Date: 201604
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: DA20-C1 Eclipse
Operator: FBO
Operating under: Part 91
Flight plan: VFR
Mission: Training
Flight phase: Climb
Airspace: Class C ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Engine
Component problem: Malfunctioning
Reporter organization: FBO
Reporter function: Instructor; Pilot Flying
Reporter qualification: Flight Crew Commercial; Flight Crew Flight Instructor
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: A pre-private pilot student and I planned on taking a cross country flight. After checking weight and balance and checking out; we went out to preflight. I supervised the preflight and did the usual follow up checks behind a student that included checking the oil; exhaust; and fuel. We had just short of 5 quarts of oil on board; and the fuel was topped to 20 gallons. After starting up and programming the avionics; we taxied out to the ramp for our run-up. Run up was normal; with the magneto check indicating no more than 50 rpm drop for either mag. Oil pressure was indicating on the low side of the green area; but I was told a long time ago that this indication is normal for this aircraft for run up. After run up was complete; we called Ground and taxied to [the runway]. Engine power during taxi ranged from idle to approximately 1300 RPM.After cleared for take-off; we performed a normal take off. Engine was at full throttle and mixture was at full rich. Oil pressure was in the normal range. We were vectored to 320 and we climbed to 2000. Shortly before we reached 2000; we were cleared to 4500. Just after climbing above 2500; there was a loud bang and a burnt smell; and the engine started vibrating. There were no initial indications on the engine gauges that anything was wrong. I was monitoring my pressure gauges primarily. There was a gradual indication of losing oil pressure. The engine performed with power; but with vibration and rough operation. At this time; I took control of the airplane and began a turn back [to departure airport]. ATC saw that we were making a turn and tried to vector us back on course. During a break in the radio traffic; I called [advised ATC] and informed them we were heading back to [departure airport]. ATC responded well and moved traffic out of our way. We proceeded to do a normal landing. There was little need for increased power on the engine during the return; but any time I did try to increase the power; the engine vibration increased; so I did what I could to minimize the need to increase engine power. Fortunately; we were at a distance from the airport where we didn't require a climb. The landing itself was a normal landing; and the fire trucks had already rolled and were there waiting for us. We taxied under our own power back to the GA ramp with fire truck escort.Upon securing the airplane on the ramp; we removed the engine cowling to inspect the engine when we observed oil dripping in a steady stream out the bottom of the engine. We discovered that the front left cylinder was fractured all the way around and separated from the bottom half of the cylinder.




Synopsis: DA-20 instructor pilot reported returning to the departure airport after the engine began to run rough and show a loss of oil pressure.