I have an all-electric airplane based upon a two alt system – one 70 amp PlanePower primary and a 30amp PlanePower stand-by alt (FS1-14). The FS1-14 mounts to the vacuum pump pad in place of the vacuum pump. I had meant to install it before I mounted the engine while I still had unobstructed access, but in the heat of moment I forgot to do it. In the end it turned out to be a non-issue. I was able to maneuver it around the engine mount OK. I did run into 2 minor problems. First, the alt nor the engine came with any mounting hardware. I was able to determine that the studs were ¼-20’s, but none of the usual suppliers stocked all-metal locknuts in coarse thread (-20). A post to VAF determined the Lycoming actually calls out plain nuts, split lock washers, and plain washers for items mounted on that pad so a quick trip to TSC and I had the required hardware. Note: A subsequent VAF post gave me a link to a fastener company (Fastenal) that allowed small order quantities so I ordered some ¼-20 all-metal locknuts just in case I decided to go that route. Second, there’s one nut that I although I was able to get on the stud (with the washers) that due to its location I can’t put a wrench on it. I’m thinking that I’ll need a special wrench that was designed for RAPCO vacuum pumps for this situation. For now I’ll just leave it finger tight.
UPDATE: I bought a RAPCO vacuum pump hoping that would be the solution to the one interior nut that needed tightening on my vacuum pad mounted stand-by alternator. Unfortunately, the pump wrench was a no go and waste of money (maybe I’ll try to sell it on E-bay). What I was able to do after some serious trial and error was to put a ratcheting wrench on the nut and get it tight. Just wish I had done this from the get-go.
