C172 Flight instructor and student pilot reported experiencing loss of engine RPM's during takeoff resulting in the flight crew making an off field landing. Pilots reported no aircraft damage or injuries.
Synopsis
C172 Flight instructor and student pilot reported experiencing loss of engine RPM's during takeoff resulting in the flight crew making an off field landing. Pilots reported no aircraft damage or injuries.
Narrative
On Day 0; a CFI student and I conducted a local instructional flight to practice maneuvers in the designated practice area. During the initial engine run-up; no abnormal indications were observed; including no magneto or engine irregularities. The takeoff and subsequent flight to the practice area were uneventful; and the engine operated normally throughout multiple maneuvers.Following our first landing; all applicable checklists were completed as prescribed. We then initiated a soft-field takeoff. After accelerating to Vy and beginning to climb out of ground effect; the aircraft experienced a sudden and significant drop in engine RPM. Based on auditory cues; the RPM reduction is estimated to have been approximately 500-1;000 RPM. From liftoff through the onset of the power loss; the aircraft gained approximately 100 feet of altitude.At that time; the controls were transferred to me. I reduced the throttle slightly and then advanced it fully forward in an attempt to restore power; however; there was no audible change in engine RPM. I then immediately reduced power and lowered the nose to maintain airspeed; electing to land straight ahead. I chose to clear the fence at the departure end of the runway and land in the field beyond.The aircraft touched down in wet; muddy grass and came to a stop after a relatively firm landing consistent with the surface conditions. Back pressure was maintained throughout the rollout. As the aircraft slowed and came to a stop; I pulled the mixture to idle cut-off. The student and I then verified that the magnetos were off; the ignition key was removed; the master switch was off; and we exited the aircraft promptly.Based on the aircraft's touchdown location and the soft-field takeoff and landing considerations; I believe the aircraft was placed in the most advantageous area available given the circumstances. The aircraft did not appear to sustain damage; and both occupants were uninjured.
Second reporter narrative
The planned flight was practicing maneuvers and landings in the designated practice area east of our airport (ZZZ). I was in the right seat as a cfi student; and my instructor was in the left hand seat. We found the airplane to start normally; and our run-up and magneto check was all normal. After maneuvers were completed with no incident; we returned to ZZZ for practice with landings. The first landing on Runway XX was completed normally; and we completed our after-landing checklist upon clearing the runway.We decided to practice a soft field takeoff next; and noticed no apparent engine issues while taxiing. I performed the pre-takeoff checklist before entering the runway and I slowly advanced the throttle to full and observed no indication of engine roughness or degraded performance. As we climbed out of ground effect; within about 100 feet the engine suddenly and audibly started misfiring and running very poorly and we lost almost 1000 rpm. The instructor took controls and pulled the throttle back slightly and then back to full with no change in rpm or climb rate; and the engine roughness and loss of power remained. At this point; the decision was made to land straight ahead in a field past the end of the runway since we did not have climb performance. We touched down in a soft; muddy field at normal approach speeds. The landing roll was very short as the plane dug into the muddy ground and we came to a stop. We ensured mags were off and the key was removed and exited the airplane.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.