As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FIRE EXTINGUISHER DISCHARGE SYSTEM LINE INSULATION WAS FOUND DETERIORATED IN THE LEFT SIDEWALL OF THE C-2 B/B FROM FS 1351 TO FS 1439 DUE TO CHAFING WITH THE APU PNEUMATIC DUCT AT THAT LOCATION. THE (P/N 5259381800) (R-180-F) INSULATION WAS REPLACED.