Narrative:

I am submitting this ASRS report due to an emergency I declared as pilot in command of a cessna 172S. I filed a flight plan with duats and received a standard flight briefing from lockheed flight service. My wife and I arrived at the airport early and allowed sufficient time to carefully preflight the aircraft for our flight. The preflight inspection was thorough. I found the fuel level low. Also; the oil level in the engine was at 5 quarts. The oil was at the minimum level for operation so I decided to request 1 additional quart of oil along with 11 gallons from the fueling service. The fuel truck serviced the aircraft and I confirmed the fuel quantity with my calibrated fuel stick at 42 total gallons. I also verified the oil level in the engine at 6 quarts.the engine started and indicated normal oil press. The oil temperature registered cold; as expected for the first flight of the morning. I received clearance from ground control to taxi to the active runway. As we arrived in the engine-run up area; I observed the oil temp indicator reaching the cold end of the normal operating range (lower end of the green arc on the indicator). At that point I felt comfortable to increase engine power to 1;800 RPM to continue with the remainder of the run-up checklist. Left and right mags checked good and oil temperature and oil pressure both remained in their normal operating ranges. Following the engine run-up and pre-takeoff checklist; I contacted tower for departure clearance. I was immediately cleared for take-off. At the beginning of the take-off roll; I observed the oil pressure; oil temperature; and engine tachometer readings and found all indicating normal. I continued the takeoff roll and climbed out from the airport area. I reached my initial cruising altitude of 3;500'. I flight planned 5;500' cruise altitude but had to remain at 3;500' due to the overlying class B airspace. I established radio contact with approach to transition the ZZZ class C airspace and also received continued flight following. I had flown level at 3;500' under normal cruise power for about 5 to 7 minutes and was approaching a point abeam the visual checkpoint where I elected to begin my climb from 3;500 to 5;500'. I began a climb at full power and 80kts indicated airspeed. After climbing through approximately 3;800'; I looked at my engine gauges and found the oil temperature gauge at the red line indicating an abnormally hot oil temperature. Oil pressure remained normal and the engine was running smooth. I decided to level off at 4;500' and reverse course due to an even thousand foot cruise altitude. Upon level off I reduced power and continued to monitor the oil temperature. It remained at the red line. At this point I became very concerned for the health of the engine. I realized I may have had an indication problem but due to the fact I was surrounded by rugged terrain to the south and east and a heavily populated metropolitan area to the north and west; I could not take on any additional risk. I notified approach I had a problem and needed to land at the nearest airport; ZZZ. The controller asked me to describe my problem and state number on board and fuel. I described the oil temperature problem and stated 2 on-board with 3 hours and 45 minutes of fuel remaining. He promptly gave me a vector to ZZZ but at the same time he wanted me to know that ZZZ was operating with only 1 runway in use. I told him I understood but I still felt I should be on the ground as soon as possible. I reduced power for a gradual descent and still noted the oil temperature remained at the red line. As I neared I was handed off to ZZZ tower. One of the controllers asked me if I had landing traffic for runway xxr in sight. I confirmed that I had traffic in sight. The controller then asked me if I could follow behind the landing dash 8 aircraft or if I needed to declare an emergency. I responded that I am declaring an emergency. I felt I must not fly any longer than necessarywith an engine that may potentially fail over a densely populated area. I was given clearance to land on runway xxr. It was on short final I noticed the oil temperature come off of the red line and indicated a temperature that was higher than normal but lower than what I continued to see earlier. I landed without further incident. I am still awaiting a report from maintenance as to the cause of the oil temperature problem.

Related reports:

Google
 

Original NASA ASRS Text

Title: A C172 pilot diverted to a local airport after the aircraft's oil temperature gauge indicated in the over temperature Red Band.

Narrative: I am submitting this ASRS report due to an emergency I declared as pilot in command of a Cessna 172S. I filed a flight plan with DUATS and received a standard flight briefing from Lockheed Flight Service. My wife and I arrived at the airport early and allowed sufficient time to carefully preflight the aircraft for our flight. The preflight inspection was thorough. I found the fuel level low. Also; the oil level in the engine was at 5 quarts. The oil was at the minimum level for operation so I decided to request 1 additional quart of oil along with 11 gallons from the fueling service. The fuel truck serviced the aircraft and I confirmed the fuel quantity with my calibrated fuel stick at 42 total gallons. I also verified the oil level in the engine at 6 quarts.The engine started and indicated normal oil press. The oil temperature registered cold; as expected for the first flight of the morning. I received clearance from ground control to taxi to the active runway. As we arrived in the engine-run up area; I observed the oil temp indicator reaching the cold end of the normal operating range (lower end of the green arc on the indicator). At that point I felt comfortable to increase engine power to 1;800 RPM to continue with the remainder of the run-up checklist. Left and right mags checked good and oil temperature and oil pressure both remained in their normal operating ranges. Following the engine run-up and pre-takeoff checklist; I contacted tower for departure clearance. I was immediately cleared for take-off. At the beginning of the take-off roll; I observed the oil pressure; oil temperature; and engine tachometer readings and found all indicating normal. I continued the takeoff roll and climbed out from the airport area. I reached my initial cruising altitude of 3;500'. I flight planned 5;500' cruise altitude but had to remain at 3;500' due to the overlying Class B airspace. I established radio contact with Approach to transition the ZZZ Class C airspace and also received continued flight following. I had flown level at 3;500' under normal cruise power for about 5 to 7 minutes and was approaching a point abeam the visual checkpoint where I elected to begin my climb from 3;500 to 5;500'. I began a climb at full power and 80kts indicated airspeed. After climbing through approximately 3;800'; I looked at my engine gauges and found the oil temperature gauge at the red line indicating an abnormally hot oil temperature. Oil pressure remained normal and the engine was running smooth. I decided to level off at 4;500' and reverse course due to an even thousand foot cruise altitude. Upon level off I reduced power and continued to monitor the oil temperature. It remained at the red line. At this point I became very concerned for the health of the engine. I realized I may have had an indication problem but due to the fact I was surrounded by rugged terrain to the south and east and a heavily populated metropolitan area to the north and west; I could not take on any additional risk. I notified approach I had a problem and needed to land at the nearest airport; ZZZ. The controller asked me to describe my problem and state number on board and fuel. I described the oil temperature problem and stated 2 on-board with 3 hours and 45 minutes of fuel remaining. He promptly gave me a vector to ZZZ but at the same time he wanted me to know that ZZZ was operating with only 1 runway in use. I told him I understood but I still felt I should be on the ground as soon as possible. I reduced power for a gradual descent and still noted the oil temperature remained at the red line. As I neared I was handed off to ZZZ tower. One of the controllers asked me if I had landing traffic for runway XXR in sight. I confirmed that I had traffic in sight. The controller then asked me if I could follow behind the landing Dash 8 aircraft or if I needed to declare an emergency. I responded that I am declaring an emergency. I felt I must not fly any longer than necessarywith an engine that may potentially fail over a densely populated area. I was given clearance to land on runway XXR. It was on short final I noticed the oil temperature come off of the red line and indicated a temperature that was higher than normal but lower than what I continued to see earlier. I landed without further incident. I am still awaiting a report from maintenance as to the cause of the oil temperature problem.

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.