IFR RV panels: FSDO-specific requirements?

[BuckWynd]

Every few months, I receive a sternly-worded Service Letter from the Parker-Hannifin Corporation, telling me all about the hazards of vacuum pumps, the possible severe consequences to IFR flyers whose pneumatic system contains certain parts, is not inspected at certain intervals, etc. etc.

Flying, Aviation Safety, Over the Airwaves, and other good publications often contain articles about pilots whose gyros fail in IMC, and who either survive despite the failure, or whose next-of-kin are now suing someone.

Yes, EFIS/AHRS systems need to be watched and "maintained," but I'm looking forward to never receiving these mailings again. I've made a commitment to an almost totally digital panel, with a Dynon D-10A taking the place of my "standby gauges." (The primary displays will be Grand Rapids Technology units.) This is a somewhat strange commitment from someone who loves flying open-cockpit airplanes with as little instrumentation as possible, but I'm getting used to the idea.

Has anyone had any difficulty getting an IFR signoff for their RV with an all-electronic panel? I've heard (third-hand) that some FSDOs would prefer to see a backup turn-and-bank indicator on the panel, regardless of what other equipment you have. Is this true? My FSDO hasn't said a word about a turn-and-bank.

Similarly, I want to see if anyone has had issues with a GRT single-AHRS installation and IFR. Has anyone been told that they should have a dual-AHRS setup in order to get an IFR signoff for their airplane (besides the obvious safety benefits a dual system would provide)?

Thanks in advance for any anecdotes or advice.

 

[Kevin Horton]

Has anyone had any difficulty getting an IFR signoff for their RV with an all-electronic panel? I've heard (third-hand) that some FSDOs would prefer to see a backup turn-and-bank indicator on the panel, regardless of what other equipment you have. Is this true? My FSDO hasn't said a word about a turn-and-bank.

Where does it say that you need an IFR signoff from your FSDO? The standard set of operating limitations that you should receive is supposed to have wording like:

(8) After completion of phase I flight testing, unless appropriately equipped for night and/or instrument flight in accordance with ? 91.205, this aircraft is to be operated under VFR, day only.

(9) Aircraft instruments and equipment installed and used under ? 91.205 must be inspected and maintained in accordance with the requirements of part 91. Any maintenance or inspection of this equipment must be recorded in the aircraft maintenance records.

It is up to the operator (i.e. you) to determine whether the aircraft is equipped in accordance with FAR 91.205 or not.

 

[gmcjetpilot]

EFIS, FARS and COMMON sense

Has anyone had any difficulty getting an IFR signoff for their RV with an all-electronic panel? I've heard (third-hand) that some FSDOs would prefer to see a backup turn-and-bank indicator on the panel, regardless of what other equipment you have. Is this true? My FSDO hasn't said a word about a turn-and-bank.

Thanks in advance for any anecdotes or advice.

What Kevin said. I'll add one word "Experimental". We have wide latitude.

Second what they would "Prefer" matters not, its all about regulations, FAR's , black and white. With that said there is interpretations but overall IFR is broke down into two categories in my mind, NAV and FLT INST's. I'll just mostly address FLT INST's.

NAV: You need what you plan on using, period. There is some controversy about IFR GPS or non IFR GPS but there are many long threads about that. The controversy (or whining and complaining) comes from wanting to use for example, just the Grand Rapids EFIS GPS and display for IFR GPS enroute and IFR GPS approaches, without and IFR approved GPS. I'll give you the answer in my opinion, NO, but read the threads. They may meet the requirements but if they don't go thru the process than they are not legal as a stand alone IFR GPS, IMHO. Other wise VOR/LOC/GS/MB and ADF are as required.

FLIGHT INSTRUMENTS (over VFR requirement): IFR requires a Gyroscopic attitude, Gyro heading and Rate of turn indicator, along with the usual suspects, airspeed, sensitive (accurate) altimeter. Rate of Climb is NOT required but nice to have and I use it extensively in my scan, so its a must have for me. The Attitude, Heading and Rate of Turn gyros in 'experimental' EFIS systems are considered gyro stabilized and acceptable by presidence. There are many out there in experimental aircraft flying IFR. Of course if you have a normal Certified airplane you are out of luck, write a big check for a TSO'ed EFIS.​

The question, do you need a T&B or Turn Coord, yes, but all EFIS I know of (including Dynon) have a Rate of Turn indication, so you're good to go without the extra traditional mechanical T&B/TC. Is that smart?


NOT IN FARS but IT'S ALMOST 100% IN COMMON AGREEMENT, by builders, who agree you should have some kind of redundancy to your EFIS. Some use DUAL EIFS. Some have mecahnical backups to at least some 'Gyro Info' (ATT, DG or T&B/TC).

The cheapest way to get 'Wings Level' redundancy is an old fashion mechanical stand alone T&B or TC. Although new T&B/TC's are about $500-$700. For a little more you can get a Dynon. I'd stay away from vintage WWII units at a junk sales for $75. You get what you pay for. The new China made cheap units are not super great, so some go with two Dynons or two GRT's or dual BMA's or combos there of.


Some feel their Experimental Auto Pilot, Navaid, TruTrak or Trio EZ-pilot, will do the duty of back-up to their EFIS flight instruments, like a T&B/TC. (that is your judgment, but all the autopilots say not for IFR use.)

Also most agree some mechanical back-up of the Pitot/Static instruments: Altimeter, Airspeed and Rate of Climb is a good thing to have. Clearly "Partial Panel" or "Needle Ball and Airspeed" is more than a T&B/TC, you need airspeed and Altimeter. The 'partial' panel has been the back-up to Vac instruments for decades. It does not do much good (or it would be a big pucker factor) to have a back-up T&B/TC with no airspeed/altimeter of any kind in solid IMC. If your EFIS is the only AS/Alt you have you might be screwed. Pitot/Static instruments are almost 100% reliable if the static does not get blocked.

Have you flown 'partial panel' with a T&B/TC in a RV, in turbulence? Its a handful with the T&B/TC wagging all over.


Again one word, "Experimental". If you are OK flying your wife, kids, family and friends solid IFR with a SINGLE Dynon and no backup, you can, but a loss of the EFIS in IFR conditions without an autopilot or other 'Gyro' instruments would be tragic.

General Aviation has NO REQUIRED REDUNDANCY per FAR's, but common sense says you better have some idea of what you will do. Than you better practice flying that way with a safety pilot.

The only problem I have obviously with dual EFIS is the obvious, electrical system, and something that people don't talk about, a lightning strike taking all EFIS out, dual or not. Mechanically spinning Gyros still have some warm fuzzy in my heart. Even the Boeing I fly has one Mechanical Gyro.

Electrical redundancy takes high importance with an all electrical panel. To me a second battery parallel with the main but with some isolation is plenty. If you have 45-60 min of reserve elect power that should be plenty. Some go with dual alternators, but I like the single ALT and dual batteries for simplicity and reliability. As Bob N's promotes, batteries in all electric planes need to be "life limited", meaning changed proactively before their capacity decays.

It is always the DAR's or FAA's prerogative to not sign off a plane for any reason, VFR or IFR, but frankly as Kevin says, you can "add" the IFR capability yourself. The real Head Line is, Is it safe?

 

[Ironflight]

George's Best Post!

What he said....excellent rationale and conclusions! I personally am comfortable with two electronic gyro platforms (one in my EFIS, and one in my autopilot), but everyone has a slightly different comfort level.

And I agree 100% that the FSDO has nothing to do with the IFR capability of your plane, so let's not give the idea that they do,,,

Redundancy (dissimilar, preferably) will give you real confidence that your airplane won't let you down. Then the challenge is to make sure that you know how to use the capability wisely, and when it's time to take a long nap in the pilot's lounge...

Paul

 

[TSwezey]

I have to admit it but I agree with George, having looked over all material I could find for IFR legal experimental flight.

 

[Yukon]

Let's Hear It For The Vacuum System

With everybody clamouring for glass nowdays, I think the value of vacuum systems are getting ignored. If a vacuum pump is changed every 500 hrs, they are very reliable. In the past, people changed them when they failed,
and if they were in actual IFR conditions, bad things frequently happened. Now that they are considered a life-limited part, they are required to be changed at regular intervals.

Lets not forget, a properly maintained vacuum is a separate source of power,
totally indepentant from the electrical system. This is the kind of redundany you can't get from 1, 2 or even 3 EFIS systems. It has been my experience that aircraft electrical systems are no more reliable than vacuum systems. Be it the alternator, the overvoltage system, the regulator, or the wiring, the odds are great that you will have a major electrical problem in your first 1000 hours as a pilot.

Vacuum systems can also be backed up with engine vacuum. http://www.aircraftspruce.com/catalog/inpages/stndby_vacsys.php With this type of inexpensive backup, I think steam gages are nearing 99% reliability.
Now if you back this system up with a Tru-Trak autopilot head/ turn coordinator, I think you would be approaching 100% reliability. Remember, a vacuum system works even if the engine dead and the prop is windmilling.

I fly glass and steam guages at work, sometimes flying both systems in different airplanes on the same day. The moving map is nice to have, especially with radar overlay, but as far as I can see, there is no great advantage having attitude and airspeed displayed electronically, especially if there are any reliability penalties to be paid........and I think there are. I have seen as many or more EFIS failures than I have steam gauge failures.

In my humble opinion, IF you intend to fly hard IFR, maximum redundancy is obtained with vacuum gauges, backed-up with engine vacuum and electronic gyro autopilot. Throw in a Garmin 430/530 for moving map, terrain avoidance and traffic display display and I think you have the perfect system in terms of reliability. Not as glitzy, mind you, but rock solid and not electrically dependant. I have seen way too many alternators go bad to consider an all-electric airplane.

 

[Ironflight]

In my humble opinion, IF you intend to fly hard IFR, maximum redundancy is obtained with vacuum gauges, backed-up with engine vacuum and electronic gyro autopilot. Throw in a Garmin 430/530 for moving map, terrain avoidance and traffic display display and I think you have the perfect system in terms of reliability. Not as glitzy, mind you, but rock solid and not electrically dependant. I have seen way too many alternators go bad to consider an all-electric airplane.

John,

Your system obviously will get the job done, and has for a lot of years. I've flown with that kind of equipment and been comfortable with it since that is really all that has been available in the certified GA world for decades. Looking back at the 20+ years that I flew my Grumman (much of it IFR) however, I replaced just as many vacuum pumps as alternators (three of each in about 2500 hours), so anecdotally, the reliability was about the same. I had an even split of gyros - an ADI and DG that were vacuum, and an electric T&B and HSI, and could comfortably fly with either pair. It was a good way to go, and it worked - so why upgrade?

Well, integration for one thing - I agree that you don't really need tape indications of airspeed and altitude - they can be done on the sides, on dedicated instruments (and I have them that way in my -8 as a backup). Having those functions integrated into the EFIS does give other, less direct computational benefits however - real time winds, TAS, etc, so they help with the overall SA. Electronic, non-moving-part gyros are far more reliable than any spinning mass mechanical unit I am familiar with, and I am very happy that they are now available to us in the experimental world.

So that does leave us dependent on electricity - I'll grant you that. but the laws of physics won't suddenly change, making electricity itself "not work" - the question is, can you build redundant electrical systems? And the answer is - of course! I have two separate alternators, two batteries, and three isolate-able power busses. That way, I am protected from the loss of SOURCES of electricity, as well as loss of PATHS of electricity to get to the instruments. And I have two sets of gyros - one in the EFIS and one in the A/P.

True, a massive lightning strike could take everything. Or it might not. Statistically, I think that the incidence of GA IFR airplanes getting hit by lightning is pretty small - I can't tell you why - in my case, it would be because I stay far away from those big lightning producers.

Once again, redundancy in whatever form is a good thing, and if you're comfortable with vacuum - and have a backup for when it fails - that certainly gives you what you need. The only point I want to make is that it is not hard to build a redundant electrical system to reach the same reliability as vacuum. It is done all the time.

Paul

Paul

 

[Yukon]

Yes Paul, a second alternator makes the all electric airplane much safer. I haven't heard of many people going to the troube of mounting a separate alternator, though. How did you do it, vacuum pump pad or second belt system?

 

[Ironflight]

Yes Paul, a second alternator makes the all electric airplane much safer. I haven't heard of many people going to the troube of mounting a separate alternator, though. How did you do it, vacuum pump pad or second belt system?

Vauum pump pad - it is pretty much as reliable as the engine - permanent magnet type. Provides all the amps I need to keep the EFIS and primary avionics up.

Paul

 

[BuckWynd]

Thanks

Thanks to everyone for their reasoned opinions. I appreciate the good inputs. I guess I threw my question out there in a slightly incomplete way. What I should have mentioned is that an RV builder friend of mine (in the southwest US) said that his friend was recently told by the FSDO that they would "prefer" to see a turn and bank indicator and dual AHRS in his RV if it was to be used for IFR. I have no more information about this matter other than that, but for obvious reasons, I wanted to hear from anyone who'd ever heard anything like that. (The builder in question may have been mistaken about the FSDO's comment, for all I know...)

Thanks again for all the great inputs regarding system redundancy (and good old common sense) when it comes to IFR instrumentation and aircraft systems...

Paul, my panel will resemble yours in quite a few ways. Do you have a dual AHRS system in your GRT EFISs (EFII?) ?

 

[Ironflight]

Paul, my panel will resemble yours in quite a few ways. Do you have a dual AHRS system in your GRT EFISs (EFII?) ?

I have just a single AHRS in my system now - that is all that was available at th time, and I am satisfied with the separate capability of the Tru-Trak as a form of dissimilar redundancy. However, I reserve the right to go dual GRT AHRS in the future if I just feel the need to do some tinkering and spend some money...the system is so well designed to me modular that it would probably be a one-afternoon job.

Paul