Date: 201206
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: SF 340B
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class E ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Engine Oil Seals
Component problem: Malfunctioning; Improperly Operated
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Troubleshooting; Situational Awareness; Time Pressure
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Critical
Detector: Automation Aircraft Other Automation; Person Flight Attendant; Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action; Flight Crew Landed in Emergency Condition; Flight Crew Diverted; Flight Crew FLC complied w / Automation / Advisory; General Declared Emergency; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Human Factors; Aircraft
Primary problem: Aircraft

Narrative: We were leveled off at 12;000 FT. I noticed the left engine oil pressure fluctuating. Flight crew took out the appropriate QRH checklist and it said to monitor all engine parameters and to suspect a faulty gauge. Upon further monitoring the engine oil pressure CWP light illuminated intermittently repeatedly. We declared an emergency at this point and asked for the nearest airport. As the pressure dropped below 30 PSI we were directed by the QRH to proceed to the engine shutdown checklist. The Flight Attendant notified the flight deck of oil all over the left engine. We got radar vectors from the TRACON to the ILS. We landed and taxied to the gate under our own power. The plane had a starter generator change and it is possible that the seal in the engine was compromised potentially causing oil to leak. For the kind of maintenance procedure; perhaps a longer runup would be in order before signing it off to ensure integrity of the seals.


Second narrative: The QRH advised that the instruments were probably faulty since the oil pressure gauge was still over 30 PSI and all other parameters were normal. Within a minute or so the Left Engine Oil Pressure (CWP) light began to come on and go out intermittently with the associated sounds. We ran the QRH again and were directed by the QRH that it was once again a faulty alarm since the oil pressure was over 30 PSI. As a precaution; we notified ATC that we would need to divert and they suggested a nearby airport. We declined that one and asked for one we knew better. We were directed to turn to a heading of 180 to go to that airport and then the Oil Pressure Gauge dropped below 30 PSI. We once again ran the QRH which directed us to shut down the left engine; which we did and then we declared an emergency with ATC. Once we exited the runway; we cleaned up; and taxied to the ramp under our own power. Once we stopped; we were informed that our left main inboard tire was flat. We deplaned once we were advised by emergency ground crew that it was safe to exit the plane.


Synopsis: A SF340B's left engine oil pressure was fluctuating above 30 PSI; but QRH advised a probable indication problem. Later after the Flight Attendant reported streaming oil; the PSI dropped so an emergency was declared and the flight diverted to a nearby airport where a flat tire also was discovered.