The Bambas Family

On Friday November 11th N50KB had its first engine run.

A visit was scheduled with a FAA FSDO inspector for the afternoon of Wednesday the 22nd.  In the interim I completed wiring and testing the Pilot and PAX seat heaters; and sealed seven more firewall penetrations with red high temperature silicone caulk.

Wednesday morning I started the engine with the intention of taxiing to check the brakes.  It ran rough and was shut down.  The #4 cylinder was cold. Inspection showed valve movement was OK and another start was made.  The engine again ran rough for less than a minute and was shut down.  Instruments (Garmin G3X) showed the #4 CHT and EGT rose only to 150 and 205 degrees while the other cylinder temperatures appeared normal. An overly lean condition was suspected.  The #4 fuel injection restrictor was inspected and blown clean with air.

The FSDO inspector arrived and was told of the day’s activity.  I agreed to a suggestion we do an engine start.  During the start sequence the #4 EGT was seen to rise rapidly and then decline.  Other cylinder temperatures were normal.  The airworthiness inspection was terminated.  During post run discussion a fuel flow test and plug sparking test were suggested.

Fuel Flow Test

The fuel distribution test collected avgas from the four injector lines while the fuel boost pump was running.  This photo shows the results.

From left to right the cups contain the fuel for cylinders 1,2,3 and 4.  The overly lean condition of cylinder #4 is obvious.  There was likely a problem in the AVstat fuel distributor on the top of the engine.

Plug Sparking Test

The plugs were removed and their cases connected to engine ground by safety wire.  With the master and ignition switches on, the propeller was rotated by hand.  Sparks were observed from the plugs connected to the left E-MAG.  The plugs connected to the right E-MAG did not spark.

Brad at E-MAG Ignitions was contacted by phone.  He led us through several levels of tests that at end indicated the right E-MAG was operating OK.  He then asked me to remove the right E-MAG.  I was to verify the magneto shaft is engaging the drive gear in the engine accessory case.

I removed the E-MAG.  It’s shaft and gear look OK.  I then reached into the accessory case to feel the drive gear.  This is what my fingers found. A broken magneto drive gear in a factory new Lycoming YIO-360-M1B engine that ran a total of less than 1.1 hours, with over an hour of that time on the factory dynamometer.

The following Monday began  a week of phone calls and emails with several levels of the Lycoming warranty organization.   Dolly had returned to Florida and before driving south I proceeded to pickle the engine with fogging oil and desiccator plugs for the winter.

Eventually Lycoming agreed to send a packing crate and pay to airfreight the engine back to the factory.  Dolly and I drove back to Michigan where I spent several days removing the engine from the plane and with help from friends preparing the shipment.  I took many photos of the process.  The engine arrived in Williamsport, PA on January 2nd.

 

Could not yet see the light at the end of the RV7 build, but knew it was getting closer.  The list of accomplishments in the interim included:

• Fastening the fuel tank “break away” tabs to the fuselage on each side.
• Fabricating and installing the short fuel vent lines and connecting fuel supply lines between the wing and the fuselage

  

• Making up brake lines with Berringer fittings to go from the firewall down to the wheel brakes.
• Filling the brake calipers and lines up from the bleader valves to the reservoirs over the master cylinders
• Final fastening the PAX baggage floor and PAX seat pan to underlying ribs with machine screws.  This and other tasks may sound simple, however I found them to take significant time.
• Finished wiring the flap motor and position sensor

  

• Installing a quick drain valve on the left front oil sump drain.
• Installing Clasic Aero aileron push-rod boots to seal out cold air.
• Installing SCAT tubes from NACA air scoops to the instrument panel outlets
• Timing of the PMags
• Fitting the cylinder baffles and using the “Paper clip” method to trim the baffles 1/2″ from the cowl

  

• Fitting the oil cooler to the right rear engine baffle; doing the install and connecting oil lines

  

• Cuting and glassing the engine air intake snorkle between the air filter and the fuel servo

  

• Installing the ignition wire protectors that I designed last winter

  

• Closing up the six inspection ports in the wing bottom skins
• Installing an alternate air door into the snorkle with control from the instrument panel
• Installing all interior cover panels, baggage rear wall and pilot seat pan

  

• Sealing the engine to baffle gaps with Blue RTV
• Installing wing to fuselage faring strips
• Installing seat belts

Whew, and that’s not all.

The Vans upper and lower cowl halves had to be trimmed to fit each other and the fuselage firewall.  For October 30th we had a Halloween Lantern.

The cowl interiors were painted with three coats of white two-part epoxy.

I copied the practice of many Vans builders and cut an inspection port into the upper skin in front of the canopy.  This provides access to the break fluid reservoirs, the voltage reservoirs and the forward sockets of the VPX power box.

Another deviation from the Vans standard is that I fabricated and installed a plenum cover over the top of the engine, rather than the usual flexible baffle strips that seal the baffles to the top cowl.

The potential advantages of a plenum in cooling efficiency and reduced wear on the cowl have been often debated on the Vans Airforce website forums.  Casting of the plenum was discussed in an earlier post.

Clay risers were set on the plenum to verify 1/2″ clearance from the cowl.

Aluminum and fiberglass edges were set with platenuts for fastening to the engine baffles.

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  The Catto three blade wood/carbon fiberglass propeller was installed.  Specifications:

• 68″ diameter
• 74″ Pitch
• Nickle leading edges
• Design RPM 2750
• Red Line RPM 3300

Prior to first engine start start the fuel tanks were calibrated and a weight and balance prepared.  Both of these steps will be repeated as the W&B indicates a heavier spinner ‘crush plate’ will be needed to move the center of gravity further forward.

While we were in Oshkosh, WI for the annual EAA convention, Lycoming announced a manditory service bulletin for about 1300 engines that had been manufactured in 2016, plus all engines that had been overhauled with new piston rods around that time.  Our engine serial number was one of those listed.  The inspection involved purchasing and using a special tool to find those connecting rods that may have looser than specified bearings in their upper ends.

An FAA Airworthiness Inspector friend who once owned an aircraft engine overhaul shop helped me get the job done.

The photo shows the tool (a big coil spring attached to the #4 cylinder’s rod.  If the bearing starts to slide out when the spring is compressed by six turns of its inner bolt, it fails.  We were lucky all four rods passed.  Note the red cylinder base o-rings that are used to keep the connecting rods from flopping around during the disassembly. The S/B was just a PITA that slowed progress by three days.