Is a turn and bank required with a backup electric ai in place?

[65eTurbo]

My turn coordinator is getting lazy, but it has already been moved over to put an electric AI in the same space.  Is a turn coordinator required if an electric backup AI is in place?  Would a ball alone be sufficient?

[LANCECASPER]

https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC91-75.pdf

[65eTurbo]

Thanks!  Placard inop!

[Skates97]

When it says a separate power source, does than mean you need dual alternators? I would think if there is a single alternator then it really doesn't have a separate power source. 

[ArtVandelay]

When it says a separate power source, does than mean you need dual alternators? I would think if there is a single alternator then it really doesn't have a separate power source. 

Technically, neither does a glass display with a G5 or equivalent as backup.


Tom

[Jerry 5TJ]

3 hours ago, Skates97 said:

When it says a separate power source, does than mean you need dual alternators? I would think if there is a single alternator then it really doesn't have a separate power source. 

The definition of “a separate power source” is found in 23.1331. 

I haven’t found the basis for approval of a separate battery powered backup.  

“Seems reasonable” that a solid hour of backup operation is enough for single engine Part 91 operations  

 

[larrynimmo]

My instrument installer as with mike studly of Aspen both agreed that my newly installed E5 could be mated with a Garmin G5 in lieu of the turn coordinator.. even though that the E5 while rated as a primary instrument, it is technically not rated as a back up instrument.

i feel much safer having two ai each with their independent back up battery packs.

both ai give you “ball” coordination and info for a stabilized standard turn 

[Jesse Saint]

Separate power source means it can be electric if the primary is vacuum.