A cessna T210 in climb at 9600 ft had electrical system failure due to a severed alternator drive be...

Attributes
ACN	403004
Time
Date	199805
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : zse
State Reference	WA
Altitude	msl bound lower : 9000 msl bound upper : 9600
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zse
Operator	general aviation : personal
Make Model Name	Cessna 120
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude descent other other
Route In Use	enroute : on vectors
Flight Plan	VFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument pilot : cfi
Experience	flight time last 90 days : 15 flight time total : 2400 flight time type : 300
ASRS Report	403004
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : critical altitude deviation : overshoot other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa
Resolutory Action	none taken : unable other other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Airplane is new to me, though I have a good deal of time in type many yrs ago. It has a king GPS, which is also new to me. During climb, I was programming GPS and was thus distraction from flight. I climbed through my assigned 9000 ft altitude to 9600 ft. I had just noted this and started correcting when ATC asked for my indicated altitude. About 30 mins later I noted ammeter showing discharge, indicating alternator failure. I was above clouds, on vectors for approach to astoria. I shut down all radios/electrical except communication/navigation #1 and transponder and notified ATC (ZSE). I asked for vector back home to 75S where repairs would be easier/cheaper. Thought I could go VFR on top, then descend through large holes I'd remembered at 75S. Shortly after, my transponder failed, so I accepted vector to ocm to below clouds, then canceled IFR and proceeded VFR home. Problem was: my eagerness to get home put me at risk of being lost above clouds, IFR descent needed without radios! Callback conversation with reporter revealed the following information: the reporter stated that this aircraft had 6 alternator drive belts replaced before the cause of failure was found. The reporter said the cause was at high power settings a throttle body cotter key would rub on the drive belt cutting and damaging the belt. The reporter stated the throttle body was shimmed to avoid conflict with the cotter key and the drive belt and checked ok on engine run.

Original NASA ASRS Text

Title: A CESSNA T210 IN CLB AT 9600 FT HAD ELECTRICAL SYS FAILURE DUE TO A SEVERED ALTERNATOR DRIVE BELT CAUSED BY A THROTTLE BODY COTTER KEY INTERFERENCE AT HIGH THROTTLE SETTINGS.

Narrative: AIRPLANE IS NEW TO ME, THOUGH I HAVE A GOOD DEAL OF TIME IN TYPE MANY YRS AGO. IT HAS A KING GPS, WHICH IS ALSO NEW TO ME. DURING CLB, I WAS PROGRAMMING GPS AND WAS THUS DISTR FROM FLT. I CLBED THROUGH MY ASSIGNED 9000 FT ALT TO 9600 FT. I HAD JUST NOTED THIS AND STARTED CORRECTING WHEN ATC ASKED FOR MY INDICATED ALT. ABOUT 30 MINS LATER I NOTED AMMETER SHOWING DISCHARGE, INDICATING ALTERNATOR FAILURE. I WAS ABOVE CLOUDS, ON VECTORS FOR APCH TO ASTORIA. I SHUT DOWN ALL RADIOS/ELECTRICAL EXCEPT COM/NAV #1 AND XPONDER AND NOTIFIED ATC (ZSE). I ASKED FOR VECTOR BACK HOME TO 75S WHERE REPAIRS WOULD BE EASIER/CHEAPER. THOUGHT I COULD GO VFR ON TOP, THEN DSND THROUGH LARGE HOLES I'D REMEMBERED AT 75S. SHORTLY AFTER, MY XPONDER FAILED, SO I ACCEPTED VECTOR TO OCM TO BELOW CLOUDS, THEN CANCELED IFR AND PROCEEDED VFR HOME. PROB WAS: MY EAGERNESS TO GET HOME PUT ME AT RISK OF BEING LOST ABOVE CLOUDS, IFR DSCNT NEEDED WITHOUT RADIOS! CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT THIS ACFT HAD 6 ALTERNATOR DRIVE BELTS REPLACED BEFORE THE CAUSE OF FAILURE WAS FOUND. THE RPTR SAID THE CAUSE WAS AT HIGH PWR SETTINGS A THROTTLE BODY COTTER KEY WOULD RUB ON THE DRIVE BELT CUTTING AND DAMAGING THE BELT. THE RPTR STATED THE THROTTLE BODY WAS SHIMMED TO AVOID CONFLICT WITH THE COTTER KEY AND THE DRIVE BELT AND CHKED OK ON ENG RUN.

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.

A cessna T210 in climb at 9600 ft had electrical system failure due to a severed alternator drive belt caused by a throttle body cotter key interference at high throttle settings.