Jesus nut

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Jesus nut is also a derogatory term for a conservative Christian.

The Jesus nut, also called the Jesus pin, is the hexagonal nut that holds the main rotor to the mast of some helicopters, such as the UH-1 Iroquois helicopter. It is a slang term first coined by American soldiers in Vietnam; the technical term is main rotor retaining nut.

The origin of the term comes from the idea that, if the Jesus pin were to fail in flight, the helicopter would detach from the rotors and the only thing left for the crew to do would be to pray to Jesus. Real examples of the Jesus pin failing are few and far between, although in 2002 a civilian helicopter of the Mercy Air Services suffered a "main rotor blade separation" resulting in the death of all on board. The exact cause was never determined, but it is likely that the Jesus nut failed for reasons unknown [1]. Some more recent helicopter systems do not have a Jesus nut.

In literature the term Jesus Nut was used in "Chickenwing" by Robert Mason, a novel about the Vietnam War.

A picture of a Jesus Nut is found here [2].

The Rattler/Firebird Association is a Vietnam War veterans organisation. It awards a chrome plated Jesus nut to the member who traveled the longest distance to their reunions. [3]

More recently, it has come to be a generic engineering term, referring to any single component of a system whose failure would cause catastrophic failure of the whole system.

Jesus Nut is also used in reference to the nut on the front of the recoil mechanism on some artillery pieces. Should this nut fail, the gun tube will come out of battery upon firing, potentially leading to death for the gun crew.

A derivative term used in radio-controlled helicopters is the Jesus Bolt which refers to a bolt whose function is analogous to the Jesus nut in a full size helicopter.