What was found
AIR TURN BACK CABIN PRESS ALTITUDE WARNING HORN SOUNDED & PRESSURIZATION NEVER RECOVERED. R & R NR 1 ENG PNEU BLEED HIGH STAGE REGULATOR IAW MM.
As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
AIR TURN BACK CABIN PRESS ALTITUDE WARNING HORN SOUNDED & PRESSURIZATION NEVER RECOVERED. R & R NR 1 ENG PNEU BLEED HIGH STAGE REGULATOR IAW MM.