# SDR 2026FA0000879

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: October 20, 2026
- Submitted: October 20, 2026
- Operation: General aviation
- Aircraft: [N797DL](https://openairdocs.org/aircraft/N797DL), registered now
- Engine: Lyc IO360B1B
- Engine time: 765 hours
- System (JASC): [7414 · Magneto/Distributor](https://openairdocs.org/jasc/7414)
- Part: Impulse Coupling
- Part number: M3529
- Condition: Sheared
- Location: Engine
- Part time: 765 hours, 123 cycles
- Component: Magneto, Slick, 4373
- Component part number: 4373
- Stage of operation: TX
- How discovered: V
- Nature of condition: Y, J
- Precautionary procedure: E
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/2026FA0000879

## Discrepancy

IMPULSE COUPLING FAILED ON SLICK 4373 MAGNETO. MAGNETO HAD 230 HOURS AND 123 START CYCLES SINCE 500 HOUR IRAN. TOTAL TIME ON MAGNETO 765 HOURS. IMPULSE COUPLING WAS REPLACED WITH NEW M3529 SLICK IMPULSE COUPLING AT TIME OF IRAN DUE TO EXCESSIVE WEAR ON EXISTING COUPLING. DISASSEMBLY OF THE COUPLING AFTER FAILURE SHOWED EXCESSIVE WEAR (HOLES HOGGED OUT) IN RETENTION PLATE, ONE RIVET FAILED IN SHEAR, SECOND RIVET WAS CLOSE TO THE SAME FAILURE. PAWL ARM AND SHEARED RIVET DROPPED INTO ACCESSORY CASE. CASE OF MAGNETO DESTROYED DURING FAILURE.

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