As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
VERY LOUD AIR NOISE COMING FROM LEFT AC BAY. INSPECTED AND FOUND LEFT HEAT EXCHANGER BLOWN. SEE PHOTO. REMOVED PIMARY AND SECONDARY HEAT EXCHANGER REF AMM 21-51-02-004-001 INSTALLED NEW PRIMARY HEAT EXCHANGER ON TO THE SECONDARY HEAT EXCHANGER ON GROUND STEP G UP TO SUBSTEP 1 (D) REF AMM 21-51-02 HEAT EXCHANGER INSTALLED REF TASK 21-51-02-404-019 EMPLYEES 349261, 349381, 351397 SDR CREATED.