Wire Terminals and Splices for the A&P Practical

October 20, 2026 · Primary sources checked October 20, 2026

For the Airframe and Powerplant (A&P) oral and practical (O&P), A&P practical wire splicing starts with confirming the repair is allowed and ends with inspecting the finished connection. During preparation, explain terminal selection, tool choice, and the limits on where a splice belongs.

What does this O&P project evaluate?

Use the Federal Aviation Administration (FAA) Airman Certification Standards (ACS) skill below to organize your wire-repair rehearsal.

The examiner evaluates a skill together with two practical questions in each project.

FAA Order 8900.1, Vol. 5, Ch. 5, Sec. 11, CHG 929, printed 16, PDF 16, 5-5-11-7C3)c)

You may consult the available, applicable references while performing the skill and answering those questions.

FAA Order 8900.1, Vol. 5, Ch. 5, Sec. 11, CHG 929, printed 16, PDF 16, 5-5-11-7C3)c)

A project is graded pass/fail.

FAA Order 8900.1, Vol. 5, Ch. 5, Sec. 11, CHG 929, printed 16, PDF 16, 5-5-11-7C3)f)

The first skill attempt and both practical answers must be successful for the project to pass.

FAA Order 8900.1, Vol. 5, Ch. 5, Sec. 11, CHG 929, printed 16, PDF 16, 5-5-11-7C3)f)

The downloaded test supplies the performance standard that the completed work must meet. According to the Mechanic Test Generator (MTG) FAQ, practical projects cannot be combined during testing.

FAA Order 8900.1, Vol. 5, Ch. 5, Sec. 11, CHG 929, printed 16, PDF 16, 5-5-11-7C3)g) · FAA Mechanic Test Generator FAQs, updated May 22, 2023, unnumbered page, PDF 4

The sample oral and practical test identifies itself as material for practice only. Our study advice: select the approved wire repair before reaching for a crimper.

FAA sample oral and practical test, unnumbered page, PDF 6

FAA-S-ACS-1, printed 38, PDF 43

Choose an allowed repair before preparing the wire

Some manufacturers prohibit splicing, so the applicable manufacturer’s instructions should always be consulted. Power-wire, coaxial-cable, multiplex-bus, and large-gauge wire splices must have approved data. Splicing is permitted when it does not affect wiring reliability or electromechanical characteristics.

FAA-H-8083-31B, Airframe, printed 9-91, PDF 507 · AC 43.13-1B, Change 1, printed 11-65 (and 11-66), PDF 555, 11-167

Advisory Circular (AC) 43.13-1B’s repair methods cover nonpressurized areas of civil aircraft when manufacturer repair or maintenance instructions are absent. The circular generally concerns minor repairs. Our data-selection advice: use the current manufacturer repair and any required approved data first; the circular is not blanket approval for a particular wiring repair.

AC 43.13-1B, Change 1, printed unnumbered cover page, PDF 1, Purpose, paragraph 1

Risk list before terminating a wire

Current maintenance and overhaul procedures are part of the ACS safety assessment.

FAA-S-ACS-1, printed A-3, PDF 67

The ACS safety list includes observation of precautions and the required personal protective equipment (PPE).

FAA-S-ACS-1, printed A-3, PDF 67

The ACS says disregard for safety will result in failure. For an action that would jeopardize safety, the evaluator will request simulation of that portion.

FAA-S-ACS-1, printed A-3, PDF 67

• The electrical-system ACS identifies energized-system maintenance and terminal selection or installation as risks.
• AC 43.13-1B gives this caution: for personal safety, and to avoid the possibility of fire, turn off all electrical power before starting an inspection of the aircraft electrical system or performing maintenance.
• Our setup advice for this rehearsal: also isolate the assigned wire under the aircraft procedure before stripping, splicing, or attaching its terminal.
• The circular specifically cautions that power is to be turned off before electrical-equipment cleaning.
• Electrical current through the body can create severe entry and exit burns.
• In addition, the nervous system is affected and can be damaged or destroyed.
• The General handbook says the use of rubber gloves, safety glasses, rubber or grounded safety mats, and other safety equipment contributes to the overall safety of a technician working on or with electrical equipment.
• Our safety preparation: use the task’s specified eye protection, manage wire offcuts, and check the Safety Data Sheet for any cleaner or other hazardous material used.

FAA-S-ACS-1, printed 38, PDF 43, AM.II.K.R3, R7 · AC 43.13-1B, Change 1, printed 11-43, PDF 532, 11-96 · AC 43.13-1B, Change 1, printed 11-2, PDF 493, 11-4 · FAA-H-8083-30B, General, printed 1-1, PDF 22

Select the terminal and prepare the conductor

Terminal selection should account for current rating, wire gauge and insulation diameter, conductor and insulation compatibility, stud size, environment, and soldered versus solderless construction. Preinsulated crimp-type ring-tongue terminals are preferred. Aluminum terminal lugs should be crimped to aluminum wire only.

AC 43.13-1B, Change 1, printed 11-67, PDF 556, 11-174a · FAA-H-8083-31B, Airframe, printed 9-90, PDF 506 · FAA-H-8083-31B, Airframe, printed 9-91, PDF 507

Hold the wire perpendicular to the stripper’s cutting blades. Adjust automatic strippers carefully and follow their manufacturer’s instructions to avoid strand damage, especially for aluminum wires and for copper wires smaller than No. 10. Aluminum strands break very easily after being nicked, so aluminum wire must be stripped with extreme care. Inspect the stripped conductor for damage. If nicked or broken strands exceed the manufacturer’s allowance, cut off and restrip where sufficient length remains, or reject and replace the wire.

FAA-H-8083-31B, Airframe, printed 9-88, PDF 504 · FAA-H-8083-31B, Airframe, printed 9-87, PDF 503

Leave a clean-cut insulation edge without fraying or ragged material, trimming if necessary. Remove all insulation from the stripped area, including any transparent inner layer. Retwist copper strands when necessary to restore their natural lay and tightness.

FAA-H-8083-31B, Airframe, printed 9-88, PDF 504

Match the crimp tool and die to the connection

Preinsulated crimp lugs and splices must be installed with a high-quality ratchet-type crimping tool. The circular recommends the proper calibrated tool. Crimp tools have wire-size positioners and are adjusted for each wire size. The circular says it is essential that the crimp depth be appropriate for each wire size. Our tool-selection check: match the terminal or splice and wire size to the specified tool, die, and positioner in the applicable instructions.

AC 43.13-1B, Change 1, printed 11-69, PDF 558, 11-178

Crimp tools must be carefully inspected: make sure the full-cycle ratchet mechanism is tamper-proof so that it cannot be disengaged before or during the crimp cycle. Reject a faulty or nonfunctioning crimp tool and send it for repair. Tool calibration and adjustment are made only by the manufacturer or an approved calibration laboratory. Suitable Go/No Go gauges shall be used before any crimping operation and whenever possible during operation to ensure crimp dimensions.

AC 43.13-1B, Change 1, printed 11-69, PDF 558, 11-178b(1) · AC 43.13-1B, Change 1, printed 11-69, PDF 558, 11-178b(2) · AC 43.13-1B, Change 1, printed 11-69, PDF 558, 11-178b(3) · AC 43.13-1B, Change 1, printed 11-69–11-70, PDF 558, 559, 11-178b(4)

When aluminum lugs are terminated on studs, the tongue or stacked tongues should be between two flat washers.

FAA-H-8083-31B, Airframe, printed 9-91, PDF 507

The wire-to-terminal joint should be at least as strong in tension as the wire itself, with negligible resistance relative to that wire. For high-temperature use, a terminal’s temperature rating must exceed ambient temperature plus the current-related temperature rise.

FAA-H-8083-31B, Airframe, printed 9-90, PDF 506

The hand-stripper example puts the wire in the center of the slot for its size, fully closes the handles, releases them, and removes the stripped wire. Our assembly advice: strip to the length and insert to the position specified for the selected terminal or splice, then complete its specified crimp cycle.

FAA-H-8083-31B, Airframe, printed 9-88, PDF 504

Apply the splice rules with their exceptions

• Splicing should be kept to a minimum and avoided entirely in areas of extreme vibration.
• Splices in individual wires within a bundle should have engineering approval and be accessible for periodic inspection.
• There should be no more than one splice in a wire segment between connectors or other disconnect points, subject to the listed exceptions.
• Those exceptions are a spare pigtail lead of a potted connector, multiple wires joined to one wire, wire-size adjustment for the contact crimp barrel, and an approved repair.
• Splices in bundles must be staggered to minimize any increase in bundle size, which could keep the bundle from fitting its designated space or cause congestion that adversely affects maintenance.
• Splices should not be within 12 inches of a termination device except for the stated pigtail, multiple-wire, and wire-size/contact-barrel cases.

AC 43.13-1B, Change 1, printed 11-65 (and 11-66), PDF 555, 11-167a · FAA-H-8083-31B, Airframe, printed 9-79, PDF 495 · AC 43.13-1B, Change 1, printed 11-65 (and 11-66), PDF 555, 11-167e–f

A self-insulated splice connector is preferred. A noninsulated connector may be used if covered with plastic sleeving secured at both ends. For severe wind and moisture problem (SWAMP) areas, the circular says environmentally sealed splices that conform to MIL-T-7928 provide a reliable means of splicing; however, a noninsulated splice connector may be used if the splice is covered with dual-wall shrink sleeving of a suitable material.

AC 43.13-1B, Change 1, printed 11-65 (and 11-66), PDF 555, 11-167b · AC 43.13-1B, Change 1, printed 11-37 (and 11-38), PDF 528, 11-78b

Inspect the crimp and finish the termination

A crimp that is too deep may break or cut individual strands. A shallow crimp may fail to retain the wire. A loose crimp is also susceptible to high resistance from corrosion between the terminal and conductor. Crimping tools crimp the barrel to the conductor and, at the same time, form the insulation support to the wire insulation.

FAA-H-8083-31B, Airframe, printed 9-91, PDF 507

Our inspection advice: judge the finished crimp by the inspection criteria in the approved data for that connection, such as conductor retention, insulation support, crimp dimensions, and any specified test, rather than by a pull test of your own. No more than four terminal lugs, or three lugs plus a bus bar, should be connected to one stud. Tightening should not deform the terminal lugs or studs. Spacers or washers should not be placed between terminal-lug tongues.

AC 43.13-1B, Change 1, printed 11-67, PDF 556, 11-174c · AC 43.13-1B, Change 1, printed 11-68, PDF 557, 11-174c · AC 43.13-1B, Change 1, printed 11-68, PDF 557, 11-174d–e

Loose, dirty, or corroded terminal contact surfaces can heat locally and may ignite nearby combustibles or overheat adjacent wire insulation. Unless another positive locking action is provided, the lug or wire should be supported beside the stud to prevent side-pull loosening. Torque recommendations for the connection are normally found in the manufacturer’s maintenance instruction manual. Equipment terminals should have the barriers and covers supplied by the equipment manufacturer.

AC 43.13-1B, Change 1, printed 11-68, PDF 557, 11-175 · AC 43.13-1B, Change 1, printed 11-69, PDF 558, 11-176d · AC 43.13-1B, Change 1, printed 11-69, PDF 558, 11-177

Common mistakes worth stopping for

Our rehearsal checks: reject damaged strands beyond the specified allowance, use the correct crimp tooling, keep the one-splice rule and its exceptions together, and inspect the completed connection before restoring the system.

Practice the reasoning out loud

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Related guides

• Aircraft electrical systems oral questions
• Fundamentals of electricity oral questions
• The practical project format
• Measuring Voltage, Resistance and Voltage Drop for the A&P Practical
• FAA A&P Practical Test Changes 2026: What’s New

Sources

Primary sources checked October 20, 2026.

• AC 43.13-1B, Change 1
• FAA-S-ACS-1
• FAA-H-8083-31B, Airframe
• FAA-H-8083-30B, General
• FAA Mechanic Test Generator FAQs, updated May 22, 2023
• FAA Order 8900.1, Vol. 5, Ch. 5, Sec. 11, CHG 929
• FAA sample oral and practical test

About this guide: drafted with AI from the FAA sources listed on this page and checked claim by claim against them. Not reviewed by an A&P mechanic or DME. How we make our guides