As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING REMOVAL OF HEAT EXCHANGER FOUND A CRACK ON THE BOTTOM IN BOARD SIDE OF PRIMARY HEAT EXCHANGER. GROUNDED - YES. REMOVED RT SIDE PRIMARY HEAT EXCHANGER REF AMM 21-51-03-000-805-002 & INSTALLED NEW PRIMARY HEAT EXCHANGER REF AMM 21-51-03-400-804-002.