Advice on a back-up attitude indicator

[M20F-1968]

I started this thread to get some ideas on how I might proceed with a back-up attitude indicator.  I have a modern panel with G-600, a 2" electric Midcontinent  attitude indicator (without the back-up battery) and a vacuum Sigma Tek 3 1/4" attitude indicator.  (For those who are thinking, why does he have 3, the answer lies in the time it took to finish my rebuild.  The panel started with steam gauges and ended up as a glass panel).  I need to overhaul the gyro, and maybe replace the vacuum pump.  I have a 1968F so I need to keep the vacuum pump to operate the retractable step.

My question is, do I keep the vacuum attitude indicator given that it is true redundancy and will survive an electrical failure (unlikely that both an electrical failure and a vacuum failure will occur on the same flight)?   Or, alternatively, do I remove the vacuum attitude indicator and replace it with a Garmin G5 which has a battery and will provide 2-4 hours of flight time in an emergency?

Is there something else I should put in the 3 1/4" hole in the panel?

The rest of the equipment is Garmin 600, 750, 650, S-Tec 60-2 with altitude pre-selector, Ryan TCAD, GDL-69. 

Pictures of my panel are on my profile.  The attitude indicator in question is mounted below the G600 and just above the pilot's yoke.

There are advantages each way.  Wanted to get a consensus opinion.

John Breda

 

[kortopates]

I think you'll find the Garmin G5 is not approved as backup for glass, just primary.

I have similar panel and went with the LSI-500 https://www.l-3avionics.com/media/8189/ESI500_Sales_Sheet.pdf , With the LSI-500 you can also ditch all 3 of your backup instruments (IAS, Attitude, Altimeter) and with the NAV function upgrade get backup for both GPS/RNAV and ILS.

[M20F-1968]

So if the G5 is certified as a primary unit, and I already have a G600 which is primary, why can a G5 not be used in a lesser role as back-up to another unit certified as primary?  It seems the FAA would be happier that 2 primary capable units are installed.

John Breda

[kortopates]

5 minutes ago, M20F-1968 said:

So if the G5 is certified as a primary unit, and I already have a G600 which is primary, why can a G5 not be used in a lesser role as back-up to another unit certified as primary?  It seems the FAA would be happier that 2 primary capable units are installed.

John Breda

Because the requirements are different for serving as a backup to glass than replacing gyro's since there is more at stake. Plus the STC's the primary's (Garmin and Aspen) have their own requirements for backups.

The L3 LSI-500 was actually designed to be a full backup to EFIS panels, unlike the G5. 

And no, you can't install the G5, and call it your primary and your G600 and call it your backup. Placement position of your G600 settles that debate right away. In case you were wondering

[M20F-1968]

I was considering the G5 as a back-up to the G600.  Perhaps Garmin themselves may be able to define this further since they hold both the STC's.

John Breda

 

[RobertGary1]

You have to look at the STC of whatever you have as primary. I believe most say that they require a backup that is fed from a different source of power.

 

-Robert

[Cruiser]

for the same reason you can't use a current, valid 3rd class medical exam to satisfy the new BasicMed physical requirement. 

The paperwork is more important (to the FAA) than the products that paperwork represents. 

Actually, the FAA is getting better at this but they still have a long way to go and modern, technological advancements will always be a step ahead of them.

[LANCECASPER]

34 minutes ago, M20F-1968 said:

I was considering the G5 as a back-up to the G600.  Perhaps Garmin themselves may be able to define this further since they hold both the STC's.

John Breda

 

Based on things I've read here and Beechtalk I don't think the G-5 is quite there yet. There have been a few updates which have improved it. I wouldn't hesitate to replace the turn coordinator with a G-5 in a 6 pack steam gauge panel, but to have it as your only back up on a glass panel, I would be nervous. The L3 LSI-500 is much more capable.

[RobertGary1]

Just now, LANCECASPER said:

Based on things I've read here and Beechtalk I don't think the G-5 is quite there yet. There have been a few updates which have improved it. I wouldn't hesitate to replace the turn coordinator with a G-5 in a 6 pack steam gauge panel, but to have it as your only back up on a glass panel, I would be nervous. The L3 LSI-500 is much more capable.

I"m going to move my current attitude indicator off to the side outside the 6 pack and install the G5. I think its the greatest thing since sliced bread. 

-Robert

[peevee]

the dynon unit is STC'd for the m20 as a backup, if I remember correctly.

[Marauder]

John -- I am installing an L-3 ESI-500 to backup my Aspens. I will be removing the vacuum system, the ASI, mechanical altimeter and the mechanical AI. From my understanding (what the avionics shop informed me of) the Sandia unit can also act as a backup with a field approval. The limiting factor for acting as a backup is stipulated in the STC for the G600 and Aspen. And as crazy as it sounds, as was mentioned above, the G5 is not certified to act as a backup but can be used as a primary.

[carusoam]

On similar topics.  

1) A second alternator is often used in place of the vacuum pump.

2) A linear actuator would then be needed for the step.

3) Rob T has been using linear actuators for his auto mixture controller in Mooneys...

4) There are a few of the electric vacuum pumps being retired lately as the glass becomes widely accepted...

5) Steven757 posted photos of the most recent modern Mooney panel in his gallery.

6) I find it a bit odd that big G doesn't have something to fit that role.  The G5 comes close.

Let me know if I can dig out some additional details for your project...

Best regards,

-a-

Edited February 1, 2017 by carusoam

[thinwing]

Hi there...why not install the backup battery for the midcontinent AI as your backup

[RobertGary1]

28 minutes ago, thinwing said:

Hi there...why not install the backup battery for the midcontinent AI as your backup

That wouldn't provide a back up instrument though.

-Robert

[StevenL757]

John, gotta' agree with Paul and Marauder here...spend a bit extra and put in the ESI-500.

- Approved for legal backup by Garmin for the GDU-620 display

- Allows NAV/VLOC/GPS inputs from either or both 650 and 750 (Don K. has this setup in his Bravo)

- MAG-500 dedicated heading (magnetometer) available for true heading redundancy

- You have a SynVis option available on the ESI-500 to even back that up from your GDU-620 if you choose

If you didn't require the vac system to power that step (can it be powered electrically?), I'd say lose the vacuum system, gain some more panel space by removing analog gauges, and increase useful load.  Check with Brian if you want additional opinion, but for the money you've spent on your panel to-date, to me, the ESI-500 is the only way to go.  I have every option available on it, and couldn't be happier.  It quite literally is a mini-G500 in this configuration.

Regards, Steve

[thinwing]

6 hours ago, RobertGary1 said:

That wouldn't provide a back up instrument though.

-Robert

Read his first post

[M20F]

If the goal is redundancy then vacuum and electric provides the best option.  

Personally I am not a fan of all vacuum or all electric set ups.  

[LANCECASPER]

1 hour ago, M20F said:

If the goal is redundancy then vacuum and electric provides the best option.  

Personally I am not a fan of all vacuum or all electric set ups.  

The long body Mooneys all have two ships batteries so with electric primary and backup there's a lot of electricity there to get it back safely on the ground.

[ArtVandelay]

8 hours ago, LANCECASPER said:

The long body Mooneys all have two ships batteries so with electric primary and backup there's a lot of electricity there to get it back safely on the ground.

I assume they have 2 alternators to pair with the batteries? Which gives more redundancy.

[Guest]

9 hours ago, LANCECASPER said:

The long body Mooneys all have two ships batteries so with electric primary and backup there's a lot of electricity there to get it back safely on the ground.

In the G1000 installation in a Mooney there is no provision for a second AHRS gyro, so when it dies you are on the standby which is not in the greatest location.

Clarence

[M20F]

10 hours ago, LANCECASPER said:

The long body Mooneys all have two ships batteries so with electric primary and backup there's a lot of electricity there to get it back safely on the ground.

The one gap there is there is no redundancy to the electricity itself.  So a fire or some sort of electrical catastrophe and you are SOL.  Vacuum is a separate and non-related back up system.  Having both provides the highest level of redundancy and it is cheaper to boot. 

[carusoam]

Long body ideas....

1) a pair of batteries.

2) a pair of alternators.

3) a pair of electrical busses.

4) a pair of electric AIs.

Mike, I'll have to think of a pair of ideas to come up with a solution for fire.  Declare the e-word and descend with gear and speed brakes out, while doing checklists...

PP ideas only...

Best regards,

-a-

 

[FloridaMan]

I'd keep a mechanical gyro as a backup if possible vacuum or otherwise. I've seen digital ones get a bit confused at times and dance around and like the redundancy in modes of failure.