What equipment is shed at the second level of integrity?

The correct choice identifies the equipment that is shed at the second level of integrity, which includes the main bus and the avionics 2 bus. Understanding the concept of power management in aircraft is vital, especially in situations where the electrical load exceeds available power. The second level of integrity generally represents a phase where vital systems are preserved while non-essential systems are shed to protect essential operations.

In aircraft systems, the main bus supplies power to numerous critical components, and when power restrictions occur, the avionics 2 bus also supports operations but generally carries less critical systems than those in other buses. By shedding these buses, the aircraft ensures that essential commanding functions remain operational. This strategic reduction helps prioritize the electrical supply for navigation and communication, which are pivotal during flight, while conserving overall airplane functionality.

This aligns with operational safety protocols, illustrating why managing electrical loads intelligently is critical for maintaining the aircraft's integrity and operability during times of system strain.