Private Pilot Private Exam

If the engine oil temperature and cylinder head temperature gauges are too high, what may have occurred?

1. The mixture was set too rich

2. The pilot was operating with too much power and too lean of a mixture

3. The fuel levels were unauthorized

4. The aircraft was flying at too high of an altitude

The correct answer is: The pilot was operating with too much power and too lean of a mixture

When engine oil temperature and cylinder head temperature gauges are reading too high, it often indicates that the engine is under stress, which is frequently due to operating conditions. Option B suggests that the pilot was operating with too much power and too lean of a mixture, which aligns with common understanding in engine management. When a pilot runs the engine at high power settings while having a mixture that is too lean, it does not provide sufficient fuel for combustion. In turn, this leads to increased combustion temperatures and can cause engine overheating, reflected in elevated temperature gauge readings. A lean mixture means that the air-to-fuel ratio is excessively favoring air, which can lead to pre-ignition or detonation, resulting in excess heat production that the cooling systems cannot adequately manage. In contrast, setting the mixture too rich typically helps to cool the engine because more fuel is available for combustion, which can absorb some of the heat. Therefore, it's unlikely that a rich mixture would result in high temperature readings, making other options less relevant in this context.