Dual vacuum failure in Ovation

[BorealOne]

9 hours ago, carusoam said:

Boreal,

Any answer to what disabled your lost back up-vac system?

Best regards,

-a-

Not yet - teardown starts on Thursday. I'm decided to have the vacuum system removed, so it's all coming out. My KI 256 will be swapped with a KI 254 (the electric version) as the backup AI. Stay tuned for the answers on the standby vac failure - I'm suspecting that it's the Tygon tube...

[MIm20c]

1 hour ago, BorealOne said:

Not yet - teardown starts on Thursday. I'm decided to have the vacuum system removed, so it's all coming out. My KI 256 will be swapped with a KI 254 (the electric version) as the backup AI. Stay tuned for the answers on the standby vac failure - I'm suspecting that it's the Tygon tube...

I’m not trying to nag but I don’t want your shop to have the panel torn down and then give you the bad news once they figure out the 254 is not a legal backup to the aspen. You need to have a battery back inside the AI or an expensive external battery backup solution. I know it seems crazy with dual batteries and alternators but if you want to keep it legal double check with them. I’d replace the vac and remove the backup vac and carry on. 

[gsxrpilot]

On 12/29/2019 at 3:56 PM, aviatoreb said:

KFC200?

Sorry, KFC150

[Jerry 5TJ]

4 hours ago, LANCECASPER said:

....I'll hang on to my spinning Mid-Continent Lifesaver Electric AI with battery backup

The issue is the magnetic sensor & not the  gyro, spinning or solid state.  
If you want a backup AI that won’t be affected by magnetic issues you don’t need to keep the rotating mechanical gyro. 
As an example an RCA-2610-3 will work fine at all latitudes.  And it won’t tumble.  

https://www.aircraftspruce.com/catalog/inpages/rca2610.php?gclid=EAIaIQobChMIxcyOz4vy5gIVFKSzCh0lyQsIEAQYASABEgLG_fD_BwE

[BorealOne]

9 hours ago, MIm20c said:

I’m not trying to nag but I don’t want your shop to have the panel torn down and then give you the bad news once they figure out the 254 is not a legal backup to the aspen. You need to have a battery back inside the AI or an expensive external battery backup solution. I know it seems crazy with dual batteries and alternators but if you want to keep it legal double check with them. I’d replace the vac and remove the backup vac and carry on. 

Not nagging at all. I'm finding there are different interpretations of 23.1311 and how it applies to my TKS-equipped Ovation.

 

As I understand the requirements, my Aspen PFD install requires a back-up attitude display with independent power. In a TKS-equipped Ovation, there is a both a separate emergency buss and a standby alternator. If the 254 is wired into to the emergency buss, which can be disconnected from the primary buss and can be powered by the secondary alternator in the event of the failure of the primary, doesn't it meet the requirements for independence and redundancy?

Edited January 8, 2020 by BorealOne

[MIm20c]

This is a very good question. I was told the models previous to 2003 did not have a dual bus system that had independent power from the batteries forward. Instead it was split at the panel. However, with the backup alternator piped in at that point it might satisfy the requirement. I’d really like to see a good breakdown of the emergency bus and how it works...something I should’ve looked up a long time ago. 

[BorealOne]

Here's what my POH says: 

 

The Standby Altemator for the M20R consists of a 20 Amp standby altemator mounted to

the engine accessory case vacuum pump pad. The altemator is a 24 volt unit. The

system includes a voltage regulator unit, annunciator light, Stand-by Alt ON/OFF switch, and

an electncal buss (Emergency Buss) configuration to provided specific. dedicated equipment

generated power.

The Standby Altemator system is required equipment for the installation of the certified

fight into known icing TKS STC kit. The system ls offered as a separate optional equipment

installation for the M20R for owners who desire a second source of electncal generation.