# SDR 2026FA0000536

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: June 21, 2026
- Submitted: June 23, 2026
- Operation: General aviation
- Aircraft: [N755PM](https://openairdocs.org/aircraft/N755PM), registered now
- Make and model: Pilats PC12
- Aircraft serial: 1239
- Aircraft time: 3,677 hours, 2,914 cycles
- Engine: Pwa PT6A67
- System (JASC): [3411 · Pitot/Static System](https://openairdocs.org/jasc/3411)
- Part: Adiru
- Condition: Faulted
- Location: Zone 100
- Stage of operation: CR
- How discovered: O
- Nature of condition: I
- Precautionary procedure: H
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/2026FA0000536

## Discrepancy

RIGHT SIDE PITOT LINE BECAME BLOCKED INFLIGHT AFTER EXTENDED OPERATION IN AN AREA OF VISIBLE MOISTURE AT BELOW-FREEZING TEMPERATURE. ALL PROBE HEATS WERE ON AND FUNCTIONAL AT THE TIME AND FOR THE ENTIRE DURATION OF FLIGHT PRIOR TO THE LINE BLOCKAGE. AIRSPEED ON THE RIGHT-SIDE PFD AND STANDBY INSTRUMENT SLOWLY DECREASED, WHICH CAUSED AN IAS MISCOMPARE ANNUNCIATOR. I STARTED A DESCENT FOR WEATHER AND THE AIRSPEED ON THE RIGHT-SIDE PITOT LINE (RIGHT PFD AND STANDBY) RAPIDLY DECREASED TO ZERO BEFORE AN IAS RED ANNUNCIATOR APPEARED. PRIOR TO THIS, I SWITCHED THE RIGHT-SIDE PFD TO ADAHRS 1, WHICH KEPT THE AUTOPILOT RUNNING FOR A WHILE UNTIL THE MISCOMPARE BECAME TOO GREAT AND THE AUTOPILOT DISCONNECTED. AUTOPILOT WOULDN'T REENGAGE UNTIL I PULLED THE ADAHARS CH 2 CIRCUIT BREAKER. AFTER DESCENDING OUT OF VISIBLE MOISTURE, THE RIGHT-SIDE AIRSPEED RAPIDLY RETURNED, AS SEEN ON THE STANDBY INSTRUMENT, AND WHEN THE ADAHRS 2 BREAKER WAS RESET, ALL SYSTEMS ON INDEPENDENT ADAHRS UNITS RETURNED TO NORMAL WITH NO FURTHER ISSUES.

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