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

main rotor On a helicopter, the main rotor or rotor system is the combination of several rotary wings (rotor blades) with a control system, that generates the aerodynamic lift force that supports the weight of the helicopter, and the thrust that countera ...

to the mast of some

helicopter A helicopter is a type of rotorcraft in which Lift (force), lift and thrust are supplied by horizontally spinning Helicopter rotor, rotors. This allows the helicopter to VTOL, take off and land vertically, to hover (helicopter), hover, and ...

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'') is 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 would Cascading failure, stop the entire system from working if it were to fail. The term single point of failure implies that there is not a backup or redundant option that would enab ...

and whose breakdown would result in catastrophic consequences, the suggestion being that in such case the only thing left to do would be to pray to

Jesus Jesus (AD 30 or 33), also referred to as Jesus Christ, Jesus of Nazareth, and many Names and titles of Jesus in the New Testament, other names and titles, was a 1st-century Jewish preacher and religious leader. He is the Jesus in Chris ...

, or that the component's importance could be likened to the importance of Jesus to Christianity.

Origin of name

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

Vietnam War The Vietnam War (1 November 1955 – 30 April 1975) was an armed conflict in Vietnam, Laos, and Cambodia fought between North Vietnam (Democratic Republic of Vietnam) and South Vietnam (Republic of Vietnam) and their allies. North Vietnam w ...

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 Model 28, more commonly known as the PBY Catalina (U.S. Navy designation), is a flying boat and amphibious aircraft designed by Consolidated Aircraft in the 1930s and 1940s. In U.S. Army service, it was designated as the O ...

, 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, hence the idea that all that would then be left for the crew to do would be to "pray to Jesus." The nut/pin must be checked before the flight, even though real-world examples of the Jesus nut/pin failing are rare. For example, in 2000, the mast nut of a Bell 206B 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.

Other contexts

More recently, the term has been more generically applied throughout

engineering Engineering is the practice of using natural science, mathematics, and the engineering design process to Problem solving#Engineering, solve problems within technology, increase efficiency and productivity, and improve Systems engineering, s ...

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 ot ...

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

rock climbing Rock climbing is a climbing sports discipline that involves ascending climbing routes, routes consisting of natural rock in an outdoor environment, or on artificial resin climbing walls in a mostly indoor environment. Routes are documented in c ...

, in which it refers to the first piece of

protection Protection is any measure taken to guard something 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 ...

(some of which are also called " nuts") 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 belayer 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. Marine M60A1 tankers used the term "Jesus Pin" in reference to a breech pin located on the 105mm main gun that needed to be removed in order to disassemble the breech block. Dropping the small pin would cause it to instantly disappear into the bowels of the tank's hull causing one or more members of the crew to cry out "Jesus" as an expletive.

Notes

References

{{Helicopters and rotorcraft Fasteners Helicopter components

Origin of name

Other contexts

See also

Notes

References