There used to be a prevailing attitude that if you were using a "glass panel", you'd still need backup "steam" gauges for basic stuff like compass, airspeed, and altimeter. I've done some research on this, and see no requirement mandating the backups, so maybe it's just prudence. I have an MGL Explorer and an iFly 720 GPS that I'm putting in N891JF, and they both cover these and much more individually. They'll also both have backup power. If that's not enough, I have an iPhone that'll do that and attitude also. Admittedly, GPS can and will fail (I've had it go away twice over Ft. Campbell, and I'm guessing it's training), but I also have a pretty good idea of airspeed based on engine RPM. In my mind, all I'd need to be perfectly safe is a compass, RPM-derived airspeed, and the transponder's uncorrected altitude indication. Any lapse in GPS coverage is going to be localized and brief anyway, unless the sun goes crazy for a while, and then I won't fly! I've flown and landed without airspeed or altimeter (pitot and static ports were swapped), and it was no problem at all landing.
If anybody can point me to regulation that requires more than this, please point it out to me. Otherwise, I'm forging ahead on my new panel. It's made from a carbon fiber covered "reject" from the N56ML construction effort. I had used peelply to flatten the surface, but it turned out way TOO flat, but that's easily fixed with a thin layer of satin finish polyurethane or something similar. There are a few details on it at http://www.n56ml.com/n891jf/panel/ . I have everything I need to finish it up, but finding the time will be the hard part. My goal is to have it flying by June 1st... Mark Langford ML at N56ML.com website at http://www.N56ML.com --------------------------------------------------------
