737NG SOP Question

[Guest kelvind80]

Hi there,I am reading the 737NG official Standard Operation Procedures and there's a section that is titled "Establish Electrical Power and Air Conditioning" -- and from what I have read, it is the part when the crew have done the safety exterior inspection, and safety interior inspection, and the next part to get the power running around the aircraft.So far I've had to check if the battery is supplying enough DC power (>= 23V). Basically that's the interior inspection (and ensuring a few other items are in their place). Then it goes onto the establishing electrical power part... it is about starting the APU which is fine; but it states something that doesn't make sense. It says to put it on the buses (in not such an informal way):When the APU GEN OFF BUS light illuminates, move the APU Generator Busswitches to ONBut this light never comes on in the first place... the only time it IS on, is when the standby power is on, yet the standby power switch shouldn't be touched until later on in the SOPs, and so it doesn't make sense.This is from the Official Boeing SOPs.Cheers,Kelvin

[iainsmith 9]

But this light never comes on in the first place... the only time it IS on, is when the standby power is on, yet the standby power switch shouldn't be touched until later on in the SOPs, and so it doesn't make sense.This is from the Official Boeing SOPs.Cheers,Kelvin

You have to have battery power on in order to be able to start and run-up the APU but perhaps what it means is that the rotary switch should not be switched to standby at this time?Iain Smith

[Guest kelvind80]

You have to have battery power on in order to be able to start and run-up the APU but perhaps what it means is that the rotary switch should not be switched to standby at this time?Iain Smith

But the Battery Power is on isn't it, from turning on the Battery switch? Or is that just arming it, and turning on Standby Power actually providing the power?Cause at the moment, the only main switch on is the Battery, then I start the APU which spools up fine, and is fully on... then no light (unless, like I say, Standby Power is on (auto/bat)).Kelvin

[ubersu 78]

But the Battery Power is on isn't it, from turning on the Battery switch? Or is that just arming it, and turning on Standby Power actually providing the power?Cause at the moment, the only main switch on is the Battery, then I start the APU which spools up fine, and is fully on... then no light (unless, like I say, Standby Power is on (auto/bat)).Kelvin

Not sure what SOP you're looking at; the normal sequence is: Battery ON, Standby power switch AUTO - the standby power switch simply provides a mechanism to automatically determine where power is coming from. For example: an external source, the battery, the apu (when on bus)....DJ

[AvA757Pilot 6]

When the APU GEN OFF BUS light illuminates, move the APU Generator Busswitches to ONI see this every time. Once the APU is running the lights illuminate and switching both APU GEN switches on turns it off.