Strength -Aircraft quality solderless terminals conform to MS25036 and MIL-T 7928 aircraft specifications, whereas automotive solderless terminals meet weaker UL 486A standards. One difference is in the force required to break or separate the terminal from the conductor. In other words, aircraft terminals have more metal at the crimp than their automotive counterparts. For example, aviation 18 gauge terminal manufactured to MILT-7928 Class 2 have a minimum tensile strength of 38 lbs. whereas automotive terminals are only required to meet 20 lbs.
Vibration Resistance: Aircraft vibrate significantly so it is important to support the wires and terminals to avoid crimp failure. The longer metal sleeves are designed to be crimped to the wire insulation providing strain relief and preventing premature failure.
In addition, the right crimping tool (MIL-DTL-22520) is required for aircraft specification crimps. Two crimps; one to hold the aircraft wire and one to hold the insulation.
Better Electrical Contact: MIL wire connectors also have multiple ‘V’ grooves inside the barrel to help grip the aircraft wire. These grooves also help break up the tin plating upon crimping. This exposes clean copper to the wires and assures a low resistance connection. Making a more reliable electrical connection. MS25036 terminals are double crimped. Yellow dot is the wire crimp. Red dot shows the insulation crimps.
Fewer crimp errors: Crimp connector tool forms both crimps at the same time. The ratchet handle will not open and release the terminal until it is fully squeezed. This prevents under crimps. MIL-DTL-22520 tools also come with a calibrating GO-NO-GO tool that verifies the proper crimp diameter. No operator guessing as how much to crimp the terminal. Ratchet style crimpers do both crimps at onceMIL-DTL-22520 crimp connector tool. “The crimp on terminal lugs and splices must be installed using a high quality ratchettype crimping tool” Quote from AC43.13-1B Chg. 1 11-69. These tools are qualified to MILDTL-22520 are to be used for crimping terminal lugs. These tools crimp the barrel to the conductor, and simultaneously form the insulation support to the wire insulation. Most automotive tools do not perform this function and must not be used.
UL on top and AS7928 (MIL-T-7928) on bottom. This is called a ‘window butt splice’. The window guarantees proper wire insertion and crimp tool alignment. This military qualified (MIL-T-7928/5) butt splice also provides an insulation grip for superior strain relief.
AS7928 (MIL-T-7928) terminals use two crimps – one to the wire and the other to the wire insulation. This prevents the wires at the crimp from vibrating and breaking. The colors on the insulation barrel (red, blue, yellow) are used to indicate the wire diameter range.
You may notice different shades of the same color. PVC and Nylon take the same color differently. For example, the PVC barrels will be dark yellow. The nylon barrels will be lighter, translucent yellow. Notice that the colors repeat themselves. Red is used for insulated terminals using 18-22 AWG and for 8 AWG. Vinyl is used in lower-grade terminals. Nylon is used more or MIL terminals as Nylon stands up better against hydrocarbons like gasoline, hydraulic fluid, and oils. MIL-DTL-22520 establishes a single specification, which set forth performance requirements for all crimp tools to be used on military standard connectors. It is a 3rd generation design that establishes good electrical and mechanical characteristics.