EAB IFR Certification

[Gerry]

From FAR 23.1311 (5) For certification for Instrument Flight Rules (IFR) operations, have an independent magnetic direction indicator and either an independent secondary mechanical altimeter, airspeed indicator, and attitude instrument or an electronic display parameters for the altitude, airspeed, and attitude that are independent from the airplane's primary electrical power system. These secondary instruments may be installed in panel positions that are displaced from the primary positions specified by §23.1321(d) (pfa://FDFD560B-425F-4562-ABCE-673FF2E1E51D/R.T_14.C_I.SC_C.P_23.SP_F.S_1321.d), but must be located where they meet the pilot's visibility requirements of §23.1321(a) (pfa://FDFD560B-425F-4562-ABCE-673FF2E1E51D/R.T_14.C_I.SC_C.P_23.SP_F.S_1321.a).

Would a dual screens and Dual AHRS with battery backup meet the requirements for an EAB aircraft? Whiskey compass needed?

[rleffler]

It would meet some of the requirements for IFR. Assuming you also have all the other required navigational gear, pitot static system, transponder, lighting, etc....

With your configuration, a wet compass isn't needed. It's rendundant with the AHRS.

[martymayes]

An EAB flown under IFR does not have to comply with Part 23.

[WLIU]

True, but Part 23 is solid conservative advice and a great place to start if you have questions about how to build or configure a safe system. If you are in the clouds and something goes "poof", you will regret any corners that you might have cut, possibly for the rest of your (shortened) life.

I read the quoted section of Part 23 to say that even if you have glass driven by an AHRS, you still need a backup wet compass, or another AHRS with a separate source of power. AHRS's do fail and having no way to fly a heading in the clouds often does not end well.

Best of luck,

Wes
N78PS

[Marc Zeitlin]

Would a dual screens and Dual AHRS with battery backup meet the requirements for an EAB aircraft? Whiskey compass needed?The requirements for flying IFR in a particular EAB aircraft will be defined in that aircraft's Operating Limitations. These days, the OL's will specify that the aircraft is restricted to Day VFR only UNLESS equipped per FAR 91.205. So, go to 91.205, make sure you've got the equipment as required for Day VFR, Night VFR and IFR flight, and you're legal for IFR flight.

With respect to your specific questions, as long as the EFIS (at least ONE of them) has a magnetometer associated with it that displays heading (not ground track), then that meets the requirement for a "Magnetic direction indicator" as required for Day VFR flight. The section specific to IFR equipment says nothing more about compasses or magnetometers or anything else related to heading indication. A magnetometer is nothing if not a "magnetic direction indicator", so it qualifies per 91.205.

Done.

[Gerry]

Thanks all for quick replies, that helps a great deal with planning