What might happen if a flare-type fitting is over-tightened?

Over-tightening a flare-type fitting can lead to damage of the sealing surface. These fittings rely on a precise cone angle to create a seal when the two surfaces are pressed together. Excessive torque can deform or crush the sealing surfaces, compromising their ability to form a leak-tight seal. This can lead to leaks and potential failure of the fluid system, which can be especially critical in aviation applications where leaks in fuel or hydraulic systems can have serious safety implications.

The correct answer highlights the importance of using the appropriate torque specifications to ensure that the fittings operate effectively without damaging their functional surfaces. Proper installation is key to maintaining the integrity of the assembly, preventing leaks, and ensuring the safety and reliability of the aircraft systems.