Narrative:

Departed jyo on an IFR flight plan. Pre-flight and run up was normal. After departure in the initial climb while on autopilot the carbon monoxide alarm on the G1000 activated at around 1;000 ft. Continued to follow vectors and climbed to assigned altitude of 5;000 while my safety pilot in the right seat troubleshot.despite following procedures to disable the climate control and vent fresh air the co alarm continued to fluctuate between 250 and 500 ppm. By this point we had leveled off at 5;000 and I started to notice fluctuations in oil pressure with the oil pressure indicator quickly dipping to the bottom of the white arc and coming back to the green; however oil temp remained stable in the green and all other engine indicators; sound and feel were normal.I decided to alert potomac to our primary issue with the co warning and stated that we needed to return. The controller vectored us back to jyo. After getting down near pattern altitude and identifying jyo we were handed off to local frequency. I was entering the pattern in a non-standard way for jyo since I was coming from the special flight rules area and basically meandered into a base leg on a 45 degree angle. I radio called it and then fairly quickly was able to turn final and radio called that. A single engine pilot had previously called downwind for 17 and I knew I was in front of him; however as I was now on final the other aircraft suddenly called turning base and we were now on a collision course. I could not see the other aircraft at this point but my right seat pilot did and called out to make an immediate right turn; which I did; entering a 360 loop while the other aircraft landed. We then landed after without further incident and canceled IFR on the ground.post landing we discovered the other pilot was a student on a solo who had been flustered on a previous landing and had gone around; he was anxious to get on the ground and cut his downwind to base turn tight; not realizing our position nor that our aircraft was faster. In hindsight I failed to let those on the local frequency know that we were having a mechanical issue in my radio calls about our position. Most likely due to all the other factors: dropping into the pattern from a high altitude and high speed to expedite a landing; the warning chime for the co detector on the G1000 would keep reactivating despite silencing it; and the oil pressure anomaly coupled with the co warning had us hyper focused on landing the plane quickly.

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Original NASA ASRS Text

Title: A pilot departed JYO IFR; but during climb his G1000 CO detector alerted at the same time he noticed an oil pressure fluctuation. The pilot returned to JYO; but had a conflict with a solo student pilot because he failed to notify the traffic pattern of his mechanical issue.

Narrative: Departed JYO on an IFR flight plan. Pre-flight and run up was normal. After departure in the initial climb while on autopilot the carbon monoxide alarm on the G1000 activated at around 1;000 FT. Continued to follow vectors and climbed to assigned altitude of 5;000 while my safety pilot in the right seat troubleshot.Despite following procedures to disable the climate control and vent fresh air the CO alarm continued to fluctuate between 250 and 500 ppm. By this point we had leveled off at 5;000 and I started to notice fluctuations in oil pressure with the oil pressure indicator quickly dipping to the bottom of the white arc and coming back to the green; however oil temp remained stable in the green and all other engine indicators; sound and feel were normal.I decided to alert Potomac to our primary issue with the CO warning and stated that we needed to return. The controller vectored us back to JYO. After getting down near pattern altitude and identifying JYO we were handed off to local frequency. I was entering the pattern in a non-standard way for JYO since I was coming from the Special Flight Rules Area and basically meandered into a base leg on a 45 degree angle. I radio called it and then fairly quickly was able to turn final and radio called that. A single engine pilot had previously called downwind for 17 and I knew I was in front of him; however as I was now on final the other aircraft suddenly called turning base and we were now on a collision course. I could not see the other aircraft at this point but my right seat pilot did and called out to make an immediate right turn; which I did; entering a 360 loop while the other aircraft landed. We then landed after without further incident and canceled IFR on the ground.Post landing we discovered the other pilot was a student on a solo who had been flustered on a previous landing and had gone around; he was anxious to get on the ground and cut his downwind to base turn tight; not realizing our position nor that our aircraft was faster. In hindsight I failed to let those on the local frequency know that we were having a mechanical issue in my radio calls about our position. Most likely due to all the other factors: dropping into the pattern from a high altitude and high speed to expedite a landing; the warning chime for the CO detector on the G1000 would keep reactivating despite silencing it; and the oil pressure anomaly coupled with the CO warning had us hyper focused on landing the plane quickly.

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.