What occurs if a flareless fitting is overtightened on a tube?

When a flareless fitting is overtightened on a tube, the tube can indeed become weakened. This weakening occurs because the excess torque can stress the metal beyond its yield strength, which may lead to micro-cracks or deformation in the material of the tube. Since flareless fittings are designed to create a seal by biting into the tube's surface, overtightening disrupts that balance and can compromise the structural integrity of the tube, making it susceptible to failure, such as cracking or breaking under pressure.

Understanding this mechanism is crucial for aviation mechanics, as ensuring proper torque settings is essential for maintaining the integrity and safety of hydraulic and fuel systems.