Tube repair is divided into two categories temporary and permanent. Temporary repairs are made with splice sections fabricated with flared ends or preset MS sleeves. The splice sections are to be replaced by a permanent repair or new tubing assembly at the next rework cycle. Temporary or emergency repairs should be limited to cases that are due to unavailability of equipment, material, or unusual circumstances.

Cut and remove the damaged section of tubing. Remove the rough edges of the remaining tube ends. Clean the tubing ends with a lint-free wiping cloth. Position the AN818 nuts and AN819 sleeves on the tubing ends (fig. 6-23). Flare the tubing. Install AN815 unions. Position the AN818 nuts and AN819 sleeves on the new section. A new section is not required when the length of the union is longer than the damaged section. Install the new section of tubing and tighten the AN818 nuts. Permanent repairs include removal of minor damage on tubing and fittings and the replacement of line sections or fittings by Permaswage or Dynatube swaging equipment, or by induction brazing.

NOTE: Induction brazing is limited to depot-level repair. Tube assemblies used for engine-related hydraulic, fuel, oil, vent or drain lines usually have brazed or welded end fittings. These engine-related tube assemblies are normally fabricated from corrosion-resistant steel.

Some minor surface damages to tubing are acceptable, as described in inspection of tubing damage. A nick that is not deeper than 15 percent of the wall thickness of aluminum, aluminum alloy, or corrosion-resistant steel is acceptable after being reworked by burnishing with hand tools. Minor damage to fittings is defined as

Figure 6-23.Temporary tubing repair.


Figure 6-24.Reworking damaged fittings.

damage not to exceed repairable limits, as shown in figure 6-24. Fittings that exceed repairable limits should be replaced. To repair damaged fittings, proceed as follows: To repair damaged orifices, remove any restriction in the orifice and handstone it to blend rough edges or burrs, as shown in view A of figure 6-24. To repair damaged or ridged seats, resurface circumferential ridges with annular tool, as shown in view B of figure 6-24. Tool marks other than those of annular tools (one ten-thousandth of an inch RMS) are permitted on sealing surface. Damaged wrench pads are repaired by removing minor scratches with a

Table 6-11.Tube Assembly Failures and Recommended Repair Methods

fine file, leaving no file marks, as shown in view C of figure 6-24. Resurface the 37-degree sealing surface. A minimum distance of 1/16 inch (.063) should be maintained between the 37-degree sealing surface and the start of the first thread (view E of fig. 6-24). All reworked fittings should be inspected and treated against corrosion. Reworked aluminum alloy fittings should be anodized; however, uniform color of reworked fittings after anodizing is not necessary.