# SDR 2026FA0000633

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: August 10, 2026
- Submitted: August 10, 2026
- Operation: General aviation
- Aircraft: N853Q
- Make and model: Textrn TEXTRON700
- Aircraft serial: 7000105
- Aircraft time: 3,324 hours, 1,978 cycles
- System (JASC): [2150 · Cabin Cooling System](https://openairdocs.org/jasc/2150)
- Part: Mixer Box
- Part number: 741572450
- Part serial: NA
- Condition: Failed
- Location: Zone 100
- Part time: 3,324 hours, 1,978 cycles
- Stage of operation: CR
- How discovered: O
- Nature of condition: O
- Precautionary procedure: B
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/2026FA0000633

## Discrepancy

SHORTLY AFTER REACHING CRUISE ALTITUDE OF FL410, AN AUDIBLE POP WITH ASSOCIATED RISE IN CABIN PRESSURE OCCURRED. CREW DESCENDED AND CABIN ALTITUDE AMBER CAS DISPLAYED AND QRH WAS ACCOMPLISHED. ACM O'HEAT AND HEAT EXCHG ONLY DISPLAYED UNTIL QRH PROCEDURE CLEARED MESSAGE. LANDED WITHOUT FURTHER ISSUE. PRESSURIZATION SYSTEM WAS CONSIDERED INOP BY THE FLIGHT CREW (RAPID DEPRESSURIZATION). UPON INSPECTION OF THE SYSTEM, FOUND THE MIXER ASSY FAILED AT A FACTORY WELD (ABOUT 2/3RDS AROUND THE ENTIRE PERIPHERY).

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