Small aircraft has primary electrical power source failure. Makes a NORDO return to departure airpor...

Attributes
ACN	138571
Time
Date	199002
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : etb airport : mwc
State Reference	WI
Altitude	msl bound lower : 3000 msl bound upper : 3000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : mwc
Operator	general aviation : personal
Make Model Name	Small Aircraft
Flight Phase	cruise other
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : cfi pilot : instrument pilot : commercial
Experience	flight time last 90 days : 35 flight time total : 21750 flight time type : 9000
ASRS Report	138571
Person 2
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
Events
Anomaly	aircraft equipment problem : critical non adherence : clearance non adherence : far other anomaly other other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency flight crew : overcame equipment problem other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Flight from mwc-cli for radio work. Start-up, taxi-out, run-up and takeoff all perfectly normal. Climb to 3000' MSL and setup to cruise confign all normal. Several mins into flight (25-30 NM) the ammeter went to deep discharge. Immediately turned battery and generator master switches to 'off.' we then turned the radios off. Then turned on the battery master. Fuel gauge read accurately and ammeter showed 1 needle width to discharge side. Then generator master was turned on. Large quantities of smoke started to fill the cockpit, originating from the right side of and behind the INS panel. Immediately turned both master switches off. Smoke stopped. Turned airplane back toward etb and mwc. Over etb we turned master switches on again. Smoke started again. Turned switches off and smoke stopped. Engine ran with no problems during entire episode. Decided to fly back to mwc for maintenance. 5 mi north of mwc performed emergency landing gear extension. Entered mwc traffic pattern at pattern altitude and circled to left. Saw green light. Too close and too high to runway to land, so flew 1/2-way up runway at pattern altitude. Entered normal left-hand traffic pattern and landed using the green light gun signals. Taxied to hangar and shut down west/O further incident. Called mwc tower and both crew and controller agreed that entire landing operation went nominally. There was no fire at any time--only smoke. Engine operated with no problems during entire episode. Mwc tower responded admirably. There was no known disruption to normal traffic operations. Decision to fly to mwc rather than land at etb was based on flawless operation of engine, perfect WX and fact that aircraft was based and maintenance would be performed at mwc. Preliminary investigation reveals that the voltage regulator failed and several wires became excessively hot, thus causing the smoke. No fuses were blown or circuit breaker's popped. Perhaps a current limiter or fusible link should be installed downstream from voltage regulator to prevent a recurrence of smoke (possible fire) or damage to electrical components or gauges.

Original NASA ASRS Text

Title: SMA HAS PRIMARY ELECTRICAL POWER SOURCE FAILURE. MAKES A NORDO RETURN TO DEP ARPT. LANDS WITH LIGHT SIGNALS.

Narrative: FLT FROM MWC-CLI FOR RADIO WORK. START-UP, TAXI-OUT, RUN-UP AND TKOF ALL PERFECTLY NORMAL. CLB TO 3000' MSL AND SETUP TO CRUISE CONFIGN ALL NORMAL. SEVERAL MINS INTO FLT (25-30 NM) THE AMMETER WENT TO DEEP DISCHARGE. IMMEDIATELY TURNED BATTERY AND GENERATOR MASTER SWITCHES TO 'OFF.' WE THEN TURNED THE RADIOS OFF. THEN TURNED ON THE BATTERY MASTER. FUEL GAUGE READ ACCURATELY AND AMMETER SHOWED 1 NEEDLE WIDTH TO DISCHARGE SIDE. THEN GENERATOR MASTER WAS TURNED ON. LARGE QUANTITIES OF SMOKE STARTED TO FILL THE COCKPIT, ORIGINATING FROM THE RIGHT SIDE OF AND BEHIND THE INS PANEL. IMMEDIATELY TURNED BOTH MASTER SWITCHES OFF. SMOKE STOPPED. TURNED AIRPLANE BACK TOWARD ETB AND MWC. OVER ETB WE TURNED MASTER SWITCHES ON AGAIN. SMOKE STARTED AGAIN. TURNED SWITCHES OFF AND SMOKE STOPPED. ENG RAN WITH NO PROBS DURING ENTIRE EPISODE. DECIDED TO FLY BACK TO MWC FOR MAINT. 5 MI N OF MWC PERFORMED EMER LNDG GEAR EXTENSION. ENTERED MWC TFC PATTERN AT PATTERN ALT AND CIRCLED TO LEFT. SAW GREEN LIGHT. TOO CLOSE AND TOO HIGH TO RWY TO LAND, SO FLEW 1/2-WAY UP RWY AT PATTERN ALT. ENTERED NORMAL LEFT-HAND TFC PATTERN AND LANDED USING THE GREEN LIGHT GUN SIGNALS. TAXIED TO HANGAR AND SHUT DOWN W/O FURTHER INCIDENT. CALLED MWC TWR AND BOTH CREW AND CTLR AGREED THAT ENTIRE LNDG OPERATION WENT NOMINALLY. THERE WAS NO FIRE AT ANY TIME--ONLY SMOKE. ENG OPERATED WITH NO PROBS DURING ENTIRE EPISODE. MWC TWR RESPONDED ADMIRABLY. THERE WAS NO KNOWN DISRUPTION TO NORMAL TFC OPS. DECISION TO FLY TO MWC RATHER THAN LAND AT ETB WAS BASED ON FLAWLESS OPERATION OF ENG, PERFECT WX AND FACT THAT ACFT WAS BASED AND MAINT WOULD BE PERFORMED AT MWC. PRELIMINARY INVESTIGATION REVEALS THAT THE VOLTAGE REGULATOR FAILED AND SEVERAL WIRES BECAME EXCESSIVELY HOT, THUS CAUSING THE SMOKE. NO FUSES WERE BLOWN OR CB'S POPPED. PERHAPS A CURRENT LIMITER OR FUSIBLE LINK SHOULD BE INSTALLED DOWNSTREAM FROM VOLTAGE REGULATOR TO PREVENT A RECURRENCE OF SMOKE (POSSIBLE FIRE) OR DAMAGE TO ELECTRICAL COMPONENTS OR GAUGES.

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.

Small aircraft has primary electrical power source failure. Makes a NORDO return to departure airport. Lands with light signals.