PC-12
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 80; Flight Crew Total 4800; Flight Crew Type 30
Communication Breakdown; Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Landing Without Clearance; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway; Inflight Event / Encounter Weather / Turbulence
Flight Crew Took Evasive Action; Flight Crew Landed in Emergency Condition; General Maintenance Action
Aircraft; Weather
Aircraft was positioned on the arrival and descended to 4;000 feet in IMC conditions and heavy rain. Aircraft was given a vector to turn. Aircraft was in heavy rain and light turbulence at the time. A brief period of greater severity turbulence was experienced at which a total electrical failure was encountered. The aircraft went totally dark with not a single screen or annunciator illuminated. After briefly checking circuit breakers and attempting to reset power switches I switched my scan to the standby gyro and altimeter. The aircraft radios and transponder were no longer working so [advising ATC] with conventional methods was no longer possible. I was able to get my passenger to use his cell phone to call a fellow company pilot and let them know to contact Approach on our behalf. We made what I thought was a westerly turn and my aim was to head over the ocean and then descend. The aircraft was extremely difficult to control in the turbulence solely on the standby gyro and large altitude deviations were encountered. During these altitude deviation we made ground contact and noted a freeway. Not knowing which freeway we were over we decided to descend over it while orbiting to obtain situational awareness. We encountered even stronger turbulence at this point however were able to make out the runways and elected to make an immediate landing on the first available runway. The visibility at this stage was very low and we feared that visibility would be completely lost shortly. We turned for [one of two parallel runways] however were able to make out a landing aircraft approaching from the other direction and switched to [the other parallel]. We pulled off at the last taxi exit; made a right; shut the plane down and waited for airport operations to arrive.
The reporter added that he was informed that the guarded Master Power switch; located on the upper right hand corner of the overhead panel; failed internally. Turbulence caused the switch contacts to open without any notification; dropping all power from the aircraft. He also noted that following a firm landing; the switch contacts were reactivated; and power was restored without any action on his part. This switch is intended to be used in the event of an impending ditching or gear up landing.
The pilot of a PC-12 reported a complete loss of electrical power in instrument metrological conditions and turbulence during approach. The pilot was able to find the airport and land. The electrical system recovered on rollout. It was reported that an internal failure of the Master Power switch was the cause of the unexpected loss and recovery of the electrical system.