Reviving a 1957 Temco Aircraft: Eagle CNC’s Reverse‑Engineered Parts Restore a Rare Aerospace Component

Maintaining rare or antique equipment often calls for reverse-engineered parts.  Often, the original manufacturer no longer exists—and if they do, there’s a good chance their processes have undergone such drastic changes that they’re no longer capable of producing the part. CAD files are never available, and even blueprints are hard to find. That’s the gap filled by our combination of reverse engineering and CNC machining: through precise measurement, CNC machining, and finishing, we’re able to create a copy of nearly any part that looks and performs even better than the original.

The Temco TT-1 Pinto is a two-seat jet-powered primary trainer developed in the 1950s for the U.S. Navy, designed to teach student pilots basic flight training in a jet rather than a propeller aircraft. Only about 15 were built, and although it handled well, it served only briefly in Navy training programs before being retired around 1960. Today, just five remain in operation.

When one of these rare planes suffered a structural component failure, it wasn’t simply a matter of ordering a replacement part. The failure grounded a limited-production aircraft with no active supply chain and no inventory of spares.

The broken component was part of the steering assembly, and it fractured under stress during towing. Because of the age and rarity of the aircraft, replacements were not commercially available. The part had to be recreated.

This project ultimately required reverse engineering, precision machining, and careful engineering judgment. It was not a reproduction from drawings. It began with a broken piece of metal. Our team at Eagle CNC studied the cracked casting, then set out to learn exactly how the part was used and what kind of design would replicate—or even improve upon—the original part. Together with our customer, we wanted to get the Temco back in the sky as soon as possible, and to do that, we used every tool in our reverse-engineering toolbox.

Reverse-Engineered Parts: Choosing the Right Manufacturing Path

Under normal production circumstances, a casting followed by finish machining would likely be the most efficient manufacturing approach. However, this was a one-off situation—a single aircraft in need of a single replacement component. Pure machining from billet was the only cost-effective option. As Brandon Mead, Eagle CNC’s Process Engineering Manager, put it: “The tooling cost alone for making a casting would be more than making one part from machining.”

While the original component had been an aluminum casting, supplemented by small brass and steel fixtures, the new component would be CNC machined entirely from raw aerospace-grade aluminum billet. The original brass and steel fixtures were set aside to be reinserted when the new aluminum part was finished. Our customer’s guidelines were to “make this exact part,” so that’s what we set out to do—a brand new aerospace aluminum part, fully assembled with the original brass and steel components.

Reverse Engineering from a Broken Part

“All I got was the broken part, some pictures, and a few measurements.”
-Brandon Mead, Process Engineering Manager, Eagle CNC Technologies

The reverse engineering process began with a damaged component, a few photographs, and dimensional references. Because the aircraft was not at our facility, the Eagle CNC team had to rely on those materials and conversations with the customer to understand the part.

Above: the original part once the crack became a complete fracture

Because of the unusual nature of the project, Eagle CNC chose a largely manual approach. Nearly all measurements were performed at a workstation using calipers and standard inspection tools. The component was measured feature by feature, including thread pitches, bore diameters, hole spacing, and external geometry. In one instance, a coordinate measuring machine was used to verify a large central diameter that was difficult to confirm due to distortion from cracking. Beyond that, the reconstruction relied on hand measurement and the experience of Eagle CNC’s engineering team.

In this case, reverse engineering went beyond dimensional replication. Eagle CNC also needed to understand how the part functioned within the larger assembly. The part housed bushings and bearing surfaces and operated as part of a steering interface, making the geometry, thickness, and location of each bore functionally critical.

Once the hand measurements were complete, the part was digitally reconstructed before CNC machining began. At that stage, Eagle CNC evaluated whether structural improvements could be incorporated so the new component would perform as intended and potentially outlast the original.

Above: Brandon’s workbench

Engineering Improvements Beyond Replication

Although the objective was to create an exact replacement in terms of function and material, there was some room to refine the design.

The original casting showed evidence of molding artifacts—excess material and geometry that existed only to support casting processes. Because the replacement component would be CNC machined from billet, those features were unnecessary and could be eliminated. Removing that geometry reduced complexity and allowed for improved structural consistency. The failure point in the original casting was carefully analyzed to guide design improvements that would strengthen the part’s weakest link. Additional thickness was added in critical areas to increase stiffness and durability. Where appropriate, the outer diameters were enlarged and select sections were reinforced to better distribute load.

Above: surface areas identified for removal and reinforcement

Another refinement addressed serviceability. In the original component, an internal sleeve component was difficult to remove because of limited access geometry. In the redesigned version, that internal feature was made extractable, allowing easier maintenance without potentially destructive disassembly.

Together, these refinements maintained the original mechanical spirit of the 1957 Temco, while improving long-term durability and maintainability.

Machining Strategy and Setup

CNC machining was performed primarily on a Haas UMC-500SS five-axis machining center. Initial material preparation was completed using a manual Bridgeport milling machine to create square gripping surfaces and workholding notches in the billet.

Once prepared, the billet was fixtured in the UMC with the goal of minimizing holdings. Reducing the number of setups—or “holdings”—is critical when targeting tight tolerances, since each time a part is removed and re-clamped the machining accuracy can be affected. The machining strategy therefore prioritized completing as many operations as possible within a single setup.

Most critical features—bores, faces, mounting surfaces, and press-fit locations—were machined relative to one another within one primary orientation. A secondary light setup was used only to remove excess material associated with workholding.

This approach preserved geometric relationships between holes and surfaces while minimizing cumulative tolerance stack-up.

Above: mid-milling on the Haas UMC-500SS

Tolerances and Press-Fit Precision

Tolerance targets for this part were demanding, especially for the press-fit features. General tolerances were held within ±0.001 inch. Several bores were designed as interference fits—in simple terms, the hole is intentionally made slightly smaller than the part that will be pressed into it. For this component, the interference ranged between one and two thousandths of an inch. That small difference is what holds the inserted part securely in place.

Aluminum, however, presents unique challenges in press-fit work, because it expands easily with heat. If the bore is undersized even slightly beyond specification, pressing in a steel or brass insert can create excessive stress and crack the surrounding structure. If oversized, the insert will be loose and compromise functionality.

Achieving the correct interference dimension required careful process control throughout the entire CNC machining process.

Managing Heat and Material Behavior

Because aluminum is thermally sensitive, heat management was an essential consideration throughout machining. Through-spindle air was used during roughing operations to help regulate temperature. Keeping the material cool reduced the risk of thermal expansion during cutting.

Roughing passes intentionally left excess material—approximately 0.010 inch—before finishing operations. This approach allowed dimensions to be refined incrementally, with measurements taken directly in the machine between passes. The workflow followed a deliberate sequence: rough cut, measure, adjust tool offsets where required, re-cut lightly, measure again, and only then proceed to final finishing passes.

This process ensured that each press-fit bore met its target before machining progressed further. For a one-off component with limited margin for error, iterative measurement and adjustment provided the most reliable path to achieving the required tolerances.

Surface Finishing and Final Assembly

After machining was completed, the part progressed to finishing operations. The original component had a protective powder coating, so the new part was processed to meet the same operational requirements.

Machining marks were blended by hand to smooth transitions and prepare the surfaces for coating. Critical mating surfaces were masked to prevent coating interference with precision fits. The part was then glass bead blasted to prepare the surface for powder coating adhesion. All of this was done manually at the workbench to ensure careful control of surface preparation.

Finally, powder coating was applied to replicate the protective finish of the original component. The steel and brass elements from the damaged assembly were extracted, cleaned, refinished, and reinstalled. Surfaces intended for grease retention were intentionally left uncoated.

The result was a ready-to-install reverse-engineered part: fully assembled, structurally improved, and aesthetically optimized.

Above: before and after: the original broken part, and the new and improved finished version

Technical Significance and Broader Capabilities

This project represents more than a one-off aerospace repair job. It demonstrates a broad set of capabilities, including manual reverse engineering, digital modeling, five-axis CNC machining, tight tolerance control, thermal management, finishing processes, and assembly integration. All of this was carried out within the walls of Eagle CNC’s machine shop. The project also showcases Eagle CNC’s ability to begin with an end product rather than a blueprint. When customers no longer have drawings, tooling, or casting data, starting from a worn or damaged component is often the only option. In those situations, reverse engineering and digital reconstruction provide a practical path forward—and Eagle CNC has the know-how to get those kinds of jobs done.

The same workflow used to restore this TEMCO aircraft component can also be applied to discontinued industrial parts, restoration projects, or product redevelopment. Machining from billet allows rapid turnaround for prototypes and low-volume production. If higher production volumes are later required, the same digital models can be adapted for casting design or tooling development.

By completing this project entirely in-house—from initial measurement to final coating—Eagle CNC demonstrated both adaptability and precision in a demanding aerospace application.

Restoring Function to a Rare Aircraft

The impact of this project was immediate: a grounded aircraft regained a critical structural component and got back in the air. The replacement part was built to exact tolerance, with improvements that also made it stronger and easier to service.

As original supply chains disappear, reverse engineering parts to refine and reproduce complex components provides a practical path for sustaining historic and specialized machines like the Temco TT-1 Pinto.

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