What was found
(CAN) TEE FITTING SUPPLYING TORQUE PRESSURE READING TO AIRCRAFT INSTRUMENTS WAS LOOSE, CAUSING AN OIL LEAK. THE TEE FITTING WAS WITNESSED (WIRED) AND APPROX HALF TURN WAS NEEDED TO TIGHTEN. AIRCRAFT ENGINE WAS SHUTDOWN IN FLIGHT AND AIRCRAFT LANDED SAFELY. OIL PRESSURE WAS RECORDED AT 45 PSIG PRIOR TO SHUTDOWN. THIS FITTING IS PART AN STC'D INSTALLATION OF THE ALTAIR TWIN-K031-3 ENGINE HIGH PRECISION TORQUE KIT. NOTICE 651-77-12-016 WAS CREATED TO CHECK FOR SIMILAR CONDITIONS ON COMPANY FLEET AIRCRAFT. IT WAS FOUND THAT MANIPULATING THE TEE FITTING BY HAND COULD CAUSE LOOSENING.