# SDR 2026FA0000059

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: December 25, 2025
- Submitted: January 27, 2026
- Operation: General aviation
- Aircraft: [N971LA](https://openairdocs.org/aircraft/N971LA), registered now
- Make and model: Textrn 408
- Aircraft serial: 4080012
- Aircraft time: 1,134 hours, 2,774 cycles
- System (JASC): [6140 · Propeller Indication System](https://openairdocs.org/jasc/6140)
- Part: Tach Generator
- Part number: 503890571
- Part serial: 36436C
- Condition: Loose
- Location: Zone 400
- Part time: 1,134 hours, 2,767 cycles
- Stage of operation: CL
- How discovered: O
- Nature of condition: P
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/2026FA0000059

## Discrepancy

ON 12/25/25, WE HAD AN INFLIGHT EMERGENCY DECLARED BY THE FLIGHT CREW FOR #1 ENGINE PROP SPEED ERRATIC. THE CREW REPORTED THE #1 ENGINE PROPELLER SPEED WAS JUMPING AROUND BETWEEN 1400 AND 1900 IN CLIMB SHORTLY AFTER TAKEOFF. THE CREW SAID ALL OTHER ENGINE INDICATIONS WERE NORMAL AND THE AIRCRAFT WAS NOT EXPERIENCING ANY ABNORMAL SOUNDS OR DIRECTIONAL CHANGES. HOWEVER, THEY DECLARED AN EMERGENCY AND LANDED WITHOUT INCIDENT SHORTLY THEREAFTER. 
WE FOUND THE #1 ENGINE PROPELLER TACH GENERATOR HOUSING LOOSE. THE SAFETY WIRE ON THE 4 SCREWS WAS PRESENT AND APPEARED UNDAMAGED BUT THE SCREWS WERE LOOSE AND THE HOUSING WAS LOOSE. AFTER REMOVING THE TACH GENERATOR, THE TACH SHAFT FELT VERY WOBBLY AND WOULD NOT SPIN/TURN EASILY AS COMPARED TO A NEW UNIT. WE REPLACED THE TACH GENERATOR AND THAT SEEMED TO HAVE SOLVED THE ERRATIC INDICATION PROBLEM.

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