Definition
On a splined shaft, a land is the raised ridge of metal that runs lengthwise along the shaft, sitting between the cut grooves. The lands are what engage with matching slots in a mating part, allowing the shaft to transmit torque without slipping.
Plain English
The raised strips of metal between the grooves on a splined shaft. They are the parts that grip into the matching part and turn it.
Context Anchor
Seen in powerplant maintenance when inspecting splined shafts, couplings, drive parts, and other parts that fit together to carry rotation.
Derivation
From Old English 'land', meaning a strip or area of solid ground. In machining, the same idea is used: the 'land' is the strip of original material left standing between the cut-out grooves, just as a strip of ground sits between two trenches.
Why Pilots Care
Worn or damaged lands on a splined shaft can cause slippage, vibration, or complete loss of drive to an accessory or propeller. During inspection, the condition of the lands determines whether the shaft is serviceable.
Analogy
Think of a splined shaft like a long ear of corn. The grooves are the gaps between the rows, and the lands are the raised rows themselves — the parts that actually grip when something fits over the top.
Intuition Check
Do not read land here as a place where an aircraft touches down. Here it means the raised metal surface between grooves on a splined shaft.
Example Sentence 1
The technician inspected the lands on the propeller shaft splines for wear and rounding before reinstalling the propeller.
Example Sentence 2
Wear on the lands reduces torque transfer efficiency and can cause vibration in the engine accessory section.