Acro+gyros=not gonna last
I have vac driven AI and DG and the AI tumbles fairly randomly after plenty of looping and rolling over the past six years. It will work ok sometimes, then rolls over and plays dead other times. I'm now trying to decide on 1. remove entire vac system and gyros, or 2. have them overhauled and not fly acro anymore to keep them healthy longer. NOT!
I don't fly IFR so they're there for night ops, which I'm not flying nowadays either, so, they're mostly just eye candy and fill those big holes I drilled in the panel for them back in the crazy 90's when I built the thing.
The valve idea was discussed at great length long ago on the Matronics RV list and it was almost as hotly debated as the primer issue. Unless you have the mega buck military type gyros with positive caging mechanisms, your acro flying will eventually booger up the gyros. They may last years, they may die tomorrow. But banging them to the stops while spinning or at a stand still is not good for them. They're really not suited for such gyrations. With today's solid state glass attitude EFIS displays being offered by Blue Mountain, Dynon, and probably someday Walmart, I can see the days of vac or electric gyros in RV's being numbered. The money I would spend to overhaul my gyros would be better spent to replace them entirely, methinks.
It's rather hard to equip an RV for comfortable and safe IFR flying AND aerobatics. But, it's a lot easier today with the glass options. I guess we really just need to build TWO RV's...one with bare minimum VFR gauges to fling about willy nilly and a full house IFR/leather seats/wet bar/potty for traveling.
Brian Denk
RV8 N94BD