Effective Use of Borescopes

With their ability to see places where the unaided human eye can’t, borescopes are incredibly valuable for aircraft maintenance technicians. But like all good tools, there are right ways and wrong ways to use borescopes; especially when it comes to...


With their ability to see places where the unaided human eye can’t, borescopes are incredibly valuable for aircraft maintenance technicians. But like all good tools, there are right ways and wrong ways to use borescopes; especially when it comes to nondestructive testing (NDT) of components and airframes.

To get a clear view on this issue, AMT spoke to Sean O’Connor, U.S. sales manager for RF System Lab; Doug Kindred, president of Gradient Lens Corp.; and Laura Bustamante, senior product manager at Olympus.

AMT: How are borescopes used for NDT applications in aviation maintenance?

O’Connor: First of all, while the term “borescope” is often used to refer to any type of remote visual inspection (RVI) tool, there is a difference between a “borescope,” a “fiberscope,” and a “videoscope.” Strictly speaking, a borescope is a rigid optical instrument that can be used when you have direct, straight line access to the object being inspected. Mirrors or prisms are usually used to carry the image from the distal end of the borescope to an eyepiece or camera located at the proximal end.

Unlike borescopes, fiberscopes are flexible instruments that can bend through curves and channels in order to gain visual access to an inspection area. With a fiberscope, fiberoptic bundles carry light to the distal end of the insertion tube, illuminating the inspection area. Other fiberoptic strands within the insertion tube carry the image back [to] where it is viewed through an eyepiece or captured by a camera that can then display the image on a monitor. Some fiberscopes have directional controls and an articulating tip that allow the user to point the distal end of the insertion tube in any direction once it is inserted into an inspection area.

Videoscopes are the latest advancement in RVI. With a videoscope, a very small camera is placed at the distal end of the insertion tube, allowing direct video access to the area being inspected. The image is displayed in real time, usually on an integrated viewing monitor. Because there is no intermediate step of carrying the image through fiberoptic bundles before viewing, videoscopes have much higher resolution and image clarity when compared to traditional fiberscopes. Also, most videoscopes have built-in image capture and video recording capabilities, which makes documentation, image sharing, and archiving much easier.

Whether using a borescope, fiberscope, or videoscope, there are a number of important applications for RVI instruments in aviation maintenance. Generally speaking, these applications could be lumped into three categories: engine inspection, airframe inspection, and FOD (foreign object damage) detection.

Bustamante: With borescopes and videoscopes you can get to what’s not seen with the eye, things that you have no immediate access to and can’t immediately get to. There’s also a higher cost to take things apart to get to. That’s the main reason. Second is to get to and see inside airframe or any small area you can’t physically get to without a significant amount of time or money.

AMT: What elements of RVI instruments make them so well suited for NDT work?

O’Connor: Simply stated, RVI instruments allow a technician to conduct a visual inspection of an area that otherwise could not be seen with the unaided human eye. For any technician working on complex machinery or equipment, being able to look inside and inspect small or remote internal areas is a huge advantage. When we consider the financial costs and potential loss of life that can occur with the sudden failure of an aircraft component or system, effective RVI in aviation becomes not just an advantage but an absolute necessity.

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