Skyhawk 172/Cutlass 172
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Flight Instructor
Flight Crew Last 90 Days 76; Flight Crew Total 7900; Flight Crew Type 2400
Situational Awareness; Troubleshooting; Communication Breakdown; Distraction
Aircraft Equipment Problem Less Severe; Airspace Violation All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR
Flight Crew Exited Penetrated Airspace; Flight Crew Overcame Equipment Problem; General Maintenance Action
Aircraft; Human Factors
On Date at ZZZ airport; I fueled the airplane; conducted a preflight (includes checking oil quantity and taking a sample of all three fuel sumps); reviewed my direct course back home and updated my weather (VMC) for the short flight to ZZZ1. During the pre-takeoff checklist (engine run up); I notice a slight roughness in the engine. I leaned out the mixture control which cleared out the roughness. I set the mixture control for my takeoff; but not to full rich. I left it leaned out a little for the departure and climb. During my climbout; I always look for off airport landing spots (should I need one). I did not see any good locations and I told myself that I want 4;500 feet once clear of the Class B airspace altitudes. It was shortly after my desire to get to 4;500 feet MSL ASAP that the engine was not performing as it should in cruise climb. I applied full power and checked the engine instruments (all green; but RPM was towards the low end). I was getting a shallow climb at an airspeed of about 90. I then immediately performed the initial emergency procedure; carb heat on; mixture full (then adjust if needed) and check fuel selector on both. That seemed to bring the performance back; but not immediately. Shortly after that the engine then started to run rough. My thought was spark plug fouling or magneto (I know it was not a cylinder failure; because I have experienced that in a twin engine airplane). I adjusted the mixture control first. This is logical; because if you check the mags before the mixture control you could increase spark plug fowling. At some point through all this my mind went into altitude; altitude; altitude. Unfortunately; I had that 4;500 feet MSL in my mind. While dealing with the engine situation; I continued my climb to that altitude. I got the rough running engine cleared out.  Once I was done keeping the airplane in the air (dealing with low performance and then the rough running engine during the cruise climb phase); I checked my position and noticed that I was in ZZZ3 Class B airspace (west end of and close to the 6;000 feet MSL corridor; but I was in the 4;000 feet MSL corridor). I immediately descended below 4;000 feet MSL (3;800 feet MSL). Once clear of the Class B airspace/Mode C veil; I climbed back to 4;500 feet MSL. No airplane conflicts were noted. Once on the ground at the ZZZ1; I performed an engine runup and checked the mags full and leaned mixture settings. Both checked out okay. My plan is to check the oil; fuel and talk with a mechanic. I am confident that the fuel is okay since I checked it after fueling at the ZZZ (but I will check it again). I have cancelled my planned flying for the next week and no flying the Skyhawk until the items are checked out. Once I got home; I chair flew the scenario that I just experienced and realized that all my training and personal home chair flying has been geared to multi-engine; on an IFR flight plan and in radio communications. My scenario was single engine; VFR and not in communication. Do not get me wrong; I always review the emergency procedures before a flight for the airplane that I am flying. Also; the poor engine performance that I experienced did not seem to be carb icing. Since the air filter and bracket were replaced at the annual inspection; the carb air intake system will be looked at. What I learned and what I will do going forward so that this does not happen again:I learned that in my continued personal chair flying training that I need to go over single engine emergency; VFR and not in communications scenarios. This situation reinforced with me that single engine performance (VFR; non-communications) incidents come with a high workload especially when dealing with keeping the airplane in the air. It showed me that I became focused on keeping the plane in the air (altitude and rectifying the engine situation) and that navigating and communicating was lacking with this incident.   Going forward; in addition to reading theemergency procedures that I currently do for every plane that I fly and chair flying multi-engine scenarios; I will chair fly single engine (SE) scenarios. I need to emphasize aviate; navigate; and communicate in any SE situation. When flying under Class B airspace and within a Mode C veil do the following:1.	Obtain flight following when flying VFR; especially when flying in a Mode C veil. I would already be in communications should I need to report a problem.  2.	Mark along the course line a line with an arrow from the departure airport to the point when the plane will be cleared of the Mode C veil. Also; put a B next to this manually drawn line.3.	Apply a post-it-note on the instrument panel that I am in a Mode C veil airspace.I will talk to my Flight Instructor and review this flight to obtain feedback and discuss my ideas and additional ways to prevent this from happening again.
C172 pilot reported an airspace incursion occurred when the engine began running rough and the pilot was troubleshooting. The roughness eventually dissipated and pilot exited the airspace.