C310 pilot has radio failure during approach to dal.

Attributes
ACN	554758
Time
Date	200207
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : dal.airport
State Reference	TX
Altitude	msl single value : 2000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : d10.tracon tower : dal.tower
Operator	general aviation : personal
Make Model Name	Cessna 310/T310C
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Route In Use	approach : visual arrival : on vectors
Flight Plan	None
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument pilot : multi engine
Experience	flight time last 90 days : 30 flight time total : 550 flight time type : 100
ASRS Report	554758
Person 2
Affiliation	government : faa
Function	controller : approach
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : provided flight assist flight crew : landed as precaution flight crew : diverted to another airport flight crew : overcame equipment problem
Consequence	faa : reviewed incident with flight crew other
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Prior to penetrating the dfw class B airspace, I began experiencing problems with my transponder. ATC advised me of the problem and ordered me to reset my transponder. We were unable to make it transmit but were allowed to enter class B airspace. With frequent altitude and position verification, I was allowed to proceed to dal. After arriving over love field, I entered a right downwind for runway 13R and attempted to set approach flaps 15 degrees). When I hit the flap switch, I noticed a drop in power to the aircraft flight instrument lights and the flaps failed to deploy. At this point, I knew that all power was coming from a battery which was low on power. This low supply of electricity also rendered the landing gear motor useless. Once I informed tower of my problem and explained that I would need to crank the gear down, they gave me a heading to fly and a radio frequency change for vectors to landing. After changing frequencys, I was no longer able to maintain radio contact. Shortly thereafter, I lost all electric power. Unable to see dal behind my aircraft, I maintained my last given heading until I spotted dto, at which time I made a safe landing. The cause of the electrical problem has yet to be determined, but dual generator or regulator failure is suspected.

Original NASA ASRS Text

Title: C310 PLT HAS RADIO FAILURE DURING APCH TO DAL.

Narrative: PRIOR TO PENETRATING THE DFW CLASS B AIRSPACE, I BEGAN EXPERIENCING PROBS WITH MY XPONDER. ATC ADVISED ME OF THE PROB AND ORDERED ME TO RESET MY XPONDER. WE WERE UNABLE TO MAKE IT XMIT BUT WERE ALLOWED TO ENTER CLASS B AIRSPACE. WITH FREQUENT ALT AND POS VERIFICATION, I WAS ALLOWED TO PROCEED TO DAL. AFTER ARRIVING OVER LOVE FIELD, I ENTERED A R DOWNWIND FOR RWY 13R AND ATTEMPTED TO SET APCH FLAPS 15 DEGS). WHEN I HIT THE FLAP SWITCH, I NOTICED A DROP IN PWR TO THE ACFT FLT INST LIGHTS AND THE FLAPS FAILED TO DEPLOY. AT THIS POINT, I KNEW THAT ALL PWR WAS COMING FROM A BATTERY WHICH WAS LOW ON PWR. THIS LOW SUPPLY OF ELECTRICITY ALSO RENDERED THE LNDG GEAR MOTOR USELESS. ONCE I INFORMED TWR OF MY PROB AND EXPLAINED THAT I WOULD NEED TO CRANK THE GEAR DOWN, THEY GAVE ME A HDG TO FLY AND A RADIO FREQ CHANGE FOR VECTORS TO LNDG. AFTER CHANGING FREQS, I WAS NO LONGER ABLE TO MAINTAIN RADIO CONTACT. SHORTLY THEREAFTER, I LOST ALL ELECTRIC PWR. UNABLE TO SEE DAL BEHIND MY ACFT, I MAINTAINED MY LAST GIVEN HDG UNTIL I SPOTTED DTO, AT WHICH TIME I MADE A SAFE LNDG. THE CAUSE OF THE ELECTRICAL PROB HAS YET TO BE DETERMINED, BUT DUAL GENERATOR OR REGULATOR FAILURE IS SUSPECTED.

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.