Narrative:

I took a passenger on a pleasure flight up to the closest airport with fuel that day (ZZZ) to top off the tanks with AVGAS before we hangared the plane for the day. Upon landing at ZZZ; FBO staff told us the pump was out of order. My passenger had a doctor's appointment within the hour; so we immediately taxied back out to the runway and skipped the magneto check on run-up; based on the fact that I had been flying the aircraft for nearly 2 hours and made 4 takeoffs/landings with no engine problems at all. Upon starting the takeoff roll; the performance seemed sluggish; but the runway sloped uphill slightly and having no experience on sloping runways; I assumed that was the cause. Immediately upon rotation; it was apparent we weren't getting full power. The plane would only produce 2;100 RPM and 80 mph at full throttle in level flight and was slightly shaking so I declared an emergency over the local traffic frequency and did an immediate 180 degree turn back to the runway. Our altitude was low and even with full power applied we could not climb and barely managed to make it back to the runway. Upon landing; maintenance staff at the airport looked at the engine and determined the magnetos were failing to produce their full power. This problem could have been entirely avoided had I elected to do a proper magneto check on run-up. I also believe 'get homeitis' was a factor; since my passenger needed to make it back to our original departure point for a doctor's appointment. I assumed there would be no problems since I had flown the aircraft nearly 2 hours that day with several takeoffs/landings with absolutely no engine problems at all. In the future; I will never take off in an aircraft without doing a full and proper run-up and magneto check; no matter the circumstances.

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Original NASA ASRS Text

Title: A C172 pilot experienced loss of power shortly after takeoff when he failed to check the magnetos during the runup.

Narrative: I took a passenger on a pleasure flight up to the closest airport with fuel that day (ZZZ) to top off the tanks with AVGAS before we hangared the plane for the day. Upon landing at ZZZ; FBO staff told us the pump was out of order. My passenger had a doctor's appointment within the hour; so we immediately taxied back out to the runway and skipped the magneto check on run-up; based on the fact that I had been flying the aircraft for nearly 2 hours and made 4 takeoffs/landings with no engine problems at all. Upon starting the takeoff roll; the performance seemed sluggish; but the runway sloped uphill slightly and having no experience on sloping runways; I assumed that was the cause. Immediately upon rotation; it was apparent we weren't getting full power. The plane would only produce 2;100 RPM and 80 MPH at full throttle in level flight and was slightly shaking so I declared an emergency over the local traffic frequency and did an immediate 180 degree turn back to the runway. Our altitude was low and even with full power applied we could not climb and barely managed to make it back to the runway. Upon landing; maintenance staff at the airport looked at the engine and determined the magnetos were failing to produce their full power. This problem could have been entirely avoided had I elected to do a proper magneto check on run-up. I also believe 'get homeitis' was a factor; since my passenger needed to make it back to our original departure point for a doctor's appointment. I assumed there would be no problems since I had flown the aircraft nearly 2 hours that day with several takeoffs/landings with absolutely no engine problems at all. In the future; I will never take off in an aircraft without doing a full and proper run-up and magneto check; no matter the circumstances.

Data retrieved from NASA's ASRS site as of May 2009 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.