UPDATE 1-Navy says may trim Northrop drone order due to better reliability

NAVAL AIR STATION PATUXENT RIVER, Maryland, Sept 23 (Reuters) - I mproved reliability of Northrop Grumman Corp's unmanned MQ-4C Triton spy plane means the U.S. Navy may buy fewer of the drones than the 68 it now has on order, a senior navy official said on Tuesday, a move which may result in lower revenues for the planemaker.