Archive for the ‘Firewall’ Category

Completed Control Cables (I think) – 4.5 hrs

December 29, 2012 Leave a comment

Saturday Dec 29, 2012

I continued to make incremental progress today on the firewall forward tasks. I needed to install the second firewall penetration so I knocked that out. I hate drilling the stainless steel firewall because it is tough on drills but it must be done. I start by drilling a 1/8 inch center hole that I enlarge with a 1/4 inch cobalt drill. Then I used a unibit to enlarge it further to 7/16. The shaft of the hydraulic punch is just under 7/16 so I set that up with a 1-1/8 inch punch and it does the rest of the job. Here you can see the punch head installed just before I pumped it up to cut a nice clean hole. Actually I leaves a slight ridge on the inboard side of the firewall but that cleans up pretty easily.


Here is the pass-through fully installed on the pilot’s side. Ready to receive wires!


Next I made a new control cable bracket for the fixed pitch configuration (no blue knob) and match drilled holes to attach it to the bottom lip of the panel. It is clecoed on for now.  I will install nut plates later. I replaced the temporary bracket I had been using to lay out the cable runs and routed the throttle and mixture cables to the servo.


I think I am done with this task now so I applied blue locktite to the screws that hold the servo adapter plate to the sump and torqued them. Then I mounted the servo and installed the lock nuts and torqued those also. I could not get a crows foot on the nuts so I used my fish scale to apply 120 in-lbs of torque using a 5 inch radius arm on the wrench. That is, I applied 24 lbs of force x 5 inches = 120 in-lbs. I installed the mixture cable with all the hardware including the rubber seals which I had removed for all the routing activity over the last few days. Here is a “final” view of the mixture side.


And here is a “final” view of the throttle side. My only reservation now is the exhaust system and the hangers that will be used to support it. I just hope they don’t interfere with the cables and brackets I worked so hard to fine tune. I expect the exhaust to be delivered any time now since I ordered it a month ago from Larry Vetterman. I hope I don’t get surprised.


More FWF Progress – 5 hrs

December 28, 2012 Leave a comment

Friday Dec 28, 2012

This morning I finished the modifications to the FI servo and cable adapter brackets. The photo below shows the adapter and the angles of the two brackets. The one on the left is tilted inward 5 degrees and the one on the right is tilted four degrees.


I took the angle brackets off and marked rough lines on the sides for trimming. This just reduces the weight slightly and provides a little more clearance to the engine mount. This is the throttle side.


This is the mixture side.


After I trimmed the angles I match drilled the cable attach brackets for AN3 bolts and applied alodine to the parts. Here is the completed assembly from the throttle side.


And here is the mixture side.


I put that aside now until I get my exhaust system installed so I can check clearances to the hangers. So I turned my attention then to the alternator. I was surprised to find no instructions whatsoever for installing this in the Vans FWF kit. After getting a little frustrated with that I went on the Plane Power web site and found instructions in pdf form.  Good thing. One problem was to get the belt installed I had to lower the starter about 1/4 inch. I loosened the starter bolts slipped the belt through, then retorqued and striped the starter bolts.


The main bracket for the alternator gets installed with two large bolts which I torqued and safety wired (took two tries to get it right).


The rest was pretty easy and the alternator was hung in about fifteen minutes after that. Of course, it still needs to be wired up.


I also received two firewall pass-throughs in the mail today from Avery Tools. These are the SafeAir1 pass-throughs which look like pretty good quality. I had time to install one on the right side of the firewall near the brake fluid reservoir. I plan to install the other one on the left side tomorrow.


Categories: Firewall, Firewall Forward

Starting to Install Fuel Servo and Control Cables – 4.5 hrs

December 23, 2012 Leave a comment

Sunday Dec 23, 2012

This morning early I unpacked the components of the Airflow Performance fuel injection. These were included with the engine I bought from Aero Sport Power but were not installed when it was shipped. I have no idea how this goes together. The AFP manual is included but frankly it is less than straightforward. What I really need is step by step instructions based on my aircraft configuration. I am building 7A with IO-360, AFP fuel injection and vertical induction. That is not a “standard’ configuration supported by Vans. The closest thing they support is an O-360 in a 7A so you can’t count on the plans to always be right. I haven’t been able to find any clear directions on the forums so I’ll just have to try to figure this out as I go. I’ll document it as best I can in case anybody else needs the help.


There is an adapter plate that clearly looks like it mounts directly to the induction sump. And based on some of the information in the manual I gather that the two angle brackets mount to that adapter. But the angles have to go on first because the screw heads are not accessible after it is installed. I did some fit checks and I am beginning to see that the throttle control is on the right side of the servo and is further forward than the mixture control which is on the left. So the short bracket goes on the right and the long bracket goes on the left. At least one photo in the AFP manual seems to support this. But there are multiple holes on the angles and you can adjust the position forward and aft by selecting holes. What to do? More fit checks using the brackets and servo and a control cable seems to suggest that the angles should be set with the most forward hole in the angle mating with the most forward hole in the adapter as you can see below. I went ahead and torqued the screws for this but I could change it later if necessary.


Then I mounted the adapter to the induction sump. For now the screws are dry but I will use some locktite on these when I do the final torquing. Locktite is recommended in the AFP manual.


Here is the adapter from the right side.


And here it is from the left side with the fuel servo installed. I found four free running nuts in the ASP package along with four all metal lock nuts. I am guessing that the free-running nuts are for initial fit checks like this. At least that is what I am using them for. You can see the mixture control arm is about 6 inches forward of the flag-shaped area of the angle bracket. That is where I will mount an angle to hold the mixture cable.


The right side shows the throttle control and again the flag-shape area of the angle bracket is about 6 inches aft of the control arm. It’s starting to make sense now. I can see now why the Vans plans for an O-360 show a firewall penetration near the fuel line fitting for the throttle control. It is a pretty straight shot and the angle bracket can be used to secure the cable. Now I feel confident I can punch the hole for an eyeball feed-thru in that area. I sighted along the projected path of the cable and see that the feed-thru should be between the fuel fitting and the nose gear tube of the engine mount (see below). I marked the center of the hole location and drilled a 1/8 inch pilot hole. Then I enlarged it to 7/16 using a step drill.


Fortunately a friend loaned me a hydraulic punch kit with a 1-1/8 punch and it requires a 7/16 center hole. For clearance reasons I had to put the head of the punch on the cabin side of the firewall. Here you can see it set up just before pumping the handle to punch the hole.


Wow, the hole came out nice and clean. I barely had to deburr the interior edge. I used the eyeball parts as the template to mark the locations of the screw holes and I drilled those with a 1/8 inch carbide drill bit. Notice that I rotated the hole pattern about 45 degrees from horizontal so it would fit better.  To have better access I removed the fuel servo before punching this.


Then I screwed the eyeball parts into the newly made penetration. It is ready to receive the throttle cable except the cable is .265 diameter but the hole in the eyeball is .250. I need a 17/64 drill bit to open this up just a little.


Installed Fresh Air Vent Hoses – 1 hr

December 19, 2012 Leave a comment

Wednesday Dec 19, 2012

I was really cold in the garage tonight and I couldn’t bring myself to stay out there that long so I just cleaned up a few minor details. One thing I did was measure and cut two sections of SCAT tubing for the fresh air vents and installed those.



I also modified took a picture of the plug I installed in the firewall where the nose gear bolt protrudes. If you look closely you can see that I put a bulge in the center of the plug to allow more room for the bolt. I did that by drilling a slight hemispherical dimple into a piece of 2×4 wood with a 5/8 inch drill, placing the plug on top of the dimple face down, placing the butt end of my ratchet handle on that (it has a domed shape end) and whacking it with a hammer. That worked nicely.


Bonded Nose Gear Strut, Installed Oil and Fuel Pressure Manifold – 4.5 hrs

December 15, 2012 Leave a comment

Saturday Dec 15, 2012

I have read reports on the forums that some RV owners have had problems with the nose gear bolt loosening over time and/or the bolt hole yielding allowing the nose gear to rotate slightly around the strut axis. Some builders have opted to put a large tapered pin in place of the 5/16 bolt requiring the holes to be reamed together at assembly. There are a lot of RVs flying without this problem apparently so I decided to stay with the Vans standard design. There is another way to strengthen the joint and that is to epoxy bond the mating surfaces between the strut and the engine mount around the bolt hole. I decided to go this route. The first step was to remove the nose gear strut from the engine mount.


I bought some Devcon epoxy mix at the hardware store. I chose this epoxy because it is strong (2500 psi) and it is rated for use up to 200 F. That relatively low temperature means I can easily heat the strut up and weaken the bond if I every need to remove the strut again. Other epoxies rated up to 500 F would make that very difficult. I am thinking at the gear bolt should stay well below  200 F in service.


I cleaned the journal surfaces of the strut and the mount with solvent to remove any grease. Then mixed the epoxy and rubbed a generous layer on the inside diameter of the mount. Then I inserted the gear strut half way. I applied a thin layer of grease to the lower strut journal which will not be bonded, then pushed the strut all the way in. A good bit of epoxy oozed out so I am confident I got an adequate amount in the joint. Then I just inserted the bolt and torqued up the nut. I cleaned up the excess epoxy. Here is the bolted joint starting to cure. I can’t get the bolt in from the inside of the cockpit as prescribed in the plans because the hole is slightly too high. I don’t know how that happened because I think I measured it accurately. I may be in the tolerances of the engine mount or perhaps I should have used a 1-inch hole (the plans call for a 3/4 inch hole). So I inserted the bolt with the head up. I have read that others have done this also. I may have to punch a dimple in the hole plug to clear the nut head.


I also assembled the manifold for the oil and fuel pressure sensors. First I had to rivet the F-745 ribs to the firewall. Then I installed the fittings and hole plugs on the manifold using Permatex #2 to seal the threads. I was worried that the fittings may not want to point in the right direction when I tightened them up but they came out fine. Maybe I was just lucky. If so, I’ll take it. Then I mounted the manifold to the firewall using two AN3 bolts. Finally, I installed the oil pressure hose from the kit with two Adel clamps to secure it along the top of the firewall recess.


Installed Flap Position Sensor, Riveted Firewall Recess – 5 hrs

November 10, 2012 Leave a comment

Saturday Nov 10, 2012

For some reason I decided that it was time to install the flap position sensor behind the seats. But first I removed the flap motor channel and replaced three universal head rivets with flat head rivets because the canopy release bar was rubbing against them. Best to get this done now.

The flap position sensor is a Ray Allen POS-12 linear potentiometer. The method of installation came from Mike Bullock on his web site (thank you Mike). I used the same model airplane clevis’s and control rod specified on his site. I also installed a 3-pin Molex connector on the POS-12.

Installation in the flap motor cover was easy. I did a trial fit of all the parts first with the flap motor in the fully raised position and marked the channel where the POS-12 was located with the sensor arm fully extended. The clevis’s were set at the mid point of the threads so could adjust the overall length of the rod at final installation. In this photo you can see the POS-12 mounted to the channel with two #4-40 screws and some cheap lock nuts I picked up at True Value Hardware. I’ll replace those later with better quality parts. I also installed a couple of tie bases to route the wires.

Here you can see the sensor installed. The linkage uses just about all of the 1.2 inch range of the potentiometer. I used my car battery to drive the mechanism up and down a few times to check function and alignment. I used the clevis’s to set the linkage so the POS-12 does not drive into the stops at either end.

The lower clevis is attached to a 1-inch Adel clamp using a small part I made from aluminum angle scrap. I left just enough material on one side of the angle to provide a shoulder that prevent the part from rotating on the Adel clamp screw. One small hole is all that is required to attach the clevis.

At the upper end you can see the POS-12 with the other clevis attached. All that is left here is to route the electrical wires for the POS-12 and the motor forward to the avionics bay.

Another big step today was installing the firewall recess. I wanted to keep this open as long as possible  because I makes it easier to get to things up front but I will be installing the engine soon and the recess needs to get installed first. I cleaned all the faying surfaces with scotchbrite and Simple Green first, then wiped them all down with MEK. I used Flamemaster C1900 sealant which I ordered from Sky Geek. After I mixed and applied the sealant I clecoed on the recess and began riveting. I also used C1900 to plug all the small holes in the corners. This photo shows the recess installed after I remounted the battery box and torqued it.

Installing ANL Current Limiter and Shunt – 3 hrs

October 30, 2012 Leave a comment

Tuesday Oct 30, 2012

This mini-project is to mount the ANR current limiter and ammeter shunt to the firewall. The ANL current limiter is recommended by Bob Nuckoll’s book “The Aeroelectric Connection” and I ordered it from B&C Specialty Products. The ammeter shunt came with the Dynon engine sensor kit. I laid out the parts on the firewall in a configuration that is conducive to wiring and works with the stiffener rib structure on the other side of the firewall. The shunt is wider than the current limiter so I put it beneath the current limiter base and aligned one of its mounting holes with the center of the stiffener rib and half way between two existing rivets. The current limiter base is placed such that it is in line with the terminal on the starter contactor and the left ANL post is directly above the left terminal of the current limiter. I marked the screw locations on the firewall and drilled the holes for #10 screws. The screws did not come with the electrical parts but I decided to use socket head cap screws for the shunt and I found some stainless steel 82 degree flathead screws at the hardware store that should be fine for the current limiter. Here is a photo of the parts temporarily mounted to confirm the locations.

Then I made a .062 doubler plate to go on the aft side of the firewall to back up the three holes that are not through the rib. This doubler will also support nut plates. I added a couple extra #40 holes for additional rivets in the corners. In this photo it is placed on the front of the firewall for drilling but will be installed on the far side.

Then I cut pieces of copper bar to electrically connect the starter contactor to the current limiter and shunt in series. This is basically how it will look when installed. The lower right terminal of the shunt will be connected to the alternator so this is the electrical path for current to flow from the alternator to the battery and main power bus. But I still have to prime the doubler and install it on the firewall with the nutplates before final installation.

Categories: Firewall, Firewall Forward

Miscellaneous Firewall – 2 hrs

July 23, 2012 Leave a comment

Monday July 23, 2012

I made a few more holes in the firewall tonight. First was the 3/4 inch access hole for installing the landing gear attachment bolt nut. I drilled this with my unibit. Spent more time deburring the edge than drilling the hole.


I also drilled out two holes along the top of the firewall recess and installed nut plates. These will be used to support the oil pressure lines from the engine to the VA-168 sender mount.


I also drilled the holes to mount the VA-168 sender mount to the firewall. No deviating from the plans in any of this. Right by the book.

Categories: Firewall, Firewall Forward