Date: 201208
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Weather elements / visibility: Thunderstorm; 10
Light: Daylight
Aircraft: Baron 55/Cochise
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Climb
Airspace: Class E ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Autopilot
Component problem: Improperly Operated
Reporter organization: Personal
Reporter function: Single Pilot; Pilot Flying
Reporter qualification: Flight Crew Flight Instructor; Flight Crew Flight Engineer; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Distraction; Human-Machine Interface; Situational Awareness; Workload
Anomaly: Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Contributing factors: Human Factors; Procedure; Weather; Aircraft
Primary problem: Procedure

Narrative: I was on an IFR clearance and was given runway heading to 3;000 FT. Upon checking in with Approach I was given a heading of 020 degrees and a further climb to 5;000 FT. After reading back my clearance I advised Approach what heading I needed to avoid thunderstorms. Shortly after; while approaching 5;000 FT; I was cleared to my final filed altitude of 6;000 FT and cleared on course. I entered 6;000 FT in my reminder and looked at the iPad that I was carrying in the aircraft. This aircraft is owned by another person and they had onboard WiFi and no radar. The autopilot was on; but there was no altitude pre-select requiring me to select altitude hold. The airplane was climbing and starting the turn as I looked down at the iPad to determine if the on course heading that I had chosen would keep me clear of the thunderstorm cells in the area. As my scan crossed the altimeter I noticed that I had blown through 6;000 FT and had almost reached 6;500 FT. I immediately disconnected the autopilot and continued the turn to my on course heading while smoothly lowering my nose and descending to 6;000 FT. After quickly reaching 6;000 FT I received no call from Approach. This was [the] first day that I had flown this airplane; and the third of four legs on this day. I have a Baron of my own; but they are very different; different panel; different autopilot; different scan. My aircraft has an altitude alerter. My unfamiliarity with the airplane and its controls was a contributing factor. Another contributing factor was multiple altitude and heading changes in a short period while trying to maintain good situation awareness with regard to weather avoidance. A further contributing factor was operating as a single pilot. I'm a major airline pilot by profession and I'm used to having a second pilot to double check me. Having to aviate; navigate and communicate in an unfamiliar aircraft while avoiding weather helped lead to a brief altitude deviation. Fortunately; I was not in congested airspace and there was no conflict.




Synopsis: B55 pilot attributed an altitude overshoot to lack of familiartity with the aircraft's autopilot; a succession of altitude and heading instructions from ATC; and weather avoidance.