Narrative:

This is a correction. Departed from ZZZ on the departure and was vectored for altitude climb for vxx [airway]. The departure was normal and the aircraft was stable in the climb. While passing 7;000ft MSL I notice a rise in the cht in cylinder 1;4;& 6. Temperatures where stable prior of takeoff and in the beginning climb at 356F. At 7;000 ft. MSL temperature jumped to 386F than 2mins later to 400F with several quick spikes in the egt sensors for cylinder 6 and followed later by 1 & 4. Prior to reaching 11;000 ft. MSL the temps with the cht began to climb faster to 420F. Reaching 11;000 ft. MSL I began to; trying to make small adjustments to throttle and mixture to cool the 3 cylinders down. The adjustments were not making a difference and the engine began to sputter and quit. I panic for a millisecond realizing the problem was worsening and noted the mountains; west of the ZZZ1; I was about to travel over. With a quick decision I informed approach as I felt still in control of aircraft and still had somewhat of power available. I began a quick left turn to an airport on my left about; maybe; 30 miles and tried a steep descent to see if I could cool the engine down and get power back. ZZZ2 was chosen with the help of approach and prior to the threshold of the runway power came back and engine was cooled down to 345F. Quickly did a landing checklist and through flaps in and landed safely on a 13;000 ft. Runway. Was met with arff and military police. Informed the operator/owner of the problem and concluded that the magnetos right side went bad possibly in the climb after taking a video after the landing to show him what I was seeing. Mechanics came out on date to find more problems on the engine that may of been a caused to the performance decrease with the help of the right side magnetos. Aircraft is currently grounded and is in the process of being repaired.

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Original NASA ASRS Text

Title: Pilot reported problems with the engine overheating and having to make an expedited landing.

Narrative: This is a correction. Departed from ZZZ on the departure and was vectored for altitude climb for VXX [airway]. The departure was normal and the aircraft was stable in the climb. While passing 7;000ft MSL I notice a rise in the CHT in cylinder 1;4;& 6. Temperatures where stable prior of takeoff and in the beginning climb at 356F. At 7;000 ft. MSL temperature jumped to 386F than 2mins later to 400F with several quick spikes in the EGT sensors for cylinder 6 and followed later by 1 & 4. Prior to reaching 11;000 ft. MSL the temps with the CHT began to climb faster to 420F. Reaching 11;000 ft. MSL I began to; trying to make small adjustments to throttle and mixture to cool the 3 cylinders down. The adjustments were not making a difference and the engine began to sputter and quit. I panic for a millisecond realizing the problem was worsening and noted the mountains; west of the ZZZ1; I was about to travel over. With a quick decision I informed Approach as I felt still in control of aircraft and still had somewhat of power available. I began a quick left turn to an airport on my left about; maybe; 30 miles and tried a steep descent to see if I could cool the engine down and get power back. ZZZ2 was chosen with the help of Approach and prior to the threshold of the runway power came back and engine was cooled down to 345F. Quickly did a landing checklist and through flaps in and landed safely on a 13;000 ft. runway. Was met with ARFF and Military Police. Informed the operator/owner of the problem and concluded that the magnetos R side went bad possibly in the climb after taking a video after the landing to show him what I was seeing. Mechanics came out on date to find more problems on the engine that may of been a caused to the performance decrease with the help of the R side magnetos. Aircraft is currently grounded and is in the process of being repaired.

Data retrieved from NASA's ASRS site 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.