As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT PACK PRIMARY SECONDARY HEAT EXCHANGER POLYNOME FAILED DURING HEAT EXCHANGER WASH T/C 78121000, DELAMINATED. GROUNDED - YES. REMOVED LEFT PRIMARY, SECONDARY PLENUM/DIFFUSER REF AMM 21-51-03. INSTALLED NEW PLENUM AND DIFFUSER ASSY. ON TO BOTH PRIMARY AND SECONDARY HEAT EXCHANGERS REF AMM 21-51-03-400-804-002, ALL OPS AND LEAK CK GOOD.