As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NPRM STATES TO REMOVE PART NUMBERS AND SERIES NUMBER AND REPLACE THESE ITEMS WITH A SERIES 7 OR GREATER. THE SERIES 7 UNIT WHEN INSTALLED FAILED. WHEN AN APU START WAS ATTEMPTED USING A SERIES 7 START CONVERTER UNIT. THE NEW UNIT EXPERIENCED A COMPLETE ELECTRICAL FAILURE.