Which tools are essential for APU maintenance troubleshooting?

The correct choice highlights that multimeters and pressure gauges are essential tools for APU maintenance troubleshooting because they provide critical measurements and diagnostics necessary for effective troubleshooting. Multimeters are used to measure electrical parameters such as voltage, current, and resistance, which are vital for diagnosing electrical issues within the APU. Similarly, pressure gauges help assess the fluid systems, including fuel and oil pressures, which are integral to the APU's performance and reliability.

Understanding the operational parameters through these diagnostic tools allows technicians to pinpoint malfunctions, verify system integrity, and ensure that the APU is functioning within its specified limits. This targeted approach helps in addressing specific issues efficiently rather than relying solely on basic hand tools or general troubleshooting methods.

Other choices either lack the specificity required for APU maintenance or focus on insufficient aspects. While basic hand tools are helpful for physical repairs, they alone do not provide the critical diagnostic feedback necessary for troubleshooting complex systems like the APU. Safety equipment is important for ensuring a safe working environment, but it does not contribute to the troubleshooting process itself. Software diagnostic tools can be useful, but the physical measurements provided by multimeters and pressure gauges are often the first steps in diagnosing APU issues, making them fundamental tools in this context.