« Archives in September, 2013

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!

Engine Start, Part 1.

6 hours.

A tiring and ultimately unsuccessful day.   Dave and I went out to the airport with the intention of starting the engine for the first time.   We were off to a stellar start: I’d forgotten my airport key card; it was still attached to my motorcycle safety vest at home. I didn’t notice it until we were actually in Oxnard, so that sucked.   We did manage to find somebody to let us in, then went about the business of readying the plane for engine start.   We dumped 8 quarts of oil in the tube, then attempted to time the magnetos.    This is harder than it sounds.   Once we actually figured out how to use the buzz box, the cylinder plug, and our own eyes, we got the mags in and timed to the engine.   That’s when the fun started.

We wheeled the plane outside and prepared to start it up.   We left the distributor caps off the mags so we could spin the engine a bit and pre-oil it.   with four plugs removed, we were able to spin the engine around and get oil into all the nooks and crannies and actually see an oil pressure reading come up on the EFIS.      Prop spins, there’s oil, let’s start it!  Foolish us.   Slick magnetos are designed to run when their circuit is open, that is, the two leads connected to them, when connected to each other, make the magneto safe, cold, whatever.   The AeroElectric diagram has you connecting these two switches together in such a way that the right mag fires when you’re starting and the left one doesn’t do squat until the engine’s running, that is, you’ve let go of the spring-loaded upper position toggle because the engine is running.

Somehow, I’d wired it in such a way that the mags were connected/safe when the switches were “on” and the start circuit was on.   The engine spun, but wouldn’t start.   Fortunately, safety wasn’t in question.   The way I had it wired, no matter what position the toggles were in, the mags were grounded, so it’s not like the prop would have taken our faces off.

By the time we’d gotten wind of the problem, it was too late to debug and we were tired.  Tired people working with dangerous things tend to get hurt, so we packed it in and crawled home, after begging to be let out the airport gate.

EFIS returned to service and wing root fairings on

8 hours.

Today and yesterday.  I got the EFIS back before Friday’s taildragger lesson and got it back in the plane on Saturday.   My only gripe is that the voice alerts don’t make any sound.  I”m not sure if that’s because of the EFIS or the wiring, maybe both, but it worked before I pulled it out, and now it doesn’t.   More testing is needed there.

I did get the wing root fairings on, and hoo boy, are they a pain.  They’ll have to come off again for the DAR inspection, but I don’t need to access anything between the wings and fuselage, so they can go on the plane and not be hanging off the handle of my tool box.   It took some time, because the fairings and the seals are kind of awkward and I had to do a couple of passes with the deburring wheel to gain enough clearance for the u-channel of the rubber seal, but I think they’ll work OK.

I think we’re going to start the engine next week.   Time to quit procrastinating.   Need to torque the alternator bolts down, but other than that, it’s ready to go.   I’ll pre-oil it again, then we’ll fire it up.   With a gallon in each wing tank though, It’s not going to run for long.


More odds and ends.

5 hours.

This is for Monday, Sept 2.

I really need to do these log entries directly after I do the work.   Makes for an easier time remembering what went on.   Without the EFIS in place and having wires everywhere, I wanted to stay out of the cockpit as much as possible.  I tightened up the canopy strut attach points, and completed the left aft spar bolt.  Yeah, I forgot to put the nut and cotter pin on there earlier, when we mounted the wings.  I guess I was so focused on getting that bolt in there while I had help, I didn’t think much about it afterwards.   I’m really surprised I didn’t notice it when I put the flaps on.   It would have been way easier that way.   Every time I go to some region of the plane,  I keep finding things to do, but the items are quick tasks and detail work.   I also installed a couple more heat shields on the exhaust near the throttle and mixture cables, plus I torqued down the spark plugs and the plug wire attach nuts.

No fuel smell in the cockpit, so it appears my fixes to the fuel lines and boost pump have worked, which is nice.  I also have no leaks in my fuel tanks, as far as I know, with the paltry gallon of gas in each one.

I reworked the tailwheel chains again, because last time, I had the steering link on backwards.   This meant that I cut the chains about 3/4″ too short and had to replace them.  Worked out OK, except for the fact that I overtorqued the nut on the tailwheel fork.  I might have to order a new one, which would suck, but what’s done is done.  But other than that, the tailwheel is good to go.

I should get the EFIS back this Friday, and should be able to reinstall it Saturday or Sunday.

Sunday I had more instruction with Mickey down at KTOA.  I keep making noob mistakes like trying to steer the plane with the stick, flaring too high, landing too slow, and flubbing radio calls, but considering the amount of hours I have, I actually am a noob.  I now have something like 8 hours of tailwheel time, which means I’ll crack the 100-hour total time mark during my next lesson.  I expect to solo the Citabria some time in the next couple of weeks, 3-point landings only, but that’s enough for me to build up some time.   I need to get good enough with all the basic airmanship and solidify my taildragger mojo enough to take on wheel landings.   This is important, because RV-7’s like to be wheel-landed.   The 3-point attitude is actually less than stall angle, so supposedly 3-pointing them leads to “The RV Dance,” which is a slight bounce, on the first touch and settling down after.  FA you can do, it’s just like that.