C172RG pilot experienced electrical problems in-flight. Finding pilots operating handbook inadequate...

Attributes
ACN	439470
Time
Date	199906
Day	Thu
Local Time Of Day	0601 To 1200
Place
State Reference	TX
Altitude	msl single value : 6500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zfw.artcc
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Navigation In Use	other vortac
Flight Phase	cruise : level
Route In Use	enroute airway : v16.airway
Flight Plan	None
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : private
Experience	flight time last 90 days : 25 flight time total : 275 flight time type : 200
ASRS Report	439470
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	other flight crewa
Resolutory Action	aircraft : equipment problem dissipated flight crew : overcame equipment problem
Consequence	other
Factors
Maintenance	performance deficiency : repair
Supplementary
Problem Areas	Maintenance Human Performance Flight Crew Human Performance Chart Or Publication Aircraft
Primary Problem	Maintenance Human Performance
Situations
Publication	Cessna 172RG Pilots Handbook

Narrative:

A C172RG rental aircraft. Flight was round-trip to el paso direct. About 30 mi west of ink VOR complete radio system lost. All electrical fuses appeared good. Fuel gauges went from reading almost full to about empty. Turning communication master switch off returned fuel gauges to proper reading. Without radios, landing elp was a no-go, did 180 degrees to return to mdd. Feared that used coil installed by FBO had somehow failed. Troubleshooting in-flight next 30 mins failed to resolve. Finally I pulled the alternator fuse switch out, waited 2-3 seconds and pushed back in and communication returned. Resumed flight to elp without further incident. Believe an over-voltage condition caused the alternator control unit to automatically remove alternator field current thus shutting down alternator. Cessna information manual for the cutlass rg model 172RG does not provide emergency procedures for this incident that works. Manual suggests (page 7-32) turning master switch off and on. Communication master switch didn't work. Pulling the alternator fuse switch out and pushing it back in did. My clue was page 3-10 emergency procedures for electrical power supply system 'ammeter indicator discharge' which it did. Step #2 says to check that alternator circuit breaker was in, which it was. I never cycled the engine master switch so don't know if that would have fixed it, most pilots are adverse to turning anything off that has to do with a single-engine plane unless it's on fire. Since the fuse was in and unlike the other 'pop-push to reset type' as it had a tit like it was meant to pull I figured 'what the hell' and pulled it. Nothing happened so I pushed it back in and radios, VOR, transponder all came to life.

Original NASA ASRS Text

Title: C172RG PLT EXPERIENCED ELECTRICAL PROBS INFLT. FINDING PLTS OPERATING HANDBOOK INADEQUATE, USED LOGICAL TROUBLESHOOTING TO RESTORE SYS LOST AND CONTINUED ON.

Narrative: A C172RG RENTAL ACFT. FLT WAS ROUND-TRIP TO EL PASO DIRECT. ABOUT 30 MI W OF INK VOR COMPLETE RADIO SYS LOST. ALL ELECTRICAL FUSES APPEARED GOOD. FUEL GAUGES WENT FROM READING ALMOST FULL TO ABOUT EMPTY. TURNING COM MASTER SWITCH OFF RETURNED FUEL GAUGES TO PROPER READING. WITHOUT RADIOS, LNDG ELP WAS A NO-GO, DID 180 DEGS TO RETURN TO MDD. FEARED THAT USED COIL INSTALLED BY FBO HAD SOMEHOW FAILED. TROUBLESHOOTING INFLT NEXT 30 MINS FAILED TO RESOLVE. FINALLY I PULLED THE ALTERNATOR FUSE SWITCH OUT, WAITED 2-3 SECONDS AND PUSHED BACK IN AND COM RETURNED. RESUMED FLT TO ELP WITHOUT FURTHER INCIDENT. BELIEVE AN OVER-VOLTAGE CONDITION CAUSED THE ALTERNATOR CTL UNIT TO AUTOMATICALLY REMOVE ALTERNATOR FIELD CURRENT THUS SHUTTING DOWN ALTERNATOR. CESSNA INFO MANUAL FOR THE CUTLASS RG MODEL 172RG DOES NOT PROVIDE EMER PROCS FOR THIS INCIDENT THAT WORKS. MANUAL SUGGESTS (PAGE 7-32) TURNING MASTER SWITCH OFF AND ON. COM MASTER SWITCH DIDN'T WORK. PULLING THE ALTERNATOR FUSE SWITCH OUT AND PUSHING IT BACK IN DID. MY CLUE WAS PAGE 3-10 EMER PROCS FOR ELECTRICAL PWR SUPPLY SYS 'AMMETER INDICATOR DISCHARGE' WHICH IT DID. STEP #2 SAYS TO CHK THAT ALTERNATOR CIRCUIT BREAKER WAS IN, WHICH IT WAS. I NEVER CYCLED THE ENG MASTER SWITCH SO DON'T KNOW IF THAT WOULD HAVE FIXED IT, MOST PLTS ARE ADVERSE TO TURNING ANYTHING OFF THAT HAS TO DO WITH A SINGLE-ENG PLANE UNLESS IT'S ON FIRE. SINCE THE FUSE WAS IN AND UNLIKE THE OTHER 'POP-PUSH TO RESET TYPE' AS IT HAD A TIT LIKE IT WAS MEANT TO PULL I FIGURED 'WHAT THE HELL' AND PULLED IT. NOTHING HAPPENED SO I PUSHED IT BACK IN AND RADIOS, VOR, XPONDER ALL CAME TO LIFE.

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.

C172RG pilot experienced electrical problems in-flight. Finding pilots operating handbook inadequate, used logical troubleshooting to restore system lost and continued on.