UPON RETURNING TO "JMAR" THE YUMA STATION, THE PILOT WAS FLYING NORMALLY @ 500' (AGL) THEN FLARED TO A HOVER @ 50' (AGL). A LOUD "HUMMING" NOISE COULD BE HEARD AS REPORTED BY THE PILOT, THEN A LOUD "BANG". THE PILOT AUTO-ROTATED AS BEST HE COULD WHICH RESULTED IN A NON-EVENTFUL LANDING OTHER THAN THE HI-SPEED SHAFT PUNCTURING THE FIREWALL. THE (LONE) PILOT WAS UNINJURED AND THERE WAS NO POST-EVENT FIRE.