Narrative:

This was a morning IFR flight to pick-up 2 passengers and return before weather declined. I delayed departure for a few minutes because of nearby lightning activity to the south. I took off at xa:50 local; from ZZZ airport; in VMC; under class B airspace; and contacted zzzzz departure control on frequency xxy.Y. Controller cleared me immediately through bravo (before I even reached the 1200-feet MSL base of bravo airspace) and assigned a squawk code. During initial climb (1;300 feet) I noticed slightly higher cylinder head temperature readings; but I attributed that to the relatively hot/humid weather conditions. I reached down to ensure the cowl flaps were fully open; which had been confirmed twice before via the checklist and I discovered that during the initial climb the manual lever had crept half-way to the closed position; instead of remaining to the set 'fully open.' I reopened; but I noticed the lever wouldn't stay in the dedicated detent.around 1;400 feet ATC came back with the clearance (as filed) and instructed direct ZZZ VOR after reaching 1;600 feet and 'climb to 6 thousand' which I believe I acknowledged. Airplane was put on autopilot (heading and flight crew modes). I reset the altitude preselect; hit direct navigation to ZZZ VOR as I was going through 1;600 feet and I proceeded to fold a piece of paper and use it to jam the lever in the open position. Around xb:01 I leveled-off; removed the paper 'jammer;' closed the cowl flaps; and confirmed cruise power (except for finalizing mixture leaning until TAS would be near 168 knots). The controller seemed not very busy and there was no nearby traffic on my garmin 1000 display; which I had set to normal scan and a 12 NM range. I was satisfied that the air was smooth and completed the cruise checklist; set a VNAV reminder; pending mixture fine tuning. About 2 minutes later controller asked me to confirm altitude. I replied that I was level at 7 thousand (my 'filed' altitude) and he mentioned that I was given 6 (which I believe I had also acknowledged) and proceeded to say that he needed to hand me off to ZZZ approach at 6 or 8 thousand and he offered me the choice. I apologized for the occurrence; I accepted 8 thousand and proceeded with the flight without any further incident. There were a few caveats that led to this event. Although I try to stay current my level of activity (as a contract pilot) has diminished to about 54% as compared to last year's similar quarter; thanks to covid-19; which has affected how 'sharp' one can be/stay. Departing under class B in VMC requires looking outside for traffic while establishing 2-way communication with ATC; this is routine out of ZZZ; but if combined with a distraction (cowl flaps) had made it very easy for me to 'inadvertently and unconsciously' scroll the altitude preselect button one more 'click' (to 7 thousand) while acknowledging 6 with ATC. Perhaps the early morning wake-up had taken its toll upon me; or maybe an anticipation of establishing cruise at the filed altitude of 7 thousand; numbed my brain to the point that even when the altitude buzzer went off while going through 6 thousand (for 7); no red flags were raised. I constantly read all kinds of available aviation reports; including those with scenarios that lead to altitude excursions; hoping that I would become a better pilot and more aware to avoid similar sets of circumstances; yet here I am having failed my own ongoing efforts.

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Original NASA ASRS Text

Title: Corporate pilot reported leveling off at the wrong altitude while being distracted with the cowl flaps.

Narrative: This was a morning IFR flight to pick-up 2 passengers and return before weather declined. I delayed departure for a few minutes because of nearby lightning activity to the South. I took off at XA:50 local; from ZZZ airport; in VMC; under Class B airspace; and contacted ZZZZZ Departure Control on frequency XXY.Y. Controller cleared me immediately through Bravo (before I even reached the 1200-feet MSL base of Bravo airspace) and assigned a squawk code. During initial climb (1;300 feet) I noticed slightly higher cylinder head temperature readings; but I attributed that to the relatively hot/humid weather conditions. I reached down to ensure the cowl flaps were fully open; which had been confirmed twice before via the checklist and I discovered that during the initial climb the manual lever had crept half-way to the closed position; instead of remaining to the set 'fully open.' I reopened; but I noticed the lever wouldn't stay in the dedicated detent.Around 1;400 feet ATC came back with the clearance (as filed) and instructed direct ZZZ VOR after reaching 1;600 feet and 'climb to 6 thousand' which I believe I acknowledged. Airplane was put on autopilot (HDG and FLC modes). I reset the altitude preselect; hit direct NAV to ZZZ VOR as I was going through 1;600 feet and I proceeded to fold a piece of paper and use it to jam the lever in the open position. Around XB:01 I leveled-off; removed the paper 'jammer;' closed the cowl flaps; and confirmed cruise power (except for finalizing mixture leaning until TAS would be near 168 knots). The Controller seemed not very busy and there was no nearby traffic on my Garmin 1000 display; which I had set to Normal scan and a 12 NM range. I was satisfied that the air was smooth and completed the cruise checklist; set a VNAV reminder; pending mixture fine tuning. About 2 minutes later Controller asked me to confirm altitude. I replied that I was level at 7 thousand (my 'filed' altitude) and he mentioned that I was given 6 (which I believe I had also acknowledged) and proceeded to say that he needed to hand me off to ZZZ approach at 6 or 8 thousand and he offered me the choice. I apologized for the occurrence; I accepted 8 thousand and proceeded with the flight without any further incident. There were a few caveats that led to this event. Although I try to stay current my level of activity (as a contract pilot) has diminished to about 54% as compared to last year's similar quarter; thanks to COVID-19; which has affected how 'sharp' one can be/stay. Departing under Class B in VMC requires looking outside for traffic while establishing 2-way communication with ATC; this is routine out of ZZZ; but if combined with a distraction (cowl flaps) had made it very easy for me to 'inadvertently and unconsciously' scroll the altitude preselect button one more 'click' (to 7 thousand) while acknowledging 6 with ATC. Perhaps the early morning wake-up had taken its toll upon me; or maybe an anticipation of establishing cruise at the filed altitude of 7 thousand; numbed my brain to the point that even when the altitude buzzer went off while going through 6 thousand (for 7); no red flags were raised. I constantly read all kinds of available aviation reports; including those with scenarios that lead to altitude excursions; hoping that I would become a better pilot and more aware to avoid similar sets of circumstances; yet here I am having failed my own ongoing efforts.

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.