# SDR FQAR20150731084

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: July 31, 2015
- Submitted: August 3, 2015
- Operation: General aviation
- Aircraft: [N971PA](https://openairdocs.org/aircraft/N971PA), registered now
- Make and model: Piper PA-44-180
- Registry model: [Piper PA-44-180](https://openairdocs.org/model/piper-pa-44-180) (OpenAirDocs)
- Aircraft serial: 4496031
- Aircraft time: 7,320 hours
- Engine: Lyc O360A1H6
- Propeller: Hartzl HCC2YR1
- System (JASC): [7810 · Engine Collector/Tailpipe/Nozzle](https://openairdocs.org/jasc/7810)
- Part: Exhaust Riser
- Part number: 89366011
- Condition: Fractured
- Location: Rt Engine
- Part time: 1,548 hours
- Stage of operation: TX
- How discovered: O
- Nature of condition: R
- Precautionary procedure: D
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/FQAR20150731084

## Discrepancy

DURING A PREFLIGHT RUN, WHEN THE RT ENG CARB HEAT WAS SELECTED ON, THE ENG RPM DROPPED OVER 600 RPM & THE ENG RAN ROUGH.  INSPECTION REVEALED THE NR 4 CYLINDER EXHAUST RISER HAD FRACTURED ABOUT THE FLANGE & HAD FALLEN OPEN, ALLOWING EXHAUST GASSES TO BE EMITTED FREELY INTO THE ENG COWLING & INTO THE ENG CARB HEAT AIR INLET, CAUSING THE RPM DROP & ROUGHNESS.

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