What was found
FLIGHT 839 DURING PREPARATION FOR TAKEOFF, THE CREW REPORTED THE NUMBER 1 ENGINE BLEED TRIPPED WHEN TAKEOFF POWER WAS SET, 95 PSI DUCT PRESSURE INDICATED. THE AIRCRAFT RETURNED TO THE BLOCK WITHOUT ANY FURTHER INCIDENT. MAINTENANCE TROUBLESHOT AND REPLACED THE NUMBER 1 ENGINE HIGH PRESSURE MODULATING AND SHUTOFF VALVE IAW MM-36-12-42, ACCOMPLISHED ENGINE RUN PER AMJ FORM M-53 AT TAKEOFF POWER FOR 3 MINUTES, THE DUCT PRESSURE READ 65 PSI MAX. OPERATIONAL CHECK AND LEAK CHECK OK, IAW MM 36-12-02. THE AIRCRAFT WAS RETURNED TO SERVICE.