Avionics power off mid-flight

[Will.iam]

3 hours ago, T. Peterson said:

That’s cool!! I didn’t know such an animal existed. Thanks for posting. You’re an ok fella no matter what everyone else says!

I bet Sue feels a lot better also.

I told you not to believe everything you hear and you are just now realizing it’s true told you so. Haha. 

[A64Pilot]

Many of us have foreflight, check out it’s synthetic vision which requires an AHARS of course, but that’s a Sentry or Garmin GDL-50 or similar 

You get more functionality that you do with the Dynon and on something your probably using now

Just don’t get suckered into any of the iPhone apps, maybe the newer ones do, but the older iPhones / iPads don’t have gyro’s so the app emulates an artificial horizon but as it uses accelerometers if you put it in a standard rate or any turn and hold it the artificial horizon will level itself in a short time. Graveyard spiral.

[jlunseth]

The portables only work safely if they are in a fixed mount, bolted to the structure of the aircraft. Laying on the glare shield, suction cupped to a window, RAM mounted or taped to something are all recipes for an upset in IMC. Get in turbulence, have the portable move, and you will find that the plane is upside down even if it isn’t. 

[EricJ]

14 minutes ago, jlunseth said:

The portables only work safely if they are in a fixed mount, bolted to the structure of the aircraft. Laying on the glare shield, suction cupped to a window, RAM mounted or taped to something are all recipes for an upset in IMC. Get in turbulence, have the portable move, and you will find that the plane is upside down even if it isn’t. 

When I learned to fly in the 70s it was normal for everybody to have kneeboards, at least where I flew.   So I got an appstrap that holds my big tablet to my knee like a kneeboard.    I also fly with a small tablet in a ram mount on the pilot's yoke, and I've never had that move even in bad turbulence.   During an approach I have the approach plate on the yoke tablet and the normal map on the knee tablet.   In a pinch I could put the plate on both if I was worried about losing the one on the yoke for some reason.

[carusoam]

Key thing is… what is holding your back-up AHARS in place and powered up?

When the back-up device becomes primary…without warning…

You get very little time to wonder which device is telling the truth.

The panel placed Dynon D3 makes a good comparison to measure your favorite back up system against…

PP thoughts only, not an instrument guru…

Best regards,

-a-

[bradp]

I’ve accumulated a bunch of backup and redundancy for AIs over the years.  The only common failure point is electricity drives everything 
 

Started with an iPad and stratus with ahrs

Next we installed a single G5, kept the vacuum autopilot AI in the TC position  

Then a second G5 as an HSi

Then a flight stream 210 (has an ahrs)

Then ditched the vacuum AI and installed an RC Allen 2600 electric AI 

Finally, installed a GDL-52R bolted to the avionics shelf as ADS-B.  This also happens to have an ahrs. 
 

So I’ve got three primary and backup sources of attitude information, two of which run on their own batteries.  I’ve got three additional AHRS redundantly presenting attitude information on an iPad and/or an Aera 660.  And I kept the old trusty stratus.  I better be able to keep the dirty side down.  
 

[jlunseth]

11 hours ago, EricJ said:

When I learned to fly in the 70s it was normal for everybody to have kneeboards, at least where I flew.   So I got an appstrap that holds my big tablet to my knee like a kneeboard.    I also fly with a small tablet in a ram mount on the pilot's yoke, and I've never had that move even in bad turbulence.   During an approach I have the approach plate on the yoke tablet and the normal map on the knee tablet.   In a pinch I could put the plate on both if I was worried about losing the one on the yoke for some reason.

It’s not the plates that are the concern. It is the validity of any reading from the accelerometer in the portable devices like the Stratus that report attitude information, such as in Foreflight. I keep my iPad with Foreflight and plates in a kneeboard, works good.

[EricJ]

21 minutes ago, jlunseth said:

It’s not the plates that are the concern. It is the validity of any reading from the accelerometer in the portable devices like the Stratus that report attitude information, such as in Foreflight. I keep my iPad with Foreflight and plates in a kneeboard, works good.

Portable AHRS should be strapped down somehow if they're depended on for redundancy, but these days with multiple G5s/275s/Aspen/whatever with backup batteries of their own, the likelihood of needing one is diminished.   It's a good option to have, though, if needed and it's not tough to secure a portable device if it is part of the redundancy plan.

It's also a good idea to test the utility of the portable AHRS systems even if strapped down.   The early ones that could be cobbled together in a stratux weren't very good, but I think the later ones are better.   Anything that's expected to be used should be tested ahead of time in suitable conditions, ideally.

 

[T. Peterson]

11 hours ago, bradp said:

I’ve accumulated a bunch of backup and redundancy for AIs over the years.  The only common failure point is electricity drives everything 
 

Started with an iPad and stratus with ahrs

Next we installed a single G5, kept the vacuum autopilot AI in the TC position  

Then a second G5 as an HSi

Then a flight stream 210 (has an ahrs)

Then ditched the vacuum AI and installed an RC Allen 2600 electric AI 

Finally, installed a GDL-52R bolted to the avionics shelf as ADS-B.  This also happens to have an ahrs. 
 

So I’ve got three primary and backup sources of attitude information, two of which run on their own batteries.  I’ve got three additional AHRS redundantly presenting attitude information on an iPad and/or an Aera 660.  And I kept the old trusty stratus.  I better be able to keep the dirty side down.  
 

As -a- might say, you win the day for redundancy!!

Good show!

-t-

[A64Pilot]

18 hours ago, jlunseth said:

It’s not the plates that are the concern. It is the validity of any reading from the accelerometer in the portable devices like the Stratus that report attitude information, such as in Foreflight. I keep my iPad with Foreflight and plates in a kneeboard, works good.

An AHARS is primarily gyros, not accelerometers. Accelerometers won’t drive a horizon or the iphone apps would work. Most AHARS will have a dampening or smoothing on their outputs to keep vibration from showing up in the output or you would have a jittery horizon, so any realistic mount, even velcro won’t be an issue, try it and see.

[Pinecone]

I am a big fan of the idea of separate busses with separate paths to power.   Split the the avionics so either bux gives you an AI, com, and nav.

Another possibility is a separate power path using a simple switch. That is only used in emergencies (relay fails).

[Yetti]

14 hours ago, Pinecone said:

I am a big fan of the idea of separate busses with separate paths to power.   Split the the avionics so either bux gives you an AI, com, and nav.

Another possibility is a separate power path using a simple switch. That is only used in emergencies (relay fails).

We still don't know if the relay failed.   It could very well be that the Mechanic misdiagnosed a NC relay for a NO relay.

[Pinecone]

True.

But thinking forward about how to set up my panel when I do an upgrade.

[swsmith]

Following up on this - we managed to fix the airplane and in doing so we added a "avionics master bypass" switch in case this ever happens again.

[tmo]

You mean the 'aux' circuit breaker?
Seriously, with the master on and avionics master OFF turn a radio or some other avionics device on. It should not power up. Now pull the AUX circuit breaker out and you should see the avionics come to life.

Did it really take that long to get the issue fixed?

[kortopates]

You mean the 'aux' circuit breaker?
Seriously, with the master on and avionics master OFF turn a radio or some other avionics device on. It should not power up. Now pull the AUX circuit breaker out and you should see the avionics come to life.
Did it really take that long to get the issue fixed?

What you describe is true with a factory installed avionics master switch. But vintage models don’t have these and there were many add on avionics switches that where not installed using the factory method and i’ve seen others install the bypass switch rather than install the avionics switch like the factory does with a normally closed NC relay that is powered on to turn off the radios - the fail safe method.
Of course i don’t know what model this is, but the description of the issue matches a vintage mooney without a factory avionics switch that was modded to add one - just not the way the factory does it.


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[LANCECASPER]

11 hours ago, kortopates said:

Of course i don’t know what model this is, but the description of the issue matches a vintage mooney without a factory avionics switch that was modded to add one - just not the way the factory does it.

@swsmith's signature line looks like he flies a 1979 Mooney 231. Great blog: thefiftyproject.com

[swsmith]

Thanks! Yes we didn’t have a AUX breaker. I’ve flown in later model Mooney’s with them and I’m aware of how they work. Funny enough we managed to fly to all lower 48 states on the fifty project trip only a few months before this happened with no issues so we were probably due for it. 

[tmo]

Interesting - I have a 1980 M20K, sn 396, and figured N231ER (which is also a M20K, sn 213) would be close enough. I was wrong. What a difference a few serial number make. Apologies for possibly sounding like an ass, it was never my intention.

[PT20J]

4 hours ago, tmo said:

Interesting - I have a 1980 M20K, sn 396, and figured N231ER (which is also a M20K, sn 213) would be close enough. I was wrong. What a difference a few serial number make. Apologies for possibly sounding like an ass, it was never my intention.

I'd have to check the schematics, but I'd be amazed if 1980 Ks didn't all have an AUX Bus. My 78 J had one.

[bradp]

1 hour ago, PT20J said:

I'd have to check the schematics, but I'd be amazed if 1980 Ks didn't all have an AUX Bus. My 78 J had one.

If I recall correctly all J and higher had normally closed avionics / radio masters so that if power failed the avionics would fault to an “on” state.   I believe the modern panel Fs also had relays but I can’t recall if the shotgun six pack panels had this setup.  Maybe an owner can inform.? 

 

[swsmith]

My 1979 K doesn’t have that. The relay is also the part that failed and it didn’t failed in a way that allowed power to still flow. I’ve heard the 24v systems do this but mine is a 12v system

[Will.iam]

On 12/28/2022 at 9:49 AM, T. Peterson said:

As -a- might say, you win the day for redundancy!!

Good show!

-t-

I have vacuum adi that has the engine vacuum plus a standby vacuum pump that is electrically driven. A electrically driven standby adi which i have 2 alternators to power and the battery also have the ahars ads-b with a foreflight ipad that i could use the internal battery of the ipad for another 6 hours with its own gps if i lost both vacuum pumps and both alternators and the battery. I will run out of gas before i run out of horizon information. 

[PT20J]

6 hours ago, swsmith said:

My 1979 K doesn’t have that. The relay is also the part that failed and it didn’t failed in a way that allowed power to still flow. I’ve heard the 24v systems do this but mine is a 12v system

This is interesting. I just looked at the schematic for 25-0002 thru 25-0171 (the first batch of 231s which should all be 12V) and it shows an AUX bus breaker and a normally closed radio relay. I did not trace all the wires to be certain that the relay is powered through the AUX bus, but as that was standard practice, I'm reasonably certain that it is. The AUX bus is the circuit that feeds the breaker switches at the bottom of the pilot's instrument panel (landing lights, strobes, nav lights, boost pump, pitot heat, etc.). The purpose of the aux breaker is to protect the power wire between the main bus and the aux bus. Perhaps someone rewired this ship at some point?

[T. Peterson]

4 hours ago, Will.iam said:

I have vacuum adi that has the engine vacuum plus a standby vacuum pump that is electrically driven. A electrically driven standby adi which i have 2 alternators to power and the battery also have the ahars ads-b with a foreflight ipad that i could use the internal battery of the ipad for another 6 hours with its own gps if i lost both vacuum pumps and both alternators and the battery. I will run out of gas before i run out of horizon information. 

That is a beautiful thing!!