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The Great Survivor

The latest version of the RAF’s Nimrod – over budget and 13 years late – prompted a political crisis. Can the troubled programme finally deliver on its promises?

BAE Systems expects to conclude flight test activities on its three Nimrod MRA4 development aircraft late this year, but is still seeking a commitment from the UK Ministry of Defence to fund their conversion to the full production configuration.

Nine MRA4s are under contract for the Royal Air Force, with the MoD having signed a deal for the surveillance aircraft plus an option for three refurbished design and development aircraft during the 2006 Farnborough air show.

The first production MRA4 will achieve power-on at BAE’s Woodford site in Cheshire by September, and will then enter an extended equipment fit, load and test programme before making its first flight next year. “We are expecting delivery at the end of 2009, or early in 2010,” says Joe Harland, the company’s managing director, large aircraft.

Under the current programme schedule, BAE will deliver four production MRA4s to RAF Kinloss in Scotland by the end of 2010, when the new type is expected to be declared in-service. “We are supporting the customer in their aspiration to have the in-service date in 2010,” says Harland, who adds that with eight different lines of development having to come together, “it will require a concerted effort by both parties to be successful.” Other factors needed to achieve the milestone include the availability of sufficient trained air crew and maintainers, plus ground support equipment.

Flight test activities involving the MRA4 development fleet were launched in August 2004, when the programme’s first aircraft – PA1 (ZJ516) – made its flight debut from BAE’s Woodford site.

 © BAE Systems

The programme’s third flight test aircraft, PA3, has now completed its involvement in the flying programme, where it was used to confirm, in the air, work done using a ground weapon system integration rig. Equipped with a full mission system, but carrying the least instrumentation of the development fleet, the aircraft is now parked at Woodford, where it is being used to help with production and ground testing and to assess the MRA4’s maintainability characteristics.

“We are currently forecasting that PA1 has the most to do, and it should finish this year,” says Harland. “PA2 will finish maybe a month before, but we’ve got one more mission system software release we want to check in flight.” The latter aircraft is currently on the ground receiving a scheduled software update, and will resume navigation and communication trials after returning to flight around late June or early July, he says.

The first Nimrod MRA4 to fly, non-mission aircraft PA1, was earlier this year involved in icing trials conducted from Nashville, Tennessee, in one of the last major activities to be undertaken before the joint BAE/RAF test team completes its campaign.
Flown to the USA via the Azores and Bermuda, the aircraft flew 19 sorties over a roughly six-week period, after briefly being moved to an Air National Guard base at Newburgh, New York, when tornadoes were forecast to pass through Nashville the day after its arrival in the USA.

“It conducted probably the most successful icing evaluation I’ve ever heard of,” says Harland: “We never had a flight where we didn’t find ice.” The MRA4’s long range capabilities meant PA1 could operate throughout the USA and up into Canada if required, but operations were managed by talking to a meteorologist over a satellite telephone. “We would launch into the general vicinity and then give him reports of the ice we were seeing. He would adjust us in altitude or location along the frontal system to get the ice that we were looking for on that particular day,” says Harland. “It worked well.”

Hot Air Tubes

One design issue was highlighted during the course of the trials, when some of the tubes which are used to distribute hot air along the wing leading edge leaked at full power. “This is one of those things you can’t check on the rig or with ground tests,” says Harland. The issue was resolved by using tighter couplings and jubilee clips to hold the tubes more securely, with this solution likely to be integrated with production aircraft.

Nimrod Wing
 © BAE Systems

One of the remaining overseas commitments for PA1 will require the test team to deploy the aircraft to the Istres flight test centre near Marseille in France, where it will perform ground taxi tests at maximum gross weight using the site’s 13,000ft (3,960m) runway. To include further assessment of tyre and brake heating characteristics, the work will build on preliminary activities already conducted at Qinetiq’s Boscombe Down test facility in Wiltshire, UK.

Computer System

One well-publicised recent change to the aircraft was the introduction of a stability augmentation upgrade, achieved by computer modification and actuators, as an original speed trim system failed to work as well as expected. “We’ve added an inner loop [computer system] that works the elevator really hard, so the pilot thinks he’s got a ‘golden arm’,” says Harland. “It’s making very rapid, very small corrections to the elevator, so the aircraft stays at the same place on the horizon without wavering around.”

Also exposed during the flight test programme and the final stability element to be tackled, Harland says the aircraft’s stall “is not as pronounced as the certification agents would like it to be”, a potential problem for an aircraft which could spend part of its operational life hunting for submarines at an altitude of 200ft.

“Using the same angle of attack sensors and gyros we’ve added the capability to warn the pilot that he is approaching a stall, by shaking the stick. If he persists in pulling the nose back we also have a stick pusher.” Software releases have been made during this year, and Harland says “the pilots are pretty pleased with that. It’s virtually carefree [handling], because it allows prompt recovery from the stall.”

The aircraft’s aileron rigging has been adjusted, so that the port and starboard ailerons do not move by the same amount, avoiding the onset of adverse yaw. BAE also has yet to prove some changes on roll authority, and is to investigate whether it needs to add more vortex generators/stall fences on the outer wing to provide additional lift in a slower speed regime. The latter will be tested on two or three flights using temporary structures, with both PA1 and PA2 to participate in the work, expected to be performed later this month or in early July.


Once in service, the MRA4 fleet will be expected to work hard. RAF Nimrods logged almost 117,000 flying hours in the decade ending the MoD’s financial year 2006-7, with planned use of over 8,700h in the same year. The MoD faces continued pressure over the safety of its current MR2 aircraft, with a coroner’s report into the loss of aircraft XV230 over southern Afghanistan in late 2006 having concluded that the type was not airworthy.

All 14 personnel aboard the aircraft died after a catastrophic fire broke out immediately after inflight refuelling from an RAF Lockheed TriStar tanker, causing the Nimrod to explode in mid-air. The MR2 fleet is still subject to operating restrictions following the recommendations of a Board of Inquiry investigation into the accident.

 © BAE Systems

The last of the RAF’s remaining fleet of Nimrod MR2s is expected to retire in March 2011, and Harland says: “There isn’t anything on the MRA4 programme that would cause me to think that will be later.”

The first training systems for the MRA4 are now in place, with Thales having handed over an aircraft synthetic training aids system for the type to prime contractor BAE last September. The system – which comprises two dynamic simulators, two flight training devices, two rear cockpit trainers and a part-task trainer – is being upgraded in advance of starting to support air crew training activities at RAF Kinloss from next year.

However, the MRA4 project is still affected by issues under the MoD’s ongoing Planning Round ’08 budgeting process. “The budget for this year is not fully vetted, and there is a lot to do,” says Harland. “When the contract was signed, it was a firm commitment for nine aircraft, and an option to refurbish the three development aircraft. That option was never taken up, so we’re in the process of re-pricing that.

“We’re building those [production aircraft] as fast as we possibly can to support the ISD. But if the decision gets delayed too long on what we’re going to do on productionisation, then the price for bringing those aircraft up to standard will go up, because we don’t have the appropriate amount of through-put at the factory. In the worst case scenario I wouldn’t have a workforce there any more, and I might have already closed the site.”

Under current plans, three aircraft will be produced per year, with BAE having imposed a capped headcount at its Woodford site. “We are going to close the site when production’s finished – that’s why we’d very much like to get the three productionisation aircraft.”

Nimrod R1

With the MoD’s original contract for the MRA4 having covered the preparation of 21 aircraft, BAE has previously identified the now reduced fleet as holding potential to also provide airframes to replace the RAF’s current three Nimrod R1 electronic intelligence aircraft. “We would love to be making more of these, but I don’t think that we will be,” concedes Harland.

As well as facing continued uncertainty over the conversion of the three development aircraft and activities at its Woodford site, BAE is also concerned about the type’s likely through-life support arrangements.

“Starting up a new aircraft type costs more per aircraft than running one that’s being sustained, and there is more risk around supporting a brand new aircraft, because there’s not as much historic data,” says Harland.

While early indications are promising – in mid-May the test team turned the aircraft around between sorties in 40min, against the approximately 35min achieved with the Nimrod MR2 after more than 30 years of operation. “All the forecasts indicate once we get a stable configuration that we’ll be more easily supported. But that doesn’t correlate to less expensive, particularly in the first few years.”

The first five years of operations are intended to enable BAE and the MoD to collect enough data to design a long-term, incentivised support system. “At the end of the next five years we’re going to adjust it again,” says Harland. “The company, our customer and our shareholders don’t like unbounded risk.”

Due to its busy remaining test campaign, the MRA4 won’t be seen on the UK air show circuit his summer, missing events at RAF Waddington in Lincolnshire, the Royal International Air Tattoo at Fairford, Gloucestershire and the Farnborough air show in Hampshire. Harland says that preparing for such events would create a disruption of up to three or four weeks on the type’s flight test programme. “Every additional month is a cost I share with the customer, and we just couldn’t justify doing it.

“We are programmed to fly each of the aircraft two to four times a week, but we plan to fly an aircraft every day. We have been achieving four or five times a week on the one aircraft that was [recently] in the flight test programme.”

Originally to have entered service in April 2003 under the terms of BAE’s then fixed-price development and production contract with the MoD, the planned £2.8 billion MRA4 project in 2002 encountered a financial and schedule crisis so severe that it prompted both parties to change the way in which they would undertake future such major procurements.

 © BAE Systems

The MoD also assessed whether a suitable alternative to the MRA4 was available on the market around 2003, but continued its commitment to the project after finding no adequate substitute. The project is now running 92 months behind schedule and will cost almost £790 million more than the budget allocated at Main Gate approval in 1996.


Citing fresh cost growth of £100 million from 2007-8 linked to addressing the stability pitch issues and conversion of the three development aircraft, the House of Commons Defence Committee’s recent Defence Equipment 2008 report called for the MoD to again consider its options. “We hope that the new minister for Defence Equipment and Support will look closely at this programme and consider whether it is ever likely to deliver the capability our armed forces require in the timescale needed,” it said. “If it is not the MoD should withdraw from the programme.”

Harland counters the committee’s call, by saying: “If you still want to do the mission, the customer would have to identify what the replacement is. A huge proportion of the cost on this programme is sunk. There is not really that much to go.”
More than £1.7 billion had been spent on MRA4 design and development activities by mid-2007, including £215 million since the 2006 production contract was signed.

He also defends BAE’s performance in delivering on the MRA4 since 2002, noting that the company has been very consistent in its price forecast on contracted work since recovering from the financial crisis. “The [current£100 million] growth in the costs is mostly in work that’s not on contract,” he says. “We would say the part we’re on contract for is being well managed.”

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