# SDR 2026FA0000345

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: May 9, 2026
- Submitted: May 9, 2026
- Operation: General aviation
- Engine: Lyc O360A1P
- 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/2026FA0000345

## Discrepancy

UPON INSPECTION AFTER MAJOR ENGINE OVERHAUL, IT WAS DISCOVERED THAT THE ROCKER SHAFT THRUST BUTTONS HAD EITHER PARTIALLY OR COMPLETELY MELTED, ONLY ONE CYLINDER HAD BOTH THRUST BUTTONS COMPLETELY INTACT. MELTED PLASTIC DEBRIS WAS FOUND 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 OFOUR FINDINGS AND TO REMOVE THE PARTS FROM SERVICE. SUSPECT LOT NUMBERS IN OUR INVENTORY WERE QUARANTINED.

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