Borescope Inspection of a Turbine Engine for the A&P Practical

October 25, 2026 · Primary sources checked October 20, 2026

For Airframe and Powerplant (A&P) practical borescope inspection, rehearse the O&P (oral and practical) task as a documented visual inspection: establish access, recognize findings and consult the applicable limits.

What does this O&P task evaluate?

The Federal Aviation Administration (FAA) Airman Certification Standards (ACS) inspection skill below is the basis for this borescope rehearsal.

The assigned practical project brings together a skill element and two practical questions. Both the skill demonstration and the practical questions permit use of available, applicable references.

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

Each individual practical project is judged on a pass/fail standard. If any portion of the project is not properly completed, the applicant fails it; to pass, the applicant must accomplish the skill demonstration successfully on the first attempt and successfully answer the two associated practical questions.

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

You must complete the project to the required performance standard to pass, and the examiner can find that standard in the downloaded test. Practical projects remain standalone during testing, according to the Mechanic Test Generator (MTG) FAQ.

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 published FAA sample identifies its test as being for practice purposes only.

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

FAA-S-ACS-1, printed 46, PDF 51

Our scope is the borescope portion of an engine inspection, not a complete engine teardown, blade repair or return-to-service authorization.

Find the inspection task before inserting the scope

The ACS lists use of current maintenance and overhaul publications and procedures among the safety precautions the evaluator ensures you follow. The ACS safety examples include safety glasses, hearing protection and any other required personal protective equipment (PPE).

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

The ACS states that disregard for safety is not tolerated and will result in a failure. The evaluator will ask for the unsafe portion to be simulated if a project action would jeopardize safety.

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

Turbine maintenance procedures vary widely with engine design and construction, and the detailed procedures recommended by the engine manufacturer should be followed. Review aircraft logbooks for maintenance history and use the appropriate inspection checklist to avoid overlooked items.

FAA-H-8083-32B, Powerplant, printed 10-44, PDF 412 · FAA-H-8083-30B, General, printed 10-1, PDF 377

• Before nondestructive inspection (NDI), follow preparatory steps specific to that inspection type, and generally the parts or areas must be thoroughly cleaned.
• Complete knowledge of equipment and procedures is essential, and required equipment calibration and inspection must be current.
• Our setup check: locate the engine-specific shutdown, ignition and starter isolation, cooling, rotation and access instructions and the required borescope configuration before starting the rehearsal.
• The Powerplant handbook cautions that the high energy level and voltage of turbine ignition systems can cause injury or death to personnel who contact the activated system, and says to always consult the applicable manufacturer’s instructions before any ignition system maintenance.
• Our stop condition is missing access or equipment information: resolve it from the assigned instructions rather than forcing a probe through an assumed opening.

FAA-H-8083-30B, General, printed 10-17, PDF 393 · FAA-H-8083-32B, Powerplant, printed 4-46, PDF 205

Use the designated access and establish the view

Borescope inspection is essentially visual inspection of areas otherwise inaccessible without disassembly. Turbine engines have access ports specifically designed for borescopes.

FAA-H-8083-30B, General, printed 10-18, PDF 394

• A borescope can be rigid or flexible and provides illumination for remote viewing of internal or inaccessible surfaces.
• Typical uses include turbine-blade and combustion-can inspection and assessment of foreign object damage (FOD).
• A preliminary visual inspection checks cleanliness, foreign objects, missing or deformed fasteners, part security, corrosion and damage.
• Our coverage method: identify the port and viewing direction, then follow the assigned inspection pattern so each required location has an identifiable view.
• Our rehearsal note distinguishes a feature that was examined from an area that the available view did not reveal.

AC 43.13-1B, Change 1, printed 5-10, PDF 230, 5-17 · FAA-H-8083-30B, General, printed 10-18, PDF 394 · AC 43.13-1B, Change 1, printed 5-11, PDF 231, 5-18a

AC 43.13-1B covers inspection and repair of nonpressurized civil-aircraft areas only when manufacturer repair or maintenance instructions are absent. Here the circular explains optical inspection principles; it does not supply an engine-specific borescope route or acceptance limit.

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

Recognize findings without inventing acceptance limits

• The handbook warns that maintenance of the compressor, or cold section, is a concern because damage to blades can cause engine failure.
• Any inspection and repair of turbine compressor section components requires that the technician always use the specific manufacturer’s current information for evaluation and limits of repairs.
• The handbook says emphasis must be placed on careful inspection and repair of the hot section, and its hot-section discussion calls for checking first-stage turbine blades and nozzle guide vanes for cracks, warping and FOD.
• Before the combustion case is opened, the handbook says the entire external case should be inspected for evidence of hot spots, exhaust leaks and distortions.
• In the handbook’s procedure, once the combustion case has been opened, the combustion chambers can be inspected for localized overheating, cracks or excessive wear; the combustion chamber outlet ducts and turbine nozzle are also inspected for cracks and FOD.
• The applicable engine service and overhaul manuals determine whether a hot-section crack is allowed and whether it is within limits.
• The handbook’s hot-section clearances and tolerances are illustrative, and the applicable manufacturer maintenance and overhaul instructions must always be followed.
• For turbine blades, stress-rupture cracks commonly appear as minute hairline cracks across or on a leading or trailing edge at right angles to its length.
• Overtemperature deformation may appear as waviness or varying airfoil thickness along the leading edge.
• The handbook says the leading edge must be straight and of uniform thickness along its entire length, except for areas repaired by blending.
• Do not confuse stress-rupture cracks or leading-edge deformation with foreign-material impact damage or blending repairs.
• Finding stress-rupture cracks or leading-edge deformation in first-stage turbine blades means an overtemperature condition must be suspected.
• In that condition, the handbook calls for checking individual blades for stretch and the turbine disc for hardness and stretch.
• In the handbook’s typical blade inspection requirements, a blade’s sharp bend is cause for rejection if it may crack or break a piece out, even when its curl is inside the allowable area.
• Our findings entry identifies what the image shows, the exact location and the applicable manual criterion; it leaves uncertain damage unresolved rather than calling it acceptable.

FAA-H-8083-32B, Powerplant, printed 10-45, PDF 413 · FAA-H-8083-32B, Powerplant, printed 10-47, PDF 415 · FAA-H-8083-32B, Powerplant, printed 10-50, PDF 418 · FAA-H-8083-32B, Powerplant, printed 10-50–10-51, PDF 418, 419 · FAA-H-8083-32B, Powerplant, printed 10-51, PDF 419

Record the view and close out the inspection

Many borescopes can display images on a computer or video monitor for interpretation and record them for future reference. Our image record includes engine identification, inspection task and revision, access port, stage or location, view orientation, observed condition and the image identifier.

FAA-H-8083-30B, General, printed 10-18, PDF 394

• The importance of inspections and the proper use of their records cannot be overemphasized.
• Our final check links each finding to its image and acceptance criterion and records any inspection area that remains incomplete or needs another method.
• The lack of visible defects does not necessarily mean further inspection is unnecessary.
• Our closeout plan follows the assigned engine instructions for probe withdrawal, tool accountability, port restoration and any required subsequent checks.

FAA-H-8083-30B, General, printed 10-1, PDF 377 · FAA-H-8083-30B, General, printed 10-17, PDF 393

Control foreign-object and reassembly risks

• Extreme care must be taken during assembly to keep dirt, dust, cotter pins, lock wire, nuts, washers and other foreign matter out of the engine.
• Before a turbine start, make a minute inspection of inlet ducts to ensure nuts, bolts, lock wire and tools were not left after work.
• A compressor rotor can be damaged beyond repair by tools left in the air intake; the handbook’s simple solution is to check the tools against a tool checklist.
• Do not carry objects in pockets when working near operating turbine engines.
• If the job includes disassembly, proper support of the engine and removed parts cannot be overstressed and component alignment is of utmost importance.
• Always consult manufacturer information for marking parts; wax pencils must not be used on liner surfaces or turbine rotors.
• Carbon-alloy or metallic marking pencils are not recommended because intergranular corrosion could reduce strength and cause cracking.
• Our practical boundary: a defect that needs disassembly, dimensional measurement or another inspection method leads to the applicable follow-on procedure, not a repair improvised through the scope.

FAA-H-8083-32B, Powerplant, printed 10-47–10-49, PDF 415, 416, 417 · FAA-H-8083-32B, Powerplant, printed 10-45, PDF 413 · FAA-H-8083-32B, Powerplant, printed 10-47, PDF 415 · FAA-H-8083-32B, Powerplant, printed 10-49, PDF 417

Common borescope-rehearsal mistakes

• Our checklist: avoid losing location or orientation, accepting an unseen area as inspected, copying a handbook example as an engine limit, or saving an image without a traceable finding.
• Practice explaining the difference between the observation, the manual criterion and the resulting maintenance decision.

For examiner fees and planning, read the DME exam cost guide.

Related guides

• Engine Inspection Oral Exam Questions and Answers
• Turbine Engine Oral Exam Questions and Answers
• A&P Practical Projects: What the DME Evaluates on the O&P

Sources

Primary sources checked October 20, 2026.

• AC 43.13-1B, Change 1
• FAA-S-ACS-1
• FAA-H-8083-30B, General
• FAA Mechanic Test Generator FAQs, updated May 22, 2023
• Order 8900.1, Vol. 5, Ch. 5, Sec. 11, CHG 929
• FAA-H-8083-32B, Powerplant
• 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