Narrative:

Lost essential bus a and bus B on the aircraft electrical system. This caused loss of cockpit lights, navs, and communication. The captain started an unannounced descent from FL330 and a right turn toward rdu. Communication could be momentarily re-established by resetting the circuit breakers for the ess bus, but they wouldn't stay set for more than 1 or 2 mins. Once communications were re-established after the deviation, the captain declared an emergency and got headings and distances to what he believed was the closest airport, where a safe, uneventful landing was accomplished. It must be noted, however, that nowhere in the lear 25B aircraft flight manual -- onboard the airplane or in the emergency checklist -- was there ever any mention made of loss of ess bus power. In the LR35 afm pulling the ess bus tie would have isolated the problem and eliminated the need for the emergency.

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Original NASA ASRS Text

Title: LR25B ACFT LOST ESSENTIAL PWR TO BUS A AND BUS B RESULTING IN LOSS OF COCKPIT LIGHTS, NAV EQUIP AND COMS. RESETTING CIRCUIT BREAKERS DIDN'T STAY SET, BUT APPARENTLY FLC OVERCAME PROB BECAUSE RPTR CAPT SAYS THAT 'ONCE COMS WERE RE-ESTABLISHED....'

Narrative: LOST ESSENTIAL BUS A AND BUS B ON THE ACFT ELECTRICAL SYS. THIS CAUSED LOSS OF COCKPIT LIGHTS, NAVS, AND COM. THE CAPT STARTED AN UNANNOUNCED DSCNT FROM FL330 AND A R TURN TOWARD RDU. COM COULD BE MOMENTARILY RE-ESTABLISHED BY RESETTING THE CIRCUIT BREAKERS FOR THE ESS BUS, BUT THEY WOULDN'T STAY SET FOR MORE THAN 1 OR 2 MINS. ONCE COMS WERE RE-ESTABLISHED AFTER THE DEV, THE CAPT DECLARED AN EMER AND GOT HDGS AND DISTANCES TO WHAT HE BELIEVED WAS THE CLOSEST ARPT, WHERE A SAFE, UNEVENTFUL LNDG WAS ACCOMPLISHED. IT MUST BE NOTED, HOWEVER, THAT NOWHERE IN THE LEAR 25B ACFT FLT MANUAL -- ONBOARD THE AIRPLANE OR IN THE EMER CHKLIST -- WAS THERE EVER ANY MENTION MADE OF LOSS OF ESS BUS PWR. IN THE LR35 AFM PULLING THE ESS BUS TIE WOULD HAVE ISOLATED THE PROB AND ELIMINATED THE NEED FOR THE EMER.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.