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wickedsprint

Well Known Member
So with overall price and weight and wiring simplicity glass seems like a really nice solution to a panel, however when using it as the sole reference for engine health or airspeed info it seems you essentially have a $5000 single point of failure if it doesn't power up, all the worse at a far away airport. If one has individual gauges for each engine function, you at most only have a $500 dollar single point failure item. The mission is day VFR, but the goal for panel is the most functionality with the least amount of weight. Anyway I cut it with individual gauges it weighs some 5lbs more with less functionality. Are these things reliable enough that this is an irrational fear?
 
Yeah, that last sentence :)

Just like everything else man-made..it can break.. But benefits of having glass (on engine side in particular) way outweigh any potential breakdowns... Everything here is a risk-benefit compromise... This one (IMHO) is a no-brainer by a long shot.. I wouldn't trade my graphical engine monitor for any round dial... even if you paid me to do that...

Plus there's always that track record you can count on...
 
Single Point Failures...

True Tony - if the EIS (or equivalent) quits, you have no real instrumentation insight into the engine operation. In our RV-6, when we were doing the install of a new panel, we had the box that does all the engine stuff lock-up during a software upload, and the airplane was essentially grounded (in our hangar) for a couple of days. However, with an oil pressure light operating from a discrete switch, we were not TOTALLY in the dark about how the engine would have been doing if we absolutely had to fly it - for a ferry home for instance. Knowing how the engine sounds, the approximate positions of controls for cruise - you might not be totally lost. I am not advocating flying without instrumentation, but it can be done if you really had to.

That said, aside from that particular problem with a new box during installation, I haven't had a problem with the engine instrumentation in either glass cockpit airplane in our hangar.

Paul
 
Yeah, you true that glass creates a single point of failure, but so does having a single mechanical ASI, a single mechanical altimeter, a single mechanical oil pressure gauge, etc. All of those are required so it's sort of difficult to see much of a difference between steam and glass if we're simply talking about getting stranded by equipment failure.
 
My EFIS hasn't powered up properly since I got the aircraft flying again. I haven't dug too deeply into the problem yet, as I have redundant round dial ASI, altimeter, VSI and compass. If I had no round dial backups I would be grounded.

The EFIS acts like it did when I tried to power it up using a power supply that didn't have enough amperage - it does a continual series of reboot cycles, at about one Hz. I suspect the problem is pin on a connector that has come partially out of place, or corrosion on a pin, or maybe a ground connector that is loose, so it is probably an easy fix, once I decide to take the time to chase it down. But, I have very limited time to get to the airport right now, so I don't want to use any of that time chasing this snag if the weather is good enough to fly. I'm very happy that I have enough backups to allow me to fly without the EFIS.
 
Jamie said:
Yeah, you true that glass creates a single point of failure, but so does having a single mechanical ASI, a single mechanical altimeter, a single mechanical oil pressure gauge, etc. All of those are required so it's sort of difficult to see much of a difference between steam and glass if we're simply talking about getting stranded by equipment failure.
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This is a good point. I have mechanical instruments and if one of the required ones isn't working then I'm grounded (hasn't happened so far in ~500 hrs). A more significant question is what happens if something fails in the air. If you're VFR-only I think total failure of the EFIS should be a non-event.
 
wickedsprint said:
So with overall price and weight and wiring simplicity glass seems like a really nice solution to a panel, however when using it as the sole reference for engine health or airspeed info it seems you essentially have a $5000 single point of failure if it doesn't power up, all the worse at a far away airport. If one has individual gauges for each engine function, you at most only have a $500 dollar single point failure item. The mission is day VFR, but the goal for panel is the most functionality with the least amount of weight. Anyway I cut it with individual gauges it weighs some 5lbs more with less functionality. Are these things reliable enough that this is an irrational fear?
Click to expand...

You are legal to fly day VFR with no instruments!

For day VFR, instrument redundancy is something that may be convenient, perhaps even prudent, but not essential. Install simple glass and enjoy the tremendous functionality it gives you. :)
 
91.205: Never mind...

I thought about this some more and answered my own question (no instruments are required for day VFR in experimental aircraft).
 
IMC?

Alan Carroll said:
This is a good point. I have mechanical instruments and if one of the required ones isn't working then I'm grounded (hasn't happened so far in ~500 hrs). A more significant question is what happens if something fails in the air. If you're VFR-only I think total failure of the EFIS should be a non-event.
Click to expand...

Well it should still be a non event...So there you are plugging away in the soup and the engine instruments goes dark..What are you going to do? You could head to the nearest airport with an approach but to be honest if its more than 5 minutes away and your oil pressure happened to go away in between then your going to be landing short.

as the chances of something catastrophic happening between where you are and your destination that is say two hours away is remote..I'd probably just keep flying till I arrived.

As Paul said you can fly it by ear..even if you had to set the mixture you can pull it to LOP (assuming FI'd) until it quits and nudge it forward till it just runs smooth and you'll be pretty close and the engine will run cool.

Now would i attempt to take off into the soup with no instruments..I don't think I would.

As for the primary flight instruments going dark, thats why we have backups for IFR flight..In my case the Pictorial pilot and ALtrak will keep evreything level. if my Dynon went dark.

Frank
 
I don't know about the "no instruments" for VFR--My Interstate has a compass, tach, fuel gage, oil pressure & temp, ASI, & altimeter. As I understand the regs, those 7 instruments are all required on all aircraft unless they are irrelevant, such as oil temp and pressure with a 2 cycle engine.

I am no expert, but that has been my understanding for as long as I can remember. Am I wrong on this?

And I also vaguely remember something about a minimum equipment list and that if anything on the list goes south, the plane is grounded.

Can someone who actually knows clarify this? Seems to me if an EFIS is on a minimum equipment list you are grounded if you lose the EFIS. Or is this only an IFR thing?
 
RScott said:
I don't know about the "no instruments" for VFR--My Interstate has a compass, tach, fuel gage, oil pressure & temp, ASI, & altimeter. As I understand the regs, those 7 instruments are all required on all aircraft unless they are irrelevant, such as oil temp and pressure with a 2 cycle engine.

I am no expert, but that has been my understanding for as long as I can remember. Am I wrong on this?...
Click to expand...
I do believe you are wrong. I used to own a Schweizer 1-26, which is a US factory aircraft. There are two items of required equipment, an airspeed indicator and a wheel.
 
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RScott said:
I don't know about the "no instruments" for VFR--My Interstate has a compass, tach, fuel gage, oil pressure & temp, ASI, & altimeter. As I understand the regs, those 7 instruments are all required on all aircraft unless they are irrelevant, such as oil temp and pressure with a 2 cycle engine.

I am no expert, but that has been my understanding for as long as I can remember. Am I wrong on this?

And I also vaguely remember something about a minimum equipment list and that if anything on the list goes south, the plane is grounded.

Can someone who actually knows clarify this? Seems to me if an EFIS is on a minimum equipment list you are grounded if you lose the EFIS. Or is this only an IFR thing?
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Richard, it is a "standard airworthiness certificate" versus "experimental airworthiness certificate" thing. Your understanding is based on aircraft with standard airworthiness certificates, your Interstate for example.

FAR 91.205
(a) General. Except as provided in paragraphs (c)(3) and (e) of this section, no person may operate a powered civil aircraft with a standard category U.S. airworthiness certificate in any operation described in paragraphs (b) through (f) of this section unless that aircraft contains the instruments and equipment specified in those paragraphs (or FAA-approved equivalents) for that type of operation, and those instruments and items of equipment are in operable condition.

FAR 91.205 does not apply to aircraft with experimental airworthiness certificates. However, the operating limitations associated with our experimental aircraft dictate compliance with 91.205 for night VFR or IFR operations. Day VFR is excluded from the requirement for compliance with 91.205.

Likewise, a minimum equipment list such as required with aircraft with standard certificates is an item that is not a part of experimental aircraft regulations.

This is a strange concept for those experienced with only "certificated" aircraft to accept, but yes, we can legally fly our experimental aircraft under day VFR with no instrumentation.
 
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Sam Buchanan said:
This is a strange concept for those experienced with only "certificated" aircraft to accept, but yes, we can legally fly our experimental aircraft under day VFR with no instrumentation.
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Legal to fly, but what happens if there's a problem? As builder you have signed off that the airplane is "safe". If you land off-airport due to engine failure, might the FAA conclude that you were "careless or reckless" for not installing any engine instruments?
 
Alan Carroll said:
Legal to fly, but what happens if there's a problem? As builder you have signed off that the airplane is "safe". If you land off-airport due to engine failure, might the FAA conclude that you were "careless or reckless" for not installing any engine instruments?
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Just for clarification, I don't think anyone is recommending not installing instrumentation. The original question of this thread was "are you stranded if your EFIS dies?". The regulations that govern our experimental aircraft allow us to begin a flight with no instrumentation if conducted under daytime VFR conditions. The pilot must decide if this is safe or prudent, but it is definitely legal, and it would be a stretch to deem something that is allowed per regulation as "careless or reckless". This aspect of experimental regs would allow us to legally fly our plane home or to a location conducive to repair if necessary to avoid being "stranded".

I don't think the carbed O-320 on the nose of my plane really cares whether or not it has instruments connected to it. The installation has accumulated 900 hrs of trouble-free flight, the baffling works as designed, there is plenty of oil in the engine, and I would feel quite comfortable, and safe, flying the plane with no engine monitor on a nice day if deemed necessary. I also have a big red oil pressure light on an independent sensor just for such a scenario. :)
 
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Sam Buchanan said:
Just for clarification, I don't think anyone is recommending not installing instrumentation. The original question of this thread was "are you stranded if your EFIS dies?". The regulations that govern our experimental aircraft allow us to begin a flight with no instrumentation if conducted under daytime VFR conditions. The pilot must decide if this is safe or prudent, but it is definitely legal, and it would be a stretch to deem something that is allowed per regulation as "careless or reckless". This aspect of experimental regs would allow us to legally fly our plane home or to a location conducive to repair if necessary to avoid being "stranded".

I don't think the carbed O-320 on the nose of my plane really cares whether or not it has instruments connected to it. The installation has accumulated 900 hrs of trouble-free flight, the baffling works as designed, there is plenty of oil in the engine, and I would feel quite comfortable, and safe, flying the plane with no engine monitor on a nice day if deemed necessary. I also have a big red oil pressure light on an independent sensor just for such a scenario. :)
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Agreed, mostly. I'd argue that the regulations don't actually "allow" you to do anything. They state what you can't do (same with the operating limitations). Its not clear to me that being experimental provides any exemption from 91.13 (I'm no lawyer; it would be interesting to know if there's any case law).

Regulations aside, the original post seemed mostly concerned with the safety aspect. As you point out, this "depends" (on the situation, what risks you're comfortable with, etc.). Some people probably wouldn't leave the tiedown without two working EFIS's and an autopilot; others might be comfortable flying across mountains at night with a flat tire and a flashlight. :)
 
Is glass EFIS and engine reliable

The original intent of the question is are glass panels reliable? I didn't read very many comforting answers. I've got 500 hours on vacuum gauges and vaccuum pump and some of it in IMC and never had a failure. If I make my 7A with glass EFIS will it be as reliable as vacuum gyros?
 
YUP!

sglynn said:
The original intent of the question is are glass panels reliable? I didn't read very many comforting answers. I've got 500 hours on vacuum gauges and vaccuum pump and some of it in IMC and never had a failure. If I make my 7A with glass EFIS will it be as reliable as vacuum gyros?
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Yes they are..I don't know of anyone who had a failure in flight of a glass panel so far.

Consider also that if your vacuum pump dies it will cause the AI to roll over. When an EFIS dies it would be expected to go "Phut" and be blank..Much safer than giving you a false reading.

Now this excludes the "failure" of getting erroneous readings if something should go wrong with the Pitot source with the Dynon..But as I pointed out, in IMC you will have backups and realistically an RV is a handful to fly in IMC without an autopilot.

Therefore assuming you keep your autopilot seperate from the EFIS you have a completely redundant way to keep the wings level.

To answer the question though, there are a few thousand hours now behind glass in RV's and no one is reporting a high incidence of failures..In fact so far I can't remember one.

For me I have about 350 hours behind glass with no failures and did all my IFR training that way too.

Frank
 
sglynn said:
The original intent of the question is are glass panels reliable? I didn't read very many comforting answers. I've got 500 hours on vacuum gauges and vaccuum pump and some of it in IMC and never had a failure. If I make my 7A with glass EFIS will it be as reliable as vacuum gyros?
Click to expand...

The answer depends on an a few variables.

First, naturally it depends on the Glass - all glass is not created equal.

Second, it depends on installation and the associated systems. Electrical, Pitot/Static, wiring, connectors, hoses, antennas, etc..

The quick answer is YES glass is generally far, far more reliable than a Vac system.

Cheers,
Stein
 
Glass failure modes

It is generally thought that if a glass panel fails everything goes.
Not so - at least this happens very seldom.

Typical failure modes are very much like those you will get with any analog panel. One (or more) functions fail - often due to failure of the connected sensors, sometimes perhaps due to failure of a channel on your engine monitor.
None of this results in the EFIS going south.

If the EFIS goes blank - 98% of the time that is due to loss of power and in our experience, that is often due to bad wiring practises, a $0.50 switch going intermittened or a circuit breaker that, well, broke...

One failure mode however is new and not present in a traditional panel:

This concerns failure of the software either because of a programming "bug" or because of a hardware issue in the EFIS computational part.
There is also another poorly documented EFIS failure related directly to radiation (which gets stronger at altitude) that can directly flip bits in dynamic memory (leading to anything from minor to catastrophic program failure) and it can even disrupt the workings of the processor itself. These events are not permanent and a re-cycle tends to fix it.
Radiation effects on various types of silicon memory is well researched and documented. Some types are better than others. Let's leave it at that.

So, the new panel failure mode is best described as "glitch" related to one of many possible causes. A bad, intermittened solder joint (easy to do with todays super fine pitch technology), a software issue (some of which can be real hard to track down) or a cosmic ray (all but impossible to prove post mortem).

Despite that (and non-withstanding the fact that I make these things) - I still like my glass.
Big panels with dozens of needles pointing all over the place confuse the heck out of me (but they do look impressive).

Rainier
CEO MGL Avionics
 
Yes, you can

wickedsprint said:
Are these things reliable enough that this is an irrational fear?
Click to expand...
....fly home.

If you guys want to have a more "intimate" relationship with your airplane, do this. First, see where the throttle is for a given RPM, e.g. four finger widths from the lock for 2400 and so on. Lean by ear....until you hear or see the tach needle drop, then enrichen about 1/4"..(BTW, I still lean this way)...like Lycoming used to tell us, when we didn't have EGT gauges in them...the same thing still applies.

My Air Tractor's prop RPM gauge occasionally hiccups and sits on the peg but I know where the prop lever is in relationship to the condition lever (similar to mixture knob) and simply pull it back to where it always sits. Your engine will be happy at anywhere from 2200- 2700RPM (if the prop allows), so don't sweat not having a tach, if it quits, too much. Fix it when you get home...besides, Tony did say the mission was day VFR.

Regards,
 
I now have about 600 hrs behind glass panels. I have suffered 3 complete blackouts none of them because of the EFIS.

#1 on the ground on a dry winter day I did not take care (as per the Directions) to ground myself while inserting a flash card. My wool sweater caused enough static to make a visible arc into the reader. EFIS went black and required a firmware reload.

#2 While flying my solenoid went TU and suffered total electrical failure. Again a black panel.

#3 While flying the alternator failed and about an hour later on final approach the battery gave up and panel went black.

Because of #2s & 3 I have installed a small backup ASI and Altimeter. I have also provided an emergency bypass around the solenoid through a circuit breaker to power my avionics bus.

My Hobbs meter is on an oil pressure switch and will not function without oil pressure which can be noted within about 5 seconds.


Les Featherston suffered blackout of both EFIS's in his Harmon Rocket from a lightning strike but both rebooted without difficulty.

I would rather have glass than vacuum.
 
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I can't believe this already went to 3 pages, you guys rock. I like the idea of a backup oil pressure indicator, either via the hobbs or a light as mentioned. I might consider it to be prudent to slap in a small backup Airspeed as well. I really like that glass seems to simplify erverything and also keeps it light.
 
Thanks for the question.

Jamie said:
Yeah, you true that glass creates a single point of failure, but so does having a single mechanical ASI, a single mechanical altimeter, a single mechanical oil pressure gauge, etc. All of those are required so it's sort of difficult to see much of a difference between steam and glass if we're simply talking about getting stranded by equipment failure.
Click to expand...

After reading this question, I realized that I had a SPOF in my dual glass system for the engine instruments.

I have an MGL Odyssey on the pilot side, an MGL Enigma on the copilot side. I have battery backup for both and the RDAC (engine pod) is wired to talk to both.
So, i can lose main power and still have my EFIS for about 1.5 hours. I can lose an EFIS and still fly the backup. I can lose alternater and battery and still have EFIS, etc.

But, if RDAC goes TU, all I have left is my mechanical oil pressure light, my ears, etc. While I could fly on and land without engine instruments, I would be "stranded" at whatever airport I landed at until I repaired the malfunction(s). Since the RDAC is a pretty special piece of equipment, it might be available overnight, but it might very well be backordered for a few weeks as well. That could ruin my outlook for a few days.

So, today I ordered a spare RDAC ($275). I'll be carrying it in the plane. It weighs about 8 oz and will take up almost no room in my baggage area. Should the primary go TU, I can at least get airborne again in a couple hours at most. Cheap insurance.

YMMV.
 
n5lp said:
I do believe you are wrong. I used to own a Schweizer 1-26, which is a US factory aircraft. There are two items of required equipment, an airspeed indicator and a wheel.
Click to expand...

Have to share a photo of the panel of a newly restored a 1-26. The owner went with the minimum equipment list. Bear in mind this is an aircraft capable of flying to over 30,000 feet and that has many times been flown on 300+ mile cross-countries.

This guy never has to worry about electrical failures or software bugs.


IMG_0004.jpg
 
n5lp said:
Have to share a photo of the panel of a newly restored a 1-26. The owner went with the minimum equipment list. Bear in mind this is an aircraft capable of flying to over 30,000 feet and that has many times been flown on 300+ mile cross-countries.

This guy never has to worry about electrical failures or software bugs.


IMG_0004.jpg
Click to expand...
That picture is priceless! :D
 
n5lp said:
Have to share a photo of the panel of a newly restored a 1-26. The owner went with the minimum equipment list. Bear in mind this is an aircraft capable of flying to over 30,000 feet and that has many times been flown on 300+ mile cross-countries.

This guy never has to worry about electrical failures or software bugs.
Click to expand...

Yeah, but check out the toolbox... Probably hiding a GPS and D180 in there!
 
Rainier Lamers said:
One failure mode however is new and not present in a traditional panel:

This concerns failure of the software either because of a programming "bug" or because of a hardware issue in the EFIS computational part.
There is also another poorly documented EFIS failure related directly to radiation (which gets stronger at altitude) that can directly flip bits in dynamic memory (leading to anything from minor to catastrophic program failure) and it can even disrupt the workings of the processor itself. These events are not permanent and a re-cycle tends to fix it.
Radiation effects on various types of silicon memory is well researched and documented. Some types are better than others. Let's leave it at that.

So, the new panel failure mode is best described as "glitch" related to one of many possible causes. A bad, intermittened solder joint (easy to do with todays super fine pitch technology), a software issue (some of which can be real hard to track down) or a cosmic ray (all but impossible to prove post mortem).
Click to expand...

Realizing that this is a post from a while back...

I'd be surprised if a piece of modern avionics wasn't using some sort of EDAC memory and probably a memory scrubbing routine to ensure that flipped bits are caught and fixed. I thought someone did a quick survey of most of the EFIS manufacturers recently on this...?

With EDAC and scrubbing, you'd likely never see this failure mode unless a two-bit error in a word happened (EDAC normally is able to correct a single bit error and detect but not correct a two-bit error). Shielding can help, too, but not against Galactic Cosmic Rays (GCRs).

Without going into details on Single-Event Upsets, Single-Event Latchups, gate ruptures and so forth...any manufacturers here wish to comment on their memory error-detection/correction?
 
n5lp said:
Have to share a photo of the panel of a newly restored a 1-26. The owner went with the minimum equipment list. Bear in mind this is an aircraft capable of flying to over 30,000 feet and that has many times been flown on 300+ mile cross-countries.

This guy never has to worry about electrical failures or software bugs.


....
Click to expand...

Nah... he just has to worry about the clockwork failing in his ancient technology barograph...:)

Does he want to buy a Repogle barograph as a back-up?
 
No problems

I've flown 100 hrs. with dual 10" Skyviews with no problem. Left side has a back-up battery. No steam guages.
Larry
 
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