Hydraulic Power Pack/Relays

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From: Rumburg, William <wrumburg [at] cdicorp.com>
Subject: Hydraulic Power Pack/Relays
Date: Mon, 14 Dec 1998 16:00:38 -0500
To: 'lancair.list [at] olsusa.com' <lancair.list [at] olsusa.com>

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Angier -



   Do NOT install your master relay in the same area as the power pack.

I and many others installed their battery behind the seatback on the

passenger side. Simply make a flat mounting base for the battery out of

1/4" or 3/8" honeycomb. Cut the honeycomb so that it installs

horizontally (with the plane horizontal), extending from the top of the

aft spar rearward to the fuselage bottom (about 12"-16" long and wide

enough for the Concorde RG-25 or RG-35 battery). As usual, cut back the

edges of the honeycomb and backfill with micro. Install an additional 2

ply layup on each side of the honeycomb for extra strength. Go to a

marine store and buy a nylon-strap type battery hold-down. Before

potting the honeycomb, install the two clamps supplied for the nylon

strap (template the locations forward and aft from the battery footprint

and use 3/16 area washers on the bottom of the honeycomb). Pot the

honeycomb mounting base in using micro and follow up with 3 ply

reinforcing layups. Install the master relay on the seatback, directly

above the battery. Just make small custom brackets from 1/4" phenolic,

contoured to fit the seatback. Pot them to the seatback with micro and

follow up with 3 ply layups. Do not get too fancy and make a cover for

it. It needs to radiate the small amount of heat it generates. One

builder reported in the LNN that he burned out his master relay by doing

that. There are a LOT of variations on Hydraulic power pack location. I

installed mine on the aft side of the baggage bulkhead and am happy with

that. I'll write more on that later.        

                                       Bill Rumburg  

                                       N403WR  (Sonic Boom)