Narrative:

Electrical power failed completely during a final approach to panama city-bay county airport. Because of this, the tower operator has alleged that I ignored an 'unsafe to land' instruction and a light signal. This is not true. Since the WX was excellent daytime VFR, I had almost 5 hours of fuel on board, and was not required to be anywhere at the time, there was no pressing reason for me to ignore such an instruction. My flight had taken me from milton, fl, which is roughly 1/2 hour away from panama city. My preflight checks revealed no imminent electrical problems. There are no warning lights on the aircraft to indicate a failure of either generator, but there is an ammeter which can be individually selected on preflight run-up to verify correct operation. This I did perform at milton and check was satisfactory. I had been advised by a local pilot at milton that I could contact pensacola and fly south to the gulf of mexico and then east to panama city to avoid restr airspace in the vicinity of eglin AFB, which I elected to do. I experienced a lot of radio static on climb out from milton, so I remained below 1400 ft MSL and contacted pensacola and advised them of my intentions. I had some difficulty understanding their instructions due to the static. I had similar problems with eglin approach control on the eastbound leg, but I didn't attribute these problems to electrical power, rather I thought I had a problem with my radio only. When I turned up the volume on my #2 navigation radio, it increased the volume on the communication radios. After release from eglin about 25 mi from panama city, I acquired ATIS with no difficulty and called panama city tower at 20 mi west of the airport. They did not respond, so I switched to my #2 communication radio and made contact. They told me to expect a visual approach to runway 14 and to call a 5 mi right base. I descended to 1500 ft MSL (airport is at 21 ft MSL) and set the waypoint into my RNAV. I made visual identify of the airport at about 9 mi. I slowed the aircraft to allow for gear and flap extension and called the right base at exactly 5 mi. I was cleared to land, but had to ask for a repeat of this instruction since the volume was rather weak. I acknowledged and began my pre-landing checks, including the base leg 'gump.' I surveyed the landing area and took note of an airliner holding short of the runway. I obtained a green gear light and turned final. As I conducted the final approach 'gump' check, I noticed that the flap indicator did not move when I depressed the control lever. I also noticed that the green gear light had gone out. When I glanced up at the radios, I could see that all the lights had gone out, along with the intercom light. I briefly tried the radio knobs and the avionics master, but nothing worked. Although I had felt the gear operate and had gotten a green light, I then became concerned that the gear was not extended. I looked to my left tip tank which has a small mirror inboard. I could see my outer gear door and wheel, so concluded that the gear was still down. I briefly considered aborting the landing since I was not sure at what point I had lost communications, but decided that since I had been cleared to land, the safest thing to do was finish the approach. I did shift my attention to the waiting airliner at the threshold to ensure that he did not move out onto the runway. Apparently, during the final leg of my landing approach the tower was attempting to advise me that my gear was not completely extended. I heard no instructions from the tower, nor did I expect to hear any, since the landing clearance is normally the last communication prior to contacting ground control. I did not look at the tower for light signals, since I didn't think anything was wrong. Besides, I was occupied with the discovery of the electrical power failure, checking the tip tank mirror, and watching the runway area, and did not expect any light signals from the tower. I wish I had seen the light signals or wish my electrical power had lasted a few more mins. I don't know what caused the power failure. It may have been a progressive failure of the charging system during that flight or the earlier flight that day, but my system showedno sign of it other than difficulties with radio xmissions. I have had some such difficulties in the past without having had electrical power failures. I had had the HSI replaced just prior to the flight, and thought the radio performance problem might be traceable to that work. It is also possible that the gear motor spiked during the extension cycle and caused the power failure and the earlier radio problem was coincidental. The timing of the electrical power failure was extremely bad, but not that surprising. It requires approximately 25 amps to cycle the gear and flaps. If the system was gradually failing, gear extension, landing lights, or flaps are the most likely to finish it off. These all occur during the final operations of the flight. I would propose that a possible improvement that could be made at tower operated airports is a capability to flash the runway end lights (or even the VASI when available) red when the tower needs to advise of an unsafe condition. Normally, pilots look for light gun signals prior to the ldng approach because they realize they have a communication failure. In any case, I had been talking to them right up to final, so I wasn't looking for light signals and only discovered the failure quite late in the approach. My need to observe traffic near the runway end kept my attention until the landing flare. I believe an installation at the end of the runway which permitted flashing red lights would represent an inexpensive aid for the tower to 'wave off' an unsafe landing during VMC where voice communications have been lost during the approach itself. It would require only a switch and possibly some additional lamp holders on an already existing installation. No additional power would be needed, since the switch could also stop the power to the other lights.

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Original NASA ASRS Text

Title: C320 WAS HAVING COM PROBS. LOST ALL ELECTRICAL WHEN GEAR EXTENDED ON FINAL. NO COM WITH TWR FOR FINAL LNDG CLRNC. TWR WAS GIVING A WARNING FOR UNSAFE LNDG CONDITION BUT MISSED BY RPTR. CHKED FOR GEAR DOWN VIA MIRROR SYS AND THOUGHT WAS OK. GEAR FAILED ON TOUCHDOWN. NO GREEN LIGHT INDICATION ACCOUNT ELECTRICAL FAILURE.

Narrative: ELECTRICAL PWR FAILED COMPLETELY DURING A FINAL APCH TO PANAMA CITY-BAY COUNTY ARPT. BECAUSE OF THIS, THE TWR OPERATOR HAS ALLEGED THAT I IGNORED AN 'UNSAFE TO LAND' INSTRUCTION AND A LIGHT SIGNAL. THIS IS NOT TRUE. SINCE THE WX WAS EXCELLENT DAYTIME VFR, I HAD ALMOST 5 HRS OF FUEL ON BOARD, AND WAS NOT REQUIRED TO BE ANYWHERE AT THE TIME, THERE WAS NO PRESSING REASON FOR ME TO IGNORE SUCH AN INSTRUCTION. MY FLT HAD TAKEN ME FROM MILTON, FL, WHICH IS ROUGHLY 1/2 HR AWAY FROM PANAMA CITY. MY PREFLT CHKS REVEALED NO IMMINENT ELECTRICAL PROBS. THERE ARE NO WARNING LIGHTS ON THE ACFT TO INDICATE A FAILURE OF EITHER GENERATOR, BUT THERE IS AN AMMETER WHICH CAN BE INDIVIDUALLY SELECTED ON PREFLT RUN-UP TO VERIFY CORRECT OP. THIS I DID PERFORM AT MILTON AND CHK WAS SATISFACTORY. I HAD BEEN ADVISED BY A LCL PLT AT MILTON THAT I COULD CONTACT PENSACOLA AND FLY S TO THE GULF OF MEXICO AND THEN E TO PANAMA CITY TO AVOID RESTR AIRSPACE IN THE VICINITY OF EGLIN AFB, WHICH I ELECTED TO DO. I EXPERIENCED A LOT OF RADIO STATIC ON CLBOUT FROM MILTON, SO I REMAINED BELOW 1400 FT MSL AND CONTACTED PENSACOLA AND ADVISED THEM OF MY INTENTIONS. I HAD SOME DIFFICULTY UNDERSTANDING THEIR INSTRUCTIONS DUE TO THE STATIC. I HAD SIMILAR PROBS WITH EGLIN APCH CTL ON THE EBOUND LEG, BUT I DIDN'T ATTRIBUTE THESE PROBS TO ELECTRICAL PWR, RATHER I THOUGHT I HAD A PROB WITH MY RADIO ONLY. WHEN I TURNED UP THE VOLUME ON MY #2 NAV RADIO, IT INCREASED THE VOLUME ON THE COM RADIOS. AFTER RELEASE FROM EGLIN ABOUT 25 MI FROM PANAMA CITY, I ACQUIRED ATIS WITH NO DIFFICULTY AND CALLED PANAMA CITY TWR AT 20 MI W OF THE ARPT. THEY DID NOT RESPOND, SO I SWITCHED TO MY #2 COM RADIO AND MADE CONTACT. THEY TOLD ME TO EXPECT A VISUAL APCH TO RWY 14 AND TO CALL A 5 MI R BASE. I DSNDED TO 1500 FT MSL (ARPT IS AT 21 FT MSL) AND SET THE WAYPOINT INTO MY RNAV. I MADE VISUAL IDENT OF THE ARPT AT ABOUT 9 MI. I SLOWED THE ACFT TO ALLOW FOR GEAR AND FLAP EXTENSION AND CALLED THE R BASE AT EXACTLY 5 MI. I WAS CLRED TO LAND, BUT HAD TO ASK FOR A REPEAT OF THIS INSTRUCTION SINCE THE VOLUME WAS RATHER WEAK. I ACKNOWLEDGED AND BEGAN MY PRE-LNDG CHKS, INCLUDING THE BASE LEG 'GUMP.' I SURVEYED THE LNDG AREA AND TOOK NOTE OF AN AIRLINER HOLDING SHORT OF THE RWY. I OBTAINED A GREEN GEAR LIGHT AND TURNED FINAL. AS I CONDUCTED THE FINAL APCH 'GUMP' CHK, I NOTICED THAT THE FLAP INDICATOR DID NOT MOVE WHEN I DEPRESSED THE CTL LEVER. I ALSO NOTICED THAT THE GREEN GEAR LIGHT HAD GONE OUT. WHEN I GLANCED UP AT THE RADIOS, I COULD SEE THAT ALL THE LIGHTS HAD GONE OUT, ALONG WITH THE INTERCOM LIGHT. I BRIEFLY TRIED THE RADIO KNOBS AND THE AVIONICS MASTER, BUT NOTHING WORKED. ALTHOUGH I HAD FELT THE GEAR OPERATE AND HAD GOTTEN A GREEN LIGHT, I THEN BECAME CONCERNED THAT THE GEAR WAS NOT EXTENDED. I LOOKED TO MY L TIP TANK WHICH HAS A SMALL MIRROR INBOARD. I COULD SEE MY OUTER GEAR DOOR AND WHEEL, SO CONCLUDED THAT THE GEAR WAS STILL DOWN. I BRIEFLY CONSIDERED ABORTING THE LNDG SINCE I WAS NOT SURE AT WHAT POINT I HAD LOST COMS, BUT DECIDED THAT SINCE I HAD BEEN CLRED TO LAND, THE SAFEST THING TO DO WAS FINISH THE APCH. I DID SHIFT MY ATTN TO THE WAITING AIRLINER AT THE THRESHOLD TO ENSURE THAT HE DID NOT MOVE OUT ONTO THE RWY. APPARENTLY, DURING THE FINAL LEG OF MY LNDG APCH THE TWR WAS ATTEMPTING TO ADVISE ME THAT MY GEAR WAS NOT COMPLETELY EXTENDED. I HEARD NO INSTRUCTIONS FROM THE TWR, NOR DID I EXPECT TO HEAR ANY, SINCE THE LNDG CLRNC IS NORMALLY THE LAST COM PRIOR TO CONTACTING GND CTL. I DID NOT LOOK AT THE TWR FOR LIGHT SIGNALS, SINCE I DIDN'T THINK ANYTHING WAS WRONG. BESIDES, I WAS OCCUPIED WITH THE DISCOVERY OF THE ELECTRICAL PWR FAILURE, CHKING THE TIP TANK MIRROR, AND WATCHING THE RWY AREA, AND DID NOT EXPECT ANY LIGHT SIGNALS FROM THE TWR. I WISH I HAD SEEN THE LIGHT SIGNALS OR WISH MY ELECTRICAL PWR HAD LASTED A FEW MORE MINS. I DON'T KNOW WHAT CAUSED THE PWR FAILURE. IT MAY HAVE BEEN A PROGRESSIVE FAILURE OF THE CHARGING SYS DURING THAT FLT OR THE EARLIER FLT THAT DAY, BUT MY SYS SHOWEDNO SIGN OF IT OTHER THAN DIFFICULTIES WITH RADIO XMISSIONS. I HAVE HAD SOME SUCH DIFFICULTIES IN THE PAST WITHOUT HAVING HAD ELECTRICAL PWR FAILURES. I HAD HAD THE HSI REPLACED JUST PRIOR TO THE FLT, AND THOUGHT THE RADIO PERFORMANCE PROB MIGHT BE TRACEABLE TO THAT WORK. IT IS ALSO POSSIBLE THAT THE GEAR MOTOR SPIKED DURING THE EXTENSION CYCLE AND CAUSED THE PWR FAILURE AND THE EARLIER RADIO PROB WAS COINCIDENTAL. THE TIMING OF THE ELECTRICAL PWR FAILURE WAS EXTREMELY BAD, BUT NOT THAT SURPRISING. IT REQUIRES APPROX 25 AMPS TO CYCLE THE GEAR AND FLAPS. IF THE SYS WAS GRADUALLY FAILING, GEAR EXTENSION, LNDG LIGHTS, OR FLAPS ARE THE MOST LIKELY TO FINISH IT OFF. THESE ALL OCCUR DURING THE FINAL OPS OF THE FLT. I WOULD PROPOSE THAT A POSSIBLE IMPROVEMENT THAT COULD BE MADE AT TWR OPERATED ARPTS IS A CAPABILITY TO FLASH THE RWY END LIGHTS (OR EVEN THE VASI WHEN AVAILABLE) RED WHEN THE TWR NEEDS TO ADVISE OF AN UNSAFE CONDITION. NORMALLY, PLTS LOOK FOR LIGHT GUN SIGNALS PRIOR TO THE LDNG APCH BECAUSE THEY REALIZE THEY HAVE A COM FAILURE. IN ANY CASE, I HAD BEEN TALKING TO THEM RIGHT UP TO FINAL, SO I WASN'T LOOKING FOR LIGHT SIGNALS AND ONLY DISCOVERED THE FAILURE QUITE LATE IN THE APCH. MY NEED TO OBSERVE TFC NEAR THE RWY END KEPT MY ATTN UNTIL THE LNDG FLARE. I BELIEVE AN INSTALLATION AT THE END OF THE RWY WHICH PERMITTED FLASHING RED LIGHTS WOULD REPRESENT AN INEXPENSIVE AID FOR THE TWR TO 'WAVE OFF' AN UNSAFE LNDG DURING VMC WHERE VOICE COMS HAVE BEEN LOST DURING THE APCH ITSELF. IT WOULD REQUIRE ONLY A SWITCH AND POSSIBLY SOME ADDITIONAL LAMP HOLDERS ON AN ALREADY EXISTING INSTALLATION. NO ADDITIONAL PWR WOULD BE NEEDED, SINCE THE SWITCH COULD ALSO STOP THE PWR TO THE OTHER LIGHTS.

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.