BAC 5602 (Boeing's aerospace heat treatment specification) and CQI-9 (AIAG's automotive Heat Treat System Assessment) both require calibrated pyrometry and furnace instrumentation to verify that heat treat processes consistently reach and hold specified temperatures. Compliance depends on accredited calibration of thermocouples, furnace temperature uniformity surveys, and instrumentation traceable to recognized measurement standards.
Heat treatment changes the mechanical properties of metal parts through controlled heating and cooling. If the furnace, thermocouples, or recording instruments used in that process drift out of calibration, the resulting parts may not meet the strength, hardness, or fatigue properties the design requires — a risk that matters most in industries where failure has serious consequences, like aerospace and automotive manufacturing.
Both BAC 5602 and CQI-9 exist to give manufacturers and their customers confidence that a heat treat operation's instrumentation and process controls are verified and traceable, not just assumed to be working.
BAC 5602 is a Boeing specification governing heat treatment requirements for parts supplied into Boeing's aerospace manufacturing chain. It sets expectations for furnace performance, temperature uniformity, and the calibration of instrumentation used to control and record the heat treat process.
CQI-9 is the Heat Treat System Assessment (HTSA) published by the Automotive Industry Action Group (AIAG). It's used across the automotive supply chain to assess whether a heat treat operation's process controls, including furnace instrumentation and calibration practices, meet the consistency and traceability automotive OEMs require.
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BAC 5602 |
CQI-9 |
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Issuing organization |
Boeing |
AIAG (Automotive Industry Action Group) |
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Industry |
Aerospace |
Automotive |
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What it governs |
Heat treatment process requirements for Boeing supplier parts |
Heat Treat System Assessment (HTSA) — process control audit for automotive heat treat operations |
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Pyrometry basis |
References pyrometry/furnace instrumentation requirements consistent with AMS2750 |
References pyrometry and furnace calibration consistent with AMS2750-aligned practices |
Thermocouples used to monitor and control furnace temperature must be calibrated against traceable reference standards. Drift in thermocouple accuracy directly affects whether a furnace is actually reaching the temperatures its instrumentation reports.
A uniformity survey confirms that temperature is consistent throughout the furnace's working zone, not just at the location of the control thermocouple. Both aerospace and automotive heat treat standards require documented uniformity survey results at defined intervals.
Temperature controllers, recorders, and data acquisition equipment used to document the heat treat process must themselves be calibrated and traceable — the record is only as reliable as the instruments that produced it.
A calibration certificate supporting BAC 5602 or CQI-9 compliance should include:
Accreditation to ISO/IEC 17025:2017 is the most reliable path to documentation that satisfies both BAC 5602 and CQI-9 auditors, though the specific evidence each program requires should be confirmed against the current revision of each standard.
Heat treat audits under either BAC 5602 or CQI-9 typically require evidence that calibration was performed by a qualified provider using traceable standards. Working with a lab accredited to ISO/IEC 17025:2017 gives that evidence a level of independent verification that self-performed or non-accredited calibration can't provide, which can shorten audit preparation and reduce findings.
That's the difference accredited calibration makes when the audit actually happens. Whether your heat treat operation needs to meet BAC 5602, CQI-9, or both, accurate calibration is the foundation your audit results depend on. Contact CTPM to schedule ISO/IEC 17025:2017 accredited calibration for your furnace instrumentation, thermocouples, and recording equipment.