I’ve noticed that on the electric HSI, the glideslope indicator oftentimes is stuck in the one line down position. Cross-checking this on the Garmin glideslope indicator confirms this. Obviously a big problem in IMC. Any other experience with this?
I have the vacuum HSI but I assume the glideslope mechanism isn’t that different between the two. My HSI’s glideslope flag was stuck at the center position (i.e. you’re right on the glideslope) during the Garmin 430 startup procedure. going into the Garmin setup mode and trying to force the glideslope up, down, etc. didn’t change it, it still stuck right at the center position with no flag. Flying a couple ILSs (in VMC of course!!) actually showed the needle appear to work, but since it didn’t work in the startup test, I still wasn’t very confident in it.
Anyway, I took it in, got it fixed by century, and a few weeks later the same thing happened. I took it in again, again it was fixed by Century, and so far it’s still working.
It would be nice for them to have some kind of closed-loop control system for the glideslope needle, so that if the appropriate voltage is being applied to the system, but yet the needle is not in the right place, it could be flagged…
I just read an article in the “free” book that comes with a new IFR Magazine subscription about a Lear which crashed because the co-pilot glideslope needle was showing “fly-down” even though they were already 400 ft below the glideslope… so let’s be careful, double check the glideslope intercept altitude, etc…