How frequently should the hydraulic system of a towbar be inspected?

The correct choice emphasizes the critical importance of ensuring the safety and functionality of the hydraulic system of a towbar. Inspecting the hydraulic system before each flight allows for a thorough check of essential components and fluid levels, reducing the risk of equipment failure during towing operations. This frequency ensures that any issues can be identified and addressed promptly, which is vital for maintaining safety standards and operational efficiency in aviation. Regular inspections help in detecting potential hazards that may arise from wear and tear, fluid leakage, or other issues that could compromise the system's integrity.

Other options suggest less frequent inspections, which may not adequately mitigate risks associated with the hydraulic systems used in towing aircraft. Daily or weekly checks might not provide the level of assurance needed for safe operations, as operational conditions can change rapidly, especially as aircraft movements and ground handling context vary. Monthly inspections could lead to undetected issues developing into more serious problems, thus highlighting the necessity of pre-flight checks.