Narrative:

Upon departure the gear retracted normally; however; immediately after retraction I heard a large pop; followed by a call from tower indicating that my left main gear had retracted then fallen down again. Another aircraft behind me reported seeing the same. The aircraft has an stc gear mirror installed on the right wing which allowed me to view all three gear. The left main was in a trailing position. The nose and right main were retracted. I cycled the gear. The left main didn't move from its in-trail position. I advised tower that I would troubleshoot enroute and land gear up if necessary. I troubleshot the gear; tried yawing the aircraft and maneuvering such as to swing the gear with inertia into the locked position. I was able to see the gear directly by sticking my head out of the window; but normally observed the gear's actions the right wing mirror. Unable to retract or extend the gear; I made a phone call on my cell-phone via my bluetooth headset to another a&P (I'm also an a&P); to confirm my suspicion that it was most likely the gear actuator that had broken loose from the pivot point and that the safest course of action would be to land; with the other two gear retracted; at [an appropriate airport]; and under power such as to minimize the descent and forward speed. The low energy touchdown goal was driven by the possibility that the left main may be stuck (depending on how the actuator broke); and may result in a roll to the right on touchdown. Therefore; at the cost of engine and prop; but resulting in significant risk reduction; the decision was made to land at [an appropriate airport] (>10K foot runway) and under power with right main and nose retracted. I contacted tower by radio; advised of our situation; fuel on board; one soul on board; and our intention to land gear up. We did not declare a pan pan or mayday because the situation wasn't urgent in any form as we had five hours of fuel on board. We landed uneventfully on the centerline; with a soft controlled low energy touchdown. No fuel leaks; no hydraulic leaks; no oil leaks; no fire; and no injuries. However; while working to jack the airplane to remove it from the runway; I did manage to bang my head on the door of the aircraft. The damage to the airframe was pretty minimal; however; the propeller was obviously destroyed and therefore the engine will require teardown. I felt it appropriate to make a report to document the decision making on landing under power which I would highly suggest to any pilots rather than making the error of 'trying to save the engine and prop' and reducing options on landing. Because the sink was much further than I anticipated; I did need to add a little additional power just prior to touchdown. Should I have tried to 'save' the engine; it would have made for a solid impact with the runway increasing damage to the airframe and possibly resulting in injury. Leaving the engine running; I was able to make a gentle; low energy touchdown. The result on sensation in the cockpit was like a normal landing (louder; but normal forces); zero injuries; and a happy outcome. Again; I would highly recommend a low total energy touchdown under power situation for anyone finding they need to make a forced gear up landing. The aircraft; engine; propeller can all be replaced and it's not worth 'trying to save' a machine at the cost of possible injury. Thank you for providing the reporting services; as a pilot since 1986; I do find this open sharing of information valuable to pilot safety.

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Original NASA ASRS Text

Title: A C172R pilot reported his left main gear would not retract. He made a gear up landing with some damage to the propeller.

Narrative: Upon departure the gear retracted normally; however; immediately after retraction I heard a large POP; followed by a call from Tower indicating that my left main gear had retracted then fallen down again. Another aircraft behind me reported seeing the same. The aircraft has an STC gear mirror installed on the right wing which allowed me to view all three gear. The left main was in a trailing position. The nose and right main were retracted. I cycled the gear. The left main didn't move from its in-trail position. I advised Tower that I would troubleshoot enroute and land gear up if necessary. I troubleshot the gear; tried yawing the aircraft and maneuvering such as to swing the gear with inertia into the locked position. I was able to see the gear directly by sticking my head out of the window; but normally observed the gear's actions the right wing mirror. Unable to retract or extend the gear; I made a phone call on my cell-phone via my Bluetooth headset to another A&P (I'm also an A&P); to confirm my suspicion that it was most likely the gear actuator that had broken loose from the pivot point and that the safest course of action would be to land; with the other two gear retracted; at [an appropriate airport]; and under power such as to minimize the descent and forward speed. The low energy touchdown goal was driven by the possibility that the left main may be stuck (depending on how the actuator broke); and may result in a roll to the right on touchdown. Therefore; at the cost of engine and prop; but resulting in significant risk reduction; the decision was made to land at [an appropriate airport] (>10K foot runway) and under power with right main and nose retracted. I contacted Tower by radio; advised of our situation; fuel on board; one soul on board; and our intention to land gear up. We did not declare a Pan Pan or Mayday because the situation wasn't urgent in any form as we had five hours of fuel on board. We landed uneventfully on the centerline; with a soft controlled low energy touchdown. No fuel leaks; no hydraulic leaks; no oil leaks; no fire; and no injuries. However; while working to jack the airplane to remove it from the runway; I did manage to bang my head on the door of the aircraft. The damage to the airframe was pretty minimal; however; the propeller was obviously destroyed and therefore the engine will require teardown. I felt it appropriate to make a report to document the decision making on landing under power which I would highly suggest to any pilots rather than making the error of 'trying to save the engine and prop' and reducing options on landing. Because the sink was much further than I anticipated; I did need to add a little additional power just prior to touchdown. Should I have tried to 'save' the engine; it would have made for a solid impact with the runway increasing damage to the airframe and possibly resulting in injury. Leaving the engine running; I was able to make a gentle; low energy touchdown. The result on sensation in the cockpit was like a normal landing (louder; but normal forces); zero injuries; and a happy outcome. Again; I would highly recommend a low total energy touchdown under power situation for anyone finding they need to make a forced gear up landing. The aircraft; engine; propeller can all be replaced and it's not worth 'trying to save' a machine at the cost of possible injury. Thank you for providing the reporting services; as a pilot since 1986; I do find this open sharing of information valuable to pilot safety.

Data retrieved from NASA's ASRS site as of April 2012 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.