Definition
Mechanical limits built into a constant-speed propeller that prevent the blades from rotating to a blade angle below a designed minimum. They define the flattest (lowest) blade angle the propeller can reach during normal governing, ensuring the propeller cannot move into an excessively flat pitch that would allow the engine to overspeed.
Plain English
A built-in stop inside the propeller that keeps the blades from twisting flatter than a set minimum angle. It's the lower boundary of how flat the blades are allowed to go.
Context Anchor
Encountered when studying constant-speed propeller operation, especially the point where the propeller is outside the normal governing range.
Derivation
Pitch' refers to the blade angle of the propeller (how steeply the blades bite the air). 'Low pitch' means a flat blade angle, which gives less resistance and allows higher RPM. 'Stops' are physical limits — like a doorstop — that prevent travel beyond a set point. Together: the hardware limit that keeps the blades from going flatter than allowed.
Why Pilots Care
Prevents engine overspeed that can cause damage or loss of control.
Analogy
They are like a doorstop: the door can swing only until it reaches the stop. The propeller blades can move toward a lower angle only until they reach the low pitch stops.
Intuition Check
Low pitch does not mean a low engine sound here; it means a low propeller blade angle. Stops are not a pilot action; they are physical limits built into the propeller mechanism.
Example Sentence 1
During takeoff, the propeller blades rest against the low pitch stops, allowing the engine to develop full rated RPM.
Example Sentence 2
Technicians check the low pitch stops during maintenance to confirm correct blade-angle limits.