As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER ENGINE START, THE LEFT DUCT PRESSURE INDICATES 7 PSI WITH ENGINE POWER AT IDLE, A/C PACKS IN AUTO AND ENGINE ANTI ICE OFF. GROUNDED - YES. FOUND MUSCLE AIR LINE TO NR 1 ENGINE HIGH STAGE VALVE BROKEN. REPLACED LINE AND LEAK CHECK OK. GROUND VERIFICATION OF DUCT PRESSURE PER FIM 36-10 TASK 804 PRESSURE WITHIN NORMAL LIMIT.