Fueling Around - Part Deux

I'm reasonably sure I've used the 'fueling around' pun before, simple because I can't imagine myself not using such an obvious groaner. So.... part deux.

To get this lengthy article started, I will give you a little background. It has to do with the fuel lines on the Rotax 912 engine that powers the RV-12. They are rubber lines wrapped in fire sleeve and Rotax "recommends" that they all be replaced every five years. Five years isn't as long as it sounds when measured in airplane years, and the cost and labor of this replacement is burdensome - the Rotax Rubber Replacement kit goes for around $1,200, although that includes more than just the fuel lines.

A somewhat onerous requirement like this invariably stirs the entrepreneurial spirit in people and sure enough, a collaborative effort between Steve from AircraftSpecialty and Tom from TS Flightlines has resulted in a snazzy alternative: they have created a fuel line replacement kit that addresses the life-limit issue of the Rotax rubber fuel lines by replacing them with state-of-the-art hoses. Here is how they are described on Steve's web site:

Our stainless braid conductive teflon hoses are among the highest quality hoses that exist. These hoses are impervious to all types of fuel without having to worry about hose integrity. In addition, our -4, -6 and -8 hoses, have a .030 thick layer of carbon black manufactured into the hose which provides an electrical path to the fittings on the end. Essentially, the conductive teflon hose is able to dissipate static electricity buildup that can exist when fuel flows through a hose. This is something that is found on high end certified aircraft hoses. We feel it is important, because it adds an extra margin of safety to your aircraft, and also prevents static discharges from eventually creating little pinholes in the hose. 

Please note that our -3 hoses are not conductive teflon, because there is not enough fluid flow through them to warrant the dissipation of static electricity. They are typically used as primer lines in aircraft or as brake lines on cars. For aircraft we recommend -4 hoses for brake lines to mate with the typical -4 hard lines that are used in the cabin. 

Finally, our hoses are covered on the outside with a stainless braid wire. The rated bursting pressure on these hoses is between 8,000 and 12,000 PSI depending on the diameter. Working pressure is between 2,000 and 3,000 PSI, and we test all hoses to their rated working pressure before they leave our shop to give you peace of mind. This is something that not all manufacturers do, as it is time consuming. However, we recognize that these hoses are the lifeblood of your aircraft, and so we check each and every one before it leaves.

He also has a couple of videos that describe the benefits provided from these hoses and the way they are manufactured:

All that aside, they are also far prettier than rubber hoses:

Of course, they don't look like that when they're installed on the airplane - because they are going to be located forward of the firewall and there is a lot of heat in that area, they will be covered in orange fire sleeve. Still, it's enough to just know they're gorgeous!

This is all pertinent to Schmetterling because the set of hoses custom designed for the RV-12 is relatively new. They have been flight tested on multiple airplanes and each installation has resulted in changes to the design. It would seem that the iterative design process has run its course and Steve is ready for someone to do a test installation of the hoses in their latest state of design. The idea is that the average builder should be able to do the installation him/herself. 

I was enlisted to prove the case.

I gave to confess that I was a little nervous about it - anything having to do with the engine and its accessories automatically triggers my 'CAUTION' mode - but after talking it over with Steve it seemed to be relative straightforward.

We shall see.

Because this is a product in development, albeit late-stage, there were no printed directions included with the hoses and fittings.   I should probably say a few things about the fittings, because they too are pretty darn nice. Again, in Steve's words:

Our fittings are another place that differentiate us from the competition. We use stainless steel fittings on our hoses instead of aluminum ones.

Stainless steel fittings have two distinct advantages over aluminum ones. First off, they are much stronger than the same size aluminum fitting.

Secondly, in the unlikely event of a fire, aluminum has a much lower melting point. The stainless fittings will protect against the fire much better. This will give you extra time to manage the situation without having a breached fitting that will dump extra fuel onto the fire.

The final item to be aware of is flare angle. Our fittings are all true 37 Degree flare fittings. This means that they are designed to fit perfectly with the AN fittings that are used in your aircraft. Some automotive hose manufacturers that do experimental aircraft hoses use a different flare angle. The truth is that the pressures that we run in these hoses are relatively low, so you might not see any leakage. However, we feel that it is important to have a product on the market that is specifically designed for aviation purposes.

They're nice looking too, and they have the additional benefit of being out in the open and easy to see.

I thought that the first thing to do should be to come up with a way to identify each part so Steve and I would have a common vocabulary, and to keep track of things while I was attaching them to the plane.

The fittings:

• A: fuel 'out' from the fuel pump
• B: fuel in to carburetor (B & C are identical)
• C: fuel in to carburetor
• D fuel 'in' to fuel pump
• E: fuel return line at firewall fitting
• F: fuel marshal - replaces funky block on top of engine

The fuel lines:

• 1: Gascolator to fuel 'in' on fuel pump
• 2: input to left carburetor (this is the lengthier of 2 and 3)
• 3: input to right carburetor
• 4: input to fuel pressure sensor
• 5: fuel return line (uses fitting E)
• 6: fuel 'out' from fuel pump

This is the 'before' picture:

After pondering the 'before' setup for a few minutes, I was able to position the fittings and hoses as I thought they would go onto the plane:

With a clear understanding of what went where, it became a matter of figuring out when and how.

I started with the assumption that the current lines still had fuel in them and that it might be a good idea to drain as much of it out in a controlled way as possible. 

So, Step 1: close the fuel line in the cockpit using the red fuel shutoff knob.

Step 2: remove the drain plug from the gascolator and let it drain into a bucket.

Step 3: remove the main fuel line from the gascolator.

Note that you are going to see a lot of old thread sealant on the AN fittings - using the Teflon sealant was a habit that I got into when doing the brake fittings - the Teflon gave me at least one more full turn without it feeling like I was going to break a fitting.  Once in the habit, I used it everywhere. This is NOT required, or perhaps even advisable.

Step 4: remove the main fuel line from the 'in' port of the fuel pump:

This proved difficult. The old fitting was metric (14mm), but that wasn't the problem. I have a cheapy set of metric wrenches from Harbor Freight, The Home of Easily Sacrificed Tools, but the wrench was too wide to get down onto the fitting. I would need a narrower wrench. Now, I do not recommend this as a common shop practice, but I solved that problem thusly:

Apparently 'Vanadium' is Latin for for 'really soft' because it didn't take too much effort at all to thin down the wrench to a point that would allow the removal of the fitting.

Step 4A: retain the copper washer from the old fitting. You will need it for the new fitting.

At this point, the main fuel line can be removed.

Step 5: Feed one end of Hose 1 down to the gascolator and attach it to the fitting:

With the large mail fuel line out of the way, it seemed a good time to remove the rest of the hoses. They all meet at the fussy junction box at the top of the engine.

Step 6: Remove the fuel transfer block at the top of the engine by removing the two bolts.

The old parts have no use in the new installation, so I stored them away.

Having removed the junction box, there are now hoses flopping around loose. Having started at the fuel pump, I headed back there to continue.

Step 7: remove the fuel 'out' line from the fuel pump.

Step 8: Install Fittings A and D to the fuel pump, using the copper washers retained from the old fittings:

The next line to remove ran from the junction box out to the carburetors. It is held in place with a pair of Adel clamps. These proved quite tricky to remove, but only because I was reluctant to remove the carburetors. It was possible on the right carb, but the left side was far more difficult. I ended up removing the carburetor on that side to get better access to the bolt head. The bolt is threaded into the intake manifold, but if you can get a wrench on the nut, you can remove the bolt out from under it.

Step 9: Remove the Adel clamps holding the carburetor fuel lines. Remove the carburetor(s) as required.

Step 10: Remove the carburetor fuel lines from the carburetors:

Access to the fuel line on the right side carburetor can be improved by loosening the oil tank clamps:

Step 10A: Ensure that the copper washers are removed; the new fittings have their own washers.

Step 11: Install Fittings 'B' and 'C':

I ran into a problem here. I couldn't get a wrench onto the fittings to tighten them down - there wasn't enough clearance around the flats of the fittings to allow either an open end or a socket wrench to get a grip. I called Steve and he suggested using a #4 sized AN cap by screwing it onto a fitting and using a wrench on the cap to drive the fitting in. I was concerned that loosening the cap would also remove the fitting, but he felt that the increased friction provided by the washer on the fitting would hold it in place.

He was right!

I was then able to attach Hose 3 to the fitting. Unfortunately, I did it WRONG!  You cannot allow the fitting to interfere with the operation of the engine choke arm!

The correct orientation is to point the end of the fitting downward. This explained why the hoses initially seemed to be longer than needed.

Step 12: Install Hose 2 (the lengthier of hoses 2 and 3) onto the left side carburetor. Ensure that the fitting does not interfere with the operation of the throttle and choke arms.

Step 13: Install Hose 3 (the shorter of hoses 2 and 3) onto the right side carburetor. Ensure that the fitting does not interfere with the operation of the throttle and choke arms.

Step 14: Install Hoses 1 and 6 onto the fuel pump:

Step 15: Install one end of Hose 4 onto the fuel pressure sensor.

Step 16: Attach the loose ends of the installed hoses to the appropriate locations on Fitting F:

I put off installing the fuel return line for last because I thought it would be very difficult to get at the fittings on the firewall shelf, but it turned out not to be all that bad. Every now and then, having arms as skinny as a 12 year old girl's comes in handy.  The other time is when I buy tight fitting muscle shirts: I get those cheap in the Boys 8 to 12 section at Walmart.

Step 17: Remove the fuel return like from the pass through fitting on the horizontal shelf of the firewall. Install Fitting 'E' - note that this is a very important step! Without the restrictor port in this fitting, fuel would flow unobstructed back to the fuel tank which would have an adverse impact on the fuel flow/pressure to the carburetors. 

Install the end of Hose 5 onto Fitting 'E':

Step 18: After ensuring that all fittings and hoses are fully attached and checked to make sure the gascolator drain has been replaced, open the fuel shutoff and turn on the Master switch. The electric fuel pump should be able to provide a fuel pressure indication. Visually inspect the fittings and hoses for leaks.

Step 19: Restrain the fuel lines using your preferred method:

I personally started by re-routing the main line to be below the metal tube that crosses between the carbs:

This allowed me to re-use the metal support block that had been orphaned by the removal of the old hoses. I initially tried to use a size 10 Adel clamp, but it was too tight. I didn't have a size 11 on hand, so I used a size 12. It's a loose fit, but I don't much care - it's purpose is really just to keep the hose from flopping around. That said, I'll likely replace it with an 11 at some point in the future.

I used a pair of vise grips and some safety wire to hold the clamp in place until I could get the hex bolt started back into the support block:

You can see that the size 12 clamp leaves plenty of slack in the hose, but still serves to keep it fixed in space:

I secured the right side carb line with a pair of size 8 Adel clamps, and AN3-4A bolt, and a lock nut.

Before final tightening, I snugged the Adel clamp combo right up next to the Tee fitting. This served to restrain pretty much everything all at once, but I also added a pair of tie wraps to protect the Tee fitting from rubbing on the support block underneath it:

The fuel return line seems to be half an inch to an inch too long, which is something I communicated back to Steve and Tom. The problem is that it gets awfully close to the edge of the antenna shelf. Steve tells me that they will shorten that hose by an inch from now on.

I used a couple more tie wraps to keep it from working against that edge:

The right side carb line also had the potential to rub against the rubber tube underneath it, so I used a tie wrap to fix them together. The orange tape underneath the tie wrap is the stuff I use to bundle wires. I used it here to protect the fire sleeve from any rubbing from the tie wrap.

I did the same thing with the left carb fuel line and the fuel pressure line:

And again and the fuel pressure line and the radiator hose:

Disclaimers:

  - Products described were provided from the vendor at a substantial discount. 
  - Methods and processes described in this posting are experimental in nature and are not to be taken or construed as technical direction. Use your own judgment.

Because I'm Impatient

As long as I had the cowling off to do my still secret project, I thought the time was ripe to install an oil preheater. This is a simple little device that does nothing more than provide an electric heat source to keep the oil at a reasonable temperature in the winter. There are a number of reasons to do so, ranging from protecting the engine during those first few minutes of running with cold, thick oil to saving engine wear and gas costs while waiting for the oil to heat from temps in the low teens to the required 120F before taking off. Those are valid reasons, but the primary reason is that I am impatient.  I hate sitting there for twenty minutes waiting for the oil to heat up.

Being as the preheater kit is comprised of nothing more than a couple of electric heating pads and some wires to tie it all together, it seems the height of extravagance to pay $230 for it, but in the long run it's usually worth it. And installation is nothing more than gluing one of the heating pads and a thermostat to various places on the engine/oil tank - how hard could that be?

Right.

Harder than I ever expected.

"Harder" probably isn't the right word. It was more.... finicky.

First things first. In this case that meant putting a heating element on the oil tank. That actually was easy. It strapped right on around the circumference of the tank.

The next step was to glue a flat rectangular heating element to the bottom of the crankcase. That is a difficult location to get to, but by moving the oil cooler off to the side I was able to gain access. The first difficulty arose with the glue that was included with the kit. It's an epoxy glue, and it is shipped in what amounts to a plastic envelope. To mix the epoxy, we are instructed to roll a socket on top of the envelope for a lengthy amount of time to ensure a good mix. The glue is very thick, so it was hard to even tell if it was mixing at all. It was even harder to coerce it out of the envelope and onto the heating element. Finally, it was a challenge to find a way to hold the element in place for the 24-48 hours it would take the epoxy to set.  I came up with this method using a spring clamp and a big socket:

Next was the installation of a thermostat, the function of which is to keep the oil from getting hotter than 150F. The thermostat is a small white tab at the end of a wire, and it gets glued to the bottom of the oil tank.

The glue was every bit as hideous for this application as it was for the first heating element. Basically it wanted to stick to everything but the oil tank. I grabbed a roll of masking tape to use to try to hold the thermostat in place while the glue cured. It was a three-hand job, but I have yet to be blessed with the evolutionary sprouting of such a handy (heh!) extra appendage.

C'mon, Darwin, do a bro a favah.

I glued the thermostat in place and held it with one hand while I tore off a strip of tape with the other. It was immediately apparent that a single piece of tape would not be sufficient, so I reached for the roll to tear off another, only to find.... nothing.  I had to keep one hand on the thermostat lest it just fall off of the oil tank and hunt around for the tape with the other, but no matter where I looked... nothing.

I finally gave up and resigned myself to the fact that I would just have to let the thermostat fall off. I would have to clean the old glue off and try again, once I found that daggone tape.

Which.... took a long, long, LONG time.

I did eventually find it, though:

At that point, I decided that it would be prudent to get better tape. I ran home to get duct tape.

Fast forward 24 hours and there I was with Pete,ready to put the cowling back on. Just as we started, the thermostat fell off.

It was time for better glue, too.

The J-B Weld was called out by name in the installation instructions as a replacement for the G-D Hideous glue that came with the kit, but a dire warning came with it as well: it won't set up if the ambient temps are below 76F.  They were. They will be for another four to five months.

Fine.  It would just have to he heated.  Finally, a use for those blasted incandescent spotlights.

Yet another 24 hours later, the glue had set up as strong as, uh.... a weld!  J B would be proud!

After that it was just a matter of strapping down the wires. After what seems like a month of diddling around with this, that, and the other, it is finally ready to fly again!

'N Sync

Most of us have forgotten this, but there was a 'boy band' in the mid-90's named 'N Sync. They never amounted to much, but I remember them because they came around for their brief period of notoriety right around the time young Co-pilot Egg was starting to take an interest in things like that. One of the members, Justin Timberlake, went on to have an equally lackluster career as a Hollywood actor.

All in all, they left me cold.

Which has to be one of the most labored segues ever to appear on these pages.

I may or may not have mentioned this before, but one of the reasons that I was reluctant to remove the carburetor when I was working on my soon-to-be-unveiled project was that I would then have to re-sync the carbs.

In saying this, I realize that some of you have no idea what that means, while others, who may have tinkered with motorcycles at one time or another, are nodding along and thinking, "Yeah. That sucks."

They don't know the half of it.  Syncing airplane carburetors is a hundred times worse in the summer, and a thousand times worse in the winter. Yet there I was: needing it done and 33 degrees showing on the in-car thermometer.

The reason for synchronizing the carburetors is that one carb is managing the fuel to half of the cylinders while the other is responsible for the remainder of the cylinders. If the carbs aren't delivering the same amount of fuel to their respective cylinders, the power pulses being delivered to the common crankshaft will vary in intensity.  This sets up a lot of stress and vibration, two of the worst enemies of engine and airframe longevity.

The process for syncing the carbs involves inserting a balancing device into the process. This device is inserted between the tube that runs from one carb to the other. It can be a simple mechanical device that is really nothing more than two pressure gauges, or it can be a fancy electronic thing that, as it turns out, works far, far better than the mechanical device.

I own one of the mechanical devices.

Kyle, official Syncopation Composer for The Jackson Two, has one of the electronic models.

Synching the carbs, just like moving a sofa to the fourteenth floor of a hi-rise condo, is a two-person job. And, just as with the sofa, the owner gets to do the nasty part. With the sofa, that means walking up fourteen flights of stairs backwards. With carb syncing, it means standing behind the propeller of a running engine, enjoying a buffeting wind chill factor of roughly -25 F while the helper, in this case Kyle, sits in the relatively warm airplane diddling with the screen settings on the Skyview.  No, really, I have photographic evidence of that!

Now, to be honest, this would be my first time syncing my carbs; Kyle's Dad did it for me last November.  It turns out that there is a bit of a learning curve, similar to, say.... learning to set up a tent for the first time when you reach the last base camp prior to the final push to the summit in a Mt. Everest climb, just as a winter storm hits.  Really: it was JUST LIKE THAT!

Having bought the mechanical gauges, I wanted to try to use those rather than the fancy device those spoiled modern kids are using. That was a waste of time. The carbs were so out of sync that the needles bounced around so fast that they were nothing but a blur. No meaningful information was to be had. I suppose they smooth out once the carbs get closer to being synchronized, and we could have done that by not skipping the first step in the process (which is to set the idle stops on each carb to be more or less identical), but it was easier to just ditch the mechanical gauges and hook up the electronic thingy.

Which, when activated, sent its display so far off of the scale that no amount of diddling on the adjustment nut would bring it back towards the center.

We shut down the engine and set the idle stops.

With the engine running again and the indicator now responding to changes made to the adjustment nut, I was able to get the display centered. It wasn't easy - standing behind the blast of cold air pummeling me with hurricane force wind made it very difficult to see what was going on. That, along with the vibration of the engine, made it very difficult to make adjustments to the little nut. Eventually, though, I got it centered.

But not before I decided that I needed to protect the exposed skin on my neck. I hunted around the hangar until I found an old, ratty beach towel and MaGyvered* myself a scarf out of it.

Hey!  That's not my Dynon screen!  Someone's been fiddling with it!

The centered indication lasted right up until I tightened up the jam nut to hold the adjustment nut.  Doing that threw it way off the scale again and I had to start over. I tried the same thing three or four times with the same result. Eventually I figured out that I had to keep the jam nut tight and make adjustments using a two-stage process of slightly loosening the jam nut and tightening the adjustment nut back up against it, watching the indicator the entire time.

If I thought it was tough managing one little wrench in all of that wind, I had no idea what it was going to be like to have to coordinate two of them.

It's done now, and for that I am thankful, but I don't think I will ever attempt to do that job in the winter months ever again.

And I will be buying the electronic tool, too.

UPDATE: It is also possible, as I have been informed by a reliable source, to smooth out the bouncing needles by partially (by which he meant "nearly completely") closing the ON/OFF air valves on each of the two hoses. That still seems overly finicky and since the majority of the cost of the thing was in the hoses, which worked just fine with the electronic version, I won't be losing much if I buy one of the electronic ones.

* MacGyver is an American action-adventure television series that ran for seven seasons from 1985 to 1992. Resourceful and possessed of an encyclopedic knowledge of the physical sciences, MacGyver solves complex problems with everyday materials he finds at hand, along with his ever-present duct tape and Swiss Army knife.

Winter is coming, Jon Snow

And it's time to do something about the air blowing in through the sides of the canopy. Sure, it was nice in the summer, but now? Not so much.

Easy, easy fix, though:

  

The Wright brothers would have been flying by 1895 if they had just had a Lowe's....

Blonds and Carburetors

It was a long time ago and I don't remember when or why I said it, but I do remember telling someone of a tidbit of parental wisdom shared with me by my father: stay away from blonds and carburetors, they're bad news.  He never said it, of course, but even so it has been a tenet that has served me well, particularly with carburetors. My perception of them has always been that they are delicate, finicky, internally complex, and quite simply best left to experts. That could be true of blonds as well, but I have never had occasion to find out for sure. That is no longer true about carburetors.

For reasons that I will get into in a future posting, I had occasion to remove the left carb from the plane to provide better access to a recalcitrant nut/bolt combination. I didn't consider the simple removal and temporary re-positioning of the carb to be especially risky. They've been off before as part of the initial engine installation without any harm; it's really a simple operation involving not much more than unhooking a spring, loosening the screw on a clamp, and wiggling the body of the carb side to side to remove it from the rubber cuff that holds it in place.

Upon replacement of the carb after the work was done, I ran the engine to make sure all was well.

It was not.

I almost immediately smelled fuel, and that was definitely not a sign of all being well. I shut down the engine and clambered out of the plane to see what was causing the smell. It wasn't hard to find - fuel was pouring off of the drip tray under the left carb.  "Well," I thought, "that's not good."

Yes, even my internal dialog is almost British in its level of understatement.

Once I mopped up the puddle of fuel remaining in the drip tray, I turned the master switch back on, which in the RV-12 also turns on the electric fuel pump. And there it was: fuel streaming out of the plastic overflow tube on the side of the carb. As frightening as that was, it proved that the problem was in the carb and therefore not associated with the other work I had been doing.

And thus began a series of restive nights of sleep, with the even-the-least-little-thing-causes-panic hours between 2:00 and 3:30 AM rife with angst over the broken carb. It's difficult, when you think about it, to come up with something more stressful than an engine problem on an airplane located on an airport that doesn't have a qualified engine mechanic handy to offer a helping hand. Sure, I was able to more or less calm myself by repeatedly telling myself that "it's nothing money can't fix," but those last two hours of sleep weren't easily achieved.

Let's leave it at this: between the stress of a broken airplane and the normal day-to-day grinding of my soul into a fine powder from the constant frustrations of the day job, well, my nerves were pretty frayed.

Mitigating that was the helpful advice available through various sources, all of whom diagnosed the problem as most likely being caused by a stuck float. That sounded about right because I had has this problem once before, back in the days when I drove cars acquired for under $1,000. I had a Honda once that developed a leak in the carburetor float. Unfortunately for me, it did so while I was down in Florida. I will never forget the drive home which was made possible by the use of a pair of vice grips carefully adjusted to squeeze the fuel line just enough to allow for a steady 55 mph.

While that was enough to keep the car running, it had two bad side effects: it was 55 mph on the flat parts only; uphill was much slower, downhill was much faster, and it burned through gas a prodigious rate. A rate, in fact, that quickly outpaced my impecunious economic lifestyle of the time. At each fuel stop, I would have to completely clamp down the pliers to keep fuel from pouring into the carb while I was filling the tank. That then required three or four stops on the side of the highway to get the vise grips set just right for the next 100 miles.

So yeah, I know what a stuck (or sunk) float does.

We're never alone with a problem these days and in short order I had taken the advice of Kyle, Chief Mechanic for The Jackson Two, and subscribed to Rotax-Owner.com, provider of DIY videos and other helpful data for Rotax engines. I viewed a video called Rotax Carburetor Disassembly and noticed that gaining access to the floats was so easy that it was accomplished in the first 10% of the video. This alleviated my fears that removing a part of the carb would cause it to spew forth springs and such like the coiled spring snake that jumps out of a joke can of peanuts.

So I did it. I dropped the float bowl.  And there they were, floating in a tub of fuel without a care in the world, bobbing up and down with no inclination to stick in an untoward position.  Like a pair of healthy kidneys, they were.



This did not prove that they hadn't been stuck before, of course. I had laid the carb on its side and it's possible that they had become temporarily stuck. I decided that I might as well put the bowl back on the carb and try again.

It gushed fuel like it couldn't stand the taste of it.

So much for sleep that night.

Figuring that I had done all I could do, I started the search for a Rotax mechanic that would make a house call. It took a full day, but I was able to find a guy in Delaware, OH that would make the trip down to take a look as soon as he could find time in his schedule. In the interim, another suggestion came across the transom: perhaps it was the float needle itself that had become stuck. That didn't mean a thing to me, but I did remember seeing it mentioned in the disassembly video. Still, this was too much. I had to know how this all works.

I figured Google would know since those nosy freaks know what I had for breakfast six days ago, and I wasn't disappointed:

Surprisingly, none of that mattered in the least with regards to the immediate concern, but it did make me feel a little smarter.

Pressing on, I returned to the hangar (again) and removed the carb (again) and dropped off the float bowl. Again. I'm getting pretty good at it, truth be told.

And sure enough, there was the float needle all nicely attached and moving freely, just as Rotax intended.

Having ruled out the float needle as the culprit, I was truly at a loss. I decided to just leave the carb partially disassembled for the mechanic to look at. I went back home to give him a call.

Then it hit me: just as with the floats before it, the fact that the needle wasn't stuck when I first jiggled it didn't mean it hadn't been stuck before. It was worth one more try. I went back out to the hangar and put the carb back together. With Co-pilot Egg manning the fire extinguisher, I started the engine up again.

Purred like a kitten.

Not a drop of fuel spilled.

FIXED!!

I actually fixed a carburetor!!

Now I gotta go find me a blond...