If the yellow blade stop is over the APU during blade fold, what do you do?

When the yellow blade stop is positioned over the APU (Auxiliary Power Unit) during the blade fold operation, the correct action to take is to turn off the APU. This is crucial for safety reasons, as the APU is a source of power and has the potential to create hazards if the blades are being folded while the APU is operating.

Operating the APU during blade fold could result in unintended consequences, such as damage to the aircraft or injury to personnel due to moving parts or unexpected operations. Shutting down the APU ensures that the area around where the blades are being folded is safe and free from any power supply that might cause movement or other hazards.

In this context, the other options would not address the immediate safety concern. Leaving the situation as is does not mitigate any risk, contacting maintenance might be necessary eventually, but does not provide immediate safety, and performing a run-up check is not relevant in this scenario as the primary focus should be on ensuring the APU is off before proceeding.