Supporting Life-Saving Missions: Oklahoma City Recores a Cessna Citation 650 Precooler

Cessna Citation 650 (Citation VII) Heat Exchanger Precooler, PN 9914402-1. Reversed engineered, recored and overhauled at Wall Colmonoy Oklahoma City.

May 4, 2026

Wall Colmonoy Oklahoma City (OKC) has successfully completed the reverse engineering and manufacture of a replacement Precooler Heat Exchanger core for Midwest Flying Service’s Cessna Citation 650 (Citation VII) aircraft, resolving a critical fleet‑wide supply challenge and enabling continued aircraft operations.

Midwest Flying Service identified an issue with the Precooler Heat Exchanger (P/N 9914402‑1) affecting multiple aircraft in their Citation VII fleet. With no replacement units available on the market, existing cores beyond economical repair, and no OEM or aftermarket support for recore or new manufacture, the operator faced a significant risk to aircraft availability - particularly for missions supporting time‑critical organ transport.

Midwest Flying Service completes approximately 300 missions annually. 

To address the issue, Wall Colmonoy Oklahoma City conducted a full reverse engineering effort on the original Precooler core and developed a newly manufactured replacement solution. Leveraging prior experience with Precooler cores for the Cessna Citation 560 and Citation 750 platforms, as well as multiple customer‑supported MRO recore programs, OKC’s engineering team identified key similarities that enabled the application of proven core technology.

“All design, engineering, and manufacturing activities - including high temperature vacuum brazing - were performed entirely in‑house at our Oklahoma City facility,” said Brian Martin, Director of Business Development, Wall Colmonoy Oklahoma City. “By leveraging existing core design knowledge and validated manufacturing processes, we were able to deliver a reliable replacement solution where no commercial support existed.”

The completed Precooler solution restores a viable path forward for continued operation of Midwest Flying Service’s Citation VII fleet, reducing risk associated with unsupported legacy components and helping ensure aircraft readiness for mission‑critical operations.

“These Citation VII aircraft support time‑sensitive organ transport missions, where reliability and rapid turnaround are essential,” said Brian Martin. “With no available spares and limited supplier support for Precooler recore or replacement, maintaining operational readiness posed a significant challenge. Wall Colmonoy OKC stepped in to deliver a solution for these critical components. In this context, the need for reliable Precooler support extends beyond routine maintenance - it becomes a mission‑critical responsibility.”

This program highlights Wall Colmonoy Oklahoma City’s capability to support legacy aircraft platforms through advanced reverse engineering, recore, and heat exchanger manufacturing solutions - even when OEM or aftermarket options are no longer available.

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