Narrative:

While cruising at FL280 a warning message followed by an aural alert for left engine oil pressure was received. Upon looking at the oil pressure; a rapid and continuous fluctuation was observed ranging between 25-35 psi. The warning message would extinguish and then reappear continuously with each occurrence of the oil pressure dropping to 25 psi. The power was reduced and the captain called for the QRH for lh eng oil press. After reviewing the QRH; it was decided since the warning message was not staying on; the oil pressure was above 25 psi almost the entire time and the oil temperature was not rising; it may have been a sensor or instrumentation problem; so we continued to monitor as directed by the QRH. We decided to divert to a close airport to have the problem diagnosed. After receiving a new clearance we observed that the range on the fluctuating oil pressure was becoming smaller with a lower maximum peak. The warning message was staying on and the oil pressure was dropping below 25 psi at times. It was then decided that this indication was probably accurate and that the engine was indeed losing oil. We executed an engine shutdown on the left engine per the QRH and declared an emergency. The approach and landing were uneventful.

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Original NASA ASRS Text

Title: A CRJ200 flight crew shutdown the left engine and diverted to a nearby airport due to fluctuating low oil pressure.

Narrative: While cruising at FL280 a warning message followed by an aural alert for left engine oil pressure was received. Upon looking at the oil pressure; a rapid and continuous fluctuation was observed ranging between 25-35 PSI. The warning message would extinguish and then reappear continuously with each occurrence of the oil pressure dropping to 25 PSI. The power was reduced and the Captain called for the QRH for LH Eng Oil Press. After reviewing the QRH; it was decided since the warning message was not staying on; the oil pressure was above 25 PSI almost the entire time and the oil temperature was not rising; it may have been a sensor or instrumentation problem; so we continued to monitor as directed by the QRH. We decided to divert to a close airport to have the problem diagnosed. After receiving a new clearance we observed that the range on the fluctuating oil pressure was becoming smaller with a lower maximum peak. The warning message was staying on and the oil pressure was dropping below 25 PSI at times. It was then decided that this indication was probably accurate and that the engine was indeed losing oil. We executed an engine shutdown on the left engine per the QRH and declared an emergency. The approach and landing were uneventful.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.