# SDR 2026FA0000347

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: May 9, 2026
- Submitted: May 9, 2026
- Operation: General aviation
- Engine: Lyc O540*
- System (JASC): [8530 · Reciprocating Engine Cylinder Section](https://openairdocs.org/jasc/8530)
- Part: Thrust Button
- Part number: SL12892
- Condition: Faulty
- 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/2026FA0000347

## Discrepancy

DURING MAJOR OVERHAUL INSTALLED SUPERIOR ROCKER SHAFT THRUST BUTTONS P/N SL12893.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 O FOUR FINDINGS AND TO REMOVE THE PARTS FROM SERVICE. SUSPECT LOT NUMBERS IN OUR INVENTORY WERE QUARANTINED. DEFECTIVE SUPERIOR THRUST BUTTONS WERE REMOVED AND REPLACED WITH LYCOMING THRUST BUTTONS P/N LW-12893. DEFECTIVE PARTS WERE REMOVED BEFORE ENGINE WAS TEST RUN.

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