A Line Mechanic reports the #1 engine of a four piston engine commercial fixed wing aircraft was shut-down in-flight due to being uncontrollable after a bolt had fallen out an idle control pushrod to the carburetor. The aircraft had just come out of a C-Check and post C-Check engine runs.

Narrative

Shortly after the aircraft left it had to shut down #1 engine in-flight due to being uncontrollable. Upon arrival at destination; it was found that a bolt had come out of the idle control pushrod. I had worked on the #1 engine at various times three days earlier from late afternoon [Day X] until the early morning hours the following day [Day Y]. Earlier in the day; on Day X; a post-check run had determined that the idle RPM of #1 engine was too high. There were several adjustments made to the Idle RPM throughout the night and several engine runs to determine if the problem had been corrected. I believe that factors contributing to the shutdown of #1 engine during flight can be attributed to many things. These factors include but are not limited to: Fatigue: it was my fifth night after already working over 40-hours the first four days of my week.Weather: the temperature was around -10F throughout the night; this also has an effect on the fatigue factor. Lighting: we have to work with headlamps at night; it is not the ideal lighting situation. Time crunch: the plane was fresh out of a heavy check and we put a lot of pressure on ourselves to get as much done as possible so the plane can fly and make money. Inexperience: I was receiving training on the engine; as I only have a few weeks experience working on these engines.