Narrative:

While in cruise at FL250 en route to cle in an air carrier ATR 72- 212A, a single short chime was heard from crew alerting system (ccas). No abnormalities were observed by either crew member. About 2 mins later, another chime was heard from ccas, captain observed a fluctuating oil pressure indication for #1 (left) engine. We discussed the situation for a few mins, since we were not sure if indication was correct. We were not sure of indications because engine parameters, other than the oil pressure, were all normal, and engine appeared to be running smoothly. While discussing problem, fluctuations and chime became more frequent, and I noticed a drop in oil temperature and deduced that engine was losing oil, and told this to captain. Captain told me to run checklist appropriate to low oil pressure. Checklist called for engine shutdown, which was accomplished after discussing situation with maintenance controller from company, and advising flight attendants and passenger. I declared an emergency with ZOB, and asked for vectors to toledo, oh. All checklists were completed and a normal single engine visual approach was made to tol runway 7. Landing was smooth, and we were able to taxi and park under our own power. Passenger were deplaned normally. While visually inspecting outside of aircraft on ground, a large pool of oil was seen directly under the #1 (left) engine. This was an unusual emergency because it was not apparent immediately if we had an actual problem or not. It is always difficult to shut down a running engine that is producing power. In this case, it was warranted. Callback conversation with reporter revealed the following information: the reporter stated the oil loss was caused by a failed seal on the propeller governor. The reporter said the first warning came from the ccas chime, an aural and visual warning system, but at that time no abnormal engine indications. The reporter said the #1 engine oil pressure started fluctuating with all other engine indications normal. The reporter stated the oil temperature began to drop and it was decided to shut the engine down. The reporter stated the aircraft has no engine oil quantity indicators and only has a sight gauge under the cowling not accessible to the crew.

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Original NASA ASRS Text

Title: AN ATR 72-212A IN CRUISE AT FL250 DECLARED AN EMER AND DIVERTED DUE TO LOSS OF OIL IN #1 ENG CAUSED BY A FAILED PROP GOVERNOR SEAL.

Narrative: WHILE IN CRUISE AT FL250 ENRTE TO CLE IN AN ACR ATR 72- 212A, A SINGLE SHORT CHIME WAS HEARD FROM CREW ALERTING SYS (CCAS). NO ABNORMALITIES WERE OBSERVED BY EITHER CREW MEMBER. ABOUT 2 MINS LATER, ANOTHER CHIME WAS HEARD FROM CCAS, CAPT OBSERVED A FLUCTUATING OIL PRESSURE INDICATION FOR #1 (L) ENG. WE DISCUSSED THE SIT FOR A FEW MINS, SINCE WE WERE NOT SURE IF INDICATION WAS CORRECT. WE WERE NOT SURE OF INDICATIONS BECAUSE ENG PARAMETERS, OTHER THAN THE OIL PRESSURE, WERE ALL NORMAL, AND ENG APPEARED TO BE RUNNING SMOOTHLY. WHILE DISCUSSING PROB, FLUCTUATIONS AND CHIME BECAME MORE FREQUENT, AND I NOTICED A DROP IN OIL TEMP AND DEDUCED THAT ENG WAS LOSING OIL, AND TOLD THIS TO CAPT. CAPT TOLD ME TO RUN CHKLIST APPROPRIATE TO LOW OIL PRESSURE. CHKLIST CALLED FOR ENG SHUTDOWN, WHICH WAS ACCOMPLISHED AFTER DISCUSSING SIT WITH MAINT CTLR FROM COMPANY, AND ADVISING FLT ATTENDANTS AND PAX. I DECLARED AN EMER WITH ZOB, AND ASKED FOR VECTORS TO TOLEDO, OH. ALL CHKLISTS WERE COMPLETED AND A NORMAL SINGLE ENG VISUAL APCH WAS MADE TO TOL RWY 7. LNDG WAS SMOOTH, AND WE WERE ABLE TO TAXI AND PARK UNDER OUR OWN PWR. PAX WERE DEPLANED NORMALLY. WHILE VISUALLY INSPECTING OUTSIDE OF ACFT ON GND, A LARGE POOL OF OIL WAS SEEN DIRECTLY UNDER THE #1 (L) ENG. THIS WAS AN UNUSUAL EMER BECAUSE IT WAS NOT APPARENT IMMEDIATELY IF WE HAD AN ACTUAL PROB OR NOT. IT IS ALWAYS DIFFICULT TO SHUT DOWN A RUNNING ENG THAT IS PRODUCING PWR. IN THIS CASE, IT WAS WARRANTED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE OIL LOSS WAS CAUSED BY A FAILED SEAL ON THE PROP GOVERNOR. THE RPTR SAID THE FIRST WARNING CAME FROM THE CCAS CHIME, AN AURAL AND VISUAL WARNING SYS, BUT AT THAT TIME NO ABNORMAL ENG INDICATIONS. THE RPTR SAID THE #1 ENG OIL PRESSURE STARTED FLUCTUATING WITH ALL OTHER ENG INDICATIONS NORMAL. THE RPTR STATED THE OIL TEMP BEGAN TO DROP AND IT WAS DECIDED TO SHUT THE ENG DOWN. THE RPTR STATED THE ACFT HAS NO ENG OIL QUANTITY INDICATORS AND ONLY HAS A SIGHT GAUGE UNDER THE COWLING NOT ACCESSIBLE TO THE CREW.

Data retrieved from NASA's ASRS site as of July 2007 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.