Final answer:
The question relates to the preflight procedure in aviation, where personnel verify that specific circuit breakers, referred to by their panel position '13L', are in the proper state according to the aircraft's manual for safe operation.
Step-by-step explanation:
The question "What circuit breakers are pushed in 13L pre flight?" pertains to specific procedures followed in aviation, within the field of aeronautical engineering. Prior to flight, pilots or maintenance personnel perform a preflight check that includes verifying the status of circuit breakers on the aircraft. The numbering such as '13L' refers to a specific position on the circuit breaker panel, which is usually detailed in the aircraft's operating handbook or maintenance manual. The correct circuit breakers to push in, or ensure they are not tripped, may vary depending on the type of aircraft, its configuration, and the manufacturer's guidelines. It is crucial for safety that the appropriate circuit breakers are in the correct position before takeoff, which can include ensuring that non-essential systems are deactivated to prevent electrical issues during flight.