What was found
THE FLIGHT CREW REPORTED THE NO:1 ENGINE BEGAN POPPING AND LOST 50% OF ITS POWER 11 MINUTES AFTER TAKEOFF. AN UNSCHEDULED LANDING WAS PERFORMED AT THE DEPARTURE AIRPORT - NO INJURIES OR EQUIPMENT DAMAGED RESULTED FROM EPISODE. UPON FURTHER INVESTIGATION, THE DIAPHRAGM WAS FOUND TO BE PARTIALLY BLOWN OUT OF THE COMPRESSOR BLEED VALVE WHICH CAUSED SIGNIFICANT POWER LOSS - NO OTHER FAULT WAS FOUND. THE ENGINE MANUFACTURE WAS CONTACTED (P&WC) AND AS PER THEIR GUIDANCE, AN OVERHAULED REPLACEMENT BLEED VALVE WAS INSTALLED, AND THE AIRCRAFT WAS RETURNED TO SERVICE AFTER OPERATIONAL CHECKS WERE PERFORMED.