# SDR 2008FA0000668

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: October 3, 2008
- Submitted: October 9, 2008
- Operation: General aviation
- Aircraft: [N4126A](https://openairdocs.org/aircraft/N4126A), registered now
- Make and model: Robsin R44RAVENII
- Aircraft serial: 12096
- Aircraft time: 464 hours
- Engine: Lyc IO540AE1A5
- Engine time: 464 hours
- System (JASC): [8530 · Reciprocating Engine Cylinder Section](https://openairdocs.org/jasc/8530)
- Part: Guide
- Part number: 66713
- Condition: Undersize
- Location: Engine
- Part time: 464 hours
- Component: Cylinder, Lyc
- Component part number: LW12993
- Stage of operation: CR
- How discovered: O
- Nature of condition: R
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/2008FA0000668

## Discrepancy

MOMENTARY SEVERE VIBRATION, POWER LOSS AND ENGINE RPM DROP OCCURRED IN-FLIGHT THEN RETURNED TO NORMAL.  COMPRESSION CHECK (COLD) REVEALED STUCK INTAKE VALVE ON NR 6 CYL.  INTAKE VALVE GUIDE ID MEASURED .4035" (UNDERSIZED).  LIMITS .4040 / .4050.  NO BUILDUP FOUND ON VALVE GUIDE OR STEM.  VALVE GUIDE REAMED TO PROPER SIZE PER LYC.  TABLE OF LIMITS SSP1776.  NO REOCCURRENCE REPORTED.

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