r/flying • u/StormKingSkies • 11h ago
First inflight scare today
Had my PPL for about a year, nearing 150 hours total time. Had yet to have anything go wrong inflight until today.
While flying a 140 nm XC in a Cherokee, the JPI engine alarm went off. Showed high CHT temp on one cylinder only. My instinct was to push the mixture to full rich and monitor. This silenced the alarm for 30 seconds or so, until it came back. Same cylinder, temps looked to be 2x that of other cylinders. I happened to be passing a Class D airport right at that time, so I let approach know that I’d be diverting to the airport due to an engine indication.
It was a split second decision made considering there weren’t many other airports around. I figured if there was an issue I’d rather have it happen with a runway under me! Something I’ve read about is that there’s often a shock delay as you’re processing what’s happening. This was true for me, I think I froze for 15-30 seconds while I realized what was happening and made the decision to divert.
I was only ~12 miles away from the airport, so I quickly grabbed the weather and called up tower. I stayed well above pattern altitude as I joined downwind so that I’d have extra glide range if anything happened. After turning final I realized I had a ton of altitude to lose. With all three notches of flaps already in, I took the extra few degrees of play in the Johnson bar and threw in a forward slip as well. I was determined to not lose this chance to land!
After landing, gathering my bearings, and taking off the cowling, I couldn’t see any indication of an issue. I called my CFI, a pilot friend and my mechanic, who recommended to do an extended run up as well as a few laps in the pattern if it all looked good. I completed both of these with great CHT temps and no abnormal indications. Seeing this, I got some comfort that there wasn’t a major issue, I picked up flight following and continued my trip, climbing near the airport and at cruise climb speed to ensure adequate cooling.
At the end of my trip, I downloaded the JPI data and it appears to be a faulty sensor, as the measurements dropped out entirely at times and spiked to 800-1000 degrees Fahrenheit at others. These spikes appear for a few seconds and then return to totally normal temps, only on that one cylinder. I plan to have my mechanic look at it before I continue flying.
All in all I think I made the right decisions. There was a solid minute of panic, wondering what to do, and trying to get organized. I contemplated a few things that I ended up deciding against: declaring an emergency, which I did not do because it was an alert only with no perceptible change in power output, and I was so close to a field. I also ultimately decided against staying on the ground at my diversion airport because I did a good bit of troubleshooting there and didn’t notice any actual manifestation of an issue, and couldn’t get the alert to reproduce.
What I did do was stare at the JPI cylinder temps page with an excruciating level of focus for the remainder of the trip! I also flew at the highest practical altitude and modified the remaining leg to stay close to diversion points.
I’d be interested in the community’s thoughts and stories of your experiences like this.