A Helicopter’s ‘Jesus Nut’ Is The Last Thing You Want To Bust During A Flight

Simon_g/ShutterstockWhen something breaks on an airplane, its natural aerodynamic properties tend to keep it airborne for at least a little while as the pilots work on a solution. The same thing cannot be said for helicopters, which, by all accounts, are up in the air purely against God's will. When something breaks, you're going down… quickly. Sure, some troubleshooting can be done depending on what goes wrong, but there is one component that there is almost no coming back from if it busts: the Jesus Nut.

If that little fist-sized bolt goes, well, brother, you're going too. Technically, it's called the main rotor retaining nut, and it does exactly what you think it might: it holds the main rotor to the top of the helicopter's mast, according to Technology.org, a science and tech news website. Without it, the helicopter cannot fly at all, and it'll just plummet back down to earth like the affront to aeronautics that it is.

If you are the type to fly in a lot of helicopters, but you aren't quite ready to meet your maker just yet, you can breathe a bit of a sigh of relief. According to Technology.org, many modern helicopters don't use Jesus Nuts. Tech has come a long way, and there are a slew of new ways of fixing the main rotor to the helicopter's mast that involve more fail-safes than a single nut.

Alan Radecki Akradecki via Wikimedia Commons

Where it is used, the Jesus Nut holds everything together in the anatomy of a helicopter's rotor assembly. At the center is the vertical rotor mast, which the four blade grips sit at the top of and hold onto. The mast then runs through the upper and lower swash plates, and those communicate with the flight controls that let the pilot make adjustments as needed. A vertical control rod is connected at each blade grip, joining them to the entire swash plate assembly. Holding all of that together is our dearly beloved Jesus Nut.

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It's not entirely clear who first coined the term "Jesus Nut," but it likely has little to do with Jesus freaks. According to a few accounts, it originated back during the Vietnam War. It was the first war to feature vast numbers of soldiers being transported in helicopters, so it makes sense that it would come up there.

Apparently, a soldier asked an aircraft mechanic what the component was (pointing to the retaining nut) and asked what would happen if it fell off during a flight. The answer was pretty simple, Technology.org says. The mechanic responded, saying, "pray to Jesus," and that you would be screaming "Oh Jesus" at that point because of how important the nut is to the airworthiness of a helicopter.

The nut has to be checked before every flight, even though examples of it failing are exceedingly rare. That being said, it does happen. In 2000, the Jesus Nut of a Bell 206B was removed to be repainted, but it wasn't reattached or checked before a test flight. It crashed within ten minutes of takeoff, killing two occupants, according to a Québécois Aviation Investigation Report. Still, I wouldn't worry too much; this doesn't happen very often, and when was the last time you were on a helicopter anyway?