Wire repair often requires the use of terminals and splices. The proper crimping procedures and instructions for tool use are covered in the aircraft Wiring Practices Manual. Terminals are used extensively for aircraft frame (ground) connections and terminal strip interconnects. Splices are normally used for wire repair. The use of "exposed" splices is limited to areas inside the pressure vessel with no chances of chemical (Skydrol®) contamination.
All terminals and splices are designed for double crimps. The crimp on the wire insulation provides tensile strength. The crimp on the wire itself is for electrical conductivity. To long or short of a wire strip will decrease the effectiveness of the connection.
Proper placement in the crimping tool is also needed. A terminal or splice that has not been positioned correctly will most likely be bent out of shape. Crimping tool damage could also result. Once the first "click" is heard while crimping, the tool must finish the cycle before the crimp head will open.
Quick Notes For Crimping
Color codes for wire gauge are standard for all aircraft usage. Yellow 10-12, Blue 14-16, and Pink/Red 18-22.
The inserts shown with the splices on this page allow for two different wire gauges to be connected together. The blue insert fits into a yellow splice and the red insert fits into a blue splice
The tool, terminals, and splices shown here are commonly used on aircraft manufactured in the United States. Airbus® aircraft have a slightly different style and material for their terminals. A specific tool is needed for crimping these, but a double crimp is still the result.
Crimping tools will have an alignment bar for placement. Splices will have a notch that fits under this bar. Terminal lugs also go under this bar. If the terminal is positioned correctly, the bar acts as a "stop" for the wire as it is inserted.
A good splice is characterized by the two crimps at the correct locations and wire visible through the inspection window at the midpoint of the splice.
A good terminal connection will have two properly placed crimps along with the wire visible on the lug side of the terminal.
Automotive crimpers and channel lock pliers are not proper for aircraft terminal or splice usage.
I'm spending time going back thru forum topics these days! I can appreciate the features of these crimpers to crimp the insulation independently of the wire barrel, and limit the wire exposed out the barrel end. In the automotive world, for something that should be so straightforward, it seems to be botched frequently!
They are the most reliable! We use the crimp solder and seal splices exclusively at the shop I work at. I was considering buying a DeWalt 20V cordless heat gun , instead of always dealing with a cord, especially if its a repair out in the lot. Like you said in one of your other posts...its easy to burn thru the shrink tubing with a flame.