At 01:36 PM 9/19/2015, you wrote: >My understanding is that the intent of a (wet) compass requirement >is as a last resort/emergency/always available navigation tool - >with the fluid serving as a dampening influence compared to a dry >compass with no dampening. In order for any other type to qualify, >there must be no external power needed to make it operational. >Therefore, unless one of the magnetometers you have researched will >always operate reliably without externally supplied power, then no, >I can't agree. >George ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
I think you're reading too much "intent" in to item 3 below. These types of instruments weren't available when the reg's were written. What part of "magnetic direction indicator" does the new instrument not meet? It says nothing about requiring it to be a wet compass or requiring some level of reliability. The only requirement I've ever seen is a compass correction card. If this instrument is accurate to within one or two degrees I doubt if even that is needed. If the FAA disagrees they need to come back with a description of exactly what they require. Don't impose any self inflicting restrictions. The reg's say "magnetic direction indicator". Go with that and make the FAA justify a "no" answer. A friend of mine had a restriction on the 40 hour test phase on his RV10 of operation from a single named airport. I told him that's not in the reg's and was simply a restriction put in by the designated inspector. When he went to the FSDO to get his mechanic's license for the 10, he questioned the FSDO rep and she said , yes, is in the regs. He asked her to look it up. She did and came back and removed the restriction. He then asked her about a second pilot during flight testing (40 hours) and she said "no, that's only for multi engine aircraft". Some of these people don't know what they are talking about. AC no. 90-116 has been out for one year now and she apparently has no knowledge of it. Really? Maybe a government shut down is in order. Larry FAA requirements as listed in the regs (part 91). (1) Airspeed indicator. (2) Altimeter. (3) Magnetic direction indicator. (4) Tachometer for each engine. (5) Oil pressure gauge for each engine using pressure system. (6) Temperature gauge for each liquid-cooled engine. (7) Oil temperature gauge for each air-cooled engine. (8) Manifold pressure gauge for each altitude engine. (9) Fuel gauge indicating the quantity of fuel in each tank. (10) Landing gear position indicator, if the aircraft has a retractable landing gear.
