Backup Electric Attitude Indicator

[Seth]

Just now, Gagarin said:

A Turn Coordinator together with a VSI makes an excellent backup for an attitude indicator. By having a vacuum driven gyro you have two different sources of power for attitude indication, specially if you are hit by lightning in IFR conditions.

Good point.

[Gagarin]

Lightning strike usually happens at the prop which can induce a high voltage spike at the alternator that can kill the alternator diodes and electronic equipment such as electronic attitude indicators. Vacuum systems are not affected by lightning.

[JimB]

1 hour ago, Gagarin said:

Lightning strike usually happens at the prop which can induce a high voltage spike at the alternator that can kill the alternator diodes and electronic equipment such as electronic attitude indicators. Vacuum systems are not affected by lightning.

I'll take my battery backed up independent electronic AI knowing the statistical chances of being hit by lighting as opposed to 100% knowing my vacuum pump is going to fail at some point. 

[Skates97]

3 hours ago, Seth said:

Thank you all.

1. I do indeed want to remove the KI256, vacuum system, and standby vacuum system. 

2. I'm not going to do the GI275 for a while unless its required by a major failure of the KI256A, KI525A, or Vacuum system. In the meantime, I would love an emergency backup Attitude indicator or better that is electric and not vacuum powered. The AV-20s seems interesting here, especially withe some of the other functions (like AOA which my aircraft does not have) and it is certified. Maybe just a D3 simply as a backup. I could easily install a used electric device to replace my T&B if it made sense. If anyone has any (I saw some above) PM me. 

3. If I only install 1 GI275 to replace the KI256 and keep my KI525A as my HSI for now (until a future glass upgrade), would the single GI275 have emulated GPSS steering? Or would I have to install a second GI275 for the HSI slot to get the GPSS steering - or any other GPSS device for that matter?

Thanks,

-Seth

It has been documented that the AOA does not function in a Mooney. It has other cool functions, but don't buy one planning on having AOA.

[jetdriven]

2 hours ago, Gagarin said:

Lightning strike usually happens at the prop which can induce a high voltage spike at the alternator that can kill the alternator diodes and electronic equipment such as electronic attitude indicators. Vacuum systems are not affected by lightning.

got an instance of this happening?  Garmin electronics meet the FAA requirements for lightning strike protection.

[jetdriven]

3 hours ago, Gagarin said:

A Turn Coordinator together with a VSI makes an excellent backup for an attitude indicator. By having a vacuum driven gyro you have two different sources of power for attitude indication, specially if you are hit by lightning in IFR conditions.

the FAA disagrees. there are over a hundred instances of folks losing control in IFR condition after vacuum pump gyro failure, with a T/C.  And a bunch more thaty didnt survive.  this is why they published an AC allowing substitution of a second AI in lieu of the T/C.

[laytonl]

23 hours ago, LANCECASPER said:

The AV-20 is a nice clock, but not a proper backup. The AV-20S is certified.

I love the AV20s.  It’s cheap $900, and works great.  I have one in my Citabria as a back up.  Includes AOA, g meter, timers, TAS, and it may even wash the airplane.  (Not sure about the last item.).  It took less the. 2 hours to install.  Lee

v

[takair]

Just now, laytonl said:

I love the AV20s.  It’s cheap $900, and works great.  I have one in my Citabria as a back up.  Includes AOA, g meter, timers, TAS, and it may even wash the airplane.  (Not sure about the last item.).  It took less the. 2 hours to install.  Lee

v

Lee...cant recall if I asked.  Some reports on another forum of the AV-20 leveling off during extended constant rate turns, especially after steep turns.  I’ve been really interested in the AV-20, but this has prevented me from pulling the trigger.  Have you tried extended constant rate turns (ie, 360) and does it maintain the turn?  

 

 

[Gagarin]

3 hours ago, jetdriven said:

got an instance of this happening?  Garmin electronics meet the FAA requirements for lightning strike protection.

On a lightning strike I lost all the alternator diodes so lost the alternator and so the electric turn coordinator power source but continued with the vacuum driven attitude indicator and a flash light. 

[Ragsf15e]

10 hours ago, Gagarin said:

On a lightning strike I lost all the alternator diodes so lost the alternator and so the electric turn coordinator power source but continued with the vacuum driven attitude indicator and a flash light. 

Well that’s a lot different than saying that a battery backup electrical ADI/ADHRS would have also failed.  Of course your TC died when you lost power, it doesn’t have a backup battery.  An Aspen, G5 or G275 would likely continue working just fine.

FWIW I’ve been struck by lightning twice.  Both times flying closer to embedded weather than we should have.  Not my finest hours... We did not have weather radar, adsb or xm.  Granted, both were in USAF aircraft, but everything kept working perfectly and we didn’t know we were hit until we were on the ground and found the burn holes and blown out lights bulbs.

[0TreeLemur]

2 hours ago, laytonl said:

I love the AV20s.  It’s cheap $900, and works great.  I have one in my Citabria as a back up.  Includes AOA, g meter, timers, TAS, and it may even wash the airplane.  (Not sure about the last item.).  It took less the. 2 hours to install.  Lee

v

Recently I saw the AV20s advertised for $700.  

Pros:

It fits in a small hole. 

Clock works great, as do the run time and flight timer. 

OAT is fine. 

The AI seems to be fine.  Most of the time I have it displaying the AI and it has always agreed with the vacuum AI. 

Cons:

The AOA is unuseable. 

TAS is off. 

 

 

[jetdriven]

8 hours ago, Gagarin said:

On a lightning strike I lost all the alternator diodes so lost the alternator and so the electric turn coordinator power source but continued with the vacuum driven attitude indicator and a flash light. 

You said this:

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  •  

Posted 14 hours ago

Lightning strike usually happens at the prop which can induce a high voltage spike at the alternator that can kill the alternator diodes and electronic equipment such as electronic attitude indicators. Vacuum systems are not affected by lightning.
 

you do know that these electronic attitude indicators are powered also by backup batteries right? The G5 has a 4 hour battery. 

[takair]

7 hours ago, 0TreeLemur said:

Recently I saw the AV20s advertised for $700. 

Do you recall where you saw this?  That might motivate me.  Have you noted any performance degradation in continuous turns?  I know it’s not an everyday thing, but seems to be the weakness of many of the low cost solutions.

[0TreeLemur]

17 hours ago, takair said:

Do you recall where you saw this?  That might motivate me.  Have you noted any performance degradation in continuous turns?  I know it’s not an everyday thing, but seems to be the weakness of many of the low cost solutions.

Looking through my inbox I cannot find it.  Maybe I saw it on a web site.  It was an Oshkosh special if I recall correctly so it is probably long gone.  Next chance I get to do a steep turn test I'll do that and see if it comes back to level.

[Bob - S50]

22 hours ago, takair said:

Do you recall where you saw this?  That might motivate me.  Have you noted any performance degradation in continuous turns?  I know it’s not an everyday thing, but seems to be the weakness of many of the low cost solutions.

I think it was on Beechtalk, but it sold.

[Gagarin]

More reliable than a vacuum pump is a venturi tube https://www.aircraftspruce.com/catalog/inpages/venturi2.php. Used in the early gyro systems. You can backup your vacuum pump with a venturi tube instead of another pump.

[Seth]

5 hours ago, Gagarin said:

More reliable than a vacuum pump is a venturi tube https://www.aircraftspruce.com/catalog/inpages/venturi2.php. Used in the early gyro systems. You can backup your vacuum pump with a venturi tube instead of another pump.

Good point. However, I have made the deicision to move away from the KI256 and the vacuum system. I already have a staby vac. This is good information for those that want a backup for their vacuum run mechanisms.

I plan to remove my vacuum system at some point. So I'm looking for an electric backup (can be gyro, though I'm leaning toward solid state) as a backup Attitdue Indicator - if it's a full EFIS even better. The AV20s sounds promising - but I've had some close people to me say not to do it. So more investigating for now.

It would serve as the backup to my KI256 now and likely the backup to the future GI275 whenever I go and do that as the GI275 is the least expensive glass (and a nice package on top of that) that can run my King KFC200.

The question becomes, can a single GI275 run GPSS? I know dual GI275's can, but can a single GI275 do this? If I need to get 2 GI275's it's going to change my opinion on what I do in the meantime (meaning maybe just a used Dynon D2 or a Dynon D3 which I'd then sell) vs installing another AI in the cockpit which would later get pulled out. 

Then again, even with two GI275's, if I had an earlier backup AI or even Backup EFIS, I can always move it to the pax side so a right seat could have something better in thier view.

Thanks to all for the suggestions.

-Seth

[laytonl]

On 8/18/2020 at 10:11 PM, takair said:

Lee...cant recall if I asked.  Some reports on another forum of the AV-20 leveling off during extended constant rate turns, especially after steep turns.  I’ve been really interested in the AV-20, but this has prevented me from pulling the trigger.  Have you tried extended constant rate turns (ie, 360) and does it maintain the turn?  

 

 

I’ve done lots of 60 Degree bank 360s.  The unit worked fine and levels out quickly.  My son has done loops and rolls (Citabria) and said the unit worked well through the events.  He couldn’t recall how it handled hammerheads.  As someone said the AOA is marginal at best.  I found the TAS is dead on.  Only issue I’ve had is that the airplane cannot be moved until the unit stabilizes which takes about a minute.  Shouldn’t be a problem in the Mooney but in the Citabria we have to resist rolling once started.  Lee

[takair]

26 minutes ago, laytonl said:

I’ve done lots of 60 Degree bank 360s.  The unit worked fine and levels out quickly.  My son has done loops and rolls (Citabria) and said the unit worked well through the events.  He couldn’t recall how it handled hammerheads.  As someone said the AOA is marginal at best.  I found the TAS is dead on.  Only issue I’ve had is that the airplane cannot be moved until the unit stabilizes which takes about a minute.  Shouldn’t be a problem in the Mooney but in the Citabria we have to resist rolling once started.  Lee

Lee, thanks, great feedback.  One last question.  What happens if you don’t let it stabilize?  I often want to get out of our hangar row before someone turns the corner, then stop and get ATIS and clearance.  Will it then recover or would it need a re-start?

[Skates97]

On 8/18/2020 at 4:51 PM, jetdriven said:

the FAA disagrees. there are over a hundred instances of folks losing control in IFR condition after vacuum pump gyro failure, with a T/C.  And a bunch more thaty didnt survive.  this is why they published an AC allowing substitution of a second AI in lieu of the T/C.

I just put the RCA 2610-3 in with slip indicator, turn rate, and backup battery. It was a simple installation, it replaced my old electric TC which had started making noise. I am glad we had it,on the flight to Sunriver today when the vacuum pump decided it was done. We weren't IMC but there was plenty of smoke all the way up the central valley so the horizon line was blurry, if there at all, requiring constant attention to instruments. I saw the vacuum gauge was at zero and a little while after that the AI started to lean, followed by the DG which was slowly precessing and eventually spinning, but that 2610 is a great instrument and rock solid. I put a piece of paper off my notepad over the AI/DG and flew the 2610, which is way easier to fly with than a standard vacuum AI.

[takair]

6 hours ago, Skates97 said:

I just put the RCA 2610-3 in with slip indicator, turn rate, and backup battery. It was a simple installation, it replaced my old electric TC which had started making noise. I am glad we had it,on the flight to Sunriver today when the vacuum pump decided it was done. We weren't IMC but there was plenty of smoke all the way up the central valley so the horizon line was blurry, if there at all, requiring constant attention to instruments. I saw the vacuum gauge was at zero and a little while after that the AI started to lean, followed by the DG which was slowly precessing and eventually spinning, but that 2610 is a great instrument and rock solid. I put a piece of paper off my notepad over the AI/DG and flew the 2610, which is way easier to fly with than a standard vacuum AI.

You got your money’s worth almost right away!!

[Skates97]

3 hours ago, takair said:

You got your money’s worth almost right away!!

No kidding, there was a check flight around the pattern and then the next flight is when the pump failed. After seeing how easy it is to fly that instrument it makes me wish I would have just pulled the vacuum AI years ago and put this in as it can be primary AI. Having it as a backup to the G5's will be nice. 

Oh, and thanks to your electric step I put in during annual in December my step stayed up! 

[laytonl]

20 hours ago, takair said:

Lee, thanks, great feedback.  One last question.  What happens if you don’t let it stabilize?  I often want to get out of our hangar row before someone turns the corner, then stop and get ATIS and clearance.  Will it then recover or would it need a re-start?

I haven’t been able to realign in flight.  So, I believe it would need to be shut down and restarted.  Lee

[carusoam]

+1 for the Mooney accident that never happened...

+1 for the magic of the electric Servo...
 

The vacuum system knows it’s days are number... expect a re-volt... or an un-volt?

PP humor only...

Best regards,

-a-