Evolution Battery Change

JeffHeadby jeff edwards

Have you changed your Evolution batteries yet? If you look forward past the rudder pedals and look at the batteries mounted on the firewall you likely wondered how you would get them out past the rudder pedals.

Left Battery

If you are an early Evo owner, you are probably coming up on the recommended five year battery life for your Concorde RG 24-20 battery. Given their position in front of the rudder pedals, Nick at Composite Approach says swapping the batteries is probably the hardest job task on the Evo. This post provides a step-by-step process for removing the left-hand battery. I chose the left battery because of the difficulty in disconnecting the vertical torque tube which attaches the upper assembly with the lower rudder cable bellcrank.

Required Tools

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You'll need appropriately sized Allen and open-end wrenches; a few different sized sockets; a long and short socket extension; large adjustable pliers; both Phillips- and common-head screwdrivers;  and a medium-sized C-clamp.

NOTE: Click on any image to enlarge.

Remove Pilot Seat and Floor

The first step is to remove the pilot seat and the floor board forward of the torque tube assembly. You may have to remove the forward sidewall to remove the floorboard. Get a thick moving blanket or some similar pad that you can roll up and place forward of the pilot seat position on the floor. You'll be spending hours laying on your stomach and back on the spar box; you might as well be as comfortable as possible.

Move Torque Tube

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The vertical torque tube (seen below the rudder pedals in the photo) must be moved inboard towards the tunnel to allow the battery to pass outboard of it. You must disconnect the lower U-joint assembly on the torque tube in order to gain enough room.

Start by removing all four taper pins in the U-joint assembly. To do this, apply a few drops of penetrating oil to the taper end of each pin and allow to soak. Meanwhile loosen each nut using a 3/8” socket. Spin the nut off until no threads are showing but leave the nut on the end.

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Using a small C-clamp and socket, press out the pins. Place one end of the clamp on the nut and straddle the protruding pin with the socket. Screw in the clamp, using it as a press to press out the pin. Remove all pins.

NOTE: This is the most time-consuming part of the process. To make it easier in the future you may want to upsize the smaller diameter hole and use an AN bolt upon reassembly.

Safety PinNext, remove the steel safety pin at the top of the torque tube just below the upper bellcrank bearing. This pin serves as a safety device should the bearing fall out in service. The pin is approximately 3/16” below the bearing.

A left-right orientation of the hole will make removal and reinstallation of the pin difficult due to the dual adjustment tubes on either side.

With the safety pin and the four taper pins out you can now slide the vertical torque tube up (depending on wire bundles above it) and remove the U-joint. With the U-joint out you can move the lower end of torque tube a few inches inboard—enough for the battery to pass.

Lift U-Joint Push Up Vertical Torque Tube

Remove U-Joint Click to Enlarge

Move Pilot's Left Rudder Pedal

Now, remove the two screws on either side of the bottom of the left rudder pedal using a 5/32” Allen wrench. You must insert a small diameter screw driver or other device into the hole in the center of the backside of the lower rudder pedal.

Remove Screws

Click to EnlargeThis keeps the internal tube from rotating as you remove the two screws. Once you have removed the screws, rotate the rudder pedal forward and inboard to allow the battery to pass between the rudder pedal “ears”. You do not need to remove the rudder pedal entirely or remove the hydraulic brake line.

Remove Battery

Now comes the hard part. Disconnect the electrical leads from the battery. Place insulated protective caps over the terminals. Remove attaching hardware holding the battery to the firewall. The battery weighs 47 pounds so be prepared to gently lower it. You will have to turn the battery on its long edge at a 45 degree angle to get the top between the rudder pedal “ears”.

To install the new battery reverse the above process. Good luck, and have fun!

Contact Jeff at j.edwards [at] lancairowners.com if you have questions or comments.