What is a borescope inspection? Borescope vs. boroscope, what it finds and how long it takes
The plain-English guide to the BSI: the tool, the ports, the findings, the limits, and what a report you can act on looks like.
What a borescope inspection is
A borescope is an optical probe with a camera and LED illumination at the tip. The inspector inserts it through the borescope ports provided in the engine casing and, using a turning tool on the gearbox pad, indexes each blade past the probe. Modern video borescopes — we carry the Waygate Everest XL and Mentor Visual iQ families — articulate the tip, record stills and video, and on the latest generation measure a finding in three dimensions.
Nothing is removed from the engine except port plugs. The aircraft stays on the ramp or in the hangar, and the engine is back in service the same day if nothing is found out of limits.
What it finds
Cracks, nicks and dents from foreign object damage, tip curl and tip rub, thermal barrier coating loss on high-pressure turbine blades and nozzle guide vanes, burn-through and trailing-edge distress, erosion, missing material and combustor liner cracking.
Each finding is measured and compared with the limit published in the engine manual. The result is one of three dispositions: serviceable, repairable on wing, or beyond limits — which usually means a shop visit.
When operators, lessors and investors order one
- Scheduled inspections under the operator's maintenance program.
- AOG troubleshooting after a bird strike, FOD event, EGT exceedance, vibration or oil indication.
- Pre-purchase inspections before an engine or aircraft changes hands.
- Lease return and redelivery, mid-lease and engine-trade inspections.
- Workscope planning before a shop visit, so the shop quotes against reality instead of assumptions.
How long it takes
The engine has to be cool, so a hot section cannot be inspected straight after a flight. Once cooled, a full BSI of a CFM56-7B — fan, booster, high-pressure compressor, combustor, high-pressure turbine and low-pressure turbine — typically takes three to five hours depending on access and the number of findings to document. Plan on the aircraft being out of service for half a day.
Historically the report took four to five hours more. With InspectView sorting the footage by stage and drafting each finding against the manual limit, our inspectors now spend one to two hours checking and signing instead of typing.
Borescope or boroscope?
Both spellings are in daily use and both mean the same instrument and the same inspection. Maintenance manuals, the FAA and EASA use "borescope". You will see "BSI" as the abbreviation on work orders and in our reports. We use both spellings on this site so that you find us either way.
What a report you can act on contains
- Footage and stills sorted by engine stage — fan, LPC, HPC, combustor, HPT, LPT — not by file name.
- Every finding with its image, measurement, manual reference and limit, and a disposition.
- The inspector's name, credentials and signature. In our process the AI drafts; a qualified inspector signs. The AI never signs.
Does a borescope inspection require the engine to be removed?
No. A BSI is performed on wing through the borescope ports in the casing. Only the port plugs are removed.
Can you measure a crack with a borescope?
Yes. Third-generation Waygate Mentor Visual iQ probes with 3D phase measurement give depth, length and area at the tip, so a finding is compared with the manual limit on the spot.
How much notice do you need?
Scheduled work is best booked about a week ahead. AOG and short-notice requests are handled on availability — tell us the engine, the airport and the date.
JTech Turbines performs borescope, GVI, QEC, pre-purchase and lease return inspections on site in 30+ countries. Reports are drafted in InspectView and signed by the inspector.