RV-14 ADAHRS Bracket [3.0 hours]

I originally mounted a bracket in the empennage for the Garmin magnetometer. Years ago. Then I switched to Dynon avionics, so I was going to have to make a new bracket for the Dynon ADAHRS, and wasn’t looking forward to crawling into the tailcone to install it.

Then I came across the Van’s RV-14 ADAHRS bracket, which looks like a clever design. It goes in the left wing, inside the inner access cover. The RV-14 wings are the same as the RV-10 wings, just shorter. I looked at the drawings and the dihedral appears to be the same, so I ordered the following parts from Van’s:

W-00012A
W-00012B
W-00012C
W-00012D
W-00012E

With these in hand, I prepared an installation for the left RV-10 wing using the following procedure:

  1. Prepare the parts using the RV-14 instructions on page 20-03 of the RV-14 wing manual.
  2. When fluting the W-00012C parts, do not simply hand hold the part and hit it with the fluting pliers. Mark the distance in common with the W-00012B parts, and securely clamp the W-00012C between a block of wood and the workbench so that this area remains flat. Then, use the fluting pliers only on the exposed part – see the picture.
  3. Cleco the parts together. Position on the LH inner bottom wing skin, and verify you have the correct orientation.
  4. Draw a line between the center of the two wing rib holes, these are the fourth holes down from the J strut. Reposition the bracket to be aligned with the center of the access cover, and match drill/cleco the end two holes in the Z bracket through the bottom skin. I used a #42 drill bit, and once all holes were drilled, match drilled with a #40 reamer.
  5. Remove the W-00012A bracket, drill the remaining holes from the Z bracket through the bottom skin.
  6. Remove the Z bracket, de-burr the holes just drilled in the Z bracket and the skin. Dimple the holes for flush rivets, and reassemble all parts.
  7. Keeping the bracket aligned so it is not “twisted”, match drill #40 from the W-00012A bracket into the J strut, cleco’ing as you drill each hole. Enlarge all holes to #30. Disassemble and de-burr.

That’s it. I’m not going to assemble the bracket until I prime the parts, but with the pieces cleco’d together I checked the position and clearances. You can see from the photos that there is plenty of room for the cables and air connections. The OAT sensors can be mounted in the bottom wing skin, near the access cover – see the RV-14 instructions for a typical hole position (I haven’t drilled these yet).

The RV-14 instructions call for countersinking the W-00012C retaining strips for AN426AD4 rivets. The strips are too thin for this, the countersink would need to continue on into the W-00012B parts. I see no purpose for using countersink rivets here, so I’m going to use regular AN470 rivets instead, obviating the need for countersinking the parts.

I have to mount the OAT sensors, make up a wiring harness with tie downs and re-route the air lines. I’ll do these jobs once I’m ready to close out the wings.

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    f46a
    RV-14 ADAHRS bracket parts and instructions
  • f46b
    f46b
    Fluting the retainer strips
  • f46c
    f46c
    RV-14 ADAHRS bracket parts prepared/deburred
  • f46d
    f46d
    Drilling the bottom wing skin
  • f46e
    f46e
    Deburring holes added to the bottom wing skin
  • f46f
    f46f
    Dimpled new skin, Z bracket holes
  • f46g
    f46g
    Match drilled holes into J strut
  • f46h
    f46h
    Checking Dynon ADAHRS fit
  • f46i
    f46i
    Bracket in place, old air line routing will have to change.
  • f46j
    f46j
    Bracket cleco'd inside bottom wing skin, all fits OK
  • f46k
    f46k
    Looking up through access cover. Plenty of clearance all around.

 

Engine on, sortof [9.5 hours]

I’ve hung the engine, which took all of 20 minutes once I worked out how best to do it. It’ll have to come off again, so I’m leaving the engine lift set up. It has to come off again for several reasons:

  • The biggest reason – I have to do something with the sump oil line associated with the Barrett cold air induction scheme. There’s a VAF thread about it – here. This whole topic deserves a complete post, which I’ll do once I decide how to deal with it. Suffice to say, it is a nasty issue but until I have a strategy for this I can’t oil the engine.
  • With a B&C 90 degree oil filter adapter, the B&C 462-3H vacuum pad mounted alternator requires a 1.25 inch extension, which I mounted after changing to the correct studs. However, the clearance between the field wire connector and the firewall is not adequate. I’m going to modify the connector and bring the wire out the side so that there is adequate clearance. To do this I have to remove the engine.

While the engine is on, I’ve taken the opportunity to get out all the boxes containing everything that gets added to the engine, and verify that it all fits and I have the correct hardware. I found a few things:

  • The studs that Barrett installed for the PCU-5000X Governor are too short. They are probably the 3C-17 studs that are in the Lycoming parts list. They should be the 3C-19 studs, so I have to order four of these, remove the old studs, and install the longer ones before I can install the propeller governor.
  • The exhaust pipe for the #3 cylinder looks like it will impinge on the induction pipe for that same cylinder. If so, I’ll have to get that pipe modified.
  • I don’t have the engine mounting parts for the A/C compressor. I knew about this.
  • The A/C compressor will get in the way of the left air intake, requiring modification to the intake. I knew about this also.

One job I was able to complete with the engine on – I put a 1″ tie down strap between the front fork and the engine, cranked it down, and was able to easily compress the elastomers enough to get the retaining bolt in – without the engine on to establish the right leverage points, this is just about impossible.

I also made a doubler and drilled the fuselage to install the front ADSB antenna under the passenger seat.

  • f45a
    f45a
    ADSB antenna and doubler added under the front passenger seat
  • f45b
    f45b
    Engine on!
  • f45c
    f45c
    Compressing the elastomers to get the bolt in