Definition
A reduction in turbine engine thrust output that exceeds the limits permitted by the engine manufacturer or operating specifications, indicating the engine is no longer producing the power required for safe and certified operation. Unacceptable thrust loss may result from compressor damage, foreign object ingestion, fuel control malfunction, bleed air leaks, or internal component deterioration, and typically requires the engine to be removed from service for inspection or repair.
Plain English
The engine is producing less push than it is supposed to, by more than the rules allow. When this happens, the engine is no longer considered safe or legal to keep using until it has been checked and fixed.
Context Anchor
Seen in engine performance, troubleshooting, maintenance, and certification discussions, especially when judging whether a power loss is within safe limits.
Why Pilots Care
Triggers immediate checklist actions, possible engine shutdown, or diversion to maintain safety margins.
Intuition Check
Do not assume this means total engine failure. It means the thrust has dropped below an acceptable safe level for the operation, even if the engine is still running.
Example Sentence 1
After ingesting debris on the runway, the engine showed an unacceptable thrust loss during the next power assurance check and was removed for inspection.
Example Sentence 2
The test report confirmed the engine maintained acceptable thrust with no unacceptable thrust loss at maximum continuous power.