What was found
ON CLIMB OUT NOTED LARGE DUCT SPLIT AT 5000 FT LEFT 18PSI, RT 40PSI AT 20,000 FT LEFT 16PSI, RIGHT 40PSI , AT 35,000 LEFT 18PSI, RIGHT 42PSI, AS WE LEVELED OFF AT FL 370 LEFT "BLEED TRIP OFF" LIGHT ILLUMINATED QRH FOLLOWED AT "RESET" LEFT "BLEED TRIP OFF" LIGHT WENT OUT: PRESSURE NORMAL TO LEFT 38PSI, RT 40SPI , DESCENT FL 320 IDLE LEFT 20PSI, RIGHT 20PSI. GROUNDED - YES. PERFORMED FIM 36-10 TASK 814 & TASK 804 BAR/PRSOV 1450 THERMOSTAT HEALTH CHECK PER AMM 36-11-001710-802 BAR FAILED TEST, REMOVED AND REPLACED NR 1 ENG BLEED AIR REGULATOR PER AMM 36-11-03. ACCCMPLISHED FIM 36-10 TASK 804 OPS CHECKS GOOD. ENGINE BLEED AIR CROSSOVER OPERATIONAL TEST CHECK GOOD IN REF TO AMM 36-11-00-701-801.