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List of amperage drawn by electrical components

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Aircraft Systems

I'm trying to make a list of the various electrical components on a Cessna 182R (lights, radios, flight instruments, flaps, etc.) and the amperage each one draws so that in the event of an alternator failure I have a better idea of which ones draw the most/least.  Does anyone know where to find this information?  It's not in the POH, and I haven't been able to find anything online.  

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  1. John D. Collins on Oct 05, 2012

    This type of information can usually be found in the Maintenance Manual. Often the avionics are not included in the maintenance manuals and have to researched separately, usually in the individual avionics installation manuals. When addition are made to an aircraft that consume electrical energy from the aircraft, a load analysis is supposed to be done that adds up all of the current demands. Sometimes this analysis is kept with the maintenance records. If you have an alternator failure, you will want to shed any load that isn’t required for safe flight. Newer design aircraft will have an essential Bus that can be switched on and all the other loads can be switched off if this occurs in flight. A well charged battery will often last less than 30 minutes from the time of failure of the alternator unless the load is shed soon after the failure. If it goes undetected by the pilot, the first indication of a problem may be all the avionics going off at the same time or you experience difficulty in radio communication. This can be too late. It is best to monitor the health of the electrical system by means of a voltmeter. When running on the battery alone, the voltage will quickly drop to 12 volts or lower (24 volts or lower for a 28 volt system). A healthy alternator will keep the voltage close to 13.8 to 14.5 volts (28 to 31 volts for the 28 volt system. If the alternator goes off line, you can reset it once. Often the reset requires that both the battery master and the alternator be turned off and back on, particularly if the reason was an over voltage. Regardless, follow the instructions in your POH to reset the alternator. If it doesn’t reset, shed the load to the minimum you can and land as soon as possible. I would consider this situation an emergency and advice ATC as appropriate.

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