As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SFO - FLT 0037 - LT BLEED DUCT LEAK LIGHT ON TAKEOFF. LIGHT EXTINGUISHED AFTER ENGINE BLEED VALVE CLOSED. INSPECTED AND FOUND AFT GROUND AIR SUPPLY CHECK VALVE OPEN. REMOVED AND REPLACED GROUND AIR SUPPLY CHECK VALVE. LEAK CHECK GOOD. ACCOMPLISHED HIGH POWER RUN. NO PROBLEMS NOTED. (X)