Problems with the wing structure of the Nimrod MRA4 have forced BAE Systems to push the first flight of the maritime patrol aircraft back to the second half of next year. First flight had been due by the end of this year, following an earlier delay from June.

The Nimrod MRA4 is a major rebuild of MR2 airframes for the UK Royal Air Force. The work includes a new wing as well as new engines and mission system. The programme has suffered several problems, with the in-service date (ISD)pushed back from April 2003 to March 2005. As a result of the problems, BAE is facing a £46 million ($71 million) damages charge, while aircraft numbers have been reduced from 21 to 18.

BAE says recent testing has shown the wing needs local strengthening in high load areas, thought to be around the cut outs for the engine inlets and exhausts, "to provide full reserve stress capability". It is understood the problem was found during initial structural testing. BAE adds that "it is not a redesign of the wing" although the work is complicated as the wings have already been installed on the first three aircraft, making retrofit of modifications more difficult.

Despite the delay, BAE says it still aims to meet the existing ISD, defined as delivery of the seventh aircraft. The company says it is conducting a review with the Ministry of Defence to ensure the ISD is as specified.

MoD says it is "disappointed that the first flight had to be delayed". It adds that achieving an operational capability as soon as possible is the most important consideration.

Industry observers note that meeting the ISD will be difficult as BAE was already faced with a significant flight test challenge (Flight International, 23-29 July).Aircraft two (PA2)and three (PA3)will also be delayed.

PA2 had been due to fly shortly after the initial aircraft, while PA3 was due to fly in the first quarter of 2003. The trials programme includes 200 2-4h flights for PA1, while PA2 and PA3 are scheduled for 160 and 140 6h sorties respectively.

BAE has received a £75 million, six-year maintenance contract to guarantee availability of the current Nimrod, the MR2.

Source: Flight International