Definition
In a turbine engine, a transient self-accelerating condition in which a small increase in engine speed produces more airflow and combustion, which in turn produces more thrust and a further increase in speed — causing engine RPM to drift upward without any movement of the power lever.
Plain English
The engine starts speeding itself up on its own. A small rise in RPM makes more air and fuel burn, which makes the engine speed up a bit more, and the cycle keeps going without the pilot touching the throttle.
Context Anchor
Seen in powerplant and maintenance discussions of turbocharged aircraft engines, especially when manifold pressure does not stay steady after the throttle is set.
Derivation
From the old phrase 'pulling oneself up by one's bootstraps' — making something happen using only its own resources, with no outside help. In engineering, it describes any process that feeds itself and grows on its own.
Why Pilots Care
Uncontrolled bootstrapping can produce overboost, risking engine damage; proper wastegate and controller function must limit the effect.
Grounding Statement
Picture setting the throttle, then watching the pressure keep moving because the turbocharger and engine are affecting each other instead of settling down.
Intuition Check
Bootstrapping does not mean simply starting an engine by itself. Here it means a self-feeding power or pressure change in a turbocharged engine.
Example Sentence 1
After landing, the technician noted that the engine was bootstrapping at idle, with RPM slowly creeping upward on its own.
Example Sentence 2
The density controller is designed to prevent bootstrapping from driving manifold pressure beyond red-line limits during high-power climbs.