Tonight I finished safety wiring the prop attach bolts. I had previously wired two of the 6 bolts, but had left the others so I could move on with other tasks. At the time I was working towards a deadline – moving the fuselage to the airport – and didn’t want to spend more time on the task. The first two bolts had been a real pain, and I had redone the wiring several times before I was satisfied that it didn’t suck too badly.
For the remaining four bolts, I started by practicing with the thinnest safety wire I have, which is much easier to work with. After figuring out the routing, the length required, and any other relevant details, I switched to the large diameter wire and completed the task. The bolts are wired in pairs, and each bolt has a hole through the center where the wire passes. Because of the varied orientation of the bolts, each one presents a unique challenge in getting the wire through the hole. I was lucky that only one bolt needed loosening and reorienting, and I was able to get all the others to work without adjustment.
In the end I was quite happy with how it turned out, and found that a little practice and lots of patience definitely helps.
A pair of wired bolts. The wire acts as a fail safe in case the bolts vibrate lose and start backing offAnother pair of wired bolts
Before completing the aircraft wiring, I decided to switch to a Lithium battery, and EarthX seems to be the most popular brand for RV builders. The difference in weight between the original lead acid battery and the Lithium battery is substantial. I didn’t have the original battery specs, but it must be 3-4 times heavier than the Lithium battery. There are some other benefits too, such as a longer period of output, longer store of charge, and a battery health indicator output wire.
The EarthX 1200 series is an almost exact match in size. It’s slightly deeper, slightly narrower, and the top is shaped differently. The battery came with some foam to help make up for the narrower shape. I added a washer on each side to account for the wider shape, and added some aluminum strips with foam to the hold-down bar to ensure a snug and secure fit.
The battery terminals are basically the same, so once I had modified the hold down bar and charged the battery, it was ready to go.
Original Vans supplied battery. This is a few years old now.Side by side comparison of Vans batttery (right) with EarthX battery (left)Test fitting. Not the gap under the hold down barAdded some aluminum strips and foam to the hold down barFinal installment. Note, the ground is disconnected since I’m still running on ground power at this point
This morning I finished out chapter 41 (wing attach) by installing the fuel vent lines. I opted for Aircraft Specialty vent lines, just to save some time and effort, and I also installed the JD Air fuel vents.
The standard Vans fuel vent design has a fuel line passing from the tank down through the wing fairing, where it’s chamfered at 45 degrees. I’m sure this works great, but there are a couple of downsides. The line has no screen, so there’s a risk of insects or dirt making its way into the fuel line, or even the tank, and causing an obstruction. There’s also a chance I’ll snag the vent on something and damage it. JD Air makes a streamlined vent with a built in screen, so I installed these instead. Aircraft Specialty makes a fuel line that fits the JD Air vent, so that was very convenient.
The vent itself attaches to the bottom wing root fairing using a bulk-head fluid fitting, so it simply screws into position. I was then able to loosely install the fairing, position the fuel line, final torque the fairing screws, then torque the b-nuts on the fuel line to secure it in place.
Everything went well, the only bummer is the gap at the aft end of the fuel vent, caused by the curvature of the fairing. It’s no big deal, it’s just cosmetic, and no one will see it unless they look for it specifically.
I also installed fuel placards and some grip tape on the pilot side of the wing walk area.
After a weeks off for the holidays, I was able to make some more progress this week.
I finished the wing root fairings, and installed the wing root fuel lines. These are the lines that connect the fuel tanks in the wings to the fuselage.
The wing root fairings were fairly straight forward. Getting the right shape on the bottom fairing was probably the biggest challenge.
Soon after getting the shape right I realized that I needed to countersinking the holes on the tank attach bracket. And then I noticed I had more containing to do on the wing top skin, so that the top fairing could be installed.
I brought all my countersinking, drilling, dimpling and riveting equipment to the hangar today and knocked it out. The countersinks are a little tricky because the nut plates are already installed, so a #8 countersink (the correct size) doesn’t work because the pilot interferes with the nut plate threads. I used a #21 count sink bit which seemed to be just the right size to fit into the nut plates. The countersinks are fairly deep because the fairing has #8 dimples that need to nestle down into the countersinks. The aluminum stack up is several layers deep, so there is plenty of material to support the counting depth. The only tricky part was the top, inboard countersink on the tank attach bracket. This was too close to the fuselage to get the counting cage to sit vertical, let alone the drill. I rigged up a long extension, about 18 inches long, a drilled those countersinks without a cage. It was quite easy to see the depth and I just went little by little until it was done.
There are some holes that need to be match drilled, and then 3 nutplates installed on each size. I drilled, dimpled and riveted these.
I found some proseal and used it to glue down the wing spar spacers, after giving them a little shape to conform to the wing skin.
The fuel lines were next on the list. These were pre-bent by Aircraft Specialty, and they fit exactly right. The time consuming challenge was finding a way to get them into position. The line is short and quite inflexible, and the flared ends, which are easily damaged, mate to the aluminum fittings on each side.
I loosened up the fuselage side fitting so I could flex it inboard and create enough space to insert the fuel line. I had to use a wedge to push and hold the fuselage fuel line out of the way enough to insert the new line. Once the line was in position, I torqued everything up and it all looked good.
The three nutplates that I installed, this picture is of the right hand side, it’s a mirror image on the leftClose up of one of the nut platesCountersinks on the top of the tank attach bracket. The one at the top of the image is close to the side of the fuselage and hard to reach. The spacer glued into position on top of the wing spar. This hard plastic block supports the upper wing root fairingTop fairing installed on the left sideThe underside of the bottom fairing. The screw in this position grazes the end of the wing spar. Rather than installing a full length screw, I plan to order and install some shorter screws that will stop short of touching the sparThe fuel line in place. The wing tank is on the left, and the fuselage is on the right. B-Nuts are not torqued yet.Looking down at the left hand side fuel line After torquing the B-nutsEarly morning at Ramona after a rainy night
This weekend I decided it was time to install the firewall passthrough fire-proofing sleeves that secure the wiring bundles. There are two on the RV-14, and on my setup I have the main power cables going through one, and the smaller sensor data cables going through the other.
First I confirmed there was mother else that I’d forgotten to route through the firewall. In an attempt to future-proof the setup, I ran three spare wires through the firewall. Each is long enough to run from any point on the panel to any point in most places in the engine compartment.
I figured out quickly that Vans’ plans could use an update. There’s no way to wrap the bundle of wires with the supplied fire sleeve the way they describe. However, rotating the fire sleeve 90 degrees allows you to cut it to a useful dimension. Once the fire sleeve is pushed through the opening, it’s filled with high temp RTV, then wrapped with a second layer of fire sleeve, and secured with safety wire.
I was happy with how this turned out, especially after reading other reports of a messy and difficult job.
When applying the RTV, I used a flat plastic bag (a cake decorating bag) with a small opening. This helped to get the RTV down into the tight spaces between wires, and allowed me to attack it from both sides of the wire wall.
First layer of fire sleeve in place and filled with RTV. The black protective wiring sleeves terminate right at the edge of the RTV mess, and can be removed if necessary.Second layer in place and secured.
Tonight I installed the oil cooler hose and the sniffle valve.
I had held off installing the oil cooler hose until I had filled all the gaps in the baffling. With that job done, I went ahead and installed the hose. It was easy, and the only surprise was that the hose didn’t come into contact with the oil filler. The angle coming off the baffles is just enough to provide clearance.
The sniffle valve was also straight forward. I zip tied the end to the engine mount just above the right hand exhaust pipe.
Oil filler hose installedOil cooler host attached to the oil coolerRight hand side view of engine showing oil cooler hoseSniffle valve installedSniffle valveExit from sniffle valve pipe
For some reason, Lycoming shipped the engine with an extra fitting in the fuel spider. The Vans plans warn about checking for this fitting and removing it. Unfortunately, the fitting can’t be rotated, as there is interference with the engine case. So I had to remove the spider, remove the fitting, install a plug, and reinstall the spider. This ended up being quite easy.
The fitting closest to the wrench in this picture is not used on my installation, and needs removing.Fitting removed and plug installedLooking down on the fuel spider
Over the weekend I took some time to seal up all of the visible air gaps around the baffling system. To help find and plug the gaps, I put a lead light on top of the engine, then installed the top cowl. I had to reposition the light a few times, but it did a nice job of finding many little gaps that needed to be filled with RTV.
This had to be done at night to ensure the garage was dark enough, but that works well since I’m typically working at night.
A low light picture of the procedure. Note the light projecting forward out of the air intakes and onto the wall.
Tonight I switched out two engine case bolts for longer versions. These are specific bolts, ordered from Lycoming, and are 1/8 longer than the originals. The Vans plans have you place a washer and a cushion clamp on these bolts (one on each side), and there aren’t enough threads showing if you use the original bolts. The clamps hold the starter lead on the left, and the alternator power wire on the right.
Replacing the bolts was fairly easy. The cushion clamps always a pain, but I was able to get enough fingers in there to make it work. The nuts are torqued to 96 inch pounds per Lycoming.
Note the couple of threads now showing on the bolt in the top center of the image. This clamp is holding the alternator power lead.Note the unpainted bolt head in the top left of the picture. This is holding the clamp which holds the starter lead.A view looking aft showing the left hand bolt threads protruding above the nut
It’s hard to reach the prop bolts with a regular crowfoot, so I bought a special prop-torque crow foot. I looked at a few options and decided on the Anti-splat Aero tool. It’s well thought out and did an excellent job. There’s a good video here that shows the tool in action.
The first step is to torque all bolts to 40 inch pounds, then to 60-70 foot pounds as the final torque. With the extension tool, I calculated 35 and 57 foot pounds. I measured the length of the arm of the torque wrench and the length of the extension and used the formula T1 = T2 * L1/L2 where T1 is the torque on the wrench, T2 is the target torque value, L1 is the arm of the torque wrench and L2 is the arm of the torque wrench plus extension.
Then final torque to 60-70 foot pounds (calculated as 57 on the tool). by holding the prop in one hand and torquing with the other I was able to torque all 6 bolts up myself.
The next step is to safety wire these bolts in pairs. That will be challenging due to the orientation of some of the bolt heads. Undoubtedly I’ll need to back some of these off to thread wire through and then re-torque.
Torque wrench extension in action.Applying final torque. One hand on the prop to prevent rotation and one hand torquing. Glad it didn’t need any more torque, else I’d have needed a second set of hands.
