What was found
AT FL 400 WITH ISOLATION VALVE CLOSED ENG NR 1 BLEED SWITCH OFF LEFT DUCT PRESSURE WAS 17 PSI. REF SECTION 8.000 PG 13. REMOVED AND REPLACED ISOLATION VALVE IAW B737NG AMM 36 13 04 FOUND SATISFACTORY AND NO LEAK NOTED.
As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
AT FL 400 WITH ISOLATION VALVE CLOSED ENG NR 1 BLEED SWITCH OFF LEFT DUCT PRESSURE WAS 17 PSI. REF SECTION 8.000 PG 13. REMOVED AND REPLACED ISOLATION VALVE IAW B737NG AMM 36 13 04 FOUND SATISFACTORY AND NO LEAK NOTED.