ORLANDO, Fla. — The Pentagon has suspended all test flights for the entire Lockheed Martin F-35 Joint Strike Fighter fleet due to engine problems.

The move came nine days after the Pentagon cleared the F-35B jump-jet variant, designed for the U.S. Marines, to resume tests after a monthlong suspension. Both suspensions are due to problems with the engines. It also comes at a time when the program is facing increased scrutiny from lawmakers and senior DoD officials.

Unlike the last suspension, which was only for the B variant, this suspension affects all three variants: the F-35A Air Force conventional takeoff version, the F35-B for the Marines, and the F35-C carrier variant for the Navy.

“On Feb. 19, 2013, a routine engine inspection revealed a crack on a low pressure turbine blade of an F135 engine installed in a [conventional takeoff] test aircraft at Edwards Air Force Base, Calif,” wrote Kyra Hawn, Joint Program Office (JPO) spokeswoman, in a statement.

“Engineering teams are shipping the turbine blade to Pratt & Whitney’s Engine Facility in Middletown, CT, to conduct more thorough evaluation and root cause analysis. It is too early to know the fleet-wide impact of this finding, however as a precautionary measure, all F-35 flight operations have been suspended until the investigation is complete and the cause of the blade crack is fully understood,” Hawn wrote.

“The F-35 Joint Program Office is working closely with Pratt & Whitney and Lockheed Martin at all F-35 locations to ensure the integrity of the engine, and to return the fleet safely to flight as soon as possible.”

"Lockheed Martin is fully engaged and working closely with the JPO and Pratt & Whitney to determine the root cause of the blade crack found during a routine inspection of an F135 engine on an F-35A at Edwards Air Force Base, Calif.," wrote Lockheed spokesman Mike Rein in an emailed statement. "Safety is always our first consideration."

Matthew Bates, a P&W spokesman, wrote in an email that following the test flight, “maintainers conducted a routine boroscope engine inspection and discovered the crack.”

“A routine boroscope visual inspection provided an indication there was a crack, and a subsequent Eddy Current Inspection, or ECI, appears to corroborate the results of the boroscope inspection. However, additional testing will be required to fully understand the cause,” he wrote.

Bates added that the engine with the crack has 700 total engine operating hours, with 409 of those accrued in flight. He believes the engine analysis should take “roughly” a week.

The F-35B was initially grounded after a Jan. 16 test flight at Eglin Air Force Base, Fla., was aborted due to an engine problem that was later identified as a fueldraulic system failure in the jet.

The failure was caused by an improperly crimped fueldraulic line. After an investigation by the JPO and engine manufacturer Pratt & Whitney, six non-compliant lines were discovered.

“We don’t know what it means yet,” said Richard Aboulafia, an analyst with the Virginia-based Teal Group. “It could be a one-off. We just have to investigate right away.”

Still, the timing of the F-35 grounding comes as the Pentagon is facing much budget uncertainty.

“It’s under a lot of political heat and scrutiny, both in terms of cost and performance,” Aboulafia said. “It just doesn’t need this.”

More Responsibility for Pratt

Bennett Croswell, Pratt’s president for military engines, talked to Defense News Thursday afternoon at the Air Force Association Air Warfare Symposium in Orlando, Fla.

Croswell said the lines that caused January’s issue were provided by Stratoflex, a sub-contractor, and that problems with the work done in similar situation is “rare.”

And while he believes the engine will continue to improve in performance over time, he said the company has taken on more responsibility for potential overruns to the engines.

“One of the things we did to show our dedication to the program and our confidence in our ability to keep reducing cost was, we accepted a 100-0 share ratio on the LRIP-5 contract we signed recently,” Croswell said.

That means any overruns from the production of the engines will be paid for by Pratt, and won’t come out of the JSF budget.

“We were willing to accept that to show our commitment to the program and to continue to keep reducing costs to the benefit of the program,” Croswell said.

Initially, P&W was going to move to that kind of contract in LRIP-6, but agreed to do so early to help the program.

As to LRIP-6, Croswell said he feels “pretty good” about how negotiations will go, citing how recently negotiations were handled on LRIP-5 and an understanding with the JPO on program costs.

JSF Hot Topic at AFA

The JSF was a major topic of discussion at the AFA conference, with top Air Force brass expressing concern about the impacts of sequestration on the already delayed program.

In the morning, Air Force Chief of Staff Gen. Mark Welsh told the gathered audience that three Air Force F-35s that were due to be delivered this year may be pushed back to 2014 due to the budget situation.

“I can’t give an answer on how it’s going to affect contracts in the future.” Lt. Gen. Burton Field, the deputy chief of staff for operations, planning and requirements, told reporters when asked how the delays could impact the overall F-35 buy. “It’s a balancing act to try and preserve what we can for the future.”

Field seconded Welsh’s statement at a congressional hearing last week that the program will have to be looked at in light of sequestration.

“We think everything is on the table. We’re not sure if anything is off the table,” Field said.

Despite the potential delay due to the budget, the service still believes that the target goal of 1,763 F-35 jets is the right number, and have no plans to cut it down at this time.

“Given our current strategy that we are required to execute, the Air Force thinks that is the right number of F-35s to execute that strategy,” Field said. “If the strategy changes or something else changes, maybe we will have to re-evaluate. But given what we’re tasked to do right now in light of that strategy, 1,763 is the right number for the Air Force.

“Any advancement in some kind of capabilities we may have to fight is obviously worrisome,” Field said. But the 1,763 figure has not been changed by the development of new top-line fighters from China and Russia, Field said. He argued those developments show the need for America to have the advanced F-35 systems.

Later in the day, Gen. Mike Hostage, commander of Air Combat Command, offered a full throated endorsement of the F-35.

“My job is to worry about operational effective power. I worry about it now, I worry about it when my grandkids are worried about this country,” said Hostage during the day’s closing panel. “I think we owe it to them to have a path to maintaining this, our strength and our capability for the long term. My view of that is a fleet of 1,763 Air Force F-35s.”

While acknowledging the “challenge of the current situation,” Hostage argued that the F-35 fleet is necessary to match future threats, and that going through the next two decades with a legacy fleet and a “very small” number of F-22s would leave the country vulnerable.

“We’ll do what we have to do, but I’d much rather do it with a healthy fleet of F-35s,” Hostage said.

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