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Electronic digital tap testing for composite and metallic aircraft structures. WichiTech’s RD³ replaces the coin-tap method with an objective, quantitative, recordable readout — usable in noisy environments without a trained ear.

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Coast-Line stocks the WichiTech RD³ Electronic Digital Tap Hammer — the industry’s leading low-cost NDT instrument for detecting voids, delaminations, and disbonds in composite aircraft structures. Originally developed and patented by the Boeing Defense & Space Group and licensed exclusively to WichiTech Industries, the RD³ has been in continuous use at airlines, MRO depots, and aircraft manufacturers worldwide since the 1990s. 

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Traditional Coin Tap Method
Subjective — depends entirely on the operator's hearing
Unreliable in noisy shop or hangar environments
No quantitative or recordable data
Results vary between operators
Requires experienced "trained ear" inspector
Cannot differentiate borderline cases reliably
VS
WichiTech RD³ Digital Tap Hammer
Objective numeric readout — independent of operator hearing
Works in high-noise environments
Quantitative, recordable LCD display output
Consistent results across operators of any experience level
No special training required to operate
10% pulse width change detectable vs ~25% audibly

The Physics

When a hammer strikes a composite surface, it creates a compressive wave through the material. Defect-free areas return a short, sharp force-time pulse. Delaminations, voids, or disbonds reduce local stiffness — producing a wider, softer pulse that the accelerometer measures precisely.

The Measurement

The RD³ measures the pulse width at half-amplitude after each tap. A deviation from the baseline reading immediately indicates a flaw is present. The logic circuit converts this into a numerical display — no interpretation required beyond comparing numbers to the baseline.

The Advantage

The RD³ detects a 10% change in pulse width — far more sensitive than the ~25% change threshold of trained human hearing. In FAA-validated studies, inexperienced operators using the RD³ consistently sized disbonds that agreed closely with through-transmission ultrasonic results.

WichiTech Industries Inc. · Electronic NDT Tap Hammer
WichiTech RD³
Rapid Damage Detection Device — Electronic Digital Tap Hammer
The handheld, low-cost NDI instrument of choice for detecting voids, degradation, and delaminations in composite and metallic aircraft structures. Originally developed by Boeing Defense & Space Group (Patent No. 6,748,791) and licensed exclusively to WichiTech Industries. Trusted by Boeing, Bell Helicopter, and major airlines worldwide.
Boeing-Developed Technology Composite & Metallic Structures Quantitative LCD Readout Accelerometer-Based Handheld · Portable No Special Training
Description
The RD³ consists of a lightweight hammer containing an accelerometer connected by flexible cable to a handheld electronics module with digital logic components and a liquid crystal display. When the hammer strikes a surface, the accelerometer measures the force-time pulse and the electronics module displays a numerical readout directly correlated to the structural condition at the tap location.

In a controlled comparison against other bond testers, the RD³ produced equivalent results and in some cases showed slightly greater sensitivity. The device replaces the traditional coin or tap hammer method while eliminating its inherent subjectivity — the numeric readout removes the dependency on operator hearing, experience, and ambient noise conditions that make coin tapping unreliable.

Powered by a standard 9V battery with approximately 14 hours continuous use life. Low battery indicator warns before readings become unreliable.
Key Benefits
Eliminates subjectivity of coin tap testing — quantitative numerical readout independent of operator hearing or experience
Usable in noisy shop, hangar, and on-aircraft environments where traditional tap testing is impractical
No special NDI training required — inexperienced inspectors produce consistent results in field evaluations
Detects 10% pulse width change vs. approximately 25% threshold of human hearing — significantly more sensitive
Quantitative, recordable readout enables documentation of inspection results for quality and compliance records
Low-cost alternative to expensive ultrasonic, shearography, and thermography systems for routine composite inspection
Boeing-developed and Boeing-approved — FAA CACRC validated through extensive blind trial testing at airlines, MRO depots, and OEM facilities worldwide
Portable and handheld — suitable for on-aircraft, depot, and production inspection without facility infrastructure
Application Areas
Commercial MRO
On-aircraft inspection of control surfaces, fairings, radomes, and interior panels. Enables routine ramp checks without specialized equipment.
️ Military Aircraft
Composite laminate and sandwich structure inspection on fighters, helicopters, and transport aircraft. Validated on Boeing Defense & Space programs.
Manufacturing QC
Production acceptance testing of cured composite parts. Detects manufacturing defects — voids, disbonds, and delaminations — before parts enter service.
Composite Repair
Pre- and post-repair inspection to confirm defect extent and verify repair integrity. Widely used alongside scarf repair processes in MRO environments.
Bonded Structures
Core-to-skin disbond detection in honeycomb sandwich panels. Validated on Boeing 747 Kreuger Flap — accurately located and sized three disbonds in a blind test.
Helicopter Blades
Routine inspection of composite and hybrid rotor blade structures. Used by Bell Helicopter as a standard inspection tool in manufacturing and MRO operations.
Technical Specifications
Product NameRD³ Electronic Digital Tap Hammer
Full NameRapid Damage Detection Device
ManufacturerWichiTech Industries, Inc.
PatentBoeing No. 6,748,791
SensorAccelerometer in hammer head
DisplayLCD numerical readout
ConnectionFlexible cable, 3-conductor
Power9V battery (disposable)
Battery Life~14 hours continuous use
Form FactorHandheld — hammer + module
IndicatorLow battery warning light
Max Detection Depth~6 mm (defect-type dependent)
How to Use — Operating Sequence
1
Set Up
Connect the tap hammer cord to the Electronics Module (EM) before switching ON. Turning on the EM before attaching the hammer may prevent proper zeroing of the circuit.
2
Establish Baseline
Tap a known-good area of the structure to establish the baseline reading. This number represents a sound, defect-free region of the same construction.
3
Inspect
Tap systematically across the inspection area. The LCD displays a numerical reading after each tap — compare each reading to the established baseline.
4
Interpret Results
A significantly higher reading (wider pulse width) vs. baseline indicates reduced local stiffness — a potential delamination, void, or disbond. Mark and map deviations for evaluation.
5
Record & Document
Record the numerical readings for each tap location to create a quantitative inspection record. This data supports maintenance documentation and airworthiness compliance.
Detectable Defect Types
● Delaminations between composite plies
● Core-to-skin disbonds in honeycomb sandwich panels
● Voids in adhesive bond lines
● Impact damage degradation (not visible externally)
● Core crushing and moisture ingress deterioration
● Repair integrity verification (post-repair disbonds)

Why Source the WichiTech RD³ from Coast-Line?

AS9120 Documentation

AS9120-certified distributor. Full documentation package available to support quality record requirements for your NDT program.

Application Support

Our team understands composite inspection. We can help you integrate the RD³ into your existing NDT process and answer questions about its use and limitations.

Genuine WichiTech Product

Authorized WichiTech distributor. The only manufacturer licensed to produce the Boeing-patented RD³ technology — genuine product, not imitations.

Fast Response

Quote turnaround within one business day. AOG inspection need? Call us directly for urgent shipment on in-stock units.

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