Aircraft Assembly & Structural Repair Solutions
for Aviation Maintenance, Repair, and Overhaul
Increase Fleet Readiness
Reduce Corrosion Repair costs
Validate Life Extension Credits
Aircraft Hole Repair: The Problem and the Solution
Every aircraft in service accumulates damage at the fastener hole level. Mis-drilled holes introduced during manufacture or maintenance, fatigue-damaged holes where cyclic loading has degraded the surrounding metal, and corrosion-compromised holes in structural airframe components - these are not edge cases. They are routine engineering challenges that every MRO facility, military depot, and commercial operator faces on every airframe, every inspection cycle. Left unaddressed, a degraded fastener hole becomes a crack initiation site. A crack initiation site becomes a structural failure risk. The stakes are not abstract.
Repair options have historically fallen into three categories. Oversized rivets were the traditional response: enlarge the hole, fit a larger fastener, restore mechanical function. Serviceable, but the method does nothing to address the underlying fatigue damage in the surrounding metal. Bushing inserts stepped forward as a more refined solution - a precision sleeve inserted into the damaged hole to restore original fastener geometry. Better, and widely used, but still a passive fix that restores dimension without addressing fatigue life in the host material. Cold expansion changed the equation entirely.
Cold expansion is an active repair process, not a passive one. By driving a precision mandrel through the fastener hole under controlled force, cold expansion plastically deforms the metal surrounding the hole, introducing a ring of compressive residual stress that counteracts the tensile stresses that drive fatigue crack growth. The result is a fastener hole that is not merely repaired to its original condition - it is stronger than it was before damage occurred. Independent testing consistently demonstrates fatigue life improvements of 3:1 or greater over unworked holes. For high-cycle airframes, military platforms, and any structure where fastener hole integrity is mission-critical, cold expansion is the repair method of choice.
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Increase Fleet Readiness
Fleet readiness improves significantly with PartWorks' patent-pending solutions, including ultra thin-walled bushings and bushed rivetless nutplates. These innovations dramatically reduce corrosion hole repair time and extend the fatigue life of components, delivering up to 10x life extension, which results in increased aircraft availability.
Reduce Corrosion Repair Costs and MRO Labor Costs
Fleets experience a transformative reduction in corrosion repair costs with PartWorks' patented installation and process validation tools. By standardizing the labor involved in aircraft repair and providing tools that inform operators when a task has been correctly completed, PartWorks RepĀR helps reduce MRO labor costs while ensuring compliance.
Validate Life Extension Credit
The PartWorks RepĀR cold expansion validation system allows fleets to validate repairs in situ. Using a combination of digital image correlation (DIC) and other advanced technologies, our system supports the validation of cold expansion processes, ensuring that life extension credit is justified and documented.
Watch how PartWorks solutions increase fleet readiness, reduce corrosion repair costs and validate life extension credits
Frequently Asked Questions
What is aircraft hole repair?
Aircraft hole repair is the process of restoring structural fastener holes in airframe components that have been compromised by mis-drilling, fatigue damage, or corrosion. These holes anchor the rivets, bolts, and fasteners that hold an airframe together under cyclic flight loads. When a hole is damaged or out of tolerance, it cannot be ignored — a degraded fastener hole reduces load-bearing integrity, accelerates fatigue crack initiation, and creates a structural failure risk that compounds with every flight cycle. Precision repair restores both the dimensional accuracy of the hole and, when performed correctly, the fatigue life of the surrounding metal.
What are the methods used for aircraft hole repair?
Three methods are in common use, each representing a different generation of repair practice. Oversized rivets are the legacy approach — the damaged hole is enlarged to accept a larger fastener, restoring mechanical function but leaving the underlying fatigue damage unaddressed. Bushing inserts are an intermediate solution — a precision sleeve is installed to restore original fastener geometry, offering better dimensional control but still a passive fix that does not improve fatigue life in the host material. Cold expansion is the current best practice for any repair where fatigue life is a performance requirement. It is the only method that actively improves the structural condition of the hole rather than simply restoring its dimensions.
How does cold expansion repair an aircraft hole?
Cold expansion repairs an aircraft hole in four steps. First, the damaged hole is inspected and measured to confirm it falls within the repair envelope for cold expansion — diameter, depth, and surrounding material condition are all verified. Second, the appropriate expansion mandrel size is selected based on hole geometry and the target level of compressive stress required by the repair specification. Third, the mandrel is pulled through the hole under controlled force, plastically deforming the metal wall and introducing a uniform ring of compressive residual stress that suppresses fatigue crack growth. Fourth, process execution is validated — dimensional checks confirm the hole is within tolerance and that the cold-working operation was completed correctly. PartWorks' RepAR system captures this validation data digitally, creating a traceable repair record for every hole.
What is the difference between cold expansion and traditional aircraft hole repair?
Traditional hole repair methods — oversized rivets and bushing inserts — restore a hole to a serviceable condition. Cold expansion makes the hole better than it was before damage occurred. The key difference is compressive residual stress. When a mandrel cold-works a fastener hole, it plastically deforms the surrounding metal in a controlled way, leaving a ring of compressive stress that directly counteracts the tensile stresses generated by flight loads. Tensile stress drives fatigue crack growth; compressive stress suppresses it. The result is a repaired hole with a fatigue life of three times or greater compared to an unworked hole of the same dimensions. For high-cycle airframes, military platforms operating under sustained structural loads, and any repair where return-to-service life is a contractual requirement, cold expansion is not just the better option — it is the technically defensible one.
How does PartWorks' RepAR system improve aircraft hole repair?
RepAR combines augmented reality guidance with real-time process validation to eliminate the two most common failure points in aircraft hole repair: technician error during the procedure and missing or incomplete process records after it. The system overlays step-by-step repair instructions directly into the technician's field of view, eliminating the need to reference paper manuals or interpret ambiguous maintenance documentation while working on the airframe. Simultaneously, RepAR captures dimensional measurements, mandrel selection data, and process execution results digitally, generating a complete validation record for every hole repaired. No other aircraft hole repair solution combines cold expansion tooling with AR-guided procedure and built-in process validation in a single handheld system. PartWorks is the only company that does both.