What was found
DURING PREFLIGHT ENGINE WASH, ENGINE WOULD NOT ROTATE DURING STARTER ENGAGEMENT. FOUND ENGINE COMPRESSOR DIFFICULT TO TURN BY HAND, BUT COULD TURN USING FORCE. SUSPECTED FUEL COKING OF THE FUEL MANIFOLD LABRYNTH SEAL. DISASSEMBLED ENGINE, CONFIRMED COKING OF THE LABRYNTH SEAL. INSTALLED OVERHAULED FUEL MANIFOLD, REASSEMBLED ENGINE. ENGINE FUNCTIONED NORMAL WITH NO FURTHER PROBLEMS. PROBABLE CAUSE UNKNOWN. (K)