January 2014 Archives

Miscellaneous Assembly

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I repaired the bracket and got all of the wing attachment bolts final torqued.



I also finish installing the rear spar bolt and cotter pinned it.



My brother wrapped up the vertical stabilizer.



We also installed the prop and my brother spent some time learning to safety wire.  We ended up cutting off every try we made and we'll try again later.



First Engine Start

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My brother and I came out to the airport early and got final assembly taken care of.  We bolted on the elevators and rudder, torqued and adjusted the ailerons and hooked up the flaps.  My buddy Greg came down and we got most of the safety wire on the propeller done.  We did a very thorough pre-flight and then pulled the plane out for first engine start.



We tied the plane off to my car and chocked the wheels.  Greg and his son Nicholas were on handheld radios so I could be in contact with them.



We spent a little time trying to diagnose a problem with the Andair fuel pump, but it looks like it's not working correctly.  I'll have to call Andair tonight to see what they want to do about this.

We decided to go ahead and try first engine start with just the engine driven fuel pump.  We pre oiled the engine by pulling the plugs and spinning the starter until we got oil pressure and fuel pressure.  Unfortunately, that killed the battery, so we had to hook it up to jumper cables for the final start.  After reinstalling the lower plugs, it fired up pretty quickly.  Here's a video of the first engine run.



Everything about the start went beautifully.  The engine ran perfectly and we were able to verify all engine controls are working correctly, both ignitions are working correctly, all pressure and temperature senders are working correctly.  There is one small oil drip from the cap on the oil cooler, but other than that, everything is tight and there were no problems.



First Taxi

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I fixed the oil leak we had yesterday and made another pass through every bolt and fitting firewall forward to make sure nothing had moved.  We got the spinner installed as well as the plenum.



Finally, we cowled it up and pulled it out for the first taxi test.



I spoke with Andair about the pump, and they're sending me a new one (great customer service by the way).  Without the electric pump, the engine driven pump has to pull the fuel during engine start, so the engine takes a few extra revolutions to fire over what it will once the new pump arrives.  Anyway, my brother and I jumped in and did an initial taxi test.  Other than needing to finish seating the brake pads, I was able to accomplish all of the taxi testing goals in one engine run.  Here's a video of the taxi test.



I spent most of the morning cleaning up the hangar and organizing my shelves.

Next, I tried to tighten the set screw that anchors the pilot's control stick grip, but ended up cracking the wood in the grip a little bit.  I flexed open the crack and filled it with epoxy before clamping it.  I also drilled a small hole where the set screw sits so that the set screw will screw into a hole instead of just applying pressure to the stick.  This should be a much more secure way to attach the grip and it can never loosen.



I also reattached the aileron boots.  I still need to apply the foam tape where the narrow end attaches to the push rod so that I can zip-tie that end.



Worked on Wingtips

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With the plane at the hangar, there are only a few things I can work on at home.  One is the wingtips, so I resumed fitting the wingtip lenses.



The flange widths around the lens varied fairly significantly (from 18-23 32nds), so I marked and filed the flange on the right wingtip to a consistent width.



I trimmed the lens approximately to shape and then sanded each side so that the edges are nice and straight.  Once the lens fits on properly, I will apply some filler to the wingtip so that the gap is tight and uniform all the way around.



I trimmed the lens a little more until it fit down inside the flange.



Instead of trying to sand the flange perfectly and then sand the lens to fit, I marked a line 5/8" back from the face of the recess.



I'll sand the lens back to this line and then apply filler so that the fit is perfect.



I used some scrap paper to make a template for the mounting plate.  This protrudes back inside the wingtip because the mounting bracket for the light needs to be recessed behind the plane of the other face of the recess.



Here's roughly where the light will be mounted.  I'm going to fabricate this plate out of 0.040" plate and see if that works.  There's a good chance I might have to move up to 0.063" plate if there is too much flex.  I'm going to leave the large gap around the light for now until I can fly at night and get the light aimed properly.  After that, I'll fabricate a cover plate that just clears the light to cover the hole.



I held up a piece of scrap paper where the plate will eventually cover the gap to ensure that I'm not blocking the rearmost LEDs.  This position is perfect.  All LEDs are visible and I have plenty of clearance from the lens for adjustability.



With the epoxy cured in the grip, I reinstalled them and tightened the set screws down.  The grips are rock solid now and don't move at all.



Next, I installed the screws that tie the fuselage center section to the lower wing skin.  I had waited to do this until some shorter screws showed up.  Van's uses -8 screws all over the airplane when shorter screws are sufficiently long.  I've tried to use shorter ones where I can to save weight.



I've spent a bunch of time adjusting the elevator pushrods over the last couple of nights to eliminate some interference between the aileron pushrod and the ring supporting the boot that keeps cold air from coming in around the aileron pushrod.  With that done, I was finally able to install the elevator servo stop.  This fits around the elevator servo arm and prevents the arm from going over center and jamming the elevator.



With the interference eliminated, I could finally finish installing the aileron pushrod boots.  Without this, huge amounts of cold air will leak into the area under the seats and come up into the cabin around the control sticks and other small gaps.



I trimmed the wires coming out of the wings and installed the connectors.  These are waterproof and should keep me from getting any corrosion in the contacts.  I also installed the connectors onto the remaining wire bundle that I cut off and will hook these up to the lights tomorrow.



I fabricated the light side of the wiring harness today.



I wrapped the power board with some foam to protect it from vibration and stuffed it inside the light.  I stopped by the hangar later in the day to remove the canopy and tried out the lights.  Unfortunately, the right landing light was intermittent.  I ended up tracing the problem to a poor solder connection on one of the LEDs, so I re-soldered it.



With the right lens almost trimmed to final size, I decided to drill it to the wingtip so that I could install it in the same place every time during final trimming.



Torquing the jam nuts on the rod ends used as hinges on the elevators and rudder require a special tool.  I picked up a set of these offset wrenches from Harbor Freight yesterday and modified it to fit around the rod end.  I cut a slot in the end and reduced the thickness quite a bit.  I'll try this out tomorrow and see how well it works.



I tried the modified tool and it works pretty well.  I'm going to do a little more adjustment on it so that it doesn't hit the steel bracket and clears the universal rivet heads.



I wasn't quite getting the aileron throw I wanted, so I switched to the smaller bushing I had.



Adjusting the aileron bolt required dropping the flaps.  I could almost remove the rod end that screws into the flap, but the pushrod hit the edge of the hole just before the bolt could slip out.  I sanded the hole a little bit larger, but kept it inside the black line I drew that showed where the flap overlap sits.  This covers the hole when the flaps are up.



In preparation for installing the weatherstripping that will seal the forward edge of the canopy, I fabricated a couple of strips to span the gap in the flange.  This way I can have a continuous strip of the weatherstripping across the entire edge.



Afterward, I used some Sikaflex to seal up all of the gaps.



Sealing around the canopy hinge is the most tricky, but I think this will do a pretty good job.



Miscellaneous Tasks

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No pictures tonight, but I spent a few hours at the hangar knocking various tasks off of the to-do list.  First, I trimmed the excess sealant around the leading edge of the canopy and put a little bit more where there were a couple of small holes  Next, I finished torquing the vent line fittings in the cabin and zip tied the fuel sender coax to it on the right side.
I had my airplane inspection party today.  I invited RV builders from all over the region to come give my plane a good once over before scheduling time with the DAR.  I had a great turnout; roughly 40-50 pilots and builders stopped by over the course of the day.  Overall, the inspection went very well.  Nothing major was found, but there were a number of small items people caught (some of which I knew about and some I didn't).  I just want to give a huge thank you to everyone who stopped by.

The day started with my transponder certification and pitot/static check.  The transponder check passed with flying colors, but I had a leak in my pitot system.



Unfortunately, the leak turned out to be in the wing root fittings where I didn't quite get one of the pieces of tubing fully seated.  In the process of trying to seat it, the tubing popped out and I had essentially no access to get it back in.  This was really the wrong place to put these, so I'm probably going to have to pull new lines through the wings and make the connections under the pilot's seat.  Do yourself a favor and avoid all wiring and tubing connections between the fuselage and wing on the RV-7; there is simply no room to work in there.



Now, on to the things that were caught during the inspection.  Let's start with a few things that were squawked, but are not actually issues.  A couple of people questioned the mounting of my fuel flow transducer which is simply suspended from the fuel lines.  Apparently, there are two versions of the red cube.  The earlier one didn't tolerate being rigidly mounted to the engine, but the later one could be mounted like this or to the sump.  When I purchased this, I called the manufacturer and they recommended this mounting approach.



Another builder squawked that there was not enough rubber material on the exhaust hangers which would not allow sufficient movement in the exhaust pipe.  Larry Vetterman specifies that the stainless steel tubes only be separated by 1/4" inside the rubber tubing, so this is installed as the manufacturer recommends.



Next, let's move on to some things that are actually issues, but I knew about.  Someone mentioned that the screws weren't fully installed in the fuel senders.  This is because I haven't had a chance to calibrate the fuel tanks.  I have to remove this cover plate to do the calibration, so I left the screws loose until this is taken care of.



Another builder noticed that the jam nuts on the empennage bearings weren't torque sealed.  Although I modified a tool to fit in here, I wanted to modify it further before torquing these down for good. 



Several builders noticed that my brakes weren't safety wired.  I had intentionally put this off since I thought I might need to pull the wheels off again, but I don't think I have any need now before first flight.



A builder noticed the torque seal was broken on the inlet to the spider.  I had pulled this off before first engine start because I wanted to run some fuel through the line to flush any debris out so that it wouldn't clog the injectors.  We hooked the line back up before the engine run, but I didn't put a torque wrench on this then.



When I was doing the final adjustment of the control sticks, I noticed that the torque tube that connects the control stick was slightly rubbing on the seat ribs.  The builder that also spotted this said it is worse when people are sitting in the seats, so you really want some clearance here.  Fortunately, I made this section removable on all four of these ribs.  I'll pull these off and remove some material to get a good 1/8" or so between the ribs and the tube.



Finally, let's move on to the things I hadn't caught.  I couldn't get a great picture of it, but a couple of people noticed that the alternator pulley wasn't perfectly aligned with the flywheel.  This will not only make the belt wear faster, it also is apparently hard on the alternator bearings.



There are four thread showing on the outer aileron bolt.  I'll probably have to add another washer here.



There are also four threads showing on the bolt attaching the pushrod to the elevators horns.



The torque seal was also broken on the manifold pressure hose.  I don't recall why I removed this, but I'll need to retorque and seal this.



The cushion clamp anchoring the cable sheathing on the oil cooler butterfly valve wasn't gripping the sheathing well enough and was allowing the cable to move.  I'll need to swap out this for a non-cushion type clamp.  There was also not enough thread showing on the bolt holding these adel clamps together.



The crankcase breather hose was rubbing on the adel clamps securing wires to the upper engine mount tubing.  I'll probably add another adel clamp to this group to keep this from chafing.



Apparently, the top of the gear leg will rust if left unfinished like this.  I'll clean it and paint it with the touch up paint that Van's sells to match the powder coat on the engine mount.



In preparation for wrapping up the canopy and getting it reinstalled, I applied the weather stripping to the flange and trimmed it to fit.  I also recently received my avionics cover from Flightline Interiors, so I installed the supplied velcro and tested the fit.  It works great and should hopefully help me keep my avionics dry.



Next up, I started working through the list of issues that were found in the inspection yesterday.  I safety wired both brakes since I don't think there is any reason to remove the wheels now before first flight.  I also checked the two bolts identified yesterday as having too many threads showing, and they're both fine.



Positioned Wingtip Lights

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I spent a little time playing with the positioning of the landing lights.  They need to be far enough forward that I can access all of the mounting screws on the top and bottom, and the farther forward the lights are, the better they will illuminate the area right in front of the plane.  They can't be so far forward that they bump in to the lens though.  Since I still need to aim the lights, I needed enough clearance that the lights could be moved a bit.  I ended up moving them back about 1/4" from where they are in this picture.  I've decided to just make the mounting plate sacrificial and use it to get the lights aimed correctly.  Once I've flown at night and am happy with the positioning, I'll fabricate a new plate with only the set of holes I need along with the back plate.



I got my replacement fuel pump from Andair, so I ran down to the hangar tonight to install it.  I pulled the old pump out and removed the fuel filter.  Since I've pulled fuel from both tanks, I wanted to clean the filter to remove any debris that might have made its way into the tank or fuel lines during construction.



Despite my best efforts to keep the tanks clean and sealed and clean the fuel lines before installation, there was a surprising amount of junk in the fuel filter.  I rinsed everything in a few ounces of gasoline.  It looked like mostly dust and small sandy particles, but there were a couple of small metal particles mixed in.  It's good to get all of this out of the fuel filter before the first flight.



I lubricated the o-ring, safety wired the filter and reinstalled it on the pump.



Here's the completed pump assembly with wires cut to length and a molex connector installed.



Finally, I reinstalled it in the plane and re-torqued all of the fittings.



Next, I installed the wingtip so I could get an idea how the light was aimed.  It looks pretty high, but I'll need to level the plane to be sure.  I'm pretty happy with how bright this is.  Here's the hangar across the way with the light on.



And here it is with the light off.



To get a better idea how the light is aimed, I pulled the plane out into the taxiway and put the tail up on my chair to get the fuselage level and then turned the light on.



I adjusted the light until the beam was roughly level.  You can see it does a pretty good job of lighting up the taxiway.



I walked to the far end of the taxiway to get an idea how much light was making it down there.  The picture doesn't really capture it well, but it was uncomfortable to look directly at the light, even from this far away.



This picture of the shadows cast by my legs gives a pretty good idea how well the far end of the taxiway is lit up.



Finally, I resumed work on the canopy fairing.  I started with sanding the fairing down to be flush with the two layers of electrical tape and got the overall shape where I wanted it.  Next, I removed the upper layer of tape and sanded the fairing down again to be flush with the remaining tape.



After taping over the exposed parks of the canopy bubble, I mixed up some epoxy with black pigment and applied a sealer coat on the fairing.  After this cures, I'll sand it down and apply a coat of primer.



Worked on Left Wingtip

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Now that I have a pretty good idea how the wingtip lights will be mounted, I could do the work on the other wingtip.  I marked and cutout most of the recess.



I then fabricated an approximate duplicate of the right mounting plate and then trimmed it to fit the left wingtip.  The two wingtips are slightly different, so I couldn't make an exact duplicate.  I then transferred the plate mounting holes and the center set of light mounting holes.  You can see in the previous picture that I also drilled the plate to the wingtip.  All that is left now is to finish getting the lenses to fit properly.



I sanded down the epoxy I applied the other night and painted on a few coats of primer.  There are a few pinholes I need to deal with, but this is good enough for first flight.



Between coats of primer, I fixed the pitot and angle of attack tubing.  I had previously made these connections in the wing root, but that was a mistake since there's no room to ever service them.  I had planned on running new lines down the conduit, but I realized I could use the same lines if I added a couple of additional connectors in the wing.  I disconnected the tubing at the pitot tube and slid it inboard inside the wing enough that I could pull the excess through the holes in the fuselage.  These fittings will now be trivial to service if that is ever necessary.



I then cut the lines in the wing and took some longer pieces and ran them from the pitot tube to these fittings.  This is better anyway since I can disconnect the tubing here and pull the pitot tube out of the mount.  This is looking up into the inspection port just inboard of the pitot mast.  With the way the lines were previously run, pulling the pitot tube out of the mount required disconnecting the lines right at the top of the mount.  That wasn't too painful, but reinstalling the pitot tube was a real pain since it required hooking up the tubing entirely by feel.  This way, the fittings are easy to inspect and verify correct installation.



I spent some time this morning working on the left wingtip lens before heading down to the hangar.  Since I reworked the pitot and AOA tubing yesterday, I wanted to leak check it today.  I disconnected the tubing at the new fitting in the wing inspection panel and attached some 1/4" ID latex tubing.  I could roll up the other end of the tubing to increase the pressure in the pitot system and test for leaks.  AC 43.13 recommends increasing the pressure to an indicated airspeed of 150kts and then clamping the tubing for 1 minute to check for leaks.  As long as the leaks aren't substantial enough to cause the indicated airspeed to drop more than 10kts, then everything is fine.  After 1 minute, I had a 3 kt drop, so I'm in great shape.

Next, I tackled installing the two Click Bond nutplates in the horizontal stabilizer.  I used some hemostats to scotchbrite and solvent wipe the inside of the horizontal stabilizer around the hole and then fished some 0.025" safety wire up through the hole and out through the nose of the inboard end of the horizontal stabilizer.  I pushed the safety wire through the end of the silicone installation plug so that I will be able to pull it back through the hole.



The Click Bond adhesive I had had dried up, so I mixed up some epoxy with West System 404 structural adhesive filler.  I applied a little bit on the flange of the nutplate and then pulled it through the hole.



Here's a picture taken through a mirror at the installed nutplate.  Once the adhesive cures, I can just pull out the silicone plug.



With the new fuel pump installed, I decided to determine the unusable fuel.  I rigged up the hose from the spider so I could capture any fuel pumped to the engine.  I dumped 16 oz into each wing and then ran the fuel pump until nothing came out.  Finally, I drained the fuel in each tank to see how much unusable fuel there was.  I drained almost 7 oz from the left tank and 6 oz from the right tank.  I then dumped the fuel back in the tanks so that it could be included in the weight and balance.



My buddy Greg noticed that the firewall passthroughs didn't grip these cables very securely.  I removed the eyeballs and wrapped a couple of layers of aluminum tape around each cable and then reinstalled them.  The cables are rock solid now.



Weight and Balance

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My big goal for the day was to compute the weight and balance.  To do that, I needed to have the plane ready for flight.

In preparation for reinstalling the canopy (hopefully for the last time), I applied a strip of UHMW tape under the leading edge.  This will help the flange slide over the weatherstripping without catching and dragging on it.



I then used a razor blade to trim the tape flush width the edges of the skin.



I then installed the wing root fairing.  I didn't bother tightening all of the screws all of the way since that wouldn't change the weight or CG.



The plans say to trim the rubber seal to just touch the fuselage, but I think it looks better to leave the whole seal and have it flare out at the fuselage.  It probably seals against the fuselage better too.



I also installed the wingtips with the landing lights and mounting plates.



I reinstalled the spinner and the cowl.



Jenn stopped by the hangar and helped me install the canopy.



I then installed all of the interior.



After installing the empennage fairings and all of the wing inspection panels, I leveled the plane and put it on scales.  I came in right at 1100 lbs which is great.  It probably means I'll be around 1130 or so with gear fairings and paint.  My center of gravity is farther aft than I would have liked at81.35", or 2.65" aft of the forward limit.  This makes it fairly easy to load aft of the CG limit, so I'm likely going to have to shift some weight forward or add more weight under the cowl.



I spent a little time tonight wrapping up the paperwork for the DAR who will be inspecting my airplane.  From the upper left, we have the registration, 8130-6, notarized 8130-12, program letter, weight & balance, three-view and condition inspection.  I emailed everything to him tonight and am planning on meeting with him this Sunday.



I got started tonight by taking a couple of more weight and balance measurements.  I had forgot to include the plenum, but I decided to also throw the wheel pants and gear leg fairings on at their approximate position.  All of that helped move the CG forward 0.22", but increased my empty weight to 1110.  After that, I took a measurement with me in the plane to find out exactly where my CG is.  Unfortunately, I'm 0.24" aft of where Van's says the pilot's CG should be.  This had the effect of moving the plane's CG back by 0.05".  The net result is that the CG will be roughly 0.17" forward of where I calculated on Sunday.  That still puts me 2.48" aft of the forward CG limit, so I'll still have to add some weight up front.

Afterward, I pulled everything off or out of the plane to get it ready for inspection.  I've still got a fair number of items to knock off the list before that happens though.



I couldn't go down to the hangar tonight, so I worked on some of the pieces I brought home.  I finished trimming and sanding the left wingtip lens and drilled it to the wingtip.  I'll have to install the nutplates at the hangar where the rest of my tools are, but other than than the wingtips are ready for flight.  There is still a bunch of finish work before I'll be happy with these, but I want to put that off until the landing lights are aimed right, then I can do all of the fiberglass finish work and put a coat of primer on the wingtip.



Speaking of fiberglass finish work, I resumed work on the cowl to get it ready for a coat of primer.  There are still a few spots that have pinholes, so I'll be doing a little epoxy work before priming.  I spent a little time first with a file smoothing out little high spots and fixing a couple of epoxy runs.



Sealed Cowl Inlets

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I sanded down the cowl inlets and applied a coat of raw epoxy to fill all the pinholes.  An hour or so later (after the epoxy kicked off), I came up and scraped most of it off.



The plans specify that the fuel lines are wrapped in foam where they pass under the forward center cover.  I used some adhesive weatherstripping under a couple of spots between the fuel line and the floor.



I also put some foam on the underside of the cover in the same spots to sandwich the fuel line when the cover is installed.  I also put a small piece where the aft angle is relieved just in case vibration would allow it to contact the fuel line.



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