Definition
On a reciprocating engine crankshaft, the cheek is the flat web-like section that connects a main journal to a crankpin (rod journal). It carries the load between the rotating main bearings and the offset crankpin where the connecting rod attaches, and it often holds counterweights to balance the crankshaft.
Plain English
The cheek is the slab of metal on a crankshaft that links the part spinning on the main bearings to the offset part where the piston rod connects. It is what makes the crankshaft a zig-zag shape rather than a straight bar.
Context Anchor
Seen in engine maintenance, especially during crankshaft inspection, overhaul, and damage reports.
Derivation
The word comes from the everyday sense of 'cheek' as a flat side of something (like a face). Mechanics borrowed it because the flat web of metal between the journals looks like a flat-sided panel.
Why Pilots Care
Crankshaft cheeks are inspected for cracks during overhaul because a failure here means catastrophic engine failure. They also carry the counterweights that keep the engine running smoothly, so damage or imbalance in this area shows up as vibration.
Intuition Check
Cheek does not mean part of a person’s face here. In this maintenance context, it means a solid side section of the crankshaft.
Example Sentence 1
During the crankshaft inspection, the technician used dye penetrant to check each cheek for hairline cracks before reassembling the engine.
Example Sentence 2
Excessive wear on the cheek can allow blade movement and must be corrected before flight.