The US Navy will review procurement quantities for the Northrop Grumman MQ-4C Triton following initial operational test and evaluation and operational deployment, US Naval Air’s program manager for maritime unmanned aircraft systems tells FlightGlobal.

The service has decided to purchase 70 MQ-4Cs, with a fleet of 20 aircraft for continuous patrols over five surveillance orbits and another 48 UAVs added to the buy to replace attrition losses, FlightGlobal previously reported. The navy based the attrition number on its estimate that the service would lose four aircraft per 100,000 flight hours.

The Triton attrition rate will be reviewed “as appropriate,” Sean Burke says. Earlier this year, the Defense Department’s inspector general pushed the service to review the attrition rate following operational assessment and initial operational test and evaluation.

The Navy announced Triton’s milestone C approval 22 September, kicking off the programme’s low-rate initial rate production phase. The DOD awarded Northrop a $255 million modification to a previously awarded contract for three LRIP lot 1 MQ-4C aircraft, ground control station and forward operation control station.

Earlier this year, the Navy completed the first operational assessment on Triton, which included tests of the MQ-4C’s active electronically scanned array radar and electro-optic/infrared camera. The service scheduled its second assessment for fiscal year 2017, after LRIP is awarded. The initial operational test and evaluate phase is also scheduled to start in FY17.