FAA Flight Instructor Airplane (FIA)Aircraft Systems and InstrumentsMedium
A pilot wants to achieve the best power mixture setting during a cruise climb using the EGT gauge. After leaning the mixture until EGT peaks, what adjustment should the pilot make next?
- AEnrich the mixture slightly to a point rich of peak EGT
- BContinue leaning past peak EGT for maximum fuel economy
- CEnrich the mixture fully to full rich
- DLeave the mixture exactly at peak EGT
Show answer & explanationAnswer & explanation
Correct answer: A. Enrich the mixture slightly to a point rich of peak EGT
Best power mixture is typically achieved by enriching slightly (about 50–100°F rich of peak EGT) after leaning to peak, which provides maximum power output at the cost of some fuel efficiency. Leaning further past peak (lean of peak) is used for best economy, not best power.
Why the other options are wrong
- B. Leaning further past peak yields best economy, not best power.
- C. Full rich wastes fuel and is used mainly for high-power/takeoff, not fine mixture management.
- D. Peak EGT itself is not the best power setting; it's between best economy and best power.
EGT Leaning Strategy
Exhaust gas temperature is used to set mixture: leaning past peak EGT yields best economy, while enriching slightly rich of peak EGT yields best power.
- Best economy: lean of peak EGT
- Best power: slightly rich of peak EGT (about 50-100°F)
- Always monitor CHT to avoid overheating while leaning
Memory trick: Rich of peak = power; lean of peak = penny-pinching.