Date: 201707
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Skyhawk 172/Cutlass 172
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Training
Flight phase: Takeoff / Launch
Airspace: Class G ZZZ
ATC / advisory: CTAF ZZZ
Aircraft component: Cylinder
Component problem: Failed
Reporter organization: Personal
Reporter function: Pilot Not Flying; Instructor
Reporter qualification: Flight Crew Flight Instructor; Flight Crew Commercial
Anomaly: Aircraft Equipment Problem Critical; Ground Excursion Runway
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew Returned To Departure Airport; Flight Crew Regained Aircraft Control; Flight Crew Diverted; Flight Crew Landed in Emergency Condition; Flight Crew Overcame Equipment Problem
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Landed in a field on airport property as a result of Power loss due to a cracked cylinder #4.I was on a training flight with a Student Pilot getting check ride ready; which was to take part two days later. Before takeoff I did my usual check with the student; oil was at 6qts and fuel was topped off (53 Gal) as a safety precaution. The flight was a typical training flight; took off from [home airport]; did some ground reference maneuvers in the area; followed by landings in ZZZ airport; an uncontrolled field. After two landings in the pattern; I told the student to prepare for a short field takeoff and since he was getting ready for check ride everything was by the book; from checklists to airspeed and Oil temperature and pressure call outs. On this one; I said; 'ENGINE FAILED'; student took appropriate action and stopped the aircraft; pulled throttle and said in real life he would pull the mixture and the appropriate checklist. I was satisfied and we further discussed eventualities if the engine did fail on takeoff roll; below 1000 feet and after that. After this simulated abort takeoff; [we decided to return to home airport]. On this final departure; again everything by the book; proper non-towered radio calls; checklists and use of runway space. On takeoff roll; on the Vx climb; I was satisfied and continued with a clear of obstacle call; the student then pitched for Vy. About 3 seconds after; I heard a BANG! I immediately looked at the tires to see if they popped; the oil pressure and temperature; they were green. Simultaneously the aircraft began to shake and vibrate violently. I looked at the VSI and saw the climb go from +800 FPM down to barely +50 FPM. My student looked at me and said; 'I've lost the engine...'; I took over controls and added full power; Idle; then power again. Nothing changed and clearly there was a problem. At this point; I'm still maintaining heading; airspeed began to decrease and I said; 'confirm engine loss....'; student said; 'confirm!'. I had no choice; I had to put it down. Told the student; 'seatbelt on tight; door open now; I have this'. Immediately; I knew from experience that I could not land this plane straight given the speed and rate of drop and ground roll. I banked about 15-20 Degrees left and slipped the plane down to the corner of a field and put the plane diagonally off the runway numbers; an approximate 305 heading.On touchdown; I had flaps full and hit the ground right as the stall horn went off; touchdown was rough but I held the back pressure in and did a basic soft field landing. Since I had never done a real grass landing before I did not apply brakes and knew the plane will stop eventually. When the plane came to a full stop; I told the student; 'after landing checklist now!' He ran it pulled full emergency cutoff; fuel selected off and ran the checklist. I had my left hand on the fire extinguisher and my right hand had the checklist in hand ready for a fire; explosion; oil spewing; whatever come may. To our luck; nothing came after; so when we got out; I said 'fuel check'; we had 42Gal total and Oil was still around 6quarts. Post incident:On my inspection; no oil leaked; no sign of outside damage. I called the owner/flight school and did a post check of the exterior; no damage to the propeller; wheel pants; tires; or fuselage. Luckily we found a crack in cylinder #4 next to the spark plug which caused the Partial Power Loss and vibration issue with the aircraft. 65 feet remained between the aircraft and a fence; luckily an airport tenant saw and heard the incident so he immediately sprang in to help and get a tow to get our plane out. Since my student and I were in the check ride prep mode; I believe that this led to the great outcome of our flight. The issue could not be prevented since it was a maintenance problem; so my job as an instructor was done and had I made any calls differently; surely the result would have been bad. My student remained calm and collected and I think I acted appropriately given the situation I had. I know this is not standard; but I do train my SEL students for private at a higher standard and although not a required procedure except for MEL; I train my students to react if an engine loss occurs 800 feet to return to the field in the opposite direction. My student said that me practicing this with him helped in alleviating the fear if the plane lost power and said attributed to the issue.




Synopsis: A Cessna 172 instructor pilot reported the engine failed right after takeoff.