Steam/mechanical vs. glass/solid state

[FlyDave]

In the 3 power planes I've owned I have had to rebuild/repair the following steam gauges:

 

• Standard vacuum attitude indicator
• 2 cavity tubes in a transponder (what a friggin' rip-off!!!)
• Radair 240 VOR/LOC/GS head
• KI-256 attitude indicator
• KI-525 HSI
• Now a SigmaTek electric backup attitude indicator

I've lost my attitude indicator twice - once in light IFR (could see the ground straight down but not at an angle) and another failure 300' below the base of an overcast layer I was about to enter. This last one the AI started rolling back and forth 90 degrees left, then 90 degrees right - this is VERY DISORIENTING!

I'd like a better level of reliability and not have to repair these things every few years.

I've added a poll to this topic (could only add 3 questions) but I'd like some feedback in this thread describing you ownership experience, vendor support, reliability and some (if any) of the repairs required with costs since you've owned it.

 

 

Thanks for your response,

 

Dave

 

[rbridges]

I'm interested to see what people have to say.  I've kicked around the idea of putting in the aspen panels, but I'm trying to decide which is better.  Keep the existing "simple" steam gauges or go more modern.  btw, I've had to overhaul my altimeter in 3 years of ownership.  So far, this is my only steam gauge to go bad. The 430 and UBG16 engine monitor have had to be repaired, also.

[RocketAviator]

I have had both and will never if given a choice go back to steam! My Saratoga had sudo glass with Sandel 3500 & Garmin 530 but the real back up we're a series of portable Units. I have owned and used the Garmin 296, 396, 560, 696, PC tablet now my Rocket has dual IPads, Clarity SV with Garmin G500 SVT, GTN 750 & 650.

I have had to use the portable on more than one occasion in IMC, life saver for sure. If I fly anything steam or glass I am a big believer in backup, I credit to saving my life and others with me twice!

So glass or steam get and use backups they are CHEAP life saving insurance.

Never had a failure with the G500 but less than a year old.... Subscription cost is way to high but what can u do.... I could have gone either way Garmin or Aspen both good units.

ALL man made things can and do fail, some just more than others, I am slightly more concerned with a full glass failure as you have so much data in that one or more electrical unit.... Again I say back up is a wise option (no ship power backup too).

Fly safe, let us know what you decide!

[RocketAviator]

Oh and a couple more things, fly enough and like me you will experience failures. Vacuum pump, AI, JPI engine monitor, radios, transponder, ILS antenna, v belts, alternator hence electrical power, landing lights just when you need them most, etc... I expect and practice for a glass failure too!

[Bob_Belville]

I upgraded most of the panel in 2012. Aspen, GTN750, JPI EDM90, GDL88, Plus new Garmin Audio Panel, transponder.

 

Zero issues since. From day 1. 

 

I had to check "2 years" but no PM is required. Garmin data and charts are pretty pricey for the 750 and a GPS696 backup.

 

OTOH, before the upgrades I had to have the KNS80 sent off for repairs and I had intermittent problems with the Narco HSI. Plus the STEC50 did not track the VOR signal. (It was ok with the GPS input for a first gen. GPS155.) I also had to have the Stormscope 900 rebuilt. I also had intermittent problems with the GPS antenna/coax.

 

It is a delight not to be wondering what is going to happen next.

[rbridges]

are aspen panels pretty bulletproof?

[mike_elliott]

are aspen panels pretty bulletproof?

Not a problem at all with mine, and I have had it since they first were available.

[1964-M20E]

I’d like to put one Aspen pro 1000 in the center of my 6 pack but hesitate to put out the $ at this time.  My personal feeling is that the single Aspen gives you enough glass to make it neat but enough steam gauges left over to keep it real.

 

Next avionic upgrade I a new GPS and possibly a new ADSB out transponder at the same time.

[jetdriven]

Oh and a couple more things, fly enough and like me you will experience failures. Vacuum pump, AI, JPI engine monitor, radios, transponder, ILS antenna, v belts, alternator hence electrical power, landing lights just when you need them most, etc... I expect and practice for a glass failure too!

In the first 2 years of ownership we have replaced or OH the following (all of the items failed):

 

vacuum attitude indicator

vacuum DG

turn and bank

NAV #2 swapped inop KI-201C for KI-208

Stormscope, swapped inop WX-8 for a WX-1000E

OAT gauge

GPS: swapped inop Northstar GPS for KLN-89B

NAV/COM 1 MAC1700

NAV/COM 2 KX-170B

KN-61 DME box

KT76 transponder

vacuum gauge

recording tachometer

[jetdriven]

i think it is because we bought a piece of shit airplane, Jim.  Most of that was flaky about the time we took delivery. But after replacing everything its pretty reliable now for the past year.

[Marauder]

I think for most of us steam to glass converts, it is a little early to say what the long term cost implications will be. I do know that in the 21.5 years of steam gauge ownership, I have replaced or rebuilt 3 AIs, 4 vacuum pumps, 2 CDIs and 4 DGs. I won't dare speak of the money I spent trying to keep KX-170s running or the long list of transponder issues. The issue with the steam gauges wasn't that they failed, It was that when they failed, it usually was with little or no warning (CDI flags aside). The glass stuff does internal checks and continues to monitor things.

 

Since the switch over, I would be reluctant to go back.The wealth of information they provide, not to mention the ergonomics of the displays far exceed my expectations.

[Piloto]

In general reliabilty of a machine is inversely proportional to the number of parts in it and the quality of the materials used in it. Also the environment in which it operates. Solid state instruments (glass) may appear to be more reliable than a simple airspeed indicator, VSI, altimeter or a whisky compass. But in reality the glass instruments have over 100 times more parts than the steam gauges. It only takes one bad component to fail to get a glass display failure. Unlike steam gauges solid state devices work on a relatively narrow range of temperature, this is why cooling fans are needed. In a very hot or cold environment solid state devices tend to cause failures. Another factor is electrical power. Even if your solid state devices work perfecly if the battery master relay fails you loose your glass display. Not a problem with steam gauges.

 

The failures you see in most steam gauges are mostly due to the fact that they are over 30 years old. Notice that on glass cockpits a conventional air speed indicator and altimeter are required for backup. While on a steam gauge cockpit there is no backup requirement.

 

José             

[Marauder]

In general reliabilty of a machine is inversely proportional to the number of parts in it and the quality of the materials used in it. Also the environment in which it operates. Solid state instruments (glass) may appear to be more reliable than a simple airspeed indicator, VSI, altimeter or a whisky compass. But in reality the glass instruments have over 100 times more parts than the steam gauges. It only takes one bad component to fail to get a glass display failure. Unlike steam gauges solid state devices work on a relatively narrow range of temperature, this is why cooling fans are needed. In a very hot or cold environment solid state devices tend to cause failures. Another factor is electrical power. Even if your solid state devices work perfecly if the battery master relay fails you loose your glass display. Not a problem with steam gauges.

 

The failures you see in most steam gauges are mostly due to the fact that they are over 30 years old. Notice that on glass cockpits a conventional air speed indicator and altimeter are required for backup. While on a steam gauge cockpit there is no backup requirement.

 

José             

 

I'm not sure what glass instruments you are referring to but the two most popular ones have much wider specs than you infer. In addition, the Garmin specifically does not require an external cooling fan:

 

The Garmin G500:

 

Environmental

• -20C to +55C operating temp
• -55C to +85C storage temp
• 2 degrees C per minute temp variation
• 95% at 50C humidity
• Display equipment tested to 55,000 ft max altitude
• Internal cooling, external cooling not required

The Aspen PFD/MFD:

 

Operating Temp   -20°C to +55°C

Storage Temp   -55°C to +85°C

Max Operating Altitude (unpress.)   35,000 ft.

Cooling   Integral Fan

Max Humidity   95% at 50°C

Input Voltage   +8 to +32 Volts DC

Max Current   2.4 Amps @ 28 Vdc  /  4.8 Amps @ 14 Vdc

 

Sigmatek AI Operating Parameters:

 

Environmental Characteristics

Temperature: -30° to 50° C Vibration:   - CPS: 5 to 50 - Maximum Double Amplitude: 0.020 in. - Maximum Acceleration: 1.5 G's Humidity: 0% to 95% at 32° C Altitude: 0 to 40,000 ft.

 

The inherent problem with steam gauges are the moving parts. Note the maximum acceleration for the SigmaTek AI.  When I lived in upstate New York, I saw more failures, even with new replacement gyros than I have been seeing here in the mid-Atlantic area. I'm sure it is because I never properly or fully warmed the cockpit on those 0 degree Fahrenheit days I flew often. As for your battery master relay failure scenario, my Aspens will actually go to battery power. The only way to turn them off if you lose main electrical power to the plane is use the REV button and manually power them off. As well, the requirements for mechanical backups only requires a separate source AI. With the extended battery pack in the Aspen, you can legally remove both the ASI and altimeter from the panel.

[jetdriven]

Most of those glass screen instruments have a MTBF of 10,000 hours or more. Garmin publishes that for the G1000.  Not that they can't fail, but I would bet the electrical system, the peripheral boxes, or the pitot/static system fails far more often, and they can take down a glass screen instrument.  In 8,000 hours of glass airplanes, and I have only had a couple failures, one was the AHRS, a couple ADC failures, a LCD screen fault and failure, and and one Aspen which red-x'd from static blockage right at liftoff.  I will say that the Aspen or the G1000/G500 itself feels like airliner quality but the systems it is connected to are not even close.  However I feel they are many times more reliable than round dials. Many times more expensive too, except HSI overhauls. Those are expensive.

[isaacpr7]

You could also wait until the government makes a decision two years from now and get a garmin G3X glass cockpit with autopilot for under 8K 

 

http://www8.garmin.com/aviation/brochures/g3x_brochure.pdf

[PMcClure]

I flew a 172SP and a DA-40 with the G1000 system. I really like the set-up but it was my number one no-go issue. And I found that it was difficult to get repaired if you had a problem at a small airport. I am sure they have gotten better. I have had my share of problems on the steam gauges too, with a DG replacement (40 years old) and more AI's than I can count. For me, I prefer the steam gauges along with a set of Garmin boxes along side and a iPad back-up. That said, if the AI goes again, I probably will replace it with an Aspen as the cost is about the same as 2 AI's and I would expect it should be more reliable. I personally don't think the G1000 system is worth the investment. 

[jlunseth]

In five years I have had the vacuum pump go twice, both times in VMC and because I stretched it over the 500 hrs.  I have had a little work done on the KFC200 servos.  I have never had to repair/replace/IRAN any of the instruments.  On the other hand, I have had the alternator fail twice, once after the 930 was installed which caused the failure of all engine instrumentation.  I am sure with a 30 minute battery backup it would be possible to get down safely even in IMC, but the problem is getting the aircraft to a place where someone knowledgeable can repair it.  One major advantage of steam gauges is that there are almost always signs of deterioration before something fails, where glass is an "On/Off" proposition.  Glass also has the major disadvantage of becoming obsolete and unrepairable because of lack of support, and the only recourse is new instrumentation at a very high cost.  So at least until we get past this ADS-B thing, I am sticking with my old reliables plus portable backups. 

[FlyDave]

Sigmatek AI Operating Parameters:

 

Environmental Characteristics

Temperature: -30° to 50° C Vibration:   - CPS: 5 to 50 - Maximum Double Amplitude: 0.020 in. - Maximum Acceleration: 1.5 G's Humidity: 0% to 95% at 32° C Altitude: 0 to 40,000 ft.

 

 Note the maximum acceleration for the SigmaTek AI. 

 

Wow - I didn't notice that max acceleration spec. That's outrageous!

[PMcClure]

I have learned a lot about AI's in the last few years. A lot of damage is pilot or line crew induced. You should not move (that includes towing) while the AI is winding down. You should also be careful not to bump the plane when exiting or unloading an aircraft. It can take as much as 20 minutes for the gyro's to wind down. A 90 turn while the AI is a 50% speed can damage it. Still, the quality of King AI's put in modern Mooney's (and Beech, etc...) are total crap. 

[fantom]

Ummm,all instruments have issues. I don't buy any Garmin 10,000 hour MTBF statements until I read all the fine print. What goes in a 747 may just be of a higher quality than what goes in a 172.

 

Another issue is that many of these steam gauge failures are on 50 years old planes, with suspect histories, that were purchased at deep discount. Much easier to PPI an airframe and engine, than avionics. How were they used, not used, maintained, updated, where were the planes stored.....the variables are endless. Were replacements new (quality still going down), rebuilt, from the lowest price supplier, or off ebay? You know Mooney CB's

 

In my experience, and being the only owner of the plane, I believe steam gauges are much more reliable than what reading this thread would indicate. As most of you know, I'm very leery about putting $50 to 100 K retrofits in older planes. Avionics shops come and go, manufacturer warranties run out, and today's wiz bang glass can be obsoleted overnight. As has been pointed out, the cost of keeping all these new data bases updated isn't insignificant, nor is the challenge of keeping current on all the intricacies of using the glass. When/if the poop hits the fan, most pilots revert back to their initial training, and finding that ol' 6 pack may be a chore when you're in trouble. The young ones who only know glass, and the planes that have it as OEM are a different story, of course.

 

When the glass breaks, the repair costs will, I suspect, water a CB's eyes. Glass is easy on the eyes, and if anyone wants to pick up the bill for a complete retrofit, 49GH is available, but only at a proven, top notch shop.

 

[donkaye]

I had my KI 256 OH'd numerous times.  You could almost set your watch to the number of hours you could count on it before it was OH time.  And even with a reputable overhauler I would get it back, and sure enough, roll out on final from a left turn and you could count on a 6° left bank indication when level.  You could count on the T&B getting noisy at 400 hours and it was cheaper to replace than to OH.  Once I got the Castleberry that expense went away.  The display indicators on most of the 1990ish King Radios (KX 196, KNS 81, KX 155/165, KR 87 and on and on) would need periodic replacement as the digits would go bad.  They were expensive.

 

Aside from maintenance of most mechanical legacy instruments, what about security of flight?  While instrument failures are rare, when they do happen they can be catastrophic in instrument conditions.  The usual culprit; the mechanical vacuum pump or the Attitude indicator.  Nowdays most serious instrument flyers do have a backup AI, but I fly with a lot of people who don't.  Glass vs legacy; glass wins in this department.

 

I used to have to spend 8 to 10 hours with a new instrument student in phase 1 of instrument training; basic attitude flying skills; less with younger pilots than older ones.  With the Aspen or Garmin glass panels that time has been cut down to a couple of hours with less difference between young and older.  Scanning has become a snap in that you don't have to; everything is right in front of your eyes with no eye movement.  Actually its easier with the Aspen than the G1000 because of the size difference.

 

And rather than a detriment, the backup instrument requirements of glass panels are a plus as opposed to the no backup requirement for legacy instruments.

 

To me the glass revolution is a huge step forward, and one that should be on everyone's wish list.

[Mooneymite]

The future is obviously glass. No one should invest in mechanical anythings for their panels.

The iPad has shifted the paradigm and I think we will see further blurring of the lines between hard install and soft install.

Having said that, I've had 15 years of excellent, low cost service from my steam gauges. Some of that probably due to mild climate and a hangar.

I'm not anticipating an up-grade to glass until I gain some capability that I don't presently have with steam gauges. My neighbor has the "latest, greatest", but he and I have the same minimums and fly the same places.

I fly glass at work, but don't really hanker to have it in my Mooney.

.

[N201MKTurbo]

The thing I worry about is the long term serviceability of these systems. I owned my last Mooney for 19 years and it had the same flight instruments in it as when I bought it. The steam gauges have been serviceable for the last 60 years and will probably be serviceable for the next 60 years. 

 

I wonder how long you will be able to keep an Aspen or Garmin PFD in service? Modern electronic devices like displays and the chips that drive them have a very short production life. Lets say 15 years from now, will you be able to get your Aspen fixed? or will you have to replace it with an upgraded part for another $10,000? Is Aspen or Garmin guaranteeing a service life? I read that the 430s are now obsolete and Garmin won't be supporting them.

 

How would you like to buy an engine and know that you would need to buy a new one in 10 years because you cannot get parts for it any more?

 

I'm going to wait until there are standard LRUs for GA so when my PFD display dies I will be able to buy a universal replacement not a proprietary box. I may have to wait forever, which is OK I can fly just fine with my current instruments. Besides I have an IPAD!

[Marauder]

The future is obviously glass. No one should invest in mechanical anythings for their panels.

The iPad has shifted the paradigm and I think we will see further blurring of the lines between hard install and soft install.

Having said that, I've had 15 years of excellent, low cost service from my steam gauges. Some of that probably due to mild climate and a hangar.

I'm not anticipating an up-grade to glass until I gain some capability that I don't presently have with steam gauges. My neighbor has the "latest, greatest", but he and I have the same minimums and fly the same places.

I fly glass at work, but don't really hanker to have it in my Mooney.

.

Where the jump from steam to glass makes sense is when you are looking to make the leap from a DG to an HSI. That is what happened in my case. The cost of a mechanical HSI made it easy for me to justify the Aspen. Add in built in capabilities of the GPSS, multiple Nav inputs, horizontal and vertical command bars (precision approach indicators), altimeter, AI, ASI, VSI and map overlay on the HSI and all of the warning indicators built in -- it was an easy decision.

[DonMuncy]

Don Kaye,

I had a CFII chew on me for "fixating" on one instrument rather than proper scanning. I asked how he knew I was only looking at one instrument. He said he watched my eyes. Obviously, with a glass panel you could not see that happening. Do you think that because all the information is in one place, that students (or any on us) will automatically see all the information without "scanning". Or are you just scanning a very small space. My initial impression is that if you were particularly concerned about airspeed, you could focus on the airspeed tape and not see everything else. Am I wrong.