June 2010 Archives

I didn't have much time tonight, but I wanted to get something done on the plane.  I'm trying to get all of the fixed items installed to the engine (those where I have no choice of location) before installing those items where I do have a choice.  I used some anti-seize compound and installed the CHT sensors in the port on the bottom of each cylinder.  The wires are just hanging for now until I determine for sure where the Dynon EMS box will be mounted.



I also installed the lower plugs (again with anti-seize) since I wanted to make sure the EGT probes wont interfere.



I got my battery cable and terminals from SteinAir.  I'm going with #2 Tefzel cable even though it's very hard to bend.  I considered both welding cable (recommended by Bob Nuckolls in his AeroElectric Connection book) and CCA Fatwire sold by Perihelion Designs.  Both are far more flexible, but the insulation is only good to 105ºC at best vs. Tefzel which is good to 150ºC.  It will be a little more difficult to run, and there is a slight weight penalty compared to the more common #4 wire, but this should be made up for by lower cranking wire loses which should result in a faster spinning starter and an easier to start engine.

I crimped one of the connectors on a piece of wire using an impact crimper I picked up from a welding supply company.  The crimps aren't the prettiest, but they're very secure.



I then slipped a piece of heat-shrink tubing over the joint to provide a little bit of wire support.



I then bent the end of the terminal over 90º.



This terminal is attached to the input side of the battery contactor.  The other end will attach to the positive terminal on the battery.  I need to order so more silicone nipples before attaching the other end for good.



I wanted to see if the mixture bellcrank would fit on the superior sump.  It's supposed to install under these two bolts, but this plug is in the way.



After cutting the safety wire and removing the plug, here's the hole that's left.



The bracket now fits over the boss in the sump, but unfortunately the holes are still off by almost 1/4"



I deepened the notch in the bracket enough that it could be bolted in place.  Notice that the hole in still there, and this bracket will prevent the original plug from being reinstalled.  I'll have to order an AN932-5 plug to install here instead.  That is a hex drive plug that will install flush with the surface of the case.

Here is the mixture bellcrank in the most rich setting I can get.  Unfortunately, the mixture lever is interfering with the starter.  I'll call Precision Airmotive to see if they can send me an alternate mixture lever.



Here is the mixture bellcrank in the most lean position.  I can hit the idle cutoff stop without any problems.


Finally, I spent a little time trying to figure out how to secure the throttle cable.  The Superior sump doesn't have threaded ports in the bottom in the same location as a standard Lycoming sump, so the bracket from Van's won't fit.  I'll probably have to fabricate a custom steel bracket for the throttle cable.
I called Precision Airmotive this morning, and they have a shorter offset mixture arm (1 5/8" vs. 2") that should work perfectly for me.  This should eliminate the interference with the starter and allow me to hit both stops on the mixture arm.  With the longer lever, I could hit one stop or the other, but not both due to the short throw of the control cables.

I also called around for a bit trying to find an AN932-5 plug, but couldn't find anybody who stocked them.  I ended up ordering an AN932-5D plug instead which will work fine.

I spent most of the night cleaning up the garage, but I did swap out the rocker arm cover gaskets.  You can see the old cork gasket on the left and the new silicone gasket on the right.  Surprisingly, I already found an oil leak from the old cork gasket, so I'm glad I replaced these.



I finished the battery positive cable.  There will be a couple of adel clamps securing this to the adjacent engine mount tube to prevent the terminals from carrying the full weight of the cable.



I also fabricated the engine ground strap.  I used an empty hole near the oil filler neck which required removing all of the paint on the aft side of of the boss.



Here is how the cable routes up to the grounding strap.  You can also see the battery negative cable here.  I can still easily remove the battery without having to loosen any cables.



I also put the fitting on one end of the starter cable.  I left the starter cable a little long since I'm not 100% sure of the routing right now.  It needs to pass through the same area as the mixture cable and bellcrank, so I want to have that in place before finalizing the routing.  You can also see in this shot that I added a washer under the fuel fitting.



I moved the 45º fitting up to the top port in the pressure transducer manifold and installed a 90º fitting in the bottom one for the fuel pressure hose.  I also installed a couple of polyethylene hose fittings in the top port.  One will route manifold pressure to the Dynon MAP sensor just to the left and the other will route manifold pressure to the Lightspeed electronic ignition.



I also spent a little more time playing with the locations of the various boxes that will mount forward of the subpanel and I think I came up with a layout that I like.  Here is where the Dynon EMS box will mount.  I separated the sensor wires from the 37 pin connector into one bundle that needs to penetrate the firewall and one that doesn't. 



Here is where I'm planning on mounting the Lightspeed ignition box.  This provides convenient   routing of the primary ignition wires which will run along side the battery and main bus power lines.



And here is where I'm thinking of installing the voltage regulator.  I can still easily reach the voltage adjustment screw in this position.  The only disadvantage is that I need to drill a few more holes in the firewall.



I installed my EGT probes tonight.  Dynon recommends 2-8" from the exhaust flange.  The precise distance isn't important, but it's very important that the distances are the same for each cylinder since that lets you compare EGT readings across cylinders.  Anything over 2" on my exhaust setup would put the probes past the first bends, and it would be hard to remain accurate on the measurements.  These constraints pretty much dictated that my EGT probes would be at exactly 2" from the exhaust flange.  I positioned the probes so that they stick straight out from the sides of the pipes.  I've seen a lot of builders angle these one way or the other to try and keep them from sticking out so far, but there is plenty of clearance from the cowl sides and this keeps them from interfering with other things like the lower spark plugs.



Here's a closeup of the #2 probe.  Just like other hose clamps in the engine compartment, I safety wired them to prevent them from ever backing off.



I received my AN932-5D plug from General Aircraft Hardware.  $17 bucks shipped was kind of a ripoff, but the alternatives would have been even more expensive.  I had to grind off about 3/64" from the visible face here to get the surface flush with the sump.  After installing it, I used the touch-up paint that came with my engine to paint the exposed aluminum face to match the engine.  I then installed the mixture bellcrank to the sump.



I also regreased the pivot point and installed the cotter pins in the pivot bolt and the output bearing bolt.  The other end of the output shaft is still loose until I get the replacement servo arm from Precision Airmotive.


I'm pretty swamped with our developer conference at work, so progress will be slow for the rest of the week, but I'm still trying to get a few things done here and there.
I ordered some one and two wire spark plug wire adel clamps from Sacramento Sky Ranch.  The order came in today, so I installed some of them on the cylinders.  These are stainless steel with silicone cushions that are good to 400ºF.



The forward cylinders get one wire clamps.



The aft cylinders get two wire clamps.  These are sweet because they're formed to clamp two  wires instead of something cylindrical like typical adel clamps.  I picked up a few more of the two wire clamps to anchor the spark plug wires the rest of the way to the magneto.



I also cut down the rear spar a little bit where the forward elevator pushrod passes through.  The cutter got away from me a little bit and widened the hole as well on the right side.  I put a little self-etching primer on the cut edges.



I then temporarily installed bolts in each end to check the fit.  There is almost 1/4" of clearance where the pushrod passes through the rear spar cutout.  Even under high g loads, the pushrod shouldn't be able to flex enough to contact the spar.  This the the rear end where the forward pushrod attaches to the elevator bellcrank.



This is where the forward end attaches to the center control column.



Our developer conference is finally over.  It's great fun, but a lot of work and incredibly exhausting.  We launched the revolutionary new iPhone 4 which I worked on and I can't wait to see how well it does in the market.

Anyway, I spent most of the day just taking it easy and hanging out with the family after not seeing much of them for the last week, but I did sneak out into the garage for a bit after everyone headed to bed.  First, I cut the forward cover in two so that the forward part could be easily removed without having to touch the fuel pump of fuel lines.  The aft part is still removable, but I hope that is almost never necessary.  I'll run conduit under here so that I can run additional wires without having to remove this.



I also fabricated the fuel line from the pump to the firewall fitting.  I held off on this for a long time because I was trying to decide whether to put the fuel flow sensor here or after the fuel servo.  Most people seem to install it here, but claim that the fuel flow is incorrect when the electric fuel pump is on.  Some have also claimed that there is a small risk that this location could result in vapor lock since the mechanical pump is pulling fuel through the sensor.  The fuel flow sensor manufacturer recommends installing the sensor downstream of all pumps, and even downstream of the fuel servo for the most accurate readings.  Because of this, I've decided to install the sensor just after the fuel servo, probably just under cylinder 1.  With this decision made, I could go ahead and fabricate this fuel line.  One additional benefit I hadn't really thought of is that this reduces the number of fuel fittings in the cockpit which theoretically reduces the risk of an in cockpit fuel leak.

I ran the line on the left side of the bay since a large bundle of wires from the panel will enter this area just to the right of the firewall fitting and snake down under the forward cover and then under the aft cover.  Keeping the line to the left gives me a little more room to run these wires.



Aft Top Skin

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My buddy Andre stopped by today and prepped the aft top skin for riveting.  We didn't have time to get it riveted, but it's clecoed on and ready to go for next time.



While he was working on that, I moved the tee in the static system up near the top of the bulkhead, right next to where one of the stringers will be installed.  Since I decided to mount my ADAHRS from the top rib between F-706 and F-707, I decided it would be simpler to run the static tubing along that top stringer and directly in to the back of the ADAHRS.  This has the advantage that the static ports are the lowest portion of this part of the static system, so in theory it should allow water to drain out of the system and not make its way into any of the instruments.



I also worked on the forward half of the center cover.  I've enlarged the hole at the back half for the fuel line to drop through.  I'll still need to enlarge it a little more to ensure it can never come in contact with the fuel line and abrade it.



I put the forward spar covers in place.  These are supposed to fit under the front edge of the seat pan, but I put it on top initially so that I could match drill the seat pan to one hole in the forward spar cover.



Here's a closeup of the hole that needs to be drilled.  A nutplate will mount on the spar cover and a screw will go through the seat pan and into this nutplate.  If I put the spar cover behind the seat pan, I'd be drilling this hole blind.



After match drilling those holes (one per side), I installed the nutplates and reinstalled the covers.  Next, I cut the flange off of the fuel selector mounting plate flush with the forward face of the fuel valve cover and cut a notch in the bottom of the fuel valve cover so that it could temporarily sit over the fuel pump.  I then took the fuel pump top cover that Van's sells for the Airflow Performance fuel pump kit and figured out how low I could mount it.  Since the Andair pump kit is significantly smaller than the Airflow Performance pump kit, I had previously decided to lower the cover as much as possible.  This will require fabricating custom side pieces, but that's pretty easy. 



After determining the mounting point, I drilled the fuel pump cover to the fuel selector cover.



After enlarging the opening in the bottom of the fuel selector cover, I fit the flange from the fuel pump cover inside the fuel selector cover.  These holes will get dimpled and these pieces will be riveted together along with the side covers I need to fabricate.



The shorter mixture arm arrived from Precision Airmotive today.  I installed it and then spent a little time adjusting the various linkages to get proper movement.  Here is the linkage in the idle cutoff position.



And here it is in the full rich position.  The shorter throw meant I could easily go stop to stop at the mixture arm.  With the longer arm, I could either hit one stop or the other, but not both.



Here you can sort of see that there is plenty of clearance between the mixture arm and the starter now.  At its closest, there is at least 1/4" between these two.  Since all of this is rigidly mounted to the engine, this is plenty to ensure that these will never make contact.



I used a couple of straight edges clamped to the other spar cover attach brackets to define the position of the outer attach angles.  I then duct taped the angle in place and match drilled it to the gear webs.



I blind riveted the attach angles to the gear webs using LP4-3 rivets.  I had to grind down the tips of the rivets and pull them in small steps (pounding the rivets further in each time).



I also installed the nutplates using MK-319-BS rivets since there wasn't enough room to get a normal rivet squeezer in here after riveting these to the gear webs (and the nutplates couldn't be installed first since they would have interfered with squeezing the LP4-3 rivets).  I just realized that I forgot to cut the notch in these for the fuel line grommet.  I'll have to do that in place.



Happy Father's Day everybody.  I spent most of the day with family and some friends, but had a little chance to get out into the garage late tonight.  First up, I marked and cutout the notches in the outboard forward spar cover attach angles.


Next, I decided to try and bend the fuel lines that come in from the sides of the fuselage and connect to the fuel selector.  I knew I shouldn't have started something like this at 11:30 at night.  I got the first piece mostly bent, then realized that I put one of the lines on the wrong mark on the bender and left one leg too long.  Attempting to fix it only fucked up the tube enough that I couldn't get a sleeve to slide over it anymore.  I then took the only remaining piece of tubing I had and tried again.  After carefully measuring the bends, I proceeded to put one of the lines on the wrong god dammed mark on the bender again and left a different leg too long.  Holy fucking christ!  I was pretty pissed off by now.  I'm out of tubing and it's expensive as shit to ship these 6' long pieces from Aircraft Spruce.  I don't want to order just one piece either, because what's the chance that I'll bend the next two perfectly.  So this was probably a $50 fuck up tonight just because I was not thinking clearly.  I'm going to bed...

Started Cabin Frame

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I called Bonaco this morning and put in an order for a few hoses.  I ordered a short hose that will run from the fuel bulkhead on the firewall to the inlet of the engine driven pump.  I also ordered the hose that run from the outlet of the engine driven pump to the fuel servo.  This hose needed 45º fittings on each end with 270º clocking.  We'll see soon if I measured correctly.  I also picked up the hoses that run from the brake fluid reservoir down to the master cylinders.  Since all of my other brake components are black, I had Brett do these in black as well.  Finally, I ordered the brake lines that go from the bulkhead fittings on the firewall down to the wheel cylinders.  Van's plans call for rigid lines from the bulkheads down to the wheel cylinders with generous service loops inside the wheel pants to allow for flex and vibration.  This is a notorious source of cracking though due to flex in the aluminum line.  Since aluminum doesn't have a fatigue limit, even minor flexing will eventually result in failure.  Even the MIL-PRF-83282D brake fluid (which is a huge improvement over the old MIL-H-5606 fluid) is flammable, so a brake line failure can really ruin your day.  Some people run rigid tubing down the leg and transition to flex line near the wheel cylinder, but the whole gear leg flexes when on the ground, so this really doesn't eliminate the line flex.

Since I'm waiting on an order from Aircraft Spruce for new 5052 brake lines, I decided to get started on the cabin frame.  I clamped a straight edge to the bench and then clamped wooden blocks to the vertical legs to define the overall width of the frame.



The center seam was pretty close, but I touched it up with the vixen file to get the edges perfectly aligned.



The bottom edges were not even close to parallel with the guide angle, so I marked and trimmed them flush.



Here is the result.  It looks like there is a shadow here, but that's just the black line I drew parallel with the guide angle.



The canopy frame is about 1/16" taller than the plans specify, but I'm going to leave this.  In fact, I'll likely try to cheat the canopy up another 1/4" or more in final fitting.  This will directly translate to more headroom in the plane which I've heard is a problem for someone my size.



Last up tonight, I drilled the 1.5" holes in the bottom end of the aft members the roll bar.  This is to allow access to the bolts that hold the cabin frame down to the seat back support.



An order from Aircraft Spruce showed up today with some 1/4" ID tygon tubing.  I cut a short piece to connect one outlet of the pressure transducer manifold port to the Dynon manifold pressure sensor.



I used the remaining tubing to connect to the other outlet and ran this through the firewall passthrough.  Inside the fuselage, I'll transition from 1/4" ID tubing to 1/8" ID tubing for the connection to the Lightspeed electronic ignition.



Finally, I fabricated the splice plates for the cabin frame halves.  The pieces that Vans provided for this were not square.  The two short edges were not perpendicular to the long edges.  I laid the holes out square though since the rivets will be seen on the outside of the cabin frame.



Misc Engine Tasks

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I received another order from Aircraft Spruce today with this AN816-4D fitting that is used to tie the manifold pressure line into the #3 cylinder.  The end is taped off with electrical tape to keep moisture out of the cylinder until the manifold pressure line is installed.



The order also contained some all metal lock nuts, so I used a few to install some adel clamps on the starter cable wire.  In this picture you can see an adel clamp holding the wire to the oil pan just above and behind the mixture bellcrank.  After that, the line drops down...



...and run through these adel clamps on its way to the starter solenoid.  After everything was tightened down, I removed the terminal from the starter so that I wouldn't inadvertently turn over the engine during future wiring.  It will probably not be reinstalled until just before first engine start.



Finally, I clamped the engine ground wire where it passes by the upper engine mount tube.  This was a fairly long wire (read heavy under high g loads), so I didn't want it to be entirely supported by the terminals on the end.



Worked on Cabin Frame

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I rounded over the edges of the canopy frame joint strips.  These join the front and back halves of the cabin frame.  The radius is necessary so that the halves can be pulled tightly together.



I also put a strip of masking tape around the inside edge and marked for the lowest hole.  I'll use a rivet fan to lay out holes along this strip and then use it to drill the holes evenly along the inside edge of the canopy frame.



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