# SDR 2026FA0000501

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: June 10, 2026
- Submitted: June 10, 2026
- Operation: General aviation
- Engine: Rotax ROTAX912ULS
- System (JASC): [8500 · Engine (Reciprocating)](https://openairdocs.org/jasc/8500)
- Part: Vent Line
- Condition: Faulted
- Location: Zone 400
- Stage of operation: LD
- How discovered: V
- Nature of condition: B, A
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/2026FA0000501

## Discrepancy

THIS IS AN AMPHIBIAN DESIGN WITH THE ENG MOUNTED ABOVE THE WING.  THE SEAMAX M22 HAS HAD ENGINE FIRES. THERE ARE A TOTAL OF 5 FUEL VENT LINES THAT EXHAUST INTO THE ENGINE NACELLE. 2 COME FROM THE RIGHT WING TANK, 2 COME FROM THE LEFT WING TANK, AND 1 COMES FROM THE HEADER TANK. USING UV TRACER DYE,  DETERMINED THAT NOT ONLY IS FUEL VAPOR EXHAUSTS IN TO THE NACELLE, BUT UNDER CERTAIN CIRCUMSTANCES, RAW FUEL WILL ENTER THE ENGINE NACELLE VIA THE HEADER TANK VENT LINE.  I'VE SEEN NO EVIDENCE OF THE RIGHT OR LEFT TANK VENTS EJECTING RAW FUEL, BUT DEFINITELY THE HEADER TANK LINE WILL EJECT RAW FUEL.  THE ISSUE OCCURS WHEN THE TANKS ARE FULL, ROUGH WATER TAKEOFFS, AS WELL AS STEEP TURNS.  INTERESTINGLY, THE OIL TANK VENT LINE EXHAUSTS OUTSIDE OF THE NACELLE.

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