JSF juggling cost, weight, schedule issues

From Aviation Week

JSF Juggling Engine, Cost, Schedule and Weight Issues

Apr 1, 2007

By Amy Butler and Robert Wall

The Joint Strike Fighter's price is expected to increase 4% due to Pentagon funding cuts. And if Congress reinstates development of a second engine for the stealthy aircraft, the cost could rise further.

The increase could amount to more than $6 billion over the life of the massive, 3,000-aircraft program. But cost is only one of a flurry of issues ahead as development work moves into high gear. All three F-35 JSF versions will face key hurdles in the coming months, with program officials trying to keep the Lockheed Martin-led industrial team from losing its focus.

For the conventional takeoff and landing (CTOL) F-35A, boosting the pace of flight testing is a primary concern. Key for the short takeoff and vertical landing (Stovl) F-35B are critical engine tests and a continued drive toward first flight next year. The F-35C carrier version is heading into its critical design review.

Although Stovl weight stabilization remains in the spotlight, program officials are trying to avoid prioritizing just one issue. That's partly why they rejected a call by some within the Pentagon to focus Lockheed Martin's award-fee performance primarily on the Stovl first-flight milestone, set for May 23, 2008. Unintended consequences could result from imposing such narrowly focused incentives, which can "drive bad behavior," argues U.S. Marine Corps Brig. Gen. David R. Heinz, deputy program director.

JSF managers prefer to see Lockheed Martin concentrate on weight control and other parameters, not just schedule, and balancing the award-fee criteria is the best strategy, he adds.

The scope of the award fee has been an issue for several months between program officials and some in the Pentagon oversight chain. The latter believe Lockheed Martin's rating and resulting remuneration may have been too high. Even though the company missed the first-flight date in late August for the CTOL version, it garnered 83.9% of its performance bonus for that period, which ended in October.

During that period, Lockheed Martin received $129.4 million in performance recognition. Earlier, in April, the contractor earned $123.8 million, or 87.3%, of what was available. Though the contract did not solely grade Lockheed Martin on that model's first flight, the company was under pressure because some international partners wanted to see the aircraft fly before committing to a purchase.

Even without a special focus on the F-35B first flight, the Stovl version's development will be center stage in the months ahead. Fuselage mating is planned for midyear, followed by power on by year-end. At this point, Heinz is upbeat about the schedule.

JSF officials are generally sanguine about program performance, although they will report to Congress soon that the aircraft's $53-million average unit cost will increase roughly 4%. That's the result of cuts the Pentagon has made to near-term procurement plans, which it's still trying to offset (see p. 30).

Nevertheless, Air Force Secretary Michael Wynne doesn't see any Nunn-McCurdy breach on the horizon--referring to a U.S. law mandating that price increases of 15% or more require additional congressional scrutiny for a program to move forward.

However, the cost impact could be even greater if Congress overrules a Pentagon decision to terminate the General Electric/Rolls-Royce F136 alternate engine development, but doesn't add money to pay for it. Financing the $2-billion development bill in the next five years within the current JSF program funding could force a cut of 15-30 additional fighters, which would drive up costs further, says Heinz. The Pratt & Whitney F135 is the primary F-35 engine.

The U.S. Government Accountability Office argues that adding a second JSF engine could produce some long-term savings. However, the Cost Analysis Improvement Group, a Pentagon cost-estimating division, and an independent study from the Institute for Defense Analyses both say the cost benefits of a second engine would be negligible. These reports were presented to two panels of the House Armed Services Committee last month. Congress mandated the studies in the Fiscal 2007 authorization act. Total cost for a single-source engine program is pegged at $53.4 billion, with estimated increases up to $4.5 billion if the F136 survives.

PROGRAM OFFICIALS HAVE BEEN providing data for each of the studies but have not expressed a preference on retaining or terminating the F136 effort. Heinz notes there are pros and cons to each argument: Eliminating the second engine would provide instant savings, although there are industrial-base considerations (in terms of sustaining a competitive fighter-engine capability) and operational concerns about an engine-induced fleetwide grounding that would favor making the investment.

Meanwhile, engine development activity is moving ahead. Ongoing tests are evaluating the durability of the F135, with runs up to 7,000 hr., and of the lift fan, which is critical for the Stovl version. The lift fan has undergone about 1,000 hr. of testing. In addition, 500 engagements of the clutch that links the lift fan with the F135 engine (or F136, if it's retained) are being performed.

Rig testing of the lift fan, the surrounding doors and other structural elements also is planned to assess airflow. In a prior test, the rig failed before full results could be obtained.

A watchful eye also remains on weight. The Stovl version, for which increases would pose the greatest problem, remains on track. Program officials have built in weight-growth margin of around 3% during the development phase. Surprises will eat into that margin, Heinz concedes; but for now, he appears confident another weight crisis (as occurred several years ago on the program) can be averted.

As for the carrier version, developers have seen a positive evolution, with "the weight constantly decreasing in the last 12 weeks," says Heinz. During that period, the basic design has shed about 90 lb.

The F-35C is the last in the development sequence and should complete its critical design review by the end of July. Several subsystem reviews will precede that event, such as a look at the landing gear, which is one of the main structural elements that's different on the Navy model.

For the CTOL version, test pilots are gradually expanding the flight envelope, though they've not yet exceeded 40% of design limits. Heinz says these early test flights are validating the accuracy of design models, which makes program officials hopeful that future surprises can be averted.

So far, the flight testing pace has fallen short of the desired six missions per month, partly due to weather-induced delays. In one case, the test program had to be stopped because a loads measurement in the vertical tail indicated that limits had been exceeded--although further inspection showed there was no damage.