IFR Panel Backup Strategies

[jvolkober]

I have been going round and round on this.  What if any backup guages should I have  a standared vans RV-9 panel containing an SV-1000 and SV-700 screens supported by a single ADAHRS and a GNS430W.  Interested in suggestions and opinions.  I have been considering a combination of 2 1/4 inch airspeed, altimeter, turn/bank or artificial horizon with mag compas on center post.  I want minmal but adequate.

John

 

[dynonsupport]

You can add a second AHRS to your setup for $800, which gives you redundant everything. We have a lot of customers flying with that configuration.

 

[dabear]

I use 2 SV screens (each with battery backup), 2 ADHARS, single nav/com, single GPS, single Transponder with no other backup gauges.

My thoughts are:
1. If 1 screen goes TU, I have the other.
2. If 1 ADHAR goes TU, I have the other
3. If power goes TU, I have warning on the EMS, then I have battery backup for each screen
4. Most GA aircraft have single transponder so I'm good there
5. If Com (SL30 goes TU, I have backup hand held (Dynon) radio.
6. If NAV (SL30) goes TU, I have GPS
7. If GPS goes TU, I have NAV radio.

I think that is enough backup.

It doesn't play here, but if airplane catches fire, or everything goes TU I have mr. parachute. ;D

 

[rlmarshall]

I agree, Bear.
I would add that a D6 added to the two SV's makes some sense. If I get different attitude indications from the two 10" screens, I can use the D6 as a tie breaker. The odds of both SV's going TU is probably slim, but the consequences could be major, so the D6 completes a total situational comfort zone for me. Overkill maybe, but what the hay--

 

[mmarien]

This has been discussed before on here. Some points about dual screens and dual ADHARS. The dual screens get the information from the same ADHARS so the readings will be the same. It not true redundancy where one screen uses one ADHARS and the other uses the other. The D6 is a good idea, however most of the ADHARS installations that have been shown on here have been connected to the same static and pitot sources. If either gets blocked then both ADHARS are handicapped, including the D6 if it's using the same sources.

Whatever you use for redundancy, the main point is that you are comfortable and can fly your plane out of trouble with it. A recent AOPA/ASF video describes a vacuum pump failure on a IFR flight in IMC where the pilot wasn't familiar enough with the GPS to use it for navigation.

http://flash.aopa.org/asf/pilotstories/vacuumfailure/?WT.mc_id=110415epilot&WT.mc_sect=sap

It ended well for the pilot but a case in point where redundant instruments didn't help when there was a failure. If you're comfortable with gas gauges that is probably the way to go. Keep in mind that if they are connected to the same static and pitot sources they may fail along with your glass panel.

I have some instrument training for night and OTT but don't fly IFR. I have practiced keeping the plane straight and level and on course with my GPS495. Not your normally recommended backup instrument, but it works for me and is totally independent of my Dynon SV. Of course with VFR there is always have that big gauge out front should everything else fail .

 

[rlmarshall]

Good points mmarien. I believe Dynon is going to have some kind of built in system to drop off a failing ADAHRS and switch over to the good one automatically. That would also add comfort to IFR flying.
I do intend to put a simple backup pitot in just for the D6.  I was going to connect the D6 to the Dynon GPS which connects to the SV, but I guess you can't share it.  The SV's will be connected to a heated Dynon pitot and have GPS input to backup attitude gained from A/S.
As far as static failure, I will have a valve opening in the cockpit to privide a somewhat accurate source of static pressure.

 

[dabear]

I guess it ends up to what you are comfortable flying with, knowing the system, and knowing what you have for backup. I don't see the need to have backup round gauges or D6 because I don't have a backup pitot/static system. I don't see the need for that to be redundant.

Now I might put an alternate air port in the cockpit, but running a whole other pitot tube etc. isn't on my plan. But again it is up to each pilot.