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Inspecting Scribe Marks on Aircraft without Paint Removal

The presence of scribe marks, the tiny scratches that occur when an aircraft is prepared for repainting, can cause critical safety issues for planes. These marks are caused by the sharp tools that operators use to remove the paint and sealant from the joints that hold together parts of the aircraft’s skin.

All commercial aircraft that go through this paint removal process are susceptible to scribe marks. If undetected, the scribe marks can turn into deeper cracks that spread and potentially lead to widespread damage.

Consequently, aircraft workers must routinely inspect for scribe marks to check the aircraft’s structural integrity. One common way airlines detect scribe marks is with phased array flaw detectors.

Advantages of Detecting Scribe Marks Using a Phased Array Flaw Detector

Phased array instruments like our OmniScan™ flaw detectors enable inspectors to detect scribe marks without removing paint. Benefits include:

  • Software control of the beam angle, focal distance, and spot size
  • Multiple-angle inspection with a single, small, electronically controlled, multielement probe
  • Save time by not removing paint
  • Sector scan imaging
  • The entry-level OmniScan SX PA flaw detector (16:64) can perform the inspection
  • Rugged: built to work in harsh field conditions
  • Compact and lightweight
  • Long-lasting battery: runs six hours with two lithium-ion batteries

Scribe Mark Defects

OmniScan phased array flaw detectors can detect scribe marks in a variety of sizes and shapes, including:

  • Scribe marks that are 5.08 mm (0.2 in.) long or more
  • Scribe marks should be 50% of the skin thickness in skins that are 0.81–1.10 mm (0.032–0.044 in.) thick

Scribe Marks Inspection Procedure Using a Phased Array Flaw Detector

Here is a brief overview of the typical scribe marks inspection procedure:

  • The inspection is performed with an OmniScan phased array flaw detector (16:64)
  • A 10 MHz, 16 element phased array probe (10L16) is used
  • The probe is mounted on a SA00-N60S wedge
  • Sector scans range from 60º to 85º SW
  • No encoder is needed


By using the OmniScan flaw detector, aircraft workers can perform inspections for scribe marks without paint removal. Many airlines today use this procedure to inspect for scribe marks and train their technicians to use the OmniScan instrument; airlines report a fast ROI.

Ordering Information

These items are required to perform a scribe mark inspection:

Description Ordering Number
OmniScan phased array flaw detector (16:64) OMNISX-PA1664PR or higher configuration
Phased array angle-beam probe 10L16-A00 / U8330145
Wedge SA00-N60S / U8720008
NDT Engineering Special Purpose EC Reference Standard Varies
Olympus IMS

Products Used for This Application
Every flaw detector in the OmniScan™ X3 series is a complete phased array toolbox. Innovative TFM and advanced PA capabilities help you identify flaws with confidence while powerful software tools and simple workflows improve your productivity.
The single group, lightweight OmniScan SX flaw detector features an easy-to-read 8.4-inch (21.3 cm) touch screen and provides cost-effective solutions. The OmniScan SX comes in two models: the SX PA and SX UT. The SX PA is a 16:64PR unit, which, like the UT-only SX UT, is equipped with a conventional UT channel for P/E, P-C, or TOFD inspections.
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