Definition
A ground test of a turbine engine in which the engine is brought from a high power setting back to idle, and the time it takes for the RPM to fall through a specified range is measured against limits set by the manufacturer.
Plain English
A check to see how quickly a turbine engine slows down when the throttle is pulled back. If it slows down too fast or too slowly, something is wrong inside the engine.
Context Anchor
Seen during engine run-ups, maintenance checks, and engine adjustment procedures.
Derivation
From the Latin 'de-' (down, away from) and 'celer' (swift) — literally 'to take the swiftness away.' A deceleration check measures how the engine loses speed.
Why Pilots Care
Confirms the aircraft will stop within the remaining runway length, directly affecting the decision to continue or abort a takeoff or landing.
Intuition Check
Do not read this as a brake test or a general slowing-down check. Here, it means checking the engine’s response when power is reduced quickly.
Example Sentence 1
After the overhaul, the technician performed a deceleration check to confirm the engine spooled down within the time limits in the maintenance manual.
Example Sentence 2
After the engine failure on takeoff, the crew completed the deceleration check and determined they could safely stop on the remaining pavement.