''Jesus nut'' is a slang term for the main rotor retaining nut or mast nut, which holds the main rotor to the mast of some

helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...

s. The related slang term Jesus pin refers to the lock pin used to secure the retaining nut. More generally, ''Jesus nut'' (or ''Jesus pin'') has been used to refer to any component that is a

single point of failure A single point of failure (SPOF) is a part of a system that, if it fails, will stop the entire system from working. SPOFs are undesirable in any system with a goal of high availability or reliability, be it a business practice, software appl ...

which results in catastrophic consequences, and the only thing left to do is pray to Jesus, hence the name.

Origin of name

The term ''Jesus nut'' may have been coined by American soldiers in Vietnam; the

Vietnam War The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...

was the first war to feature large numbers of soldiers riding in helicopters. The term may also have originated with the

PBY Catalina The Consolidated PBY Catalina is a flying boat and amphibious aircraft that was produced in the 1930s and 1940s. In Canadian service it was known as the Canso. It was one of the most widely used seaplanes of World War II. Catalinas served wit ...

, which had two ''Jesus bolts'' holding the wing onto the fuselage. If the Jesus nut were to fail in flight, the rotor would detach from the helicopter and the only thing left for the crew to do would be to "pray to

Jesus Jesus, likely from he, יֵשׁוּעַ, translit=Yēšūaʿ, label=Hebrew/Aramaic ( AD 30 or 33), also referred to as Jesus Christ or Jesus of Nazareth (among other names and titles), was a first-century Jewish preacher and religious ...

." Real examples of the Jesus nut/pin failing are rare. However, the nut/pin must be checked before the flight; in 2000, the mast nut of a

Bell 206 The Bell 206 is a family of two-bladed, single- and twin-engined helicopters, manufactured by Bell Helicopter at its Mirabel, Quebec, plant. Originally developed as the Bell YOH-4 for the United States Army's Light Observation Helicopter progra ...

B was removed to be repainted and was not restored and checked prior to a test flight. The helicopter crashed within ten minutes of takeoff, killing the two occupants. Some more recent helicopter systems do not have a Jesus nut.

Other contexts

More recently, the term has been more generically applied throughout

engineering Engineering is the use of scientific method, scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The discipline of engineering encompasses a broad rang ...

to include any single component whose failure would cause

catastrophic failure A catastrophic failure is a sudden and total failure from which recovery is impossible. Catastrophic failures often lead to cascading systems failure. The term is most commonly used for structural failures, but has often been extended to many oth ...

of the entire system. Another use for the term is found in

rock climbing Rock climbing is a sport in which participants climb up, across, or down natural rock formations. The goal is to reach the summit of a formation or the endpoint of a usually pre-defined route without falling. Rock climbing is a physically and ...

, in which it refers to the first piece of

protection Protection is any measure taken to guard a thing against damage caused by outside forces. Protection can be provided to physical objects, including organisms, to systems, and to intangible things like civil and political rights. Although th ...

(some of which are also called "

nut Nut often refers to: * Nut (fruit), fruit composed of a hard shell and a seed, or a collective noun for dry and edible fruits or seeds * Nut (hardware), fastener used with a bolt Nut or Nuts may also refer to: Arts, entertainment, and media Com ...

s") placed on a pitch. This piece must be placed to resist an outward pull as well as a downward pull in order to avoid the possibility of a "zipper", in which the outward pull on the rope from the

belay Belaying is a variety of techniques climbers use to create friction within a climbing system, particularly on a climbing rope, so that a falling climber does not fall very far. A climbing partner typically applies tension at the other end of t ...

er arresting a falling climber pulls protection pieces from the bottom up. In addition, the Jesus nut prevents the possibility of a factor-two fall onto the belay anchor. In literature, the term "Jesus nut" was popularized in '' Chickenhawk'' by Robert Mason, a narrative about his experiences as a pilot in the Vietnam War.

Notes

References

{{Helicopters and rotorcraft Fasteners Helicopter components

Origin of name

Other contexts

See also

Notes

References