« Posts tagged control cables

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.


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.



5 hours.

Today was about putting things back together and getting a handle on some of the chaos.   The first bit of good news is that the oil temperature probe works fine.  I pulled it out of the engine and hit it with a heat gun and sure enough, it gave me a reading.  So I’m not going to worry about that anymore.   I secured the wires back in their bundle and i’m calling that squawk done.

I also wasn’t real happy about the weird way I had the fuel pressure sensor set up.  The Adel clamp holding it was maybe a size bigger than it should have been, and this way seems more secure:


As I mentioned last time, I flipped the governor arm over and it seems to work just fine:


My biggest problem with doing it this way was where the injector line was going to go.   A piece of angle solved that.   Now it’s out of the way, and less likely to be heat-soaked down near the cylinder.  I still haven’t safety-wired the screws yet, or put the cotter pin in the cable attach nut, But I think this is how it’ll stay.

Last week, Owen recommended tightening up the tailwheel chains.   Van’s recommends a half an inch of slack, but if you ask ten different people how they like their tailwheel chains, and you’ll get at least five different answers. But my chains had an inch of slack, and if I took a link out, I’d have none.  But I did take a link out of each side, and while there isn’t really any dangling slack, I can move the chains up and down by about a half an inch, and I’ll tell you, based on today’s test, it taxis just fine:


That little gap in the rudder fairing is kind of annoying.   Not exactly sure what to do there, except put nutplates in there and hope for the best.

Today’s test was all about seeing how things went with the cowl on.  First, I wanted to make sure I could actually get the cowl on with the flipped-over governor bracket making the cable rise a bit more than it did before.   Turns out, I’ve got about 1/8″ of clearance between the cable and the top cowl, which is good enough.   And from what I remember, the cowl inflates a little in flight, so that 1/8″ becomes a little more.   And that’s fine.   I just don’t want to have to put a clearance wart in the cowl to accommodate the cable.


But before taking it out for another test, this adjustment had to be made to the baffle material on the lower cowl.  I had to cut it back a bit, because it was covering up about 6 square inches of air intake.   Bad.   So with this mod in place, I put the top cowl on, and pinned it down.   Then I put a few of the floor panels in, and you’d be surprised how much the plane stiffens up with the reinforcing action of the panels.   I ran it up, then shut down the left mag.  Engine died.   Started it again, repeated.   OK, right mag dead.   Grr.   Still runs fine on one though.

So I said screw it, let’s taxi it around.  The new tailwheel chain tension was much better.  Now it’s more like Mickey’s Citabria, and the ground handling is nice!  I took it to the end of the hangar row, turned right, went down the next row, turned right again, then went back to the barn.  CHT’s never got above 210.   As soon as I get this mag situation sorted out, it’s time for ground runs.

\Last time, shutting off the left Mag made a lot of popping and missing, which I attributed to timing.   This time, I’m pretty sure the timing’s right, but now shutting off the right mag shuts off the engine.  Now, it might have something to do with the fact that I left the pop-rivet I was using for a timing pin in the hole when I pulled the prop through, but I can’t say for sure.   What I do know is that before, on the right mag, I had backfiring.   Now I’ve got squat.


Working on engine-start squawks.

7 hours.

Last week’s engine start, while exciting, wasn’t without issues.   The one I thought was going to be most difficult to fix turned out not to be.   The governor operation was reversed, and the fix turned out to be pretty simple.   I just flipped the governor bracket over and mounted it so the cable operates the arm from below.     All I had to do was put a small piece of angle on the side of the arm to secure the #2 fuel injector line.   We’ll have to see about conflict with the cowl.  I put the top cowl on and it looks like there might be about 1/8″ of clearance between the new governor cable arc and the underside of the cowl.  That’s not a huge deal though, and I’d rather put a blister on there than go through the hassle of dismounting the governor and sending it back to American Propeller to see if maybe, just maybe, they can reverse the operation.   Either way, that would cost me in time, in shipping, in ability to test the engine in other ways and debug the two sensor squawks from last time.   The hardest part was the firewall-penetration eyeball.  It’s almost impossible to get to and I still need to torque it down, because it’s not laying flat like it’s supposed to.  I had to take it out so I could get the extra half inch of cable slack necessary for the flipped bracket.

On the others, I had no luck.   No RPM reading, no oil temperature reading, although I have no idea how long it takes the oil to warm up to a minimum of 72 degrees.    The rpm thing is a little scarier because i don’t know if it’s the wiring, the sensor, or the magneto the sensor is attached to.   I’m going to have to break down the wiring of those two pieces and go through it piece by piece.   I really hope the senders aren’t bad, because those things are not cheap.  Replacing both is about a taildragger lesson’s worth.

Speaking of which, I have replaced the ON/ON/(ON) magneto switches with ON/ON DPST  switches.   One side of the switch handles the start circuit and the other handles  the mags.   When the start circuit is enabled, the magnetos are ungrounded.   Since I have two impulse-coupled mags, I can get away with this.   At this point, the starter button on the stick is the only way to kick the engine over now, which is OK, but I plan to install a pushbutton to forcibly engage the starter should the relay the stick button actuates takes a dive.

The magneto timing still needs work.  Even after the switch replacement, the right magneto still makes the engine backfire like mad when it’s on its own.   I’ll need to retime it anyway when I install the new gaskets, but it’s still a royal pain and I’m not keen on doing too many more runs with it in that condition.

Oh, and joy of joys, there’s a small crack in my canopy, in the aft right corner, coming up from the last screw hole on the canopy frame.   I didn’t catch it until now, because it has been  covered with masking tape, which I removed yesterday.   I removed all the protective plastic from the canopy, except for a swatch between the rear canopy and the roll bar brace.   Now the fun is going to be getting that last piece of plastic out from there.  I’ll probably have to dismount the rear canopy, which I would have had to do anyway to get some kind of seal in there.

Engine Start, Part 2.

  1. 5 hours.

Armed with last weekend’s knowledge and suspicion, David and I headed up to OXR to debug and correct the mag and start wiring, then actually start the engine.    We had a copy of The AeroElectric Connection and more importantly, the airport gate card, which allowed us to come and go as we pleased.

Even though we knew what was wrong, it was puzzling, because we were trying to follow Bob’s diagram and make an open circuit for one thing while making a closed circuit for another.   Maddening.

Eventually, we did figure it out and we were rewarded with the sound of an airplane coming to life.

Hooray! Huge milestone, and only three squawks:

  1. No RPM reading.   This is most likely a bad ground or a severed wire coming from the pickup on the magneto.
  2. No Oil Temperature reading.   Maybe this shares a ground with the tach sensor.
  3. (and this is a big one)  Governor operation reversed.   The prop does cycle and the governor doesn’t leak, but it operates the wrong way.   I need to set it up so the prop increases pitch when I pull the blue lever back.

No leaks, no fires, no pieces flying off.   I’d call it a good day!

Equal parts forward and back.

6 hours.

One of these days, I’ll move forward without moving backwards.  Today I had to dismount the EFIS in preparation for taking it to MGL Avionics.   Apparently the OAT module is fried.  I tried it with a new probe last week, no dice.   Maybe, if I’m lucky, I’ll be able to drop it off tomorrow on my lunch hour.   Other than that annoyance, I got the tailwheel hardware primed, something I should have done long ago, and I got my spark plugs torqued in.   But now, for some mysterious reason, the tailwheel steering chains don’t reach their mounting points on the rudder anymore.   It’s possible I had the steering link on upside down/backwards, which would have accounted for the missing 3/4″ of chain necessary to bridge the gap between what I need and what I’ve got.   Looks like I’ll be ordering another set of tailwheel chains.  Grumble.

Anyway, once I get my EFIS back from the shop, it’ll be time to prepare the engine for first start.

On another note, I’m progressing nicely in my tailwheel training.   We flew from Torrance to Hawthorne, where I did 8 landings, unassisted.   Apparently I CAN land a Citabria in 3-point attitude.   At least when the wind is coming at me and I set up the approach right.

Still more connections.

6.5 hours.

A bit of a late start.   Since I took this week off, yesterday was my first weekday commute to OXR.   I went via PCH, which is nice enough, but it took a little longer, especially during rush hour.

I finished installing the rudder cable linkages to the pedals, so that’s another thing done.   I also got the pitch trim servo wired in.  I’ll need to adjust the throw on the trim servo, but that’s essentially done.

Then I went back to wing wiring.   I got the strobe and lights connected for the right wing, plus the autopilot servo.  It was lots of tedious, fiddly stripping and crimping in small, awkward places, which has an extra coating of suck because I did something to my right elbow and now operating hand tools like crimpers is fairly painful.

Left to do is connecting the VOR antenna wire (This may become an ADSB antenna wire if they phase out VOR) in the left wing and putting in a couple of pieces of UHMW tape here and there.  If I can have lights, strobes and VOR by the weekend, I’ll count myself lucky.


More connections and a flight

6 hours.

Today was spent tidying some wing attach stuff.   I got my order from ACS, so I was able to finish installing and torquing all the wing attach hardware.   I also did the fuel line on the left tank, remembering this time to put the rubber grommets on before flaring the ends.   There’s a $30 tool that will stretch those rubber grommets out so you can get them over flares and fittings, but I figure it’s good practice just to try to be less stupid.

The most interesting part of the day was the short flight I took in my hangar mate’s Luscombe.


I’m not sure which model this is, but I think it’s an 8C or 8D.   It burns 4 gallons per hour, which is probably about half of what the Pipers I learned on did.   It has no flaps, no lights, and only the minimum equipment of single radio and transponder to get around Southern California’s interesting airspace.


Now, I’ve never been in, much less flown a taildragger, and the oldest airplane I’ve even sat in was an old L-19 Bird Dog in Ft. Leavenworth KS when I was a little kid.    This aircraft was built some time during the early 1940’s, and Ron was kind enough to let me follow him on the pedals to get a feel for the quirks of a taildragger.   This shot is one out the right window, us taxiing to runway 22 at OXR.

20130616-093659.jpgAnd another out the front.


The instrument panel is simplicity itself.   Everything you need for day VFR, nothing you don’t.   The mount for the Garmin 296 GPS looks strangely out of place, over to the side out of frame.   There’s a single vernier cable control for throttle and a small one for carb heat.  I didn’t see one for mixture.  I don’t think there is one.   The fuel gauge is on the bulkhead behind me, between the two seats.


20130616-093736.jpgWe did a landing at Santa Paula, where I was able to get a picture of Steve McQueen’s old hangar.   I love this airport already.   I just wish we’d had the chance to buy McQueen’s old ranch when it popped up on Jalopnik last year and it was dangerously close to something we could afford at its fire-sale price.


20130616-093750.jpgThat adventure only took about 20 minutes to half an hour.   When I got back, I did most of the real work.   Here’s the right flap, on and conneted.  There’s some more rigging to be done,  and some more wiring, but the wings are nearly fully on and connected.   I also got the left rudder pedal connected to the cable, but ran out of time before I could do the right one.   I’ll hit that in a week.  Soon it will be time to mount the prop!

More firewall forward progress… And regress.

5 hours.

The latest load from ACS allowed me to finish a couple of things. I got the oil pressure line/oil line adel clamp securing done, I finished the purge valve bracket assembly, I got the fittings installed on the oil cooler, and I actually got the prop governor installed, and the front center baffle reinstalled. I painted the throttle and mixture brackets and put them back on, and I re-secured the current sensor to the alternator wire. This is where it all went south.

I also finished attaching the fuel hose to the throttle body, and securing it to the intake pipes, but this is where it all went horribly wrong. I had purchased a steel 1/4″NPT-AN6 elbow, but I was using one of the blue aluminum ones to get my fit and mount done. The Floscan is on the firewall, and the elbow points toward the intake pipes on the left hand side of the engine. I had the fuel line connected to this. Somehow, in backing out the AN6-1/4″ NPT elbow on the output side of the Floscan fuel flow sensor, I managed to cross-thread the fitting as I was taking it off. Taking it OFF, not putting it on. So what it did was essentially pull on one side of the threads but not the other, kind of just bending the whole thing. Long story short, I completely destroyed the threads on the Floscan and it will have to be replaced. That was a very expensive ($210 from MGL Avionics) lesson in not connecting loads to dry-fitted NPT fittings loose enough to jam up. I did finally manage to extract the threads left in the Floscan housing and re-tap them, but I don’t trust the connection anymore, especially not with high-pressure fuel running through it. Now would be the time to switch to the Red Cube, except that now I’m reading about failures of these units, plus my firewall mount is drilled specifically for a Floscan. The time for experimentation is pretty much over.

I also got a tube of red RTV for sealing the baffles and putting some blobs wherever things might rub that I didn’t get with Adel clamps.

I still have to track down a hose from PHT (throttle body to fuel spider), but that’ll have to wait until tomorrow. My intercylinder baffles are on their way, and once those get installed I can permanently reattach all the baffles. I can also rivet the firewall to belly skin, because I’m giving up on making an exhaust fairing for now.

Adel clamps, and lots of them.

5 hours.

Today was another iteration of finding the best way to keep things from rubbing together. I did a lot of hemming and hawing about zip ties, reading the horror stories on the Internet of that one guy who had a zip tie saw through his engine mount, and that you’re never supposed to use them on the engine mount or hard lines, and that’s all fine. Supposedly they’re big time savers, and for wiring, you bet. Lacing cord? No way, I don’t have the patience or the skill and zip ties are easy. Firewall forward though, it’s a different story. Conditions are murderous up there, and the regular Home Depot 500-for-$10 pack ones will go brittle and snap off in the heat and vibration of the engine bay. Still, there are a lot of folks who use zip ties up front with no ill effects, and there are all kinds of cool tricks to make standoffs, joins, and other fastenings, but you need to use a tie gun, and my tie gun is shite. I think I bought it at Fry’s for around five bucks, and it shows. I’m not shelling out three figures for a Panduit tie gun though, that’s just crazy. What I did do instead, is finally master the horror of Adel clamps.

Take a look:

That’s the neat little visegrip hack I bought a while ago, but never quite got the hang of. Now I’ve got the hang of it. The way this thing works is you jam a pointy thing that looks like an icepick through the holes on both the Adel clamps you’re trying to put together. Then you try to get the flanges close enough so you can wrap the forks of this gizmo around the icepick, then squeeze the clamps together as if they had a bolt throug them. You pull the icepick out, and you can put a real bolt through the holes. Problem is, the forks on the visegrip thing are pretty thick, so I ground off a couple of 32nds from each side. This way I could use a shorter bolt and not as many washers. At this point, screw it, washers are cheap and I’m not using more than 3 on a side, so this setup works fine.

I did as much as I could on the right side of the engine, where the 1 and 3 cylinders are. This means the alternator wire, the fuel pump input line, the purge return line, and the oil pressure sensor line, along with some miscellaneous wiring, needed to be isolated from the airframe, the engine, and each other.

Above my head, you can see the throttle and mixture cables, as well as my homemade steel brackets, and on the left, the double Adel-clamp assembly keeping the starter wire from rubbing on the mount.

I didn’t take a lot of pics, because I was too busy fiddling with clamps, and that makes my hands hurt, especially the knuckle on the middle finger of my right hand, where that stupid cow knocked me off my motorcycle with the door of her minivan this summer. I did get some, like this one:

This is the purge line, all secured and isolated.

This one:

shows the fuel pump feed and the purge return, held off from each other and the mount. Also clamped up here is the alternator wire and starter wire.

Gratuitous Adel clamp porn of the alternator wire.

Gonna do the rest of it this week. Happy new year!

Cables, hoses, pipes

6 hours.

For a “simple” engine this thing sure has a lot of frippery. Today was spent optimizing the routing of various members and employing different methods to insure they don’t chafe on each other, or the multitude of hazards awaiting the unsuspecting flammable-liquid-carrying hose beneath the cowl. Oh, and heat. There’s lots of heat down there. The control cables, I wrapped in some Thermo Tape I bought a while back for that very purpose. I think I’ll also use the heat shields that clamp onto the exhaust pipes as well, but I’ll do those later.

I actually wound up dropping the exhaust so I could get better access to things that needed to be secured. I’m also debating hooking up a fuel pressure sensor, since thanks to an error in my PHT hoses order, I now have a firesleeved hose that will work great as an oil pressure line.

I also spent a good chunk of time chasing down the intercylinder baffles for my engine. There are about three or four different variants, some with the hole drilled for the fuel injection hose, some without. I finally wound up just ordering the ones the book calls out for that engine, and I’ll drill the hole for the injector feed line later.