« Posts under Finishing

More legals.

3.5 hours.

Today’s big story was attaching the N number.

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Behold my legalness.

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And yay, more legalness.  This gets covered up with masking tape until it’s airworthy.  No sense giving the tax man a foot in the door before it’s necessary.

After this, I went for a quick flight with Don in his RV6A.   Don’s between medicals at the moment, and I’m in need of RV hours, so we both get to fly if we’re both at the airport at the same time.  Today I flew us over to Santa Paula to get some fuel.  Apparently, I don’t suck at flying the 6A.  But today was an optimum day for flying, with clear skies and smooth air, so that helped.

After that, I replaced the silicone fuel line I was using for the fuel pump overflow connector and replaced it with some real 5/16″ tubing and secured it with hose clamps.   Then I dismounted the spinner and empennage fairing so I could bring them home to paint them.  Or at least shoot a half-assed covering of primer on them.

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I’m getting tired of the pink cowl and the purple spinner, so even though it might be kind of a pain to deal with later, I decided to spray the cowl down with Krylon Olive, which is pretty close to the same color as the dropship in James Cameron’s “Aliens.”  It’s flat.  It’s easy.   And when I get around to spending a hundred hours or so touching up and filling in the cowl, maybe I’ll do something different.   Or it’ll go to the paint shop and it’ll be somebody else’s problem.

The result you see here is before the paint’s actually dry, which accounts for some of the streaks.  But when it’s done it’ll be a nice, uniform olive drab.

Maybe I’ll do the spinner bright red.  Or black with a twisting white stripe.  Although, the metallic purple actually looks good with this color green, so maybe I’ll leave it as is.

One more thing re Weight and Balance

1.0 hours.

I almost forgot.   Yesterday I had to lift the tail to make the plane level again, because I forgot to do a couple of crucial measurements.

Without going into great detail on what weight and balance is and how it’s calculated, just understand that all the center-of-gravity or CG calculations are done based on distance from a fixed point in space, called the datum.  Yeah, it’s the singular form of ‘data’ but you knew that.  Moving on.

The datum for the RV7 is established by the designers at 70.00 inches forward of the leading edge of the wing in level attitude.    Distance from the datum is measured at a couple of places, like the center of the main wheels and tail wheel, and other distances are given, like the passenger position and the baggage position.   Those distances are called “arms” and when multiplied by the weights at the wheels gives “moments” in inch pounds.   This lets you do all sorts of interesting things like figure out how much that diet of cheeseburgers and Budweiser  is preventing you from taking off with more than half-tanks of fuel and a pair of silk briefs in a tube for baggage.

To get these measurements, I took a couple of plumb bobs and hung them over the leading edge of each wing near the wheel centers.   That distance +70 was the arm at the main gear.   Another couple of plumb bobs got me what I needed at the tailwheel.

So now I have all the relevant weight and measurements to work up my weight and balance sheets.

Idle fixed.

5.5 hours.

 

I don’t have time for a lot of jibber-jabber, so I’ll make this short and sweet:

I installed the new idle linkage bearing and spent a bit of time dialing in the idle.   I got it to idle smoothly at 750 RPM with a solid transition to power on throttle advance.   CHT’s sitting there uncowled don’t get past 245, which is good.   We had a really strong wind today, so it was a good day for engine testing, but a crap day for flying.  Nobody was out there, so I was left to my own devices.  The idle fix took about two hours, so then I went for a drive.   I taxied down to the west end of the runway, then came back.   20+ knot winds variable from 070 to 085 make for some fast footwork on the pedals.

After that was done, I set about making the fire extinguisher mount.   I ended up putting it on the fuel pump cover, in easy reach of both pilot and copilot.  Of course, if the fuel pump’s on fire, getting the the extinguisher is going to be interesting.   I had to reinforce the fuel pump cover with some .032 so the bracket could be safely bolted on, but it seems to work.

 

The Weight of the World

6 hours.

I got a bit of a late start, since I spent about an hour trying to source a Heim joint of the correct size from a local speed shop rather than waiting for ACS to ship me one.  In the end, I was unsuccessful, so I made my ACS order and headed out.   Once I got to Oxnard, I stopped in at Aswell Trophy on Oxnard Blvd and they engraved my data plate while I waited.   Took about 15 minutes.

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This was the first task of the day.   After that, I went on to the process of weighing the airplane.   The scales are for weighing race cars, so there are 4 inputs, but I was only using 3.  The measuring unit connects to big metal pads that the airplane sits on and totals up the readings from all of them.

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Some clever person at EAA723 built these ramps to roll the wheels up onto the scales, which was awesome.   I couldn’t find a soul around when I was doing this and I couldn’t get enough oomph behind the airplane to roll it up on there by myself.  I didn’t want to get too big of a running start at it because I didn’t want the wheels to overrun the chocks at the end of the ramps.   So I turned the ramps around backwards, wrapped a strap around my tailwheel spring, hooked that up to my truck hitch, and towed the airplane, very slowly, into position.  The reason you see the wheel pant sitting on the wheel is because I wanted to account for the fairing weight and I haven’t actually finished the fairings yet.   The clecos will probably equal the fastening hardware, and if not, they’re well within the margin of error on the scales.

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The airplane needs to be weighed in level flight attitude.   This means the tail has to go up.   I used my smart levels on the longerons and cranked up the tail on Ron’s old lift with the tailwheel on the 3rd scale.   With all that stuff in place, I came up with these numbers:

  • Left Wheel:     524lbs
  • Right Wheel:   523lbs
  • Tail Wheel       67lbs
  • Total:              1114lbs

So not too bad.   The reference example they give in the construction manual totals in at 1111, so I’m 3lbs more portly than the book.

 

Zero Sum

6 hours.

I spent a whole lot of yesterday doing various things, which is the surest way to feel like I got nothing done.   I had two goals: Fix the idle stumble and run down that AP engage joystick wire issue.

The first part was almost easy.   I set the mag timing to 25 degrees per the engine data plate.  I’m getting to be an old hand at setting mag timing.  I got them both firing in sync, then made the idle richer by a couple of flats of the adjustment linkage, per the AFP manual.  Sure enough, that cured the off-idle stumble and my CHT’s and EGTs dropped noticeably.  But there was still a rough idle, so more adjustment needed to happen.

The manual says that adjusting the idle is done with the engine running.  The problem with that is twofold: One, working near a spinning prop scares the crap out of me.  I haven’t had the training to do so safely.  Two, because of the orientation of the throttle body, the idle linkage is on top, between the throttle body and the engine case, and the only way to get at it is by reaching past hot exhaust pipes.  Even if I did have the stones to crawl under there with the prop spinning, I can just see burning my forearm on the #1 pipe and yanking it back into the arc of the prop.  No thanks.  I did my idle adjustments with the engine off.

With Mike as the casual observer, it appeared that my idle was too rich, because there was a bit of smoke coming from the pipes when I was idling and the idle was definitely a bit rough.   This is caused by multiple symptoms, but a too-rich mixture is the first and most obvious culprit.

The manual also says that the best way to adjust the idle is to leave one of the jam nuts “just snug” and turn the block one flat at a time.   Well, yours truly interpreted “just snug” as “don’t touch” and after a couple of turns of the block, the left-hand rod end bearing snapped off at the jam nut.

BrokenBearing

So now I have to find/buy a LH thread #3 rod end bearing and I can get back to business.

As for the other stuff, I did chase down the AP engage wire.   Turns out I have to figure out a way to do some kind of voltage differential and use the MGL script editor in order to remote-control the EFIS to engage the autopilot.   A simple “Hey, I’m Grounded” won’t work.   This will take a minute to work out the logic, but I’ll email Matt at MGL and see what he says.

Also, Owen and Ron got the racing scales, so I can do weight and balance.    This gets done first thing today, because I need to return the scales ASAP.   It’s   I’m just hoping the W/B comes in as expected.

I also fiddled about with the wheel pants, but that’s not high on the priority list right now.

“Twas the Weekend Before Christmas, and All Through the Hangar…”

4 hours.

“Not a creature was stirring, save this rivet banger…”

This encompasses Saturday through Monday.

With the holidays in full swing, the schedule gets a little weird, but better, because I have a few days off.   I’m keeping a decent balance between building, home obligations, holiday festivities, and the occasional video game.   I’m also coming to terms with the fact that the endgame for this project is approaching rapidly, or so it seems to me.   Last weekend, I’d started on the gear leg fairings.   This weekend, I pretty much got them done.

The most important thing with the gear leg fairings is to build them without any twist in them.   They come taped together from the factory, but Van’s fiberglass is usually so crappy for fit, I didn’t trust them.   The way you verify no twist is to put the leading edge on a flat surface and using a square, insure that both trailing edges line up.   Once that’s done, you can use the full-scale template cut from the plans to mark all the cut lines.   Easier said than done, though.  You really need two squares, one for each end, and another pair of hands, or at least a boatload of tape.   But I found a solution in our hangar that worked very nicely:

IMG_1710That brass thing is a piece of channel from one of those godawful floor-to-ceiling mirrored sliding doors, usually found in cheesy SoCal apartments that saw their last renovation some time before Saddam Hussein rolled his tanks into Kuwait City.   But it makes a very nice, very straight jig for lining up the trailing edges of the gear leg fairings.   Not only that, it provides an excellent platform for match-drilling the hinges.   Some of you are looking at this and saying “hey, those are the wrong size hinges!”  Yes they are.   But it’s what I had.   I used up all my 1/16″ piano hinge on various attempts at the cowl.   If it should come to pass that these hinges cost me knots and fuel, I’ll change them out, but at this point, I want to be done.

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A selfie, checking the alignment of the hinge.

With those done, I could check out the fit of my intersection fairings.

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Upper intersection fairing fits, sort of.   It needs some work.   It’ll also need to be taped into position to hug the contour of the fuse and cowl, and then a couple of layups on top of that.   After that, it gets trimmed back to where it’s supposed to be.   Van’s fiberglass may be crap, but it’s better than mine and it sure beats fiddling around with modeling clay.

Monday was all about tying up as many loose ends as I could before starting on the wheel pants.   This meant, among other things, getting as ready for the inspection as possible.   I attached the ‘EXPERIMENTAL’ sticker to the roll bar:

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This is a bit redundant because the baggage bulkhead cover that came with the interior has it embroidered into the leather, but that won’t be installed during the inspection.   The canopy frame covers this one up when the canopy is down, but I don’t think that matters.   If it does, those stickers are cheap.

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This is required by the Feds to be in the airplane in plain view of the occupants.  It’s like a magic amulet to ward off the unadventurous.

Left Gear Leg

Left Gear leg

Left Gear leg works much the same way.

After this, I spent some time doing odd jobs.   I safety-wired the tailwheel chain hardware, then moved to the cockpit, where I zip-tied the wires made loose by the magneto troubleshooting and the addition of the OAT probe.    I also attached bolts in the center section per Van’s SB 12-08-14.   Apparently enough people forget this step that Van’s thought it merited a Service Bulletin.   Guess what?  I forgot it too.   In addition to the close-tolerance bolts that hold the wing spars to the center section, there are two on each side that secure the center section to the vertical bar on the wing spar.  These need some AN4 bolts in there to lock things down.

Part of getting airworthy is checking all the relevant SB’s and AD’s to make sure you don’t have anything hanging in the breeze that might kill you.   The rules on experimental aircraft and AD’s are fuzzy, and are interpreted by various people in various ways, because different sections of the FAR’s appear to contradict each other.    But the safe thing to do is check for AD’s and SB’s that apply to your stuff and fix them if you find any.   If I hadn’t gone through this process, I wouldn’t have found those missing bolts and the inspector would have.

When I moved on to the engine, I discovered some oil running down from the spacer on the right mag and at the oil drain fitting of the #1 cylinder.   This was alarming enough to merit a quick engine test.   I cleaned off the oil and wheeled it out to start up, to verify that the oil was new and not left over from the last time I had to loosen them up to get to one thing or another.

I did a quick runup and brought the cht’s up to operating temperature, but even with good, timed mags, it still stumbled off idle.   Advancing the throttle slowly would bring the RPM up, but moving it smartly, like I would for takeoff, killed the engine.   After consulting VAF and then my AFP manual, it looks like my idle mixture is set too lean.   This will need to be corrected, and I can probably do this tomorrow.  The good news is that I didn’t see any new oil in the spots where I found the drips, so it looks like the oil around the mag spacer was from when I had the mags off, and the oil from the #1 drain line is from the time I had to undo the fitting at the cylinder head to get at either the bottom spark plug or the EGT probe.

 

 

Gear Leg Fairings Continued

6 hours.

I found my missing length of piano hinge (hidden inside a piece of PVC to keep it from getting damaged), and took it and my intersection fairings up to OXR to see what I could get done.   I got up there and spent a lot of time pondering the instructions and plans.  I spent a lot of time doing that because this is real work about to be done here, and it involves fiberglass, and the cutting of things that affect the flight characteristics of the airplane.

The first thing I did was put the wheel fairing attach brackets on.   This is a stupid process if ever there was one.  I had to wrangle the engine hoist from down at the EAA hangar, walk it halfway across the airport, then lift each side of the plane  by running a strap around the engine mount so I could get the wheel off   I’m not shelling out a couple hundred bucks for some weird attachment, this seems to work just find.  With the wheel off, I could attach the bracket.

The gear leg fairings, on the surface, are not that complex.  They’re teardrop-shaped covers for the round gear legs.  The only tricky part is that they have to be built with no twist in them.   There’s a full-scale section of a drawing that needs to be cut out and used as a template.   This lets you know where you can cut the fairings, and the fairings are the same ones used for all Van’s aircraft except the -8 and the -8A.   They are attached by means of a couple of hose clamps and secured by a piece of piano hinge running up the trailing edge.   So they have to be cut straight, then there’s the hinge installation, then the alignment to the fuselage.   I got one part of one leg cut, and had to move brake tubing out of the way and cut clearance divots where that wasn’t feasible.

Other time was taken up by moving the late Jim Ayers’s RV3 (with the Walter LOM engine) out of the EAA hangar and down to his private hangar waaaay at the other end of the airport.   Ron and I rigged up a way to lash the tailwheel to one of the forks of the old propane forklift and he towed it, driving backwards, really slowly.   I followed him in his VW.  After we got back from that, we went for a ride in the Pacer.

Starting on gear leg fairings and wheel pants

6 hours.

My pre-molded intersection fairings arrived from Van’s this week, but of course I forgot to take them up to the hangar.    The last major bit of fiberglassery is the landing gear stuff, so I tried to get started on that today.   There’s a .063 plate that bolts on to the brake caliper and its job is to hold the two halves of the wheel pants together, on each wheel.   I made them, cut all the spacers, and installed them, then took them off, anticipating that I could just put them  back on as needed. But it’s impossible to access the bolt head on the inside of the brake caliper without taking the wheel off.   I made two attempts to bend a 7/16 wrench 90 degrees at the open end, one resulting in a broken wrench, the other a wrench with too wide a bend to fit inside the rim and access the bolt.

So I figured taking the wheel off would be the best option.  I searched the hangar in vain for a floor jack.   Those guys don’t have one.   The engine hoist I used before is down in the EAA hangar, but it was all locked up and I couldn’t get to it.   So that was out.

I did get the plans and the manual out so I could begin working on cutting the leg fairings to fit.    That didn’t take long, so I went up to the aviation department of O’Reilly Auto parts and picked up another tube of red RTV.   I finished the front baffle bead and the left mag duct, and also isolated a couple of things from chafing via the RTV Blob method.

Red Goo.

5 hours.

A shortish day, after Thanksgiving weekend.  But decent.   I got the pax side restraint system involved in addition to the pilot side crotch strap or “anti-submarine” restraint, as it’s called.  That took longer than I thought because of the number of times I had to hop in and out of the plane to find washers and other hardware and tools.

But now they’re both in.  This unflattering photo is just to show that both seat belts are hooked up.

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So I went on to the red goo.   I’ve been putting this off, because of my usual aversion to non-solids, but it was finally time to RTV the baffles.   Squeezing a tube of red RTV into all the places it has to go is really hard on the hand muscles, especially when you have to get the nozzle into nooks and crannies now blocked by FWF equipment.

IMG_1685So I’m not the best RTV’er in the world, but I think the bases are more or less covered – a bead running along the baffle meterial, and anywhere light gets between the baffle and the engine.   OK, maybe not everywhere, but everywhere I could get the stuff in there.

IMG_1686Oops.  Didn’t get around the right magneto blast tube.  I’ll have to get that later.

But I was sure to get RTV into all the gaps between baffle and oil cooler, because that’s kind of important, and as for other leaks, we’ll have to see what happens to CHT’s in flight.

Odds, ends, and annoyances.

6 hours.

Last weekend I had to work to deliver a product launch, so no airplane.   This weekend, I had a list, and I knocked out a bunch of stuff on it.  To sum up:

  • Tensioned and safety-wired alternator bracket
  • Removed protective plastic from aft canopy and removed tape residue
  • Relabeled mag switches and made “OFF” labels for everything else
  • Reconfigured quadrant for extra travel on governor
  • Added a wider heat shield to protect the throttle cable
  • changed out a too-short bolt on the purge valve cable bracket.

Apparently the way you do alternator belt tension is by increasing belt tension until it takes 12 ft/lbs of torque on the alternator nut to slip the belt.   That’s it.   That also gives you the 1/4″ deflection (on a new belt) called out by the usual procedure.   This is important, because a slipping belt can cause over/under voltage problems.  I did that, and safety-wired the bracket tension bolts together, like so:

Alt bracket saftey wire

Alternator bracket Safety wiring

 

When I put the aft canopy in all those many moons ago, I left the protective plastic on it, because why not?  Why subject the vulnerable plexiglas to my fumbling ministrations while I’m climbing in and out of the tailcone to adjust one thing or another, swinging tools and wires about?   Because once the canopy is attached, it’s difficult if not impossible to get all the plastic out from between the roll bar support and the canopy.   I had to put a space heater in the cockpit and run it for a while, until it was a balmy 75 degrees and the plexi and surrounding aluminum were warm to the touch.  I took out all the fasteners and removed the aft canopy section, which I put on the bench, then removed the rest of the protective plastic and cleaned off all the tape residue I couldn’t get to before.  100% better.

Protective plastic and tape residue gone

Protective plastic and tape residue gone

 

The magneto switches on the panel were cryptically labeled “MAG 1” and “MAG 2.”   I don’t know why I thought this was a good idea, and it broke with common practices in aircraft UI/UX design.   I relabeled them “L MAG” and “R MAG” because that made the most sense, and that’s how everyone else does it.   While I was in a labeling mood, I made about a dozen or so “OFF” labels to describe the down position of most of my toggle switches.   The double-throw switches like flaps up/down already had good labels in both directions, but there wasn’t anything labeled “OFF” anywhere.  The switch pointing toward the function described seems obvious to me, but apparently it isn’t to whoever wrote that reg at the FAA, so now everything is labeled according to the AC’s.

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Like I said, there were odds, ends and annoyances.   Firewall forward, there was the matter of a heat shield, a too-short bolt, and the prop governor travel.

Heat shield on throttle cable

Heat shield on throttle cable

I did have a shield in place at this spot, but I remembered I had an extra double-wide one, so I put that one on in its place.  On the topside of the engine, I changed out the bolt holding the purge valve cable.   It was a temporary thing when I did it, and it didn’t have the required number of threads showing to meet spec, and since it’s pretty important that the purge valve remain closed in flight, it’s also important that everything connected to it is not half-assed.  This is what the proper bolt length looks like:

Purge valve cable bracket

Purge valve cable bracket

As to the prop governor, if you’ll recall from last time, the prop didn’t cycle at the low end of the throw.  The quadrant was only moving the lever arm about halfway through its arc of travel.   The simple fix to that was to drill a #12 hole about 5/8″ up the quadrant lever from the original one and voila, I get me 75-80% travel instead of 50%.   That story ended with a quick runup to 1800rpm and getting the prop to cycle, so that’s good enough for now.   Whether or not I have the rpm set right due to the arm position relative to the governor shaft is another story, and it will be resolved on either a full power run or first flight.  Even so, the engine is more responsive, now that it’s firing on all the plugs, which are now more or less synchronized in their ignition, so that’s a plus as well.

What was really awesome about this weekend was that for the most part, it was forward motion, not playing catch-up.  New things got done and good fixes were made, rather than unsuccessful stabs at a persistent and difficult problem.   There’s still a bunch of stuff to do to get ready for first flight, but I think if I can keep up the pace, I’ll be on track to fly it in early 2014.