Primarily for general aviation discussion, but other aviation topics are also welcome.
By Gas Guzzler
#1790337
Hi G5 users, I'm having a pair of G5's fitted soon and am wondering about the power down arrangement, since they have a back-up battery, do they automatically shut down after switching off the main aircraft power or do they have to be turned off manually. Maybe a dumb question but I had a look at the pilot's guide but it's not clear. Thanks.
By ArrowStraight
#1790340
We have one as an AI. It does automatically turn off but takes it's time. You can hold the power button to turn it off in 3 seconds.
After one particularly hot flight the other day it was turning itself on an off again, using the internal battery, for some considerable time. On a later flight, there was apparently a brief "critical battery" message, but since it's cooled a little where we are it seems to have settled down.
A little worrying as the extra money was spent in the hope it would last longer than the "new" steam gauge that died after 2 years.
By Gas Guzzler
#1790345
Ah thanks for that, like you I replaced the "steam powered" AH within the last 2 years and that has fauiled again. In 14 years I've had 3 new DI's and 2 new AH's definitly time to replace with G5's methinks and hope they last!
By AndyWW
#1790351
We put 2 G5's in our RV-6 just over 2 years ago and had no problems so far. We have back-up batteries in both. They turn off after 45 secs once they lose aircraft power unless you press a button (at least on the ground - haven't tried turning off the master in flight yet!) We are very happy with them.
Andy
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By TLRippon
#1790395
My 2 power off after 45 seconds but if you press the buttons for three seconds they power off immediately. If for some reason they don’t start up then you need to keep your finger on the button for up to 20 seconds while it goes through background startup tasks. Be careful they start the countdown to turning off when you cut the master, if they don’t and you don’t manually switch them off then the internal batteries will be drained by the next time you use the aircraft. This happens if you switch the master on for a few seconds to do something and switch it back off again quickly before the G5 has time to start properly.
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By rdfb
#1790396
To be clear: when the master switch is turned off, the G5 displays something along the lines of "I will shut down unless you ask to keep me on" with a 30 second countdown. In the normal case this is what you want, you don't have to pay any attention and the G5 shuts down after the countdown completes. All you had to do was turn the master off as normal at the end of your flight.

The intention being, presumably, that if you're in IMC (for example) and have a power failure, you can press a button to keep the G5 on with its battery backup.
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By Dave W
#1790677
On a related subject:

Do people switch off the G5 for engine startup and shutdown? The manual doesn't advise one way or the other.

I was taught "avionics off" for startup and shutdown, and told that is why some aircraft have split Master switches. I have assumed this to be still valid for modern avionics but a couple of conversations recently have suggested it isn't what everybody does with modern kit.
By AndyWW
#1790718
Our G5s and JPI EDM-350 stay on for engine start and shutdown. No ill-effects so far (2 years for the G5s, less than a year for the JPI).
Andy
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By alexbrett2
#1790720
The G5s have a setting called "Automatic Power Off" - for certified aircraft I believe it's required to be set to 'Ground Only', at which point if the G5 believes you're on the ground (not sure how it decides, guessing either airspeed or GPS height), it'll give you the power down message then turn off, but if in the air it should continue to operate on its standby battery, which makes sense from a safety point of view...
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By NDB_hold
#1790742
@rdfb that's not why the master is split - if you look you’ll find the two sides are battery and alternator.

Starting with the alternator field off is easier for the engine (as the alternator doesn’t 'fight back' since it’s not generating power). This is normal procedure and in the POH for some aircraft (e.g. Firefly) but for common spamcans the POH checklists usually seem to have 'master on' as a single item. Don’t know why.
By jacekowski
#1790769
Dave W wrote:On a related subject:

Do people switch off the G5 for engine startup and shutdown? The manual doesn't advise one way or the other.

I was taught "avionics off" for startup and shutdown, and told that is why some aircraft have split Master switches. I have assumed this to be still valid for modern avionics but a couple of conversations recently have suggested it isn't what everybody does with modern kit.


Modern avionics can be powered when cranking - it is not recommended for a different reason (same reason why cars used to shut down all electrical equipment when cranking) - less load on the battery and on cold winter day it could be the difference between having enough current available to start the engine or not.
By User72
#1790947
Dave W wrote:On a related subject:

Do people switch off the G5 for engine startup and shutdown? The manual doesn't advise one way or the other.

I was taught "avionics off" for startup and shutdown, and told that is why some aircraft have split Master switches. I have assumed this to be still valid for modern avionics but a couple of conversations recently have suggested it isn't what everybody does with modern kit.


Dave, the answer is in DD160, all equipment available now must be able to cope with the power transients from start up and shut down. The 'power spikes' at start up that ppl instructors talk about don't exist, they are brown outs rather than spikes, equipment can now cope. The need to keep the alternator off while cranking may have been of (a little) benefit 50 years ago but no longer. Treat the split master as one switch. I don't have a separate alternator switch in my aeroplane. I also don't have an avionics master.

Switch stuff off before you press the starter if it makes you feel better, but there is no technical reason for it.