# SDR 2026FA0000346

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: May 9, 2026
- Submitted: May 9, 2026
- Operation: General aviation
- Engine: Lyc IO540*
- System (JASC): [8530 · Reciprocating Engine Cylinder Section](https://openairdocs.org/jasc/8530)
- Part: Thrust Button
- Part number: SL12892
- Part serial: 250923000028574
- Condition: Faulted
- 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/2026FA0000346

## Discrepancy

DURING MAJOR OVERHAUL INSTALLED SUPERIOR ROCKER SHAFT THRUST BUTTONS P/N SL12893.INFORMATION THAT WE RECEIVED STATED THAT FAULTY THRUST BUTTONS WILLFLOAT IN WATER AND GOOD PARTS WILL SINK. WE PERFORMED THIS TEST ON EVERY LOT NUMBER IN OURINVENTORY AND FOUND SEVERAL LOT NUMBER BATCHES THAT FLOAT. WE THEN CONTACTED ANY CUSTOMERSWITH 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 INVENTORYWERE 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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