Unwise takeoff decision
Posted: Thu Aug 09, 2018 9:24 amFirst of all, nothing bad happened, but I took of with my engine in a less than optimal state, and it continued to worsen as I flew.
I've been troubleshooting my autopilot servo that keeps disengaging almost instantly every time I try to use it. Thinking that electrical noise from the regulator might be the issue, I decided to unplug the voltage regulator, and just run off fully charged battery power for a short flight.
After starting the engine, I notice that my RPM was incorrect because I normally get it from the alternator, and must have my mag RPM set up incorrectly. During the preflight run-up it seemed like things we're quite right, as one of my CHTs was around 20 degrees higher than normal, and the engine just seemed different. I did the mag checks and one side seemed to have more of an RPM drop than usual judging by sound, but I didn't notice any EGT going cold.
On takeoff the plane climbed ok, but the CHT on one cylinder didn't come down as quickly as I expected it would, and the engine just didn't seem to have the punch that it normally does. I continued to adjust the RPM by sound.
My autopilot still disengaged almost instantly, so I dissapointedly returned to the pattern.
The engine continued to run more sluggish, and at one point it seemed to miss. Upon landing I did a mag check, and this time the engine ran really rough on one of the mags. Once parked, I took off the cowling to discover that one of the spark plug wires hanging loose from the distributor cap, and another only barely holding on. I must have bumped these when unplugging the regulator. I found that even when I plugged them back in, they didn't want to stay. Per the Jabiru manual, I expanded the contact, and they held much better. I'll do this on the rest of the contacts next time because I got tired of burning my arm on the engine.
So anyway, the error chain that we hear about in magazines was certainly on display yesterday. Like I said, nothing bad happened, but I was sure frustrated with myself. In my defense, the engine ran way better during the preflight mag check than after, but I should have aborted and checked things out. I don't think the spark plug became disconnected until I was in the air.
I'll be keeping a better eye on the spark plug wires in the future.
I've been troubleshooting my autopilot servo that keeps disengaging almost instantly every time I try to use it. Thinking that electrical noise from the regulator might be the issue, I decided to unplug the voltage regulator, and just run off fully charged battery power for a short flight.
After starting the engine, I notice that my RPM was incorrect because I normally get it from the alternator, and must have my mag RPM set up incorrectly. During the preflight run-up it seemed like things we're quite right, as one of my CHTs was around 20 degrees higher than normal, and the engine just seemed different. I did the mag checks and one side seemed to have more of an RPM drop than usual judging by sound, but I didn't notice any EGT going cold.
On takeoff the plane climbed ok, but the CHT on one cylinder didn't come down as quickly as I expected it would, and the engine just didn't seem to have the punch that it normally does. I continued to adjust the RPM by sound.
My autopilot still disengaged almost instantly, so I dissapointedly returned to the pattern.
The engine continued to run more sluggish, and at one point it seemed to miss. Upon landing I did a mag check, and this time the engine ran really rough on one of the mags. Once parked, I took off the cowling to discover that one of the spark plug wires hanging loose from the distributor cap, and another only barely holding on. I must have bumped these when unplugging the regulator. I found that even when I plugged them back in, they didn't want to stay. Per the Jabiru manual, I expanded the contact, and they held much better. I'll do this on the rest of the contacts next time because I got tired of burning my arm on the engine.
So anyway, the error chain that we hear about in magazines was certainly on display yesterday. Like I said, nothing bad happened, but I was sure frustrated with myself. In my defense, the engine ran way better during the preflight mag check than after, but I should have aborted and checked things out. I don't think the spark plug became disconnected until I was in the air.
I'll be keeping a better eye on the spark plug wires in the future.