A Lockheed Martin F-35C on 11 April completed the final test flight of the programme’s system development and demonstration (SDD) phase, capping off an 11-year-long saga spanning 9,200 sorties and 17,000 flight hours for three major variants.

Programme officials hailed the completion as a historic accomplishment for an advanced, high performance aircraft, with zero injuries or deaths and no aircraft lost since the original AA-1 prototype flew for the first time on 15 December 2006 with then-Lockheed chief test pilot Jon Beesley at the controls.

“There was not one lost aircraft, not one lost team member,” F-35 programme executive Vice Adm Mat Winter said on 11 April, speaking at the Navy League’s Sea Air Space exhibition.

“Most major weapon systems go through a lot of learning,” he added.

The F-35 programme encountered no unrecoverable safety incidents during flight test, but the learning began only seconds after Beesley’s first take-off in 2006. Instead of smoothly lifting skyward, the AA-1 abruptly tilted right before Beesley’s correction returned the wings to level. Lockheed engineers blamed the unexpected tilt on the single-piece nose gear door, which they fixed by splitting the single-panel door into two panels with one on each side.

More surprises still awaited flight test pilots after December 2006. On the 19th test flight less than six months later, the programme narrowly escaped a serious incident. With Beesley again in the cockpit, the AA-1 prototype suffered a major electrical malfunction, which spun the aircraft out of control. After Beesley again righted the aircraft and landed, engineers launched a redesign of critical components of the electrical system.

More issues, including a transonic roll-off problem on the carrier-based F-35C, persistently over-heating electronics and software bugs, continued to dog the programme for years.

But the F-35’s greatest challenges proved to unfold outside of the flight test department, as engineering changes and supply chain bottlenecks caused a series of delays and major cost overruns over a period between 2009 and 2012.

When Beesley, now a retired 67-year-old, completed first flight in 2006, programme officials predicted that the already five-year-old system development and demonstration phase would end in 2012.

For the last half-decade, the joint programme office has put a lid on the overall cost to develop and produce the 2,456 aircraft in the US military’s spending plan, along with nearly 800 more committed orders from foreign buyers. The flyaway price of the F-35A fell to $94 million in the 2016 round of orders (Lot 10, which was technically signed in 2017). Winter remains committed to driving the price down to no more than $85 million for the F-35A in Lot 13.

Meanwhile, the programme has made significant progress clearing development hurdles since 2012. The US Marine Corps achieved initial operational capability in 2015 with a subset of the F-35B’s intended attributes. The US Air Force’s F-35A reached IOC a year later, followed by the Israeli Air Force’s F-35I in 2017. The US Navy’s F-35C is on track to reach the same milestone later this year or early next year.

Though flight testing under the system development and demonstration phase is complete, the F-35’s integrated test force’s work will never be done. Indeed, Winter said he expects the joint programme office to maintain a database of discrepancies through the length of the F-35’s service life, which now calls for the last aircraft to be retired in 2077.

Behind the scenes, Lockheed is inserting a new computing architecture into the F-35, Winter says. The so-called “Tech Refresh 3” will replace the current computing system used for operational flight program with an open architecture, allowing the insertion of new software-based capabilities much like adding a new application on a smart phone.

As Tech Refresh 3 becomes standard, the programme is shifting to a new approach to add new capabilities. Instead of upgrading the F-35 with capability “increments” on a two-year interval, Lockheed instead will be tasked to deliver smaller batches of software and hardware upgrades in six-month “sprints”, Winter says.

The first such upgrade under the continuous capability, development and delivery (C2D2) phase is expected to be completed in June, Winter says. Instead of adding new capability, this next software release and another scheduled by the end of the year are designed to fix shortfalls in the go-to-war, Block 3F suite of applications.

Starting in 2019, the C2D2 phase will begin delivering upgrades with new capabilities for the flight test team to validate, including an automatic ground collision avoidance system (auto-GCAS), Winter says.

Source: FlightGlobal.com