What is the focus of Block 4 in the Aircraft Inspection Record?

Block 4 in the Aircraft Inspection Record specifically pertains to oxygen levels. This block is important because it ensures that the aircraft's oxygen system is functioning properly, which is crucial for the safety of crew members, especially at high altitudes where oxygen availability decreases. Monitoring oxygen levels helps to prevent hypoxia and ensures that the crew can operate effectively in high-pressure environments.

Each of the other options represents different types of information relevant to aircraft operations but does not pertain to Block 4 of the Aircraft Inspection Record. For instance, the date of pilot acceptance is not about the oxygen system, fuel load involves the quantity of fuel onboard rather than oxygen levels, and a maintenance inspection summary would cover a broader range of checks and repairs but does not specifically address the oxygen system's functionality. Hence, recognizing the purpose of each block in the record is essential for maintaining the operational readiness and safety of the aircraft.