In most aircraft hydraulic systems, two piece tube connectors consisting of a sleeve and a nut flare are used when a tubing flare is required. The use of this type connector eliminates which of the following?

• A. the possibility of reducing the flare thickness by wiping or ironing during the tightening process
• B. the need for lubricants
• C. leak paths at the joint
• D. misalignment at the joint

Answer: (A)

The main idea is that a sleeve inside the nut provides a fixed seating surface for the tubing flare, so tightening doesn’t wipe material off the flare edge. When the nut is torqued, the flare is pressed against the sleeve shoulder rather than the nut face, eliminating the rubbing that would otherwise shave metal away and reduce the flare thickness. By preserving the flare thickness, the joint maintains its strength and sealing capability.

Lubricants may still be used as specified for threads or sealing surfaces, and leak paths or misalignment can occur if surfaces aren’t clean or torqued correctly, so those aspects aren’t inherently eliminated by this design. The primary benefit here is preventing thinning of the flare during assembly.