Jesus nut

Rare card · No. 52054

The main rotor retaining nut or mast nut, often colloquially referred to as the Jesus nut, holds the main rotor to the mast of some helicopters. The related slang term Jesus pin refers to the lock pin used to secure the retaining nut. A failure of this nut is likely to result in a crash. More generally, Jesus nut (or Jesus pin) is used to refer to any component that is a single point of failure 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."

Read on Wikipedia · Image Alan Radecki Akradecki, CC BY-SA 4.0