Auto plug testing in the Pmag

I have been testing plugs along with long reach adapters. I started with an RPM drop of 120 with the standard NGK plugs... switching to Iridium Denso brought that down to 60 or so... the same Denso plugs in long reach form have the drop down to 40. All of the plugs seemed to work well with the exception of a single NGK installed in the bottom of #4 that accumulated quite a bit of debris.

The long reach adapters that I found are from http://www.sparkplugadapters.com/services.html (they focus on farm tractor performance). The adaptors were cheap (6 each including shipping). They are machined anticipating a taper seat but will accommodate a gasket seat which is how it works out to be longer...

long reach auto plug compared with the long reach massive aviation plug

these adapters are not ideal since they are cut to accommodate a tapered seal or a gasket seal... I added some high temp RTV on the threads to fill the void from the tapper cut

after several hours plug color is looking very nice

Pmag wrap up and testing

I completed the Pmag installation and tested the system, put everything away and did a test run.  The first start took a bit more effort to fire than expected but I attribute that to having plugs out, new plugs first fire, having turned the prop quite a bit during the install... after the first try it started with a couple of blades and ran very smooth.  I did a run up and checked out the operation of the Pmag generator and observed operation on the single magneto and with the Pmag alone.  The Pmag runs smooth at all RPMs and is notably smooth at low RPM.

The Pmag provides a tach signal continuously so only a single source is needed but I left the tach signal from the magneto installed and replaced the wiring from the switch from the old mag with the signal from the Pmag.  On run-up it was obvious that the RPM reading on the SkyView was twice actual and I had to poke around the menus a bit to find the pulse counter and change it from 1 per revolution to 2.

Most of the time doing the installation was spent on routing and securing everything.  One interesting item to note is that the wires are not shielded and must be separated from each other to prevent signal coupling... not a big deal but it does add a bit of extra time to keep everything tidy and functional while ensuring that good access is maintained for everything else.

Pmag wiring to the top of #1 and #3

Pmag routing from the bottom plugs on #2 and #4

One of the most challenging connection and routing issues turned out to be getting the manifold pressure to the Pmag.  I have a standard Vans -4 braided hose from a restrictor fitting on the #3 primer port to a firewall fitting with a hose to the manifold pressure gauge in the cabin.  So... I needed to come up with a way to tap the line where I can easily access the Pmag tap to initialize the timing mode.  After a bit of puzzling out a plan I ended up using a 1/8" pipe thread T with a couple of -4 fittings and a quick connect 1/4" tube connection using left over static line.  I have an extra quick connect T that I plan to use if/when I change the other magneto over.  I decided to use the existing -4 braided hose and figure out a location where I could use some hard pipe from the T to the firewall.  It worked out great.  I might end up replacing the hard pipe with a braided line but there is no relative movement between T and the firewall fitting so it can stay.

manifold pressure tap for the Pmag

Pmag engine wiring complete

Pmag electronic ignition

I have been looking to move to an electronic ignition for a long time... even before ordering the engine.  Initially, the credit offered to delete magnetos with the engine order were pretty modest so I decided to simply take them and get flying then evaluate options later.  After 320 hours on the tach and much research I decided to replace the standard magneto on the right side with a Pmag unit using auto plugs.

The Pmag uses the existing drive gear on the magneto to gain crank position information and is mostly a drop in replacement with some minor wiring changes.

One outstanding issue in using auto plugs is the reach into the heads.  My engine uses long reach heads that are about 1/4" deeper.  Pmag reports good success with standard length plug adapters and plugs but other systems specifically call for long reach adapters and plugs so I am looking to find longer adapters and test for myself.

Pmag installed on the right side

standard auto plug and insert compared with a long reach aviation plug

long reach auto plug with a standard reach insert... looking for long reach adapters

removed magneto ignition harness

removed standard magneto Model 4370

removed magneto drive gear to be used with the Pmag

I used a 3" gear puller to remove the gear from the shaft

looking into the case and the idler gear from the main crankshaft to the magneto

imprints from closing up Adel clamps in tight spaces... ouch!

new hat!

Gear leg stiffeners

I don't really have much of an issue with gear leg movement but there is just a bit of oscillation that gets introduced right around 20 knots.  The idea of adding a wooden dampener to the metal gear leg to dampen out any induced oscillation is introduced with the plans but is not specifically required.

After reading a number of enthusiastic stories about gear leg stiffeners on VAF I contacted a fellow from Florida who makes them up but he did not have any on hand and only made them up in batches once in a while.... it's only wood... how hard can it be?

I looked at the racks of base molding at Lowe's and settled on an 8' stick of tapered pine.  I back cut the stick with a 30 degree angle so the joined halves would nest the gear leg.  The back side of the base has some raised ridges that need to be knocked off so that they can be glued back together.  I used a my vixen file to remove the ridge and finished it with a sander.

raised ridge on the back side of the base before and after sanding it off

glued halves back to back together

ready for finishing

I used a wooden dowel about the size of the gear leg and wrapped some sand paper to shape the join.

sanding the stiffener to match the gear leg

testing the fit of the finished piece

The plans suggest bonding the stiffener to the gear leg with an extensive glass and resin wrap but I was not committed to the idea or the position of the stiffener and wanted a more flexible solution.  I tried some long zip ties and found that the ones that I had were not strong enough to stand up to my efforts to tighten them hard... it turns out that the small lock tab on a zip tie is where the pull strength is from and the higher rated ties have a more stout tab.  I found some stronger ties and used them to bind the stiffener to the leg.  

It is a better solution than wrapping it in glass.

ready to put back together

So, how do they work?  They give a bit more solid feel to the gear when taxiing and have knocked down the last bit of oscillation.  I am keeping them on!

Dynabeads

I don't really have any particular problems lately, but I like to tinker.  As it turns out this is one of the great joys of experimental aviation.  This past weekend I installed new HID landing lights in my ductworks leading edge units, put together a wing jack, and loaded up my tubes with an ounce of Dynabeads in each tire.

The Dynabeads are very small ceramic beads that are inserted into your tire or tube and dynamically balance the wheel assembly while it is rotating.  I initially ran into these on a motorcycle forum some time ago and have had it on a fuzzy list to give a try with the airplane.

a two ounce package of dynabeads

It takes some patience and persistence to coerce the beads through the valve but eventually I was able to get an ounce into each tube.

feeding the dynabeads into the tube throughout the valve

they recommend replacing the stems with new ones with filters

HID lighting retrofit

With the plunging price of HID retrofit systems I researched on VAF and ordered a 55 watt system from DDM Tuning for a whooping 50 dollars plus shipping.  For that price I selected the low profile 'slim' lighter weight ballast 55 watt unit with 5000k H3 bulbs.

It shipped via USPS directly from Shanghai China and included all the pieces and fittings to directly plug into my existing Ductworks lights.  After verifying operation and getting a bit hypnotized from the lights I spent a bit of time deciding on how I would mount everything.

The first light on the left side is a 100 watt halogen.  Take note of the fade in and out for wig wag operation as the light dims and brightens. On the right side the electronic ballast provides complete cut out and on making the operation very strobe like.  The output and visibility from these lights is just amazing!

HID landing light retrofit

Finally removed the panel mounted transponder

After flying for some time with the new remote transponder I finally decided to remove the Garmin GTX 327 panel mounted transponder after coming up with a plan to fabricate a plate from some of the original panel cut outs.  It came out quite nice.  I have had a fuzzy plan to fill the space with a certified GPS unit but given the rising initial cost and the direction the FAA is going with user fees and increased currency requirements I am abandoning the plan in favor of something more modest like a second SL40 radio.

removed panel mounted transponder

removed GTX 327

all back together... looks pretty good!

New GPS puck antenna works great

I decided to research the remote antenna solution and came up with an alternate brand that had very good reviews including technical evaluation of the performance as superior to the Garmin unit at less cost.  Go figure.  I give the Gilsson antenna a big thumbs up!  The magnets were removable with a couple of screws and the satellite lock up is quicker than ever with stronger signal strength reported by the 696.  My only complaint is the black finish is a bit glossy and the white lettering adds to the reflection off of the windshield.  I have a plan to scuff the finish, remove the white lettering, and paint it with some flat black but it is wired and tied up nice and neat so I have ignored it.  Works great though!

Garmin XM and Gilsson GPS puck on the dash

rapid lock up of satellites with the Gilsson GPS puck

Dynon remote transponder wiring

I wired up a Dynon remote transponder and tucked it up behind the sub panel on the left support rib to the firewall.  Pretty easy access here once you crawl into position... The wiring is pretty straight forward and does not involve a lot of rework.  I used the 5A power line from the old transponder, a new ground, a couple of data lines, and two loop back connections on the transponder I left all of the other connections for the 330 in place incase I need to switch back and will remove them after proving out the new system.

this is 'easy' access!

I have the serial connection to the SkyView documented in my installation notes making it a snap to keep all of the connectors straight.

SkyView serial port pinout

For serial connections I now have:
Serial 1 old out to the 330
Serial 2 Garmin 696 GPS
Serial 3 Dynon transponder transmit and receive on Serial 3
Serial 4 is available
Serial 5 is dedicated to the Dynon GPS

serial connection to the SkyView harness

Garmin 696 GPS remote antenna is dead

The performance of the Garmin 696 in getting an initial satellite lock has been degrading for a bit but I was pushing the issue out of my mind since it would eventually work fine but the initial lock was taking far too long.  I did a bit of basic trouble shooting, called Garmin tech support.  They indicated that a 5 minute lock up was all that they could count on but that was inconsistent with other published data and the original performance of the unit which always got a lock within 30 seconds or so.  I tried another online tech the next day and got a suggestion to do a hard reset of the unit... finally from VAF a Garmin tech with much more experience suggested testing the unit using the internal antenna to see if the external antenna or connector had failed.

With the unit out of the plane the internal antenna worked as expected and the external was mostly worthless... unfortunately I could not determine if the fault was with the connector, the internal interface, or the antenna.  I tried to grab another antenna to test but could not find one so I ended up ordering a replacement to be delivered within a week.

It took about 5 minutes with the plane sitting outside in the sun an it still sat there on Autolocate.

crappy performance form the external Garmin antenna

Trailing edge of upper gear leg fairings

When I initially fabricated the upper intersection fairings they were pretty close fitting but after paint they were splayed out a bit on the trailing edge.  I ignored them but it has been an issue that has been simmering thoughts of doing something... since then I have been noticing how other similar aircraft address this and found that they were attached with a screw and nut on a local extra 300.  

Today I was noticing a bit of a squeaky chaffing sound during taxi and chased it down to the gear fairing on the right side where the inside tab has broken allowing quite a bit of movement.  I decided to fix the pieces at the intersection by adding an attachment on the trailing edge. this really cleans things up and i should have done this earlier...

added a screw to join the trailing edge of the upper gear leg fairing with the gear leg fairing 

I might end up painting these screw heads