« Posts tagged EFIS

Time To Fix Some Stuff.

March 9, 2019 / posted in Firewall Forward / No Comments

For a while now, the MGL RDAC XD engine monitor module has been a little weird, mostly in the form of erratic oil pressure and temperature readings. To wit: Whenever the oil temperature would get above a certain point, the reading would bounce around all over the place, and the oil pressure reading would do the same, resulting in a low pressure warning. It’s very important that neither of those two lie to me, so I installed a steam gauge for the pressure. Oil pressure is solid on the steam gauge, no matter what shenanigans the temp and pressure sensors are up to.

The story so far…

Oh, that’s just a bad ground, you’ll say. Check your connections. Yeah, been there, done that. A lot. And it’s no use. A couple of weeks ago, I went for a nice flight after all the rain, and on takeoff from OXR, I had a complete failure of the RDAC module. Every measurement flashed “rdac fail.”

This, as you may imagine, was almost a code brown, at least until the RDAC came back to life, upon which I promptly flew back to SMO. Popped the cowl, checked the connections to the EFIS, to the grounding block, to all the things. Went for another flight. This time, the RDAC packed up over Malibu and didn’t come back. I flew home old-school, with only the sound of the engine (which I know by heart) as my RPM indicator.

Eventually, I made the connection: When the RDAC gets heat-soaked, it fails. It’s mounted on the firewall, which is extremely convenient because only a couple of wires go through the firewall port back to the panel. Unfortunately, it’s a harsher environment than I anticipated, and after less than 200 hours, I suspect the RDAC has succumbed to the heat and vibration of the engine compartment.

So now I have a job to do: Replace the RDAC, with MGL’s shiny new RDAC XF unit, and this time, don’t mount it low on the firewall where the engine radiates all the heat into it. And maybe, figure out some sort of enclosure for it to keep the worst of the engine’s emissions off it.

When I first installed the RDAC, I had no engine, no accessories, and no clue. I had a vast, untouched expanse of stainless steel where just about anything could go. Over the course of the build, the left side of the firewall got really crowded, and I think the logic was to avoid running data wires along the main power cable coming off the battery on the right-hand side. What we have is a job broken into two lists, for starters: stuff to buy and things to do.

Oh, and by the way, it’s time to start thinking about plumbing the mandated ADSB equipment for 2020. But that’s a whole ‘nother post.

To Buy:

  • MGL RDAC XF
  • CHT probes and wire (2x probes, 4x wire, steel crimp connectors)
  • EGT probes and wire (2X probes, 2x wire, steel crimp connectors)
  • Heat-resistant shrink tube
  • 3-wire shielded cable (+, -, and ground, plus shield). See http://spectrum-instruments.com/resources/documents/splicing_STP.pdf
  • 4″ SCEET tube (See the oil cooler scoop post, the tube’s getting ratty).
  • 1″ Fire sleeve for firewall port
  • 3″ Fire sleeve for cable wrap in firewall port
  • Aluminum Z-channel to mount new RDAC (this is a maybe)
  • Blast tube (look for this in the garage)
  • EZ-Up (to keep the sun off while working. Yeah, I park outside at SMO)
  • Fire barrier goop
  • Tarp/cover (in case I have to leave the cowl off overnight. Or for a whole damn week)

To Do:

  • Dismount Oil Cooler Scoop, gain access to old RDAC
  • Dismount CHT probes from 1 and 4 (these are the ones that work intermittently)
  • Dismount old RDAC, fill firewall holes
  • Mount new RDAC. Somehow.
  • Extend fuel flow wires to new RDAC location
  • Extend fuel pressure and oil pressure probe wires to new RDAC location (Do this at home)
  • Run and wrap all wires to new RDAC location (The existing Adel clamps will work)
  • Wire up new RDAC.
  • Remount Oil Cooler Scoop
  • Devise a way to keep the hose clamps from cutting up the SCEET tube
  • Install SCEET connection from baffle to cooler scoop (Do it right this time)
  • Test all connections!
  • Fly.

Zero Sum

December 27, 2013 / posted in Finishing / No Comments

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.

Equal parts forward and back.

August 26, 2013 / posted in Electrical, Finishing, Firewall Forward, Fuselage, Panel / No Comments

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.

A Fix and Some Finishing

July 29, 2013 / posted in Fuselage / No Comments

7 hours.

Although the last three shouldn’t count because I spent them fixing something I should never have had to in the first place.

20130728-192738.jpgThat little corner of aluminum is the bane of my life.    Since I put the wings on, I’ve caught it on shoes, shirts, and finally, the belt on my jeans.   When this happens, it bends.   This time, I bent the crap out of it, so badly, that I had to remove the fasteners on the skin, peel it back, and hammer it flat again.  The light makes it look worse than it is, but it’s still pretty bad.   Fixed now, though.

 

20130728-192751.jpgThe day wasn’t all bad.   I got the fuel pump overflow plumbed.   I used some of the tubing I had from the MAP sensor install to create a flexible link between the output of the fuel pump to the hard line shown here.   The engine wiggles.  The aluminum tubing doesn’t.   I need a flexible line between the two.

20130728-192805.jpgThe fuel sensors concerned me for a minute.   When I connected the wings, I had some little extra wires that I thought I’d run for spares.   I guess this is why you label things.   After some pondering, I realized these were the fuel level sender wires.   Duh.  The good news is that I didn’t have to do any splicing and apparently I cut them to the right length.   A couple of connectors later and I had fuel level, which was, of course, zero.

No luck on the OAT sender though.   Either my EFIS or the probe is bunk.   OAT reads a steady 32 degrees F.  Have to contact MGL for a new one.

Avionics Install (almost) DONE!

January 3, 2012 / posted in Electrical, Panel / No Comments

4 hours.

Sweet FA got done over the weekend (New Years, hangover, etc, etc.), but today I finished wrapping and securing various wires, as well as rerouting the starter ground in a bundle instead of floating around all by its lonesome.

Only two things left to do, really, and that’s to install the OAT probe and reconnect the IOX when it comes back from MGL in a couple of weeks.  For now, i’m not sure whether or not to start the baffling or the FWF sensor wiring.