Circuitbreakers

Presented to:

By:

Date:

Federal AviationAdministrationCIRCUIT

BREAKERS

PROTECTING YOUR

ELECTRICAL SYSTEM,

YOUR AIRPLANE,

AND YOU

THE SATURDAY MORNING CREW

BEN McQUILLAN

MARCH 20, 2010

Federal AviationAdministration

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WHAT TO TAKE HOME FROM THIS SEMINAR…

• A MORE INTIMATE KNOWLEDGE OF THE ELECTRICAL SYSTEM OF YOUR AIRPLANE

• AN OPERATIONAL UNDERSTANDING OF ELECTRICAL SYSTEM PROTECTION

• FLEXIBLE DEFINITIONS OF ESSENTIAL & NON-ESSENTIAL ELECTRICAL SYSTEMS

• A “CAPTAIN MINDSET” FOR THE MANAGEMENT OF YOUR AIRCRAFT SYSTEMS



WHAT IS A CIRCUIT BREAKER?

• A “GATE” THROUGH WHICH ELECTRICITY TRAVELS FROM THE BATTERY TO THE COMPONENT WHICH THE CIRCUIT BREAKER PROTECTS

• ABLE TO OPEN AUTOMATICALLY WHEN THE WIRING OF THE CIRCUIT GETS TOO HOT (TOO MUCH VOLTAGE AND/OR RESISTANCE) TO REMOVE ALL ELECTRICITY FROM CONTINUING BEYOND THE BREAKER TO THE COMPROMISED AREA



TYPES OF

CIRCUIT BREAKERS



PULL-TYPE CIRCUIT BREAKERS

• THERMALLY DISCHARGED (POPPED OUT)

• ABLE TO BE DEACTIVATED (PULLED OUT) BY THE PILOT

• ABLE TO BE RESET (PUSHED IN) BY THE PILOT AFTER CIRCUIT & BREAKER COOL



NON PULL-TYPE CIRCUIT BREAKERS • THERMALLY

DISCHARGED (POPPED OUT)

• NOT ABLE TO BE DEACTIVATED (PULLED OUT) BY THE PILOT

• ABLE TO BE RESET (PUSHED IN) BY THE PILOT AFTER CIRCUIT & BREAKER COOL



CIRCUIT BREAKER SWITCHES• DOUBLES AS THE PRIMARY

CONTROL SWITCH FOR PROTECTED COMPONENT

• AMP RATING STAMPED ON END OF SWITCH

• THERMALLY DISCHARGED (SWITCHED OFF)

• ABLE TO BE DEACTIVATED (SWITCHED OFF) BY THE PILOT

• ABLE TO BE RESET (SWITCHED ON) BY THE PILOT AFTER CIRCUIT & BREAKER COOL



WHAT DO THEY DO?

• A CIRCUIT BREAKER SENSES AN OVERLOAD CONDITION WITHIN ITS ELECTRICAL CIRCUIT– GROUND FAULTS/ARCING– OVER-VOLTAGE/OVER-TEMPERATURE

• IT WILL AUTOMATICALLY PREVENT ANY BATTERY POWER FROM CONTINUING BEYOND THE BREAKER TO THE FAULTY WIRING & COMPONENT



HOW DO THEY DO IT?

• NORMAL LOAD VS. OVERLOAD– CIRCUITS TYPICALLY CARRY ½ THEIR RATED

LOAD (NUMBER ON BREAKER LABEL)

• OVERLOAD = EXCESSIVE HEAT• EXCESSIVE HEAT TRIPS BREAKER• NORMALLY FLAT LAYERED METAL STRIPS

EXPAND AT DIFFERENT RATES, CURVE, AND BREAK AWAY FROM ELECTRICAL CONNECTION



IT WORKS!



FAULT

POWER REMOVED

= HEATCIRCUIT ISOLATED



WHAT TO DO WITH A TRIPPED CIRCUIT BREAKER

-FAA SPECIAL AIRWORTHINESS INFORMATION BULLETIN (SAIB) CE-10-11, DECEMBER 23RD, 2009

-FAA ADVISORY CIRCULAR AC 120-80

-FAA ADVISORY CIRCULAR AC 25-16



DURING PRE-FLIGHT

• IF YOU FIND A CIRCUIT BREAKER POPPED, IT’S PROBABLY POPPED FOR A GOOD REASON– SERIOUS ELECTRICAL PROBLEM ON A PREVIOUS

FLIGHT– MECHANIC TROUBLESHOOTING A MALFUNCTION

OR INSPECTION– ANNOYING SADISTIC FLIGHT INSTRUCTOR

• DO NOT RESET THE BREAKER UNLESS THERE ARE NO CONCERNS OR QUESTIONS ABOUT THAT SYSTEM’S CONDITION



DURING FLIGHTSTOP!...THINK BEFORE ACTING• NON-ESSENTIAL SYSTEMS

– DON’T TOUCH IT!– CALMLY CONTINUE THE FLIGHT TO YOUR

DESTINATION OR DIVERT AS YOU SEE FIT, CONSIDERING THE NOW INOPERATIVE EQUIPMENT

– THINK AHEAD ABOUT HOW THE INOPERATIVE EQUIPMENT WILL AFFECT THE REST OF YOUR FLIGHT, PLAN AS NECESSARY

– AFTER LANDING, HAVE A MECHANIC ADDRESS THE SITUATION PROPERLY



DURING FLIGHT (CONT.)

• ESSENTIAL SYSTEMS– LOOK FOR A REASON FOR THE TRIPPED

BREAKER BEFORE JUST RESETTING IT– BE CERTAIN YOU REALLY WANT THAT SYSTEM

ENOUGH TO RISK A POSSIBLE FIRE– WAIT AT LEAST 1 MINUTE TO RESET TO ALLOW

CIRCUIT & BREAKER TO COOL DOWN– BE VIGILANT FOR ANY SMOKE OR BURNING

SMELL– HAVE A “PLAN B” IN THE EVENT YOU DO START

A FIRE…DO YOU HAVE A FIRE EXTINGUISHER?



ESSENTIAL SYSTEMS



DAY VFR• HMMM…NOT A WHOLE LOT WE ACTUALLY

NEED• ELECTRIC FUEL PUMP• LANDING GEAR ACTUATOR• FLAP ACTUATOR• ELECTRIC ENGINE INSTRUMENTATION• ELECTRIC TRIM IN A CIRRUS• MAYBE A RADIO• MAYBE A TRANSPONDER• DEFINITELY NOT A GPS!



NIGHT VFR

• COCKPIT/INSTRUMENT PANEL LIGHTING• NAVIGATION SOURCE (GPS, VOR, ETC.)• MAYBE A RADIO• MAYBE A TRANSPONDER• ANTI-COLLISION LIGHT• POSITION LIGHTS• LANDING LIGHT?...CHICKEN



IFR

• ELECTRIC FLIGHT INSTRUMENTS• AT LEAST 1 RADIO• AT LEAST 1 NAVIGATION SOURCE• TRANSPONDER• NECESSARY LIGHTING



TRAINING & PRACTICE• SPEND A FEW MINUTES IN YOUR COCKPIT, LOOK

AT THE CIRCUIT BREAKER PANEL, & THINK ABOUT WHICH SYSTEMS ARE ESSENTIAL & NON ESSENTIAL FOR THE TYPE OF FLYING YOU DO

• TAKE A CFI UP AND HAVE THEM POP SELECT CIRCUIT BREAKERS, DISCUSS WHETHER TO RESET THEM, AND HOW THAT SYSTEM’S FAILURE WILL AFFECT YOUR FLIGHT IE. THE FLAP ACTUATOR BREAKER & NO-FLAP LANDING

• BE DILIGENT IN YOUR PREFLIGHT INSPECTIONS, AND SYSTEMS MONITORING IN-FLIGHT



• JOIN US NEXT SATURDAY FOR:

GARMIN’S TERRAIN AWARENESS & WARNING SYSTEM (TAWS)

• JOIN OUR NEWSLETTER & DOWNLOAD THIS PRESENTATION @

www.inflightpilottraining.comSATURDAY SEMINARS PAGE

• FLY SAFE!

Circuitbreakers

Education

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