Heat Exchangers Repair & Overhaul

Heat exchangers are the workhorses of an aircraft's environmental control and thermal-management systems, transferring unwanted heat from one fluid stream to another without allowing the streams to mix. In a typical air-conditioning pack, an air-to-air heat exchanger uses cool ram air to draw heat out of hot engine bleed air before that air reaches the air cycle machine, while hydraulic and other dedicated units manage heat loads elsewhere in the airframe. The component class spans simple single-core units through Primary and Secondary Heat Exchangers, Dual and Quad Heat Exchanger assemblies, ducted designs, and integrated configurations such as PECS/FCAC and NGS units.

Construction is almost universally a brazed plate-fin or tube-and-fin matrix built from aluminum or stainless-steel alloys, with the thin fin stock and braze joints engineered for maximum surface area and minimum weight. That same delicate geometry is what makes overhaul necessary. Over thousands of cycles, cores accumulate fouling and corrosion that throttle airflow and degrade cooling, while repeated thermal cycling drives fatigue cracking at braze fillets and header joints. The result is internal or external leakage, reduced heat-rejection efficiency, and out-of-tolerance pressure drop. Restoring a heat exchanger to serviceable condition requires specialized cleaning, leak isolation, and core repair rather than simple replacement, which is why operators turn to a qualified repair station to recover these high-value units.

QTC begins every heat exchanger overhaul with incoming inspection and documentation review, recording the unit's configuration and pre-test condition before any work proceeds. The core is then cleaned to strip fouling, oil residue, and corrosion products from the internal passages and external fin matrix, after which the unit undergoes dimensional and visual inspection along with non-destructive evaluation to locate cracks, blockages, and braze-joint defects that are not visible externally.

Confirmed leaks and damaged fins, tubes, or headers are repaired using techniques appropriate to the core construction, and degraded passages are cleared to restore airflow and heat-transfer performance. Each repaired unit is then functionally tested and subjected to leak and pressure testing across its operating fluid circuits to verify integrity and rejection capability against the applicable specification. Once the unit meets all acceptance criteria, QTC completes the required documentation and returns it to service with airworthiness certification under its Part 145 approvals.