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February 16, 2021

Wrong Bolts Installed on F-35 Combat Jets, You Say?

Wrong Bolts Installed on F-35 Combat Jets, You Say?

The bad news is that the multiple F-35 single-engine combat aircraft used by the United States Military is equipped with the wrong fasteners in certain parts of the planes. The good news is that their manufacturer, Lockheed Martin, has announced that it likely won’t be necessary to swap out the fasteners with the correct ones.

Different Materials

The plane’s design calls for bolts made from both titanium and an alloy called Inconel. Titanium is lighter, but Inconel is stronger. The parts made from the two materials look so similar that installation technicians must look at the numbers stamped on them to tell the difference. Although the bolts look nearly identical, the Inconel fasteners are more expensive, however.

Given that some titanium bolts are installed in parts of the planes where the stronger Inconel bolts are supposed to be installed, it would appear that there is a safety issue. However, Lockheed Martin and the Air Force state that the titanium bolts should be strong enough. The Inconel bolts would be ideal, but they are about twice as strong as necessary.

Several different military branches use F-35 aircraft, and there are approximately 50,000 total bolts in each plane. By design, of these 50,000 fasteners, roughly 1,000 are made from super-strong Inconel. The Inconel bolts’ strength is an advantage in the Navy aircraft that perform hard landings on aircraft carriers.

What went wrong?

A Joint Program Office (JPO) oversees getting to the bottom of what went wrong, and their report is expected soon. Lockheed Martin is looking closely at its manufacturing process to see why the incorrect structural fasteners were installed.

So far, Lockheed Martin has concluded that the mistake was made at a company manufacturing plants in Texas and Italy but not Japan. The company further states that it found several bins full of a mixture of both types of structural fasteners on factory floors and moved to correct the situation.

While it’s not known for sure why the two types of parts were mixed in the same bins, in the past, workers returned parts to the wrong containers at the end of their shifts. This was during the manufacturing process for F-16 jets, and it’s likely the same thing happened with the parts for the F-35. Lockheed Martin is putting a remediation plan into effect, but the plan’s details have not been revealed.

In The Future

It’s not known precisely how many planes in operation have the wrong bolts, and no further action is necessary as the aircraft are considered safe. However, Lockheed Martin is exceptionally concerned with improving its manufacturing process and acknowledging that the situation could have been far worse. They dodged a bullet, and they know it.

Inconel 718 fasteners

The F-35 uses Inconel 718 fasteners, and the situation with the F-35s has been a reminder of just how strong these bolts genuinely are. Furthermore, they are highly resistant to corrosion. These fasteners have the rare distinction of generally being far more robust than what is usually needed, and they can be used in a wide variety of applications. In short, they are remarkably safe and effective fasteners.

Our Take

It is widely expected that they will follow Lockheed Martin’s advice and let the planes fly as they are. All parties involved say that their focus is not on playing the blame game but rather on improving the manufacturing process.

We agree. As a significant supplier to LMCO and the F-35, including both Inconel and Titanium Fasteners, we have complete confidence in the protocols established moving forward.

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AMI is an AS9100 and ISO:9001 accredited, vertically integrated manufacturer of high strength, close tolerance aerospace pins, bolts, threaded rods, studs, screws, and built-to-print specials.

Our clientele includes industry-leading OEMs like Boeing, Bombardier, DLA, General Electric, Lockheed Martin, and Sikorsky.

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