Date: 201904
Local time of day: 1201-1800
Location: ROA.Airport, VA
Flight conditions: IMC
Weather elements / visibility: Turbulence; Rain; 1
Light: Daylight
Aircraft: Baron 58/58TC
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Descent
Airspace: Class E ROA
ATC / advisory: TRACON ROA
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Commercial; Flight Crew Multiengine; Flight Crew Instrument
Human factors: Distraction; Situational Awareness
Anomaly: Deviation - Altitude Overshoot; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Deviation / Discrepancy - Procedural FAR; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance; Flight Crew Became Reoriented
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: I was bringing a Baron BE-58 from ZZZ to Roanoke after maintenance. The conditions were IMC with light turbulence. I was in cruise at 6;000 feet and was requested by ATC to descend to 5;400 feet. During the descent; and shortly before reaching the assigned altitude of 5;400 feet; I reached over to add the Tower frequency into the standby radio position; during this process; the aircraft descended through the assigned altitude of 5;400 feet; banked right; and turned 30 degrees to the right and began a descent which reached approximately 1;300 feet per minute. Control was regained at 4;300 feet; well below the assigned altitude of 5;400 feet. During the descent; I was alerted by ATC that a low altitude alert had gone off and I was instructed to climb back up to 5;400 feet. I was already aware of that and had begun to regain control and slow the aircraft by pulling power back and beginning a climb after the aircraft slowed. The speed had gone from 205 knots to 252 knots during the descent. I climbed back up to 5;400 feet and continued in cruise and completed an instrument approach to LDA 6 at Roanoke without incident. While descending; I had inadvertently disconnected the autopilot while entering the radio frequency; which caused the loss of control and altitude. I believe the following may have been contributing factors to this occurrence: Switching aircraft in ZZZ; I'd flown another aircraft there prior to picking up the Baron. Leaving ZZZ; I discovered an oil door open on the right engine cover after I began taxiing out and had to shut down the aircraft during taxi to close the oil door; and then taxi back to the runway again. During call up for taxi and taxiing out; I repeatedly misstated the number on the aircraft (I used the number of the aircraft I'd flown into ZZZ). The Controller even confusingly used the number of the aircraft after I had used it several times. Of course; adjusting a radio frequency while in a descent in IMC conditions caused distraction. During the descent and radio frequency adjustment; I had inadvertently turned off the autopilot. The combination of distraction from changing the radio frequency and inadvertently switching off the autopilot created a situation in which a significant loss of altitude occurred. Contributing factors were surely the open oil door on the right engine and the confusion over using the call sign of the prior aircraft flown.




Synopsis: BE58 pilot reported becoming disoriented during descent in IMC when experiencing light turbulence.