WASHINGTON — The Pentagon's head of acquisition is preparing to alert lawmakers that F-35 developmental flight tests, originally slated to end in October 2017, could extend as long as May 2018. Should more money be needed to fund those activities, the F-35 joint program office plans to seize it from the follow-on modernization account, which would defer those activities by proxy, the head of the F-35 joint program office acknowledged on Monday.

Since the F-35 program was re-baselined in 2011, the F-35 joint program office has used Oct. 31, 2017, as its target date to end System Development and Demonstration flight testing. The JPO will probably miss that date by a couple months, and now projects that it will complete flight tests by the end of February 2018, said Program Executive Officer Lt. Gen. Christopher Bogdan.

A letter from Pentagon acquisition chief Frank Kendall to Senate Armed Services Committee Chairman John McCain — expected to be sent to Capitol Hill either today or tomorrow — goes a few months further. According to Bogdan, the letter states that the JPO has been directed to prepare to add funds that would prolong flight testing to May 2018 if necessary.

If the Defense Department needs more money to carry flight tests beyond February 2018, the JPO will dig into funding from the F-35 Block 4 follow-on modernization (FOM) program, Bogdan told reporters on Dec.19.

"I estimate that the extended flight test period, if needed, will not exceed $100 million. However, if I have to take money out of FOM, depending on how much money I would have to take out of it, there is a chance that the follow-on modernization program may be delayed," he said.

A $100 million debit from that account would amount to at least a six-month delay to the program, Bogdan said.

"That only makes sense, because if you haven't finished SDD, the development program—which is our number one priority—you probably wouldn't want to start FOM any sooner anyway," he said. However, Bogdan acknowledged a delay to the modernization program is not ideal.

"That would not make our partners and that will not make our services happy because they are banking on us improving the airplane and getting their unique weapons on there, so that's why we're trying to do everything we can not to have that happen."

The JPO estimates it will need an additional $532 million to completely wrap up SDD. About $265 million of that sum is money the department cut from the SDD budget in 2014 as well as additional requirements that the Pentagon added, such as cybersecurity upgrades and a modification to the plane's logistics system to make it deployable, Bogdan said.

The remaining $267 million could fairly be designated a cost overrun, Bogdan said. That additional funding was needed to pay for redesigning the F-35 helmet and the C-model's landing hook, to retrofit aircraft after a problem revealed problems with the F-35 engine, and to solve software stability problems.

Although schedule delays and cost overruns are never the optimal outcome, Bogdan stressed that the program had made significant progress since 2011 and that current problems are much more minimal in scope. For example, a May 2018 conclusion of flight testing would only put the program seven months behind schedule. An additional $532 million bill would bring the development program up to $14.2 billion, still below the $15.1 billion threshold level set in 2011, he said.

"From 2001 to 2011, this program underwent a six year delay and a $13.5 billion overrun," Bogdan said. "If anybody would have told us in 2011 that we would be within a few months and a couple hundred million dollars of a $13 billion re-baseline, we'd all slap the table and say, 'We'd take it!'"

The program office is also within range of its target dates to deliver full warfighting capability, which is tied to the aircraft's 3F software, Bogdan said. Both the A and C models are slated to get 3F software before the February 2018 threshold date. The Marine Corps' B variant will obtain the 3F software in two stages, with its final update in May 2018.

Valerie Insinna was Defense News' air warfare reporter. Beforehand, she worked the Navy and congressional beats for Defense Daily, which followed almost three years as a staff writer for National Defense Magazine. Prior to that, she worked as an editorial assistant for the Tokyo Shimbun’s Washington bureau.