What was found
(CAN) CREW ADVISED FLIGHT DISPATCH THAT THEY HAD A "YELLOW HYDRAULIC" FAILURE AND REQUIRED A PATCH TO MOC. PATCH WAS COMPLETED, FLIGHT CONTINUED, ATC WAS ADVISED AND TRUCKS WERE CALLED OUT AS A PRECAUTION. FOUND NR 2 ENGINE HYD PRESSURE LINE B-NUT LEAKING PROFUSELY AT PRESSURE FILTER. LINE REPLACED AND LEAK CHECKS CARRIED OUT WITH NO LEAKS EVIDENT. CONS SERV IAW DELAY REPORT (DUE PART IDENTIFIED IN DELAY REPORT) FOUND NR 2 ENGINE YELLOW HYD HIGH PRESSURE LINE B-NUT AT HP FILTER LEAKING PROFUSELY, PN AE707420-3, ORDERED AND IN STOCK.