Date: 202107
Local time of day: 1201-1800
Location: ZBW.ARTCC, NH
Flight conditions: VMC
Light: Daylight
Aircraft: Lake Aircraft Undifferentiated or Other Model
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Personal
Flight phase: Cruise
Airspace: Class E ZZZ
Aircraft component: Electrical Distribution Busbar
Component problem: Failed
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Commercial; Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor
Human factors: Troubleshooting
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Diverted; Flight Crew Overcame Equipment Problem; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: On a flight intended for ZZZ to ZZZ1; I noticed a little way into the cruise portion of the flight that my hydraulic pressure was low. I confirmed that the hydraulic pump switch was in the ON position; and then cycled the switch to see if this would resolve the problem. When I did that; the radio stack lost power with the switch in the ON position and the pump did not activate. Moving the switch to the OFF position; the radio stack returned to life. I performed this action again with the same results: with the pump switch in the ON position; the radios died; but in the OFF position the radios returned to life. I imagined that the pump system had shorted out somehow and left the switch OFF and used the manual pump handle to restore pressure. At that point; I decided not to fly all the way to ZZZ1 but instead to ZZZ2; which was somewhat closer (although still an hour ahead) and where the propeller was scheduled to be inspected the next day; thinking to repair the pump at that same time.Flight continued normally after this for some time; until I noticed that the landing light switch was in the ON position; and I moved to turn that switch off. When I turned off the landing light switch; the radios again failed. Recycling the landing light; radio master; and master switches did nothing. The next day; the Mechanic discovered that the battery terminal connector was broken; not the hydraulic pump; and it was this that explained the electrical failures.The problem had actually started before the flight: the landing immediately prior to this flight had resulted in a significant nose wheel shimmy due to the castering nose wheel not being aligned with the longitudinal axis of the plane (This can happen in this plane when the nose wheel has been down in the water and it casters; during a water takeoff there is no runway to naturally realign it). The shimmy had probably caused a pre-existing crack in the terminal connector to nearly; but not completely; open the circuit. So the engine start; taxi; takeoff and climb were normal; but additional vibration and heat caused the crack to spread until finally it broke completely. So at first there were wonky partial failures and then a total failure later in the flight.




Synopsis: Lake aircraft pilot reported numerous electrical systems failures during flight and elected to divert.