What was found
CLIMBING THROUGH 17,000' @ CLIMB 1, 270KTS, GOT A BLEED 1 FAIL CAUTION AND A BLEED 1 OFF ADVISORY MESSAGE ON THE EICAS. RAN THE CHECKLIST, MESSAGE DISAPPEARED, PRESSURIZATION NORMAL. PRIOR TO RUNNING THE CHECKLIST WE COULD SEE AND FEEL PRESSURE FLUCTUATING. ( ENGINE BLEED SYSTEMS – CROSS BLEED VALVE OPERATES NORMALLY ). REMOVED FROM SERVICE. C/W STEP 5.A OF FIM 36-11-00-810-809-A ON #1 ENG. TEST PASSED. DUE TO HISTORY REPLACED LH NAPRSOV AS PRECAUTIONARY, LEAK CHECK GOOD. REF AMM 36-11-00-000/400-801-A. C/W ENG PNEUMATIC BLEED SYS OPS CHECK IN IDLE CONDITION, OPS CHECK GOOD. REF AMM 36-11-00-710-802-A. NO EICAS MESSAGES NOTED DURING TESTS. CLEAR MEL. AIRCRAFT RETURNED TO SERVICE.