Since production of the F-16 started in 1976, more than 4,500 of the single-engine fighters have been sold to more than 20 nations. Now, however, the decades-long production run for the fighter, once said to “sell itself” to customers globally, is facing an unfamiliar predicament: potential shutdown.

To stave off termination activities in the hope that near-term deals will come to fruition, prime contractor Lockheed Martin is paying some of its suppliers' bills, much as Boeing has done for the C-17 and F-15. However, Lockheed will not receive help from the U.S. Air Force, which is continuing with its plans to buy the company's new single-engine, stealthy F-35 while eyeing an upgrade to add 50% more life to its existing F-16s.

With a total order book of 4,540, the F-16 has been a wildly successful project. But details remain to be sorted out for pending deals with Iraq and Oman.

Lockheed Martin is feeling pressure from delays in sealing deals with Oman for 12-18 fighters and Iraq for another 18, and the company is funding some long-lead activities at its own risk. Counting recent sales to Morocco and Egypt, Lockheed has a backlog of 57 aircraft. The production rate is 18 per year, and each aircraft requires 30-36 months of cycle time including orders of the longest-lead parts. One company official notes that a decision needs to be made by year-end on whether to continue financing line activities into next year if the deals are not signed.

“We are protecting the schedule,” says Bill McHenry, F-16 business development director. “We have protected components” to ensure that those longest-lead suppliers can avoid work gaps. McHenry declined to say how much has been spent to finance these operations. “Sometime in the fourth quarter of this year, many of our suppliers are going to reach the point where they need an order or they are just going to go out of business.”

Although the sales to Iraq and Oman have “slowed down,” McHenry suggests that both are “actively being pursued” now, and “fundamentally we have a letter of acceptance in progress.” Congress has not objected to the sales, but the government-to-government talks to finalize details are still under way.

Some USAF leaders had objected to the sale of F-16s to Iraq over concerns that the young nation's pilots would not be ready to operate or maintain the high-performing system. Additionally, unrest in the Middle East is thought to have contributed to delays in the projected sales.

Potential buys from Romania and Taiwan are also being eyed. Taiwan hopes to buy as many as 66 aircraft and Romania has eyed as many as 48. The latter deal may see progress, with senior Romanian officials slated to visit Washington this month. A decision on the sale to Taiwan—which is politically thorny, given objections from China—is expected from the White House by the end of next month. Last week, Sens. John Cornyn (R-Texas) and Robert Menendez (D-N.J.) introduced legislation to support the Taiwan sale. Cornyn, who represents the state where the F-16 final assembly line is located, argues that the sale could generate $8.7 billion in economic output and support employment for workers on the line.

However, the U.S. Air Force, which operates more than 1,000 F-16s of varying blocks, has no plans to procure more F-16s. Rather, the service is exploring options to extend the life of its fleet until the F-35 is introduced into service in enough numbers to handle the suppression and destruction of enemy air defense roles.

Originally designed for 4,500 flying hours, a previous upgrade extended the lifespan to 8,000 hr. But after conducting a monitoring program on the fleet, Air Force officials have found that they are flying the aircraft 15-20% “less hard” than planned, meaning pilots are not flying the jets to their maximum limits regarding such elements as speed or g-forces. This is partly because in the decade since the 9/11 terrorist attacks, the F-16s have been used largely to support ground forces or patrol the skies in permissive airspace, missions that do not require the taxing maneuvers seen while operating in hostile environments, says Maj. Luther Cross, F-16 program element monitor for Air Combat Command.

This has prompted the Air Force to calculate what officials call equivalent flying hours for each airframe, just as they do actual flying hours. Using the equivalent-hour metric, service officials are able to estimate the projected life, taking into account lighter use of the fleet in recent years, says Cross. This practice is also being applied to other fleets in the service.

This alone adds “several years” of life to each aircraft, he says. Still, the Air Force is considering a structural service life extension program (SLEP) to the newest Block 40/50 F-16s, with a 12,000-hr. goal per airframe.

The aim is to develop a program that is scalable and provides Air Force leaders with the flexibility to add or remove aircraft as needed without spiking cost. Price is a major consideration, given the pressure to reduce spending in light of debt-reduction talks in Washington. Notionally, the service is considering the SLEP for 300 of the Block 40/50s, but this could change if the F-35 delivery schedule continues to shift.

The Air Force has 640 of the later Block 40/50 airframes—ranging in age from 17-21 years—and another 400 Block 25, 30 and 32s averaging 24 years in age.

Lockheed Martin is working on a study contract and is conducting durability tests on an F-16 with a goal of subjecting it to 24,000 hr. of flight, twice the goal of the SLEP, says Cross. The trials, slated to end in 2017, are intended to reveal which structural components must be included in the SLEP.

To keep the F-16's mission systems relevant along with its structure, Cross says the Air Force is exploring an avionics upgrade that would allow the aircraft to operate in the projected electromagnetic spectrum environment expected beyond 2025.

This improvement would include an active, electronically scanned array radar as well as a replacement for the AN/ALQ-213 electronic warfare management system, says Cross. Additionally, two 4 X 4-in. cockpit displays would be upgraded to a single 6 X 8-in. screen, providing a better interface for using an infrared targeting pod. Finally, the aircraft must be able to operate using the Integrated Broadcast Service.