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otterhunter2

Active Member
Getting into the planning stage for a future panel which will be used for VFR, Night VFR, VFR on top and should provide a path for future upgrade to an IFR panel. So far I'm looking at a single GRT Sport(map option), Trio autopilot, SL40, 327 tpx, EIS 4000, vertical compass and a dual battery architecture as the core elements. Now I'm considering as backup 2 1/4" flight instruments - UMA altimeter, Vans airspeed, UMA VSI and a TruTrak ADI(GPS + Bat option).

Now what I'm considering is to ditch the backup 2 1/4" instruments and just go with a Garmin 496 as my backup flight instruments. Rationale is that the traditional backups are just as expensive as the 496, the 496 is spec'd to give 4hr ops with a battery, the 496 now has a 5Hz update for the panel page and finally this would provide for an independent flight instrument and navigation system for a GRT or total electrical failure (unlikely but possible).

So what do you guys/gals think, nuts or progressive??? :D

Thanks in advance.
 
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First thing that would bother me here is that the Garmin does not give you airspeed. It give ground speed. Not good for backup airspeed. It might be OK for cruising, but if you loose primary instruments, you would have no airspeed indicator for landing.
 
496 as IFR backup

There is a discussion of this in the October issue of Flying (page 28). The author describes using a 496 under the hood (with safety pilot) and felt it was adequate for backup - actually better than needle/ball/airspeed.
 
Assuming you're referring to the Garmin alt, T&B, heading, speed display, I would consider those "instruments" my absolute, last choice for flight reference before punching out.

I've tried flying under the hood with the instrument panel display and it's barely useful in calm air and with no stress.

The RV's are not stable enough for them to be of much use for IMC situational awareness. The GPS "instruments" would be good for a backseat "autopilot" reference though.

2 cents
 
Back up's

As far as I am concerned you can't have too many back up's. Do both. Take a look at a redundant VFR panel. Covered three ways. Two units with battery back up and good old manual gauges.

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Tony,
I like the way you think! It really bothers me to see all the new glass panels without any backup at all.
BTW, I see you even selected the correct canopy.
 
Airspeed display loss doesn't seem that serious and ...

I took off from Palm Springs once flying through Banning Pass on that dog leg to Paradise airway. Started icing up in the clouds detween the mountains at night. Very intense concentration did not turn on pitot heat so airspeed went to zero. It didn't even cause any tension. The engine sound and feel was right, I had attitude, DG, Nav Rec for course and the flight went as planned.

I have never had a GPS with an instrument panel display but I have lusted for one. I certainly would use it to save the day if everything else failed. Yes it might not work but I can't imagine it being worse than no instruments at all.

I have heard very good things about the tru trak ADI but I haven't used one. I do have a Pictorial Pilot and I have seen it give up displaying the track data if I make a very steep turn for more than a very brief time, like if I want to make a ~90 deg bank 180 turn. I've never seen that reaction in a spinning gyro instrument.

I have had many total electrical failures (most due to alternator/wire failure and subsequent battery dying that I detect as the digit elements in the frequency displays start flickering off) so they are not as rare as you might think.

Bob Axsom
 
You might consider going with an SL-30 now in lieu of the SL-40. VOR is still required for IFR and will be for awhile. You will avoid buying the nav later and redoing your panel.

Also, the math seems a bit off, you should be able to install a full suite of annalog backups for well less than half the price of a 496.

Another thought would be to use the T/T Pictorial Pilot which can provide you dual hat capability by providing your partial panel guidandce and an A/P.

All this can get you equal cabability now for less and can actually deliver IFR capabiility now for less than your VFR list (or close to it). Think about running your MB antenna and coax along with your nav coax now when everything is open and accessable.

I might also recommed you look at a Z-13/8 electrical system to save the weight and life cycle cost of running 2 batteries. Should you decide to run conventional mags, lasar or at least one P-mag, you can theoretically run on a Z-13/8 e-bus indefinitly after an alternator failure. This avoids the risk of running on batteries that may have an unknown capacity due to in-service deterioration. Of course, the real issue is that your backup power must last only as long as a full tank of gas.

Jekyll
 
Thanks everyone for the replies.

So far, yes if I go with the 496 there will still be a need for an ASI, then why not Alt and TC, man I'm talking myself back into the 2 1/4" backup option. Still need to find a total electrical failure method to keep the wings level (ie gyro capability), only solution appears to be the TruTrak ADI with internal battery. Any thoughts on alternatives??

Anyways the 2 1/4" solution seems to be more reasonable and traditional (safe).

Great comment on wiring of the Fus/wing for future upgrades, smart forward thinking.

Can you wire a SL30 tray to ant/pwr/efis but put in a SL40 radio in the same tray until the upgrade??

Now I have to read up on Z-13/8 electrical architecture or will it be Z-14 or Z12. More studying but it is rejuvenating the old tech school brain cells!! LOL

:D
 
Dynon has an EFIS with dual display; engine and flight instruments on one user configured screen. Before you had to buy two displays. Now you buy one, for two thirds the price of two. I haven't flown any of dynon's stuff, but it looks pretty slick to me.

As a day VFR my panel isn't too cluttered, and there's not much space to waste in my 8A. However, when I upgrade, I'll have the new dynon package, panel mount gps, the radio stack and still have room for the big screen tv...
 
airspeed for landing?

Mel said:
First thing that would bother me here is that the Garmin does not give you airspeed. It give ground speed. Not good for backup airspeed. It might be OK for cruising, but if you loose primary instruments, you would have no airspeed indicator for landing.
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Question on this point Mel. If airspeed for landing is important as you indicate, would an AOA instrument replace that functionality for landing? Just curious.
 
Tony what panel is that in your plane?

Tony, that's an interesting modular panel in your plane. Where did you get it?

Rick
 
LRI/AOA backs up AI

RVbySDI said:
Question on this point Mel. If airspeed for landing is important as you indicate, would an AOA instrument replace that functionality for landing? Just curious.
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That's exactly my view. I have an LRI which is sort-of AOA but excellent for approaches and landings. Airspeed only matters for approaches and landings. You need to be aware of flap extension speeds and approach speeds. The rest is no biggy. If you are unsure of wind enroute, the GPS can show you that approximation if you fly a 360 once and watch your ground speeds. I have no intention of wasting panel space on an AI. The LRI can do everything needed for approach/landing without an AI. My $.02.
 
The LRI should suffice for landing information. I was commenting on the use of the GPS "panel" as backup gauges.
 
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