# SDR 2026FA0000781

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: June 10, 2026
- Submitted: September 23, 2026
- Operation: General aviation
- Aircraft: [N280TT](https://openairdocs.org/aircraft/N280TT), registered now
- Make and model: Gulstm G280
- Aircraft serial: 2049
- Aircraft time: 1,605 hours, 708 cycles
- Engine: Hnywl AS90721G
- System (JASC): [3411 · Pitot/Static System](https://openairdocs.org/jasc/3411)
- Part: Pitot Tube
- Condition: Blocked
- Stage of operation: CL
- How discovered: O
- Nature of condition: J
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/2026FA0000781

## Discrepancy

AT APPROX 34,500' WHILE IN IMC CONDITIONS, EXPERIENCED UNRELIABLE AIRSPEED INDS ON BOTH PRIMARY & STANDBY SOURCES. FLUCTUATIONS (APPROX. 250 KIAS-100 KIAS) LASTED FOR APPROX 8 MINS, DURING WHICH TIME THE AUTOPILOT & YAW DAMPER DISCONNECTED & ACFT BEGAN TO DUTCH ROLL. CONCURRENTLY, OBSERVED AN UNCOMMANDED THRUST REDUCTION BY AUTOTHROTTLE SYS AS WELL AS SPLIT THROTTLE POSITION DURING UNCOMMANDED THRUST REDUCTION. NO AIRFRAME ICING OBSERVED DURING EVENT &  SHIP'S ONBOARD ICE DETECTORS DID NOT INDICATE AIRFRAME ICING. ONCE CLEAR OF IMC CONDITIONS AIRSPEEDS RETURNED TO NORMAL & ALL AUTOMATED FLT CONTROL SYS SUCCESSFULLY ENGAGED. POST FLT MAINT INSP REVEALED NO ANOMALIES OR DEFECTS WITH REGARD TO THE PITOT STATIC SYS & NO MOISTURE OBSERVED IN THE SYS. FOLLOWED BY A FULL PITOT STATIC TEST WITH NO DEFECTS. POST FLT ANALYSIS BY MANUFACTURER INDICATES THIS EVENT LIKELY DUE TO INADVERTENT FLT INTO ICE CRYSTALS, WHICH ARE UNDETECTABLE TO AIRCREWS.

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