What was found
RELIEF VALVES STICKS. WILL NOT RELIEVE AT RATED PRESSURE. THIS PHENOMENA HAS BEEN OBSERVED AS LITTLE AS TWO MONTHS AFTER A PREVIOUS STOP VISIT. SUBMITTER BELIEVES THE CONDITION RESULTS FROM THE RUBBER COMPOSITION OF THE VALVE FACE MAKING CONTACT AND STICKING. NOTE: IT IS IMPERATIVE THAT THE RELIEF VALVE (20, IPL FIGURE 7) BE CHECKED FOR PROPER OPERATION EVERY SIX MONTHS/1500 FLIGHT HOURS, OR EVERY SHOP VISIT.