Torque on the A&P Practical: Wrench Use, Extensions and Values
The Airframe and Powerplant (A&P) oral and practical (O&P) test includes hands-on work. For A&P practical torque work, show how you select the applicable value, identify the wrench units, account for an adapter, and apply a smooth pull. Start with the specified maintenance data rather than treating a general hardware table as a universal setting.
On this page
- What does the O&P practical evaluate?
- How do I choose the torque value?
- What does this torque values table actually cover?
- How do I use the wrench without changing the result?
- What is the torque wrench extension formula?
- How do I work and check an inline example?
- What do friction drag and cotter-pin alignment change?
- Which torque mistakes affect the joint?
- How should I rehearse before test day?
What does the O&P practical evaluate?
The Federal Aviation Administration (FAA) Airman Certification Standards (ACS) identify the skills below. A Designated Mechanic Examiner (DME) evaluates the assigned project against its stated performance standard, including your selection of appropriate tools and data. Each project has a skill element and two practical questions. The project is pass/fail: the skill demonstration must succeed on the first attempt, and both practical questions must be answered successfully. These study topics do not promise a particular test assignment.
FAA Order 8900.1, Vol. 5, Ch. 5, Sec. 11, para. 5-5-11-7C3), p. 16
| ACS skill | Exact published skill |
|---|---|
| AM.I.E.S2 | Determine and properly torque aircraft hardware. |
FAA-S-ACS-1, printed 7, PDF 12
Follow the applicable manufacturer’s instructions and approved data for the assigned work. The ACS safety appendix calls for current maintenance publications, safe tool handling, equipment preparation, safety glasses, hearing protection, and any other required personal protective equipment (PPE). Disregard for safety will result in failure. If a project action would jeopardize safety, the evaluator will ask you to simulate that portion.
FAA-S-ACS-1, printed A-3, PDF 67
Use Advisory Circular (AC) 43.13-1B only within its applicability. The FAA status page describes its methods for inspection and repair of nonpressurized areas of civil aircraft only when no manufacturer repair or maintenance instructions exist; the data generally concerns minor repairs. For major repairs, the repairs identified in the AC may only be used as a basis for FAA approval. The repair data may also be used as approved data, with the AC chapter, page, and paragraph listed in block 8 of FAA Form 337, when the user has determined that the data is appropriate to the product being repaired, directly applicable to the repair, and not contrary to the manufacturer’s data.
FAA AC 43.13-1B Active status and applicability, retrieved October 19, 2026
How do I choose the torque value?
Find the value and conditions in the applicable manufacturer’s maintenance instructions first. AC 43.13-1B Table 7-1 gives recommended torque for use when the manufacturer does not supply a specific torque. Choose by bolt-shank size, not wrench-opening size, and identify the nut and thread condition.
AC 43.13-1B with Change 1, editorial update, printed 7-7, PDF 362 · AC 43.13-1B with Change 1, editorial update, printed 7-9, PDF 364
What does this torque values table actually cover?
These selected fine-thread rows are recommended installation ranges from AC 43.13-1B Table 7-1 for bolts loaded primarily in shear, with oil-free cadmium-plated threads and the stated standard nut/bolt combinations. The tension-type-nut column assumes 40,000 psi in the bolts; the shear-type-nut column assumes 24,000 psi. Values are in inch-pounds. The separate maximum-allowable-tightening columns are not reproduced and must not be mistaken for the recommended installation range. Do not use these rows for an unrelated fastener, lubricated thread, or manufacturer-specified application.
| Fine thread | Tension-type nuts MS20365 / AN310 (in-lb) | Shear-type nuts MS20364 / AN320 (in-lb) |
|---|---|---|
| 10-32 | 20–25 | 12–15 |
| 1/4-28 | 50–70 | 30–40 |
| 5/16-24 | 100–140 | 60–85 |
AC 43.13-1B with Change 1, editorial update, printed 7-9, PDF 364
How do I use the wrench without changing the result?
Verify the tool’s condition, calibration status, range, and units before use. Unless the manufacturer specifies otherwise, the threads should be clean and dry. Use the correct socket or adapter. Pull smoothly and evenly at the designated handle location; the General handbook says a fast or jerky motion results in an improperly torqued fastener. If chattering or a jerking motion occurs during final torque, AC 43.13-1B says to back off the nut and retorque. A drive-end adapter that changes the effective lever length requires a corrected wrench setting. Apply force at the point used for the length measurement; otherwise the resulting torque is incorrect.
- Identify the specified torque, units, thread condition, and the friction drag torque to add.
- Fit the wrench and adapter, calculate any effective-length correction, and confirm the setting.
- Apply a controlled pull at the intended grip. For a preset wrench, release the pull when the preset indication occurs.
AC 43.13-1B with Change 1, editorial update, printed 7-7, PDF 362 · FAA-H-8083-30B, General, printed 7-49, PDF 293 · FAA-H-8083-30B, General, printed 7-51, PDF 295
What is the torque wrench extension formula?
For an adapter extending straight in line beyond the drive, use wrench setting = desired fastener torque × L ÷ (L + E). L is the distance from the wrench-drive centerline to the prescribed handgrip centerline; E is the added inline distance to the fastener centerline. This formula is for that geometry. An adapter pointing back toward the handle reduces the effective length; Figure 7-2 gives T × L ÷ (L − E) for that case, so do not apply the plus form to every arrangement.
| Symbol | Meaning |
|---|---|
| T | Desired fastener torque |
| L | Wrench-drive center to prescribed grip center |
| E | Added inline distance from wrench drive to fastener center |
| Setting | T × L ÷ (L + E), for an extension increasing effective length |
AC 43.13-1B with Change 1, editorial update, printed 7-8, PDF 363 · FAA-H-8083-30B, General, printed 7-51, PDF 295
How do I work and check an inline example?
Illustration only: suppose the required fastener torque is 120 inch-pounds, L is 12 inches, and an inline adapter adds 3 inches. Set the wrench to 120 × 12 ÷ (12 + 3) = 96 inch-pounds. Check backward: 96 × 15 ÷ 12 = 120 inch-pounds at the fastener. The 120-inch-pound target equals 10 foot-pounds because 12 inch-pounds equal one foot-pound. The inputs are chosen for the arithmetic; they are not a torque specification for a real bolt.
| Illustrative check | Arithmetic | Result |
|---|---|---|
| Wrench setting | 120 × 12 ÷ (12 + 3) | 96 in-lb |
| Reverse check | 96 × 15 ÷ 12 | 120 in-lb |
| Unit conversion | 120 ÷ 12 | 10 ft-lb |
AC 43.13-1B with Change 1, editorial update, printed 7-8, PDF 363 · FAA-H-8083-30B, General, printed 7-50, PDF 294
What do friction drag and cotter-pin alignment change?
AC 43.13-1B says to run the nut down to near contact with the washer or bearing surface, check the friction drag torque required to turn the nut, and add it to the desired torque; the sum is the “final torque” that should register on the wrench. Follow the manufacturer’s procedure where it differs. For a castellated nut, start at the recommended minimum torque plus drag, then align the slot without exceeding the maximum plus drag. If alignment cannot be obtained within that limit, change the washer or nut and try again; do not simply keep tightening.
AC 43.13-1B with Change 1, editorial update, printed 7-7, PDF 362
Which torque mistakes affect the joint?
Undertorque can result in unnecessary wear of nuts and bolts and the parts they secure; overtorque can cause failure of a bolt or nut by overstressing the threaded areas; uneven or additional loads applied to the assembly may result in wear or premature failure. Other avoidable errors are selecting a value by wrench size, confusing inch-pounds with foot-pounds, lubricating nuts or bolts without instructions to do so (the General handbook’s exception is corrosion-resistant steel parts), and forgetting an effective-length correction. Check the complete setup before relying on the wrench indication.
AC 43.13-1B with Change 1, editorial update, printed 7-7, PDF 362 · FAA-H-8083-30B, General, printed 7-50, PDF 294
How should I rehearse before test day?
Our study suggestion: work through hardware torquing with an instructor, name the applicable source before selecting tools or values, and inspect the finished work against that source. Keep a note of the step you need to repeat in supervised practice. Rehearse the explanation separately from the physical task.
Frequently asked questions
How often should a torque wrench be tested or calibrated?
The FAA sources give two different intervals: the General handbook says all torque wrenches must be tested at least once a month or more often if necessary, and AC 43.13-1B says to calibrate the torque wrench at least once a year, or immediately after it has been abused or dropped. Before the practical, check the calibration status of the wrench you will use.
FAA-H-8083-30B, General, printed 7-49, PDF 293 · AC 43.13-1B with Change 1, editorial update, printed 7-7, PDF 362
Must I always turn the nut rather than the bolt head?
No, but turn the nut whenever possible; AC 43.13-1B says this reduces rotation of the bolt in the hole and reduces wear. When torque is applied to a bolt head or cap screw, AC 43.13-1B says to apply the recommended torque plus friction drag torque, and the General handbook says to approach the high side of the torque range without exceeding the maximum allowable torque. Follow the specific installation instructions for the assigned fastener.
AC 43.13-1B with Change 1, editorial update, printed 7-7, PDF 362 · FAA-H-8083-30B, General, printed 7-50, PDF 294
Can a flexible-beam wrench take a handle extension?
No. The General handbook says it is not advisable to use a handle length extension on a flexible beam-type torque wrench at any time. On the other wrench types, a handle extension alone has no effect on the reading.
Rehearse the spoken answer with DMEReady
DMEReady is an AI voice examiner for the A&P oral in your phone or computer browser. You answer out loud, and it asks follow-up questions the way a DME would. You can also rehearse an oral built from the ACS codes on your Airman Knowledge Test Report (AKTR). It rehearses the oral; it does not train hands-on practical skills. After each session, the report shows what you covered, what you missed, what a complete answer includes, and where to read in the FAA handbooks. You can save the report as a PDF study sheet and share a result image that never shows your answers or name. The first drill is free, with no sign-up. DMEReady is an AI examiner, not a human DME. It is independent and is not affiliated with or endorsed by the FAA; it does not predict or guarantee results.
Start your free drillFor examiner fees and planning, read the DME exam cost guide.
Oral coming up soon? Try the full thing free for 30 days
We are running a small pilot before launch. If your oral and practical is in the next few weeks, you get every section of the voice mock oral free for 30 days, no card. In return, tell us honestly what helped and what didn’t.
Start the free pilotLimited spots. The pilot closes on November 30.
Passed a written? Get your oral study plan by email
Paste the ACS codes on your Airman Knowledge Test Report (AKTR). We’ll email you a study plan now, then two short tasks built from your codes: one on day 3, one on day 7. That’s all.
Related guides
- Aircraft Hardware and Materials Oral Exam Questions and Answers
- Fluid Lines and Fittings Oral Exam Questions and Answers
- A&P General Oral Questions: The Complete Breakdown
- A&P Practical Projects: What the DME Evaluates on the O&P
- Safety Wire Practical Test: Double-Twist and Turnbuckles
Sources
FAA sources checked October 19, 2026.
- FAA-S-ACS-1
- FAA AC 43.13-1B Active status and applicability
- FAA Order 8900.1, Volume 5, Chapter 5, Section 11, Administer an Oral and a Practical Test: Mechanic Applicant Under Part 65 Subpart D (CHG 929, 9/17/2024), para. 5-5-11-7C3)
- AC 43.13-1B with Change 1, editorial update
- FAA-H-8083-30B, General
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
Report an error or ask a question
Email hello@dmeready.com.