A Pratt & Whitney F135 engine undergoes ground testing at Arnold Air Force Base in Tennessee. (Rick Goodfriend/U.S. Air Force)

一台普惠F135发动机在田纳西州阿诺德空军基地进行地面测试。(Rick Goodfriend/U.S. Air Force)

WASHINGTON — All F-35 fighter jets should be retrofitted within 90 days with a fix intended to solve a potential engine vibration problem, the F-35 Joint Program Office said Thursday.


The JPO issued an order Wednesday evening recommending the fleetwide retrofit — globally, not just American aircraft — over the next three months, as well as immediately putting it in place for a “small number” of fighters that have been grounded since December.

首席检察官周三晚上发布了一项命令,建议在未来三个月内进行全机队的改装--在全球范围内,而不仅仅是美国飞机--以及立即对12月以来停飞的 "少量 "战斗机实施改装。

In a statement to reporters on Thursday, the JPO said it is not grounding other F-35s, aside from the newly built fighters believed to be susceptible to the vibration problem in their Pratt & Whitney-made F135 engines and that have been grounded for more than two and a half months.

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The office also said it plans to work with the military services flying the F-35 and international partners to ensure they understand the technical order. “The safety of flight crews is the JPO’s primary concern,” the JPO said.

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F-35 deliveries were halted in mid-December after a mishap involving a new F-35B in Fort Worth, Texas. That F-35B, which was undergoing a quality check flight, was videotaped bouncing, tipping forward, and spinning around on the ground before its pilot ejected safely.

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After that mishap, Lockheed Martin, which makes the aircraft, stopped acceptance flights for new F-35s. Those flights must occur before the company delivers the jets to the U.S. government. Those groundings had the effect of halting deliveries.


Lockheed confirmed to Defense News on Thursday that it has not yet resumed flight operations or deliveries of new F-35s, most of which are constructed at its Fort Worth, Texas, facility. Lockheed Martin has delivered more than 890 F-35s around the world.

洛克希德公司周四向《防务新闻》证实,它尚未恢复飞行作业或交付新的f -35战斗机,其中大部分是在德克萨斯州沃斯堡的工厂建造的。洛克希德·马丁公司已经在全球交付了890多架f -35战斗机。

The Pentagon as well as Pratt & Whitney halted engine deliveries later in December. An investigation found a vibration issue in the engine led to the mishap. The JPO said that vibration issue was a “rare occurrence” and announced in February that Pratt & Whitney, which is owned by Raytheon Technologies, and other engineers had developed a fix for it.

五角大楼以及普惠公司在12月下旬停止了发动机的交付。调查发现,发动机的振动问题导致了事故。JPO表示,震动问题是“罕见的”,并于今年2月宣布,雷神技术公司(Raytheon Technologies)旗下的普惠公司(Pratt & Whitney)和其他工程师已经开发出了解决方案。

The JPO on Thursday said the vast majority of F-35s are not experiencing this engine vibration problem. But it is retrofitting the entire fleet because the fix is “inexpensive [and] non-intrusive,” and will mean all F-35 engines have the same configuration.

JPO周四表示,绝大多数的F-35飞机没有遇到这种发动机振动问题。但它正在对整个舰队进行改造,因为该修复方案 "成本低廉[且]不具侵入性",并将意味着所有F-35发动机具有相同的配置。

This fix can be done at the operational level in four to eight hours, the JPO said. But the office did not detail what this short-term fix will include, besides saying it “mitigates the risk of loss of aircraft should the harmonic resonance occur.”

JPO说,这种修复可以在四到八小时内完成操作层面的工作。但该办公室没有详细说明这种短期解决方案将包括什么,只是说它 "减轻了发生谐波共振时飞机损失的风险"。
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A longer-term fix is also in the works to keep the vibration problem from happening again, the JPO said, but it did not say what those solutions might be.


In a Tuesday conference call with reporters, Jen Latka, vice president of F135 programs at Pratt & Whitney, said the company is shipping new engines with the fix already installed.

在周二与记者的电话会议上,普惠公司F135项目副总裁Jen Latka说,该公司正在运送已经安装了修复装置的新发动机。

The JPO said Feb. 24 that it had cleared Pratt & Whitney to resume delivering engines.


Latka said the problem is “very rare,” and pointed to the F135′s 600,000 flight hours before the vibration issue happened. Nothing had changed in the F135 engine before this vibration issue happened, she added, and “multiple parameters” had to take place for the dangerous vibrations to show up. She did not identify those factors.


When asked why the vibration issue only cropped up now, the JPO responded: “The harmonic resonance is caused by other systems performing their normal function. Root cause investigation is still ongoing to determine where these system sensitivities intersect with the excitation frequencies.”


Latka said Pratt & Whitney had dealt with “resonance” issues with the F135 engine before the Dec. 15 mishap. But what happened with that F-35B involved “new aspects,” she explained.

拉特卡(Latka)说,在12月15日事故发生之前,普惠公司已经处理了F135发动机的“共振”问题。但在F-35B上发生的事情涉及 "新的方面",她解释说。

“There was new learning there,” Latka said.


The JPO as well as Pratt & Whitney declined to comment on who would bear the cost of the retrofit and other issues with the F135 engine and the delivery halt.


“We will not comment on financial responsibility,” the JPO said. “We are focused on returning the fleet to full safe flight operations.”