# SDR 2026FA0000344

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: May 9, 2026
- Submitted: May 9, 2026
- Operation: General aviation
- Engine: Lyc AEIO540*
- System (JASC): [8530 · Reciprocating Engine Cylinder Section](https://openairdocs.org/jasc/8530)
- Part: Thrust Button
- Part number: SL12892
- Part serial: 250923000028574
- Condition: Melted
- Location: Cylinders
- Stage of operation: IN
- How discovered: V
- Nature of condition: O
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/2026FA0000344

## Discrepancy

UPON INSPECTION AFTER MAJOR ENGINE OVERHAUL, IT WAS DISCOVERED THAT ALL ROCKER SHAFT THURST BUTTONS HAD EITHER PARTIALLY OR COMPLETELY MELTED. MELTED PLASTIC DEBRIS WAS DISCOVERED IN THE ROCKER COVERS AND OIL SUMP SCREEN. DEFECTIVE THRUST BUTTONS WERE REMOVED AND REPLACED WITH LYCOMING THRUST BUTTONS P/N LW-12892. DEBRIS WAS REMOVED, ENGINE OIL AND FILTER CHANGED AND GROUND RUN FOR 2 HOURS, THEN CHANGED AGAIN BY CUSTOMER AND RETURNED TO SERVICE. INFORMATION THAT WE RECEIVED STATED THAT FAULTY THRUST BUTTONS WILL FLOAT IN WATER AND GOOD PARTS WILL SINK. WE PERFORMED THIS TEST ON EVERY LOT NUMBER IN OUR INVENTORY AND FOUND SEVERAL LOT NUMBER BATCHES THAT FLOAT. WE THEN CONTACTED ANY CUSTOMERS WITH THE SUSPECT LOT NUMBER THRUST BUTTONS INSTALLED IN THEIR ENGINES TO INFORM THEM OF OUR FINDINGS AND TO REMOVE THE PARTS FROM SERVICE. SUSPECT LOT NUMBERS IN OUR INVENTORY WERE QUARANTINED.

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