Narrative:

I departed in a CE525 single pilot with no passengers. I was bringing the airplane back to our home base. Climbing through FL300 the low oil pressure light came on. I confirmed it by checking the oil pressure gauge. I notified center of the situation and declared emergency. I requested a turn back to the departure airport and a descent in order to shut down the engine. On the descent; I followed the checklist procedures and shut down the engine. My initial intent was to go back to my departure airport but I was right over a large suitable airport and decided that would be a better choice. I landed single engine with no issues. Upon landing; I checked the oil level on the engine and there was none in the sight glass. When I departed; the oil level was midway between the full and add line. There was oil running outside the cowling. The maintenance department was notified and they sent two mechanics. The mechanics replaced a seal on the starter generator; which seemed like the location of the leak. The next day; I departed enroute to home base. Upon leveling at FL330; I noticed the same engine oil pressure gauge gradually decreasing. I notified the center controller of the situation and requested a return to departure airport which was 100 nautical miles away. On my descent; the low oil pressure light came on again on the same engine. I followed the checklist procedures and shut down the same engine again. I landed back at the departure airport. The same mechanics went back to work on the engine. They were unable to find exactly where the oil was leaking from but they were told then to replace every possible component that could cause that issue. After that; I test flew the airplane and no more issues.

Google
 

Original NASA ASRS Text

Title: A CE-525 pilot shut the same engine down on two consecutive flight and diverted after low oil pressure warnings from oil loss. Eventually; all accessories were replaced and the ferry flight completed.

Narrative: I departed in a CE525 single pilot with no passengers. I was bringing the airplane back to our home base. Climbing through FL300 the low oil pressure light came on. I confirmed it by checking the oil pressure gauge. I notified Center of the situation and declared emergency. I requested a turn back to the departure airport and a descent in order to shut down the engine. On the descent; I followed the checklist procedures and shut down the engine. My initial intent was to go back to my departure airport but I was right over a large suitable airport and decided that would be a better choice. I landed single engine with no issues. Upon landing; I checked the oil level on the engine and there was none in the sight glass. When I departed; the oil level was midway between the full and add line. There was oil running outside the cowling. The Maintenance Department was notified and they sent two mechanics. The mechanics replaced a seal on the starter generator; which seemed like the location of the leak. The next day; I departed enroute to home base. Upon leveling at FL330; I noticed the same engine oil pressure gauge gradually decreasing. I notified the Center Controller of the situation and requested a return to departure airport which was 100 nautical miles away. On my descent; the low oil pressure light came on again on the same engine. I followed the checklist procedures and shut down the same engine again. I landed back at the departure airport. The same Mechanics went back to work on the engine. They were unable to find exactly where the oil was leaking from but they were told then to replace every possible component that could cause that issue. After that; I test flew the airplane and no more issues.

Data retrieved from NASA's ASRS site as of July 2013 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.