Piper Arrow II Aircraft

[swarajharne]

What does it mean if the circuit breakers are popped for the 'Alternator' and 'Engine Group'? What is their function? Can engine failure in-flight be linked to these circuit breakers? Please explain.

 

[Clip4]

What does it mean if the circuit breakers are popped for the 'Alternator' and 'Engine Group'? What is their function? Can engine failure in-flight be linked to these circuit breakers? Please explain.

Since you don’t remember this from ground school, the AFM/POH contains an electrical schematic showing you what is on each breaker.

The engine group is the engine gauges. The alternator breaker goes to the voltage regulator and alternator.

Your engine operates an engine driven fuel pump, a mechanical fuel injection system, and magnetos.

If both these breakers were tripped, the engine would run fine. You would lose the electrical systems such as the lights, radios, electric fuel pump, landing gear pump ect as when the battery went dead.

 

[swarajharne]

Since you don’t remember this from ground school, the AFM/POH contains an electrical schematic showing you what is on each breaker.

The engine group is the engine gauges. The alternator breaker goes to the voltage regulator and alternator.

Your engine operates an engine driven fuel pump, a mechanical fuel injection system, and magnetos.

If both these breakers were tripped, the engine would run fine. You would lose the electrical systems such as the lights, radios, electric fuel pump, landing gear pump ect as when the battery went dead.

Thank you!

 

[swarajharne]

Since you don’t remember this from ground school, the AFM/POH contains an electrical schematic showing you what is on each breaker.

The engine group is the engine gauges. The alternator breaker goes to the voltage regulator and alternator.

Your engine operates an engine driven fuel pump, a mechanical fuel injection system, and magnetos.

If both these breakers were tripped, the engine would run fine. You would lose the electrical systems such as the lights, radios, electric fuel pump, landing gear pump ect as when the battery went dead.

If the engine were to fail in-flight or if it was shut down in-flight, would the BAT-ALT switch need to be 'on' to restart it? Is it advisable to turn it off after a CB pops? Additionally, is the switch required to be 'on' for take-off?

 

[flyingron]

If the engine were to fail in-flight or if it was shut down in-flight, would the BAT-ALT switch need to be 'on' to restart it? Is it advisable to turn it off after a CB pops? Additionally, is the switch required to be 'on' for take-off?

Depends on how you are restarting it. Usually, all you need to do is undo what you did to kill the engine (unground the mags or turn the fuel back on), the windmilling prop will "crank the engine" for you. If you want to try the starter, then you will have to turn on the master.

Nobody but a fool would kill the entire electrical system when one breaker pops. That would be pointless.

You'd be foolhardy to not have the switch on for takeoff. Your battery is depleted for engine start and needs recharging. If you have anti-collision lights, they're required to be on (which would need the master). If you need the radio (advised for all places, required for controlled fields) or the transponder or electronic navigation, all of that mandates the electrical system being on.

 

[swarajharne]

Depends on how you are restarting it. Usually, all you need to do is undo what you did to kill the engine (unground the mags or turn the fuel back on), the windmilling prop will "crank the engine" for you. If you want to try the starter, then you will have to turn on the master.

Nobody but a fool would kill the entire electrical system when one breaker pops. That would be pointless.

You'd be foolhardy to not have the switch on for takeoff. Your battery is depleted for engine start and needs recharging. If you have anti-collision lights, they're required to be on (which would need the master). If you need the radio (advised for all places, required for controlled fields) or the transponder or electronic navigation, all of that mandates the electrical system being on.

Thank you so much!

 

[Clip4]

If the engine were to fail in-flight or if it was shut down in-flight, would the BAT-ALT switch need to be 'on' to restart it? Is it advisable to turn it off after a CB pops? Additionally, is the switch required to be 'on' for take-off?

The purpose of circuit breaker is protect against an overload and fire. Once the two breakers have tripped, there is no current going to the engine gauges and the alternator/regulator.

Under the condition you provide, the battery has 30 minutes of power. You should conserve power by turning off anything that is not needed. The only reason to turn off the master switch would be to conserve electric for some period and the starter is not operable with the master turned off. The aircraft is no longer airworthy and FAR 91.7 requires you to terminate the flight.

 

[swarajharne]

The purpose of circuit breaker is protect against an overload and fire. Once the two breakers have tripped, there is no current going to the engine gauges and the alternator/regulator.

Under the condition you provide, the battery has 30 minutes of power. You should conserve power by turning off anything that is not needed. The only reason to turn off the master switch would be to conserve electric for some period and the starter is not operable with the master turned off. The aircraft is no longer airworthy and FAR 91.7 requires you to terminate the flight.

So if I understand correctly; switching off the master would mean there is no electrical power to systems like landing light, anti collision lights, pitot heat and fuel pump?

 

[Clip4]

So if I understand correctly; switching off the master would mean there is no electrical power to systems like landing light, anti collision lights, pitot heat and fuel pump?

That’s why it’s called the master switch. The battery side turns off / on all battery power. The alternator died turns on/off the alternator.

 

[mandm]

Alternator charges the battery.
Battery powers your electrical instruments.

CB or circuit breaker pops if the wires are getting too hot (means drawing too much current) for the CB amp limit on that CB, this is either due to wiring issue or the device it’s powering is acting up. The CB popping is to prevent a fire. You should let the wires have a few minutes (5+) to “cool” down before resetting and probably better to not reset it at all during flight as it means there is an issue (consider your situation, are you near an airport, good VFR weather, etc before your risk adding an emergency landing). It isn’t normal for CBs to pop in flight. I had this issue before and my mechanic put in a new alternator and I haven’t had the issue again until my fuel pump went out and it popped when I tried to run my broken fuel pump. So had to get a new one of those. Separate incident dates but now I have new ones instead of 40-60 year old ones and they have been working without issue.

Engine uses Fuel, Air and Spark to run
It doesn’t require electric for the engine to run on the Arrow, from what I believe at least, keep in mind your instruments may run on pitot static air, vacuum, or electric. Unsure if vacuum requires electric to run either if anyone knows?

Fuel is fuel flow, on low wing, the engine driven fuel pump is driven by the moving engine or the auxiliary backup electric fuel pump (you have a switch for that). On high wing, fuel flows by gravity but you still have the 2 fuel pumps.

Air is your induction air, if blocked you have alternate air. (Open / close). Alt air receives less air than induction air so your performance will drop a little bit (you can see this on the gauges during run up).

Spark is your magnetos, you have 2 mags (L and R), they are self contained units that gives spark to each spark plug in each cylinder. Each cylinder has 2 spark plugs, one controlled by the L mag and the other controlled by the R mag. That’s why if something is funky you can try to run on either the L or R mag, and also why during run up you do a mag check, the drop in RPMs show the loss of performance by using only one mag instead of 2 and that they both work independently of each other.

Keep in mind some aircraft do not have any electrical or battery in them, they start by hand propping. If you have engine out in flight, I’d say you might not have time to restart it. The wind will turn the dead engine prop automatically (unless you have feathering prop which is a multi engine thing), and that is acting as your starter, you just have to make sure you have fuel air and spark to start up. Given you have very limited time, and given my luck trying to start the engine after I fuel her up (aka a hot start), I’m not sure that I could do it successfully or not so I won’t try it. It would surely be a final test for your power off 180 if over an airport, and that’s easy to mess up depending upon the winds and luck.

 

[midlifeflyer]

So if I understand correctly; switching off the master would mean there is no electrical power to systems like landing light, anti collision lights, pitot heat and fuel pump?

The electrically run auxiliary fuel ("boost") pump, but not the engine-driven one.

LOL! I'm reminded of a student I once had who was convinced the prop was a "fan" that required the battery to turn. When I shout off the master in flight, I thought he was going to have a cow.