DURING ICING trials in the USA, the three-strong Nimrod MRA4 development fleet passed the milestone 1,000 flying hour mark in February. The icing certification flights are the latest step in the MRA4 trials programme and involved the first prototype, ZJ516 (PA01). The aircraft arrived at Nashville International Airport, Tennessee, on February 1 for the month-long test programme, having flown more than 4,500nm (8,325km) from the UK, via overnight stops in the Azores and Bermuda. A wide range of test conditions were experienced, with up to 2in (5cm) of ice accreted on the wings and ground conditions ranging from snowfalls to monsoons.
Sorties from Nashville ranged from 900nm (1,665km) west to Colorado Springs to 600nm (1,110km) northeast to Scranton, Pennsylvania. Each flight routing was planned with assistance from a meteorologist, who had real time contact with the aircraft via satellite telephone. After over 60 flying hours of productive testing in ten flights and a new record duration flight of 7hrs 15mins for PA01, the aircraft was scheduled to come home in the week beginning March 2.
As of February 29, ZJ516 (PA01) had undertaken 457.05 hours of flight testing in 140 flights, whilst ZJ518 (PA02) has reached 341.01 hours in 99 flights. The total for ZJ517 (PA03) is 205.14 hours in 64 flights. This brings the overall total for the three aircraft to 1,003.2 hours and 303 flights. Recent and planned trials milestones with the three development aircraft are as follows:-
Over the past six months, PA01 completed planned pause 1.5, a seven-month lay-up during which the Stability Augmentation System was installed. The manufacturer said that subsequent flight trials had been «extremely positive», the aircraft undertaking 26 flights and five days of ground runs in just 35 working days before being prepared and deployed on time for the natural icing tests. PA01 plays a key role in the Design and Development (D&D) phase and principal activities still to be completed include further stalling investigation, high mass aircraft handling, an assessment of handling with simulated ice shapes attached to the wing and tailplane, and two European detachments to assess airfield performance.
Recent achievements by PA02 include release of the first Stingray torpedo at the Aberporth range in Wales on its 75th flight in June last year. On February 25, 2008, PA02 flew to Woodford to begin the Utilities Systems Management System (USMS) U5b fuel B+ test programme in order to confirm that software correctly manages the fuel system. Results will be used in the overall production qualification process supporting Release to Service recommendations. Once fuel tests are complete, PA02 will return to the flying programme to complete D&D activities. These will include final safe separation trials of Stingray and other key bomb bay stores, detachments to Boscombe Down, Wiltshire, and the USA (MCAS Yuma, Arizona) to assess, respectively, high mass characteristics and natural hot weather performance, particularly during taxi and take-off. The remainder of the programme will complete outstanding qualification work, including gathering performance data in flight and completing auto pilot qualification.
PA03 has completed several key ground trials over the last six months, all essential to completing programme qualification objectives, including auxiliary power unit fire extinguishant tests. Lightning strike trials have also been carried out with the aircraft in Hangar 358 at Warton, during which it was cocooned in more than 2xh miles (4km) of specialised aluminium framework before being subjected to over 400 high voltage (up to 50,000 amps) pulses to simulate lightning strikes. Final development electro-magnetic hazard (EMH) testing was undertaken to support production aircraft EMH qualification. The aircraft flew back to Woodford on February 15, 2008, after completing successful assessment of aircraft stalling characteristics, marking its last flight in support of the D&D phase. Its contribution continues with the start of a Maintainability and Testability demonstration programme.
Production Aircraft Progress
Progress on the production line al Woodford means that PA04/ZJ514 (ex XV251) is now 47% complete, with the first fit of flying controls in Region 6 now completed and flaps currently being rigged. Region 4 forward weapons bay panniers were also being fitted at the end ol February. Power on for the aircraft is planned for the third quarter o! 2008. The next aircraft, PA05/ZJ515 (ex XV258), is 12.85% complete, with equipping of Regions 6 and 3 currently under way. The hangai is being prepared for delivery ol the new wing for PA06/ZJ519 (ex XZ284). Wing to fuselage join-up for this aircraft is anticipated in the third quarter of this year.
The D&D phase is forecast to be completed by the end of 2008, with delivery of the first production aircraft (PA04) expected at the end of 2009.