What is jesus nut on helicopter?

A Jesus nut is a slang term used by helicopter mechanics for the main rotor retaining nut that holds the main rotor to the mast of the helicopter. This nut is critical to the safe operation of the helicopter and if it were to come loose, the main rotor would detach and the helicopter would crash.

The term "Jesus nut" is thought to have originated in the Vietnam War when soldiers would look up at the helicopter and pray that the nut would stay in place.

Today, the Jesus nut is carefully inspected and torqued to specific requirements during routine maintenance checks. In addition, the nut is typically covered with a safety wire or locking clip to further ensure that it does not come loose.

While the term may sound humorous, the importance of the Jesus nut cannot be overstated. It remains a vital component of helicopter safety and operations.