Pentagon officials are satisfied with the pace of flight testing in the nine-nation F-35 Joint Strike Fighter program. However, the initiation of pilot training has once again slipped and prime contractor Lockheed Martin's production pace fell behind owing to a recent strike at the company's Fort Worth final assembly plant.

Despite these hurdles, the project—which has been mired in turmoil for years because of delays in flight testing and multiple multibillion-dollar cost overruns—has “nothing shocking or alarming going on,” says Vice Adm. David Venlet, the Pentagon's F-35 program executive officer. “This is a time of quiet stability for the program.”

Venlet opted not to attend the Farnborough air show, choosing instead to remain in Washington to oversee the program's progress. Senior defense officials from the U.K. will, however, be traveling to Lockheed Martin's Fort Worth facility this month for a ceremony to commemorate acceptance of their first F-35B.

Training for F-35 pilots is slated to begin no earlier than 2013, according to U.S. Air Force Col. Andrew Toth, commander of the 33rd Fighter Wing at Eglin AFB, Fla., the first F-35 training wing. This will mark when the Block 1B software needed for flight training is slated for delivery to Eglin.

Meanwhile, program officials are focused on continuing the pace of flight trials, a key requirement to continue burning down the excessive concurrency between the testing and production phases. In recent months, a major focus has been on preparing for the first F-35 weapons drop, which is slated for the fall, says Venlet.

The test team has already executed load and fit trials for the weapons bay. The aircraft has also been flown in various maneuvers with the weapons bay loaded and doors open to evaluate stresses. This includes carriage of 5,200 lb. of munitions supersonically. Finally, the aircraft has been loaded for external carriage of weapons; though this negates the aircraft's low radar cross section, the external positions offer more flexibility for users to carry various munitions and missiles.

“The lessons are tracking with our predictions,” says Steve O'Bryan, vice president for F-35 business development for Lockheed Martin.

The lessons, however, are not considered major by Venlet, who describes the fixes as merely tweaks to various bolts and supports needed to ensure that maneuvers in the most stressing regimes can be executed. The first weapons test will include a bomb drop, followed later by the release of Raytheon's AIM-120C7, the medium-range air-to-air missile of choice for allied nations. Weapons testing was a major requirement for Lockheed Martin's portion of its fee for the F-35 development contract in 2012.

Though Venlet is satisfied with the progress of weapons testing on the aircraft, other work continues to lag. The Block 2A software—which will facilitate expanded weapons capability (such as the use of precision-guided munitions), improved sensor fusion in the cockpit and data-linking—was slated to be delivered late last year for testing. It will now be delivered to the fleet in low-rate-initial-production (LRIP) 4 aircraft at the end of this year, says Orlando Carvalho, F-35 vice president at Lockheed Martin. The 2A software is being tested by F-35As at Edwards AFB, Calif., and is slated to be used in training in July 2013, says Lorraine Martin, Lockheed Martin's F-35 deputy program manager.

This software is behind about three months, says Venlet. Though he characterizes the delay as small relative to the overall test program that continues through 2017, it is a “very serious three months for me,” he notes. When the program was rescheduled in 2010, some capabilities—including various radar modes, data-linking capabilities and messaging formats—were slipped to Block 2 from Block 1 in order to simplify the work into more achievable increments, he notes.

The 2A software, which has begun flying at Lockheed's facility in Fort Worth, was slated to be delivered for flight testing in midsummer, says Venlet. The lag is partly owing to a slip in developing the 1B software release last year. 1B will be delivered on the LRIP 2 and 3 aircraft, and includes basic navigation, communications, sensors and “limited simulated weapons,” according to government officials. This software package will be used for initial flight training at Eglin; currently aircraft there have the 1A software. The 1A package supports basic pilot training and qualification as well as maintenance training.

However, the 1B release to Eglin is near, according to government officials.

The U.S. Air Force needs the 1B software in order to begin its F-35A operational utility evaluation (OUE), a three-month phase of flying required to determine if the aircraft are ready to conduct routine training operations. Toth says his wing plans to use all six F-35As at Eglin for the OUE phase, and pilots will follow the 1A software syllabus, which will include only basic flying and navigation. The first six weeks of the plan will be restricted to academics for the trainees, and the final six will include flights.

Four pilots will participate in the OUE phase.

Data generated from the OUE, such as sortie turn rates and aborts, will be used by Air Education and Training Center Commander Gen. Edward Rice to assess readiness for formal training.

F-35A flights are ramping up from roughly eight per week in June to 14 in July and 16 in August, says Toth. The F-35B just began flying at Eglin and achieved 6.7 hr. in the air as of May, the latest available figure.

The Marine Corps plans an OUE process similar to the Air Force's prior to beginning formal pilot training for the F-35B, though the time required may be trimmed owing to lessons learned from the Air Force. The Marines, meanwhile, are required to conduct 120 hr. of local familiarization flights prior to beginning their own OUE.

Toth says it is unclear whether a mini-OUE will be needed in the future for additional software releases.

The F-35s employing the 1A software at Eglin are slated for retrofit to the 1B package, a process that should not take more than two weeks per aircraft, he says.

Though expected in December, a trove of LRIP 3 aircraft carrying the 1B package is slated for delivery to the Florida base this month, says Venlet. All 17 of the LRIP 3s have been assembled; nine are flying and awaiting acceptance by the Pentagon, says Michael Rein, a Lockheed Martin spokesman. This type of delay is “not unnatural early in a program,” says Venlet, adding that a “healthy delivery” is expected soon, once the paperwork is complete. LRIP 3 includes seven F-35As for USAF, seven F-35Bs for the Marine Corps, two F-35Bs for the U.K. and a single F-35A for the Netherlands.

Challenges with the multilevel security required on the 1B software pushed the effort behind, Martin acknowledges. She says Lockheed intends to reduce the three-month slip as much as possible. And an additional laboratory established as part of the $4.9 billion restructuring last year is helping. It is now being converted to testing the 2B software, which will be the package used by the Marines to declare initial operational capability following flight testing.

The 2B release will allow for basic close-air-support and interdiction activities as well as initial air-to-air and data-linking capabilities. Weapons included will be the AIM-120C7, Joint Direct Attack Munitions and the GBU-12 laser-guided, 500-lb. munition.

Overall, the software requires 9.3 million lines of code, 8.5 million of which is already being tested on the aircraft or in the laboratory, says Martin.

In addition, the Pentagon has broken the Block 3 increment into two pieces—Block 3I (initial capability) and Block 3F (full capability), says Venlet. “We don't want to throw too much in it so that it can't be done,” he says, noting that Block 3 may also include some regression work from Block 2B. The 3I package, to be installed on aircraft in LRIPs 6-8, will include the 2B release rehosted on new computer hardware, selected to handle obsolescence issues. The 3F tranche will feature new capabilities that are key to the F-35's core mission‚ such as multi-ship suppression and destruction of enemy air defenses as well as new air-to-air and air-to-ground modes. This package also will include the full complement of weapons carried internally and externally on the aircraft, says Venlet. It is slated for inclusion on the LRIP 9 aircraft, and defines the capability that will be available at the end of the development phase of the program in 2017, he notes.

Once the process is stable, Venlet says the program office hopes to issue a software refresh every two years.

Talks with allies on what capabilities and weapons will be included in Block IV are in the early phases, he says. This block is likely to be approved in 18 months, with initial capabilities slated for delivery in 2020. The U.K. is pushing for inclusion of the Advanced Short-Range Air-to-Air Missile, and Norway is promoting inclusion of the Joint Strike Missile into this package—though country-unique requirements must be paid for by the participant wanting that capability.

Lockheed Martin, meanwhile, is making measured headway on two snags that came to light in testing: jitter, latency and night acuity in the Vision Systems International (VSI)helmet system, and lackluster performance of the original F-35C tailhook design.

VSI is implementing fixes to the helmet, which is designed to replace a head-up display and project symbology, day or night, onto the pilot's visor. “Small software tweaks” are needed to fix the latency issue, Lockheed Martin officials say. Slight delays cropped up during the most stressing mission scenarios, they note. A solution for this and the jitter involves installing new micro-internal measurement units. This fix is being tested this summer, says Martin. Massachusetts Institute of Technology's Lincoln Laboratory also is crafting a new camera designed to resolve the night acuity problem; it is slated for testing later in the year.

In the meantime, BAE Systems is working on an alternative helmet design which does not include the night camera, but will employ night-vision goggle capabilities.

Critical design reviews for both helmet systems are set for the fourth quarter of this year. “We have some choices ahead that will be very useful,” says Venlet.

Work also continues on a redesigned tailhook and dampener for the F-35C. The original design failed to grasp the arresting wire in slow, ground-based trials last year. Carvalho says Lockheed Martin began testing the tailhook—which has a sharper point designed to scoop under the wire—in May and it “caught the wire every time” in ground tests. Work is also underway on the dampener, and Venlet hopes to see it tested by early fall. The first arrested landing on a runway is expected in 2013. The aircraft is due to start carrier trials at sea in 2014.

Now Lockheed Martin is hoping to make up for lost time stemming from a strike at its Fort Worth facility. Venlet says that during the disruption, the company was able to achieve about 40% of the planned work using salaried employees and temporary staff. At the start of the strike, the company had only enough workers for a single shift, but after several weeks a second shift was added, improving throughput. Don Kinard, a senior fellow at Lockheed in Fort Worth, says the company has prioritized final assembly of the LRIP 4 aircraft, but officials still plan to try to deliver all 30 aircraft expected in 2012 by year-end, “though there is some pressure on that,” says Carvalho. Options include adding a third shift of workers. Although the company may not be able to recover the schedule, “I wouldn't necessarily say that we can't recover cost,” he says.

The LRIP 4 contract, which is 57% complete, is thus far running over the target by about 7%, says Venlet. Though the company will exceed the estimate at completion, says Carvalho, “we believe that differential is smaller than reported.”