As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) WHILE ON PAD, WITH ROTORS ENGAGED, IT WAS NOTICED ZERO AMPS ON DC AMMETER. THE GEN IREC SWITCH WAS SELECTED TO REC (RECTIFIED) AND 150 AMPS WAS READ. SUSPECTED DC GEN FAILURE. CARRIED OUT CHECK LIST PROCEDURE & THAT WAS WHEN THE DC GEN LIST ILLUMINATED. UPON REMOVAL OF THE ABOVE UNIT THE SHAFT WAS FOUND SHEARED. UNIT REPLACED & A/C RETURNED TO SERVICE.