In addition to secure clamping, what is another requirement for installing metal fuel, oil, and hydraulic lines?

Installing metal fuel, oil, and hydraulic lines requires that they be electrically bonded to the structure to prevent the buildup of static electricity, which can lead to sparks and potentially result in fires or explosions. This bonding helps to ensure that any stray electrical currents are safely dissipated into the airframe, thereby enhancing safety during operation.

Proper bonding is especially crucial in high-flammability areas, such as those involving fuel and hydraulic fluids. Ensuring that the lines are electrically bonded to the structure minimizes the risk of different electrical potentials contributing to electrical faults, which is paramount in maintaining safe operating conditions.

While painting for visibility, applying protective coatings, and insulating lines may have their respective uses in certain circumstances, these aspects do not address the immediate electrical safety concerns associated with the metal lines carrying fuel, oil, and hydraulic fluids. Thus, the requirement for electrical bonding stands out as the most critical safety measure in this context.