Quote Originally Posted by terrykrummrey View Post
I am building a Sea Rey and want to equip it for IFR flight since I am an IFR pilot and A&P. My Dynon D180 EFIS/EMS is sufficient for IFR instrumentation to the extent the D180 has the needed instrument functions in it.... what other backup or secondary instruments are people actually using to supplement the EFIS to be able to realistically recover from a primary EFIS failure in IFR conditions. For example, a separate airspeed indicator, altimeter, artificial horizon, etc.
While the D180 EFIS has both an AI and an Gyroscopic rate of turn indicator built in, they're not independent (if you have a display failure, you lose both). So while it can be argued that from a legal standpoint (91.205), the D180 is sufficient, I'd argue that you want either a separate AI or Turn Coordinator. The 496 MAY be an acceptable substitute, but I'd rather have a gyro instrument (be it mechanical or electronic) vs. a purely GPS based device.

I have a D10 EFIS and a mechanical TC as a backup (along with a steam gauge altimeter and airspeed indicator). If I were setting up the IP from scratch rather than having it evolve over 14 years, I'd probably put in a Garmin G5 or GRT Mini-EFIS as a backup to the D180. Then you have a full backup panel with ALL required instruments for a reasonable cost, and with a different MFG, no common mode failures (other than power loss). Get the battery backup version and you've got pretty good redundancy in the event of many possible failures.

My $0.02.