Overtemp Condition (Turbine Engine)
An overtemp condition in a turbine engine occurs when the temperature of the exhaust gas stream (EGT) or turbine entry temperature (TET) exceeds the manufacturer's specified limits. This can cause significant damage to the engine's hot section.
What it is[edit | edit source]
An overtemp occurs when the temperature of the hot gases flowing through the turbine section exceeds the design limits.
Why it's dangerous[edit | edit source]
Turbine engines are built to operate within strict temperature ranges. Exceeding those limits can damage turbine blades, combustion chambers, and other essential components.
Causes[edit | edit source]
- Hot start: Occurs during engine startup when the temperature rises too quickly or exceeds safe limits due to poor airflow, improper fuel scheduling, or slow acceleration.
- Hung start: Happens when the engine fails to reach proper idle RPM, resulting in elevated temperatures due to inefficient combustion.
- Bleed Air Issues: Insufficient bleed air from the auxiliary power unit (APU) or ground support unit (GSU) can also contribute to a hot start.
- Other factors: Engine wear, poor maintenance, or incorrect operation can lead to overtemp events.
Monitoring[edit | edit source]
Turbine engine temperatures are closely monitored to ensure they remain within safe operating limits.
14 CFR § 33.88[edit | edit source]
This regulation outlines overtemperature testing, requiring engines to be tested at max RPM with temperatures at least 75 °F (42 °C) higher than the steady-state rating.
Transient Over-temperature[edit | edit source]
Testing efforts are made to replicate transient turbine entry temperatures during in-flight conditions over endurance tests.