Da-20 flight instructor reported diverting to an alternate after observing a drop in oil pressure.

Attributes
ACN	1431504
Time
Date	201703
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	DA20-C1 Eclipse
Operating Under FAR Part	Part 91
Flight Phase	Climb
Route In Use	None
Flight Plan	None
Component
Aircraft Component	Engine
Person 1
Function	Instructor Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor Flight Crew Multiengine Flight Crew Instrument
Experience	Flight Crew Last 90 Days 10 Flight Crew Total 10000 Flight Crew Type 20
Events
Anomaly	Aircraft Equipment Problem Critical

Narrative:

During climb; engine began to run rough. Immediate level off. Engine roughness disappeared; engine ran normally. Continued flight. While adjusting mixture control; observed oil pressure begin to drop rapidly from approximately 55-60 psi to approximately 20 psi; then pressure returned to 55-60 psi. Decided to proceed direct [to an alternate]. Approximately 8 miles [out] I tuned the communication transceiver to tower frequency and realized there were other aircraft operating in the traffic pattern. Requested priority for landing due to oil pressure issue. Tower controller gave immediate clearance as requested. As the approach to the airport continued; observed oil pressure drop from 55-60 psi to approximately 40 psi twice more. Landing was uneventful. Tower had; on their own initiative; called on-field crash-fire-rescue and advised them of our situation. They were standing by near the touchdown point. Later; maintenance inspected the aircraft and the engine and did not observe any deficiencies.

Original NASA ASRS Text

Title: DA-20 flight instructor reported diverting to an alternate after observing a drop in oil pressure.

Narrative: During climb; engine began to run rough. Immediate level off. Engine roughness disappeared; engine ran normally. Continued flight. While adjusting mixture control; observed oil pressure begin to drop rapidly from approximately 55-60 PSI to approximately 20 PSI; then pressure returned to 55-60 PSI. Decided to proceed direct [to an alternate]. Approximately 8 miles [out] I tuned the communication transceiver to tower frequency and realized there were other aircraft operating in the traffic pattern. Requested priority for landing due to oil pressure issue. Tower controller gave immediate clearance as requested. As the approach to the airport continued; observed oil pressure drop from 55-60 PSI to approximately 40 PSI twice more. Landing was uneventful. Tower had; on their own initiative; called on-field Crash-Fire-Rescue and advised them of our situation. They were standing by near the touchdown point. Later; maintenance inspected the aircraft and the engine and did not observe any deficiencies.

Data retrieved from NASA's ASRS site 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.