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Avionics failure in IMC

MConner

Well Known Member
Ok so here I go exposing myself to the flame thrower to hopefully help someone else avoid my SNAFU.

I departed In my -10 at night on a stormy, night IFR flight plan for a 50 minute hop home after a long duty day as a corpotate jet jock. I climbed into the clouds around 2000? climbing to 10?000? and upon entering the soup, the landing light was glaring off the clouds. I reached up to turn it off and grabbed the avionics master instead. The G3 and all three displays went black as did the com radio just as ATC was issuing a change to my clearance.

Luckily I had added a G5 with it?s battery backup shortly after buying the plane. I immediately went into mental reversionary mode and began hand flying while the G3x system ran through the reboot process. It was a long 2-3 minutes for the ADAHRS to realign and even longer for the Garmin 650 to join the fun.

There was never a time that I was not flying the plane just fine but I have spent a lifetime in the soup and with 24,000 hours, it still required me to focus on the G5 to stay right side up and on course.

My jet co-captain said, ?you know an inexperienced pilot could wake up dead in this situation?.

As a professional pilot, I am duty bound to review my performance and to be brutally honest to myself. The factors were simple.

1. I was tired. I am in my 60?s and after a 14 hour duty day, I was not at 100%.

2. My -10 has three switches next to each other, avionics master, nav/strobe, and landing light. With only limited night time in my newly acquired -10, the muscle memory to grab the correct switch failed me.

3. The lighting in my -10 is weak at best. The switches are not lighted and there is no under panel flood. I relied on a flashlight to ID the right switch and didn?t even turn it on as I was sure I had the right switch. (Did I mention that I am old and was tired?)

This episode had a happy ending mostly due to the instincts developed over a career of good habits. 1. Fly the plane, 2.fly the damned plane, 3, fly the GD airplane.

I am adding lighted switches and under dash lighting.

I hope this helps someone else to stay safe,...flames on.
 
IMC switch

Been there and made a similar switch mistake. I was day when I hit the avionics master switch. Didn't take quite as long to recover. I'm 74 and have started giving myself more time to hit the switch. I think I flew my last corporate jet trip last month. We will see, it's been a great ride for 51 years flying corporate jets.
 
Mark,

I am glad you had the presence of mind to realize what you had just done and keep flying the airplane. Also, thanks for sharing your experience.

I bought an RV-4 with avionics master next to the boost pump. At least once I made this mistake, but it was a VFR airplane. I later sold the -4 and bought a -6a and did a complete IFR panel upgrade. I spent quite a bit of time considering equipment failure and potential pilot errors. Two things that I did that I think are helpful; I grouped all of the "master" switches to the left of the panel well away from any switches I would regularly be using such as boost pump and lights. I also have a backup battery on a separate switch to power one G3X screen, so it takes turning off two switches to lose all of my screens. If you are doing quite a bit of IFR, I would recommend adding an IBBS or similar backup battery to your primary G3X screen.

-Levi
 
This is exactly I insist that when people design their panel, they place the switches by phase of flight, not function.

I have seen more than one plane with the avionics master and fuel pump switches side-by-side. It always made me wonder how often they turn off the master when trying to turn off the fuel pump.

Happy to hear you are writing about it and not the NTSB!
 
I can envision a toggle guard going on my avionics master. One that can be closed and have the switch remain on. Thanks for sharing.
 
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switches

Don't know if this would help, but on my rv I have toggle switches with a colored plastic over on each one. Red, green, etc. So my intent is to only move switches with a certain color. Red for instance is the starter, green is the master etc. For me it is kind of a safety feature.
 
I have one screen and com on the master switch and the others on the avionics switch. The Dynon backup battery is instantaneous and a power loss shouldn’t cause a reboot.
 
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I have one screen and com on the master switch and the others on the avionics switch. The Dynon backup battery is instantaneous and a power loss shouldn?t cause a reboot.

This is a good point. The Dynon's give you a power fail message and 30 seconds to press a button to keep it powered by the backup battery. The battery is good for an hour +, which is enough time to turn the master back on.
 
Thanks for sharing the story, and for the debrief - professional all the way around - great job!

Here’s one additional thing for everyone to think about. Why have switches for the EFIS screens at all? In a modern glass airplane, you really don’t have an airplane (instrumentation-wise) unless the EFIS is powered. It’s just like in the old “heavy glider” - the primary computers were powered up any time the main busses were powered, and the only way to turn them of was to cut the power feeds (they were fused of course).

I always wire the EFIS screens to come on with the master - if I really need to turn one off,or power cycle it, I can cycle the breaker (you can do the same thing with a fuse if that is your choice of circuit protection). I frankly don’t consider EFIS screens and ADAHRS to be “Avionics” - I reserve that phrase for transmitters and recievers (Comm, Nav, Xponder).

The truth is, almost all modern electronic boxes I can think of can be “on” for engine start, so there is even a good debate if you need an avionics master.

And yes - I put my Master Switch far away from anything else, so I have to be really brain dead to accidentally power everything off. Which isn’t to say it can’t happen...but it is at least less likely....
 
With my RV-7, the VP-X Pro turns on the primary display with the master similar to what Paul mentions above.

This is standard with the VP-X product.
 
Another reason not to have an avionics master?
I do have a switch on my main EFIS, but only a breaker on the stand-by, because there are enough times I only want to power up the fuel gauges or a radio.
 
LOCK

I replaced my avionics master switch with a locking toggle switch.

631H~22V.jpg
 
Why have switches for the EFIS screens at all?...
Extending that line of thought, why have an Avionics Master at all? Bob Nuckolls of Aeroelectric Connection makes a good case against them at Avionics Master Switches: Really Necessary?. His basic argument is that if the switch fails, you're well and truly screwed. After much consideration, I went ahead and installed an Avionics Master anyway in my plane. (I'm VFR only and carry a backup handheld radio and battery powered Stratus/iPad.)

P.S. I've accidentally hit the power button on a GPS by mistake - just when ATC was clearing me to a new destination. I faked it ;)
 
Here?s one additional thing for everyone to think about. Why have switches for the EFIS screens at all?...

I wish there was a like button sometimes...

I'm building an electrically-dependent airplane (EFI and glass, eventually IFR). One thing I'm trying hard to do is eliminate single-point failures on the electrical side, so that the failure of one component (or a single accidental switch bump) can't cause the pilot-cooling fan to stop working. I've already decided to do basically as Paul suggests--anything critical for flight comes on when its power bus comes on; the bus power switches and critical engine switches (coil power, fuel pumps) will be covered or be locking*.

I've killed everything in the panel once, in Dad's -6. I was trying to look up a frequency on the Skyview when I hit a bump and killed the avionics master (toggle switch below the Skyview). At the time there was a bug that kept the backup battery from activating, so everything went dark. I was VFR so it was no big deal, just an annoyance... but it made me think.


* depends on what kind of switches I decide to go with...
 
Similar thing happened to me after an alternator failure on a low IFR day while flying my Bonanza. Meant to cycle the alt switch and got the master at the same time. NY Center sounded tense when they lost my transponder. RV has the master and alt switches by themselves and high on the panel. Radio master by it self about two inches down. All other switches in the conventional location at the bottom of panel. Fuel pump at one end, flap switch at other end. Lights, strobe, etc. in the middle of the row. I've got to look for the strobe or nav light switch but never have to look for the pump or flap.
 
On my -7 the master and avionic switch (also ELT remote) is located far left on the panel hard to reach from the passenger, and during normal ops not used during flight. The switches are double pole so less chance of failure. There is a switch guard around it and they are high so no chance bumping them with the knee.
On my -8 the critical switches are locking toggle switches, also double pole, but grouped together with other switches.
I´m flying VFR only, however the planes are at least capable flying safely in IMC.

I found that on some certified airplanes like the Mooney the avionics master actually opens when the avionics are switched on. This makes the switch itself kind of redundant.
 
I wish there was a like button sometimes...

I'm building an electrically-dependent airplane (EFI and glass, eventually IFR). One thing I'm trying hard to do is eliminate single-point failures on the electrical side, so that the failure of one component (or a single accidental switch bump) can't cause the pilot-cooling fan to stop working. I've already decided to do basically as Paul suggests--anything critical for flight comes on when its power bus comes on; the bus power switches and critical engine switches (coil power, fuel pumps) will be covered or be locking*.

I've killed everything in the panel once, in Dad's -6. I was trying to look up a frequency on the Skyview when I hit a bump and killed the avionics master (toggle switch below the Skyview). At the time there was a bug that kept the backup battery from activating, so everything went dark. I was VFR so it was no big deal, just an annoyance... but it made me think.


* depends on what kind of switches I decide to go with...

Personally I'm a control freak and want to be able to turn things on/off when I want to. Lots of things these days lack on/off switches, EFIS/GTN etc., and I want to be able to control power to these units.

Starting your aircraft requires max energy from the battery, load it up with a full avionics panel and you just add to the burden the battery has to carry (do you start your aircraft with all your lights, strobes, pitot heat on?). So I want everything off for start, no other way to turn many things off than with an avionics master. Avionics power supplies are generally rated for 11-33 volts, running them outside these limits is not generally recommended, start voltages will always be less than 11v.

I even go one step further and add a "radio" master, this is just for the radios (GTN units have no on/off switch). This also has the advantage of redundancy as splits the avionics load between two switches.

Another reason I like avionics/radio masters is the ability to shut these power sources off in the event of a problem, like smoke in the CP. Shutting off these switches kills power before it even gets to the fuse/CB panel.

Essential equipment all has a seperate aux battery inputs, so turning off both the avionics/radio masters still leaves me with primary instruments, GPS and a single com.

These switches also let me do ground checks/updates etc. with only the equip I need running. Like I said, for me it's all about control.

PS: I've been around/used the Honeywell 'TL' series switches most of my career, I still use them and personally have never seen one fail and won't use any other switch if I can avoid it.
 
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Thanks for sharing the story, and for the debrief - professional all the way around - great job!

Here?s one additional thing for everyone to think about. Why have switches for the EFIS screens at all? In a modern glass airplane, you really don?t have an airplane (instrumentation-wise) unless the EFIS is powered. It?s just like in the old ?heavy glider? - the primary computers were powered up any time the main busses were powered, and the only way to turn them of was to cut the power feeds (they were fused of course).

I always wire the EFIS screens to come on with the master - if I really need to turn one off,or power cycle it, I can cycle the breaker (you can do the same thing with a fuse if that is your choice of circuit protection). I frankly don?t consider EFIS screens and ADAHRS to be ?Avionics? - I reserve that phrase for transmitters and recievers (Comm, Nav, Xponder).

The truth is, almost all modern electronic boxes I can think of can be ?on? for engine start, so there is even a good debate if you need an avionics master.

And yes - I put my Master Switch far away from anything else, so I have to be really brain dead to accidentally power everything off. Which isn?t to say it can?t happen...but it is at least less likely....

My RV-10 is wired exactly as Paul described. My screens and only necessary equipment comes on with the master. The rest are on the Avionics master. I also have an EBUS. The screens are also connected to the EBUS which has its own dedicated battery and alternator.

Yes, there is a combination of switches that will turn everything off, but their separate locations and the fact that I would intentionally have to do it makes the odds of that happening very small.

Also, my master is black, Avionics master is white, and ebus switches are red. Even if all the lighting goes out, it can still distinguish them from the lint coming from the screens.
 
Good on you for being objective.

I had a TERPS book slide off the glare shield and strike ONLY the avionics master on the way down in a C177 on climb out into a layer INSIDE the SFRA in DC a decade ago. Vacuum gauges, so less scary I would say. But really unnerving for a junior pilot. Ive never recycled a transponder as fast fun my life.

Lycosaurus posted an awesome switch which is going in my RV as soon as it gets here.
 
The Honeywell 'TL' series switches with the ?lockout? are bulletproof. I have them on both the fuel pump and master. My master switch is a three position switch that does double duty as the master and monetary start (off/master on/momentary start). I actually do have a separate avionics switch that allows me to power down all non-critical avionics such as coms, audio panel, transponder, and one of my G3x screens (MFD), but my PFD and all electronics that are critical for flight are powdered up when the master switch is turned on and it?s impossible to inadvertently turn them off. If I?m working on something that requires the master to be turned on but I want ?all? avionics to be powered down, I have to pull a breaker.

Mark
 
My RV-10 is wired exactly as Paul described. My screens and only necessary equipment comes on with the master. The rest are on the Avionics master. I also have an EBUS. The screens are also connected to the EBUS which has its own dedicated battery and alternator.

Yes, there is a combination of switches that will turn everything off, but their separate locations and the fact that I would intentionally have to do it makes the odds of that happening very small.

Also, my master is black, Avionics master is white, and ebus switches are red. Even if all the lighting goes out, it can still distinguish them from the lint coming from the screens.

Bob, your AF-5000 EFIS screens will not turn off in this situation. We made a software change years ago that prevented the Advanced EFIS screens from doing the 30 second shutdown if you have airspeed or RPM. Glasair had a very similar event at night and the pilot did not notice the 30 second shutdown warning and it got really dark.

The other thing that everyone should verify is to make sure you get an audible warning as soon as your alternator fails. A few years ago I noticed my radios acting really funny just as I was about to request an IFR LPV approach into Boeing Field in deteriorating weather. My Alternator had failed and the voltage was down to 11 volts. When I downloaded the logs I found the alternator had failed almost an hour before I figured it out. I would have bet anyone $100 that I constantly scan my engine gauges and would have notice it. I now have the low voltage warning set to 12V and the alternator warning set to less than 10 AMPS.

Rob Hickman
N402RH RV-10
 
The Honeywell 'TL' series switches with the ?lockout? are bulletproof.

I am a fan, I installed locking TL?s when I updated my panel to address inadvertent actuation of critical switches. But they are not bulletproof, once your brain gets used to unlocking switches you can in fact actuate the wrong switch when they are in the same neighborhood on the panel (I have not yet done that in the RV, but I did it once in another airplane, and it resulted in the unnecessary spending of federal tax dollars and a confession to my Skipper). Towards that end, like Paul, I designed the electrical system so that as long as there is some source of power coming from the airframe, the big screen stays on.
 
I asked Garmin G3X team if I needed an avionics master about two years ago when I was planning my panel. The response was as follows:

"It is not necessary to have these avionics devices powered off during engine start. As you know, the keep alive feed from the GAD 27 keeps the PFD/GEA24/GSU25 from resetting during engine cranking.
The attached page from Bob Nuckolls book explains that an avionics master is not required.
http://www.aeroelectric.com/Book/AEC_R12A.pdf"

Subsequently I don't have an avionics master, however I do have pullable Klixon 7277 breakers incase smoke leaks out of any specific device. I am very satisfied with how the system has been operating.

Tom.
 
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