Which condition does NOT trigger an automatic APU shutdown?

The condition that does not trigger an automatic APU shutdown is low oil temperature. The APU (Auxiliary Power Unit) is equipped with various sensors and thresholds to monitor its operation and protect it from potential damage.

When the APU operates, it requires sufficient oil temperature for optimal performance and to ensure proper lubrication. However, low oil temperature is not considered an immediate threat to the APU's operational integrity, so it does not result in an automatic shutdown. Instead, the APU can continue functioning even when the oil temperature is low, albeit potentially with reduced efficiency or increased wear over time.

In contrast, conditions like high oil pressure, APU undertemperature, and APU overspeed or underspeed are critical indicators of malfunctions or potential failures. High oil pressure can indicate a blockage or fault in the lubrication system, while APU undertemperature may signify that operational parameters are not being met, leading to shutdown for safety reasons. Similarly, overspeed or underspeed can result in mechanical failures if the APU operates outside its designed speed range, prompting an automatic shutdown to prevent damage.