Narrative:

Aircraft loss of both current voltage limiters. Aircraft became solely powered by emergency backup power. 'Battery no charge' light did not illuminate and will not illuminate under this circumstances. First indication of electrical malfunction was loss of autoplt and radios. Squawked 7600 and communicated with ATC using identify flashes for approximately 15 min. Diverted VFR into ZZZ1. Was able to contact tower through sat-phone before entering class D and declared emergency. Made one low pass to verify gear down and locked. Landing was uneventful. ZZZ center was contacted immediately and debriefed on flight particulars. ATC said no further action required. FAA ad on electrical system should address 'battery no charge' light should similar situation occur. Callback conversation with reporter revealed the following information: the reporter stated while in cruise the only indication of the busses being unpowered was the autoplt and instrumentation failure. The reporter said the generators were operating but the busses were not powered and the 'battery no charge' light was out. The reporter stated it took a few mins for the crew to discover the airplane was operating on emergency bus power. The reporter said this airplane has no bus power warning lights and the quick reference lists no procedures for this type of event. The reporter stated the cause of the electrical power loss was the installation of the incorrect undersized current limiters.

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Original NASA ASRS Text

Title: A HAWKER 125 IN CRUISE AT FL330 DECLARED AN EMER AND DIVERTED DUE TO LOSS OF L AND R BUS POWER CAUSED BY INCORRECT CURRENT LIMITERS INSTALLED.

Narrative: ACFT LOSS OF BOTH CURRENT VOLTAGE LIMITERS. ACFT BECAME SOLELY POWERED BY EMER BACKUP POWER. 'BATTERY NO CHARGE' LIGHT DID NOT ILLUMINATE AND WILL NOT ILLUMINATE UNDER THIS CIRCUMSTANCES. FIRST INDICATION OF ELECTRICAL MALFUNCTION WAS LOSS OF AUTOPLT AND RADIOS. SQUAWKED 7600 AND COMMUNICATED WITH ATC USING IDENT FLASHES FOR APPROX 15 MIN. DIVERTED VFR INTO ZZZ1. WAS ABLE TO CONTACT TWR THROUGH SAT-PHONE BEFORE ENTERING CLASS D AND DECLARED EMER. MADE ONE LOW PASS TO VERIFY GEAR DOWN AND LOCKED. LNDG WAS UNEVENTFUL. ZZZ CENTER WAS CONTACTED IMMEDIATELY AND DEBRIEFED ON FLT PARTICULARS. ATC SAID NO FURTHER ACTION REQUIRED. FAA AD ON ELECTRICAL SYSTEM SHOULD ADDRESS 'BATTERY NO CHARGE' LIGHT SHOULD SIMILAR SIT OCCUR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED WHILE IN CRUISE THE ONLY INDICATION OF THE BUSSES BEING UNPOWERED WAS THE AUTOPLT AND INSTRUMENTATION FAILURE. THE RPTR SAID THE GENERATORS WERE OPERATING BUT THE BUSSES WERE NOT POWERED AND THE 'BATTERY NO CHARGE' LIGHT WAS OUT. THE RPTR STATED IT TOOK A FEW MINS FOR THE CREW TO DISCOVER THE AIRPLANE WAS OPERATING ON EMER BUS POWER. THE RPTR SAID THIS AIRPLANE HAS NO BUS POWER WARNING LIGHTS AND THE QUICK REFERENCE LISTS NO PROCS FOR THIS TYPE OF EVENT. THE RPTR STATED THE CAUSE OF THE ELECTRICAL POWER LOSS WAS THE INSTALLATION OF THE INCORRECT UNDERSIZED CURRENT LIMITERS.

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.