Dec 31, 2021     INTRODUCTION...       Category: INTRODUCTION

Hello - I started my Bearhawk 4 Place Quick Build Kit on June 1, 2018. At the time I was documenting my building on Google BlogSpot https://bearhawk4place.blogspot.com/. (you can still follow my building activity there.). On May 23, 2020 I created this EAA Builder Log, primarily to comply with the FAA/DAR when it becomes time for my airworthiness inspection. Secondarily, to connect with the EAA building community. My BlogSpot building log was feeling kinda lonely out there all by itself...

BlogSpot allows for the linear placement of text and pictures. Unfortunately, this EAA Builder Log does not and you will notice this as you scroll through my entries below. I copied and pasted everything from the BlogSpot log so it doesn't flow as well as I would like.

For those interested, I also have a YouTube Channel where I document my build and provide more information about the Bearhawk in general. You can find my YT channel here:

  Feb 17, 2020     Wiring and the Electrical System       Category: Avionics

Video from my YouTube Channel discussing the Wiring and Electrical System



I won't get into the specifics of the ignition system in this post, but I need to say what ignition system I am going with for the purpose of understanding what I am wiring. Because, I previously stated that I would be using a Light Speed dual electronic ignition system. But I changed my mind and decided I would go with a SureFly electronic ignition on the left side, with a Slick Magneto on the right side. Then, I changed my mind again... NOW, I am installing dual Slick Magnetos (6393 retard left, 6350 plain right). Why? Because Champion Aerospace offers the SureStart Ignition Booster for their dual Slick Magneto Systems. They claim engine starts on the 2nd or 3rd blade every time, hot or cold. I'll explain more when I post the Ignition System blog...

Ok, the Electrical and Wiring process went very well! But I could not have done it without the help of Jason Smith at Aerotronics. Aerotronics built my instrument panel and then shipped it to me. After I mounted the panel and it was my job to bring all of the wires (fuel pump, lights, sensors, battery contactor, P-Leads, etc) through the firewall to panel. This is accomplished with a 37 pin P1 Circular Connector Plug, a.k.a., the P1 Plug. Aerotronics prewires the female end of the P1 Plug at the panel. They map all of the pin locations and then send me the pin map for wiring the male end of the P1 Plug that I assemble. In addition, based on my choice for a ignition system, Aerotronics also supplied me with a schematic for everything else to be brought through the firewall going to the circuit breaker panel. It's a full diagram of the entire wiring system firewall forward. I couldn't have done it without their help. I read Bob Knuckles book, The Aeroelectric Connection as well as other related books and websites to help me understand the process, methods and technical aspects.



Some of the items that will be mounted to the firewall.




A partial list of electrical components installed in the engine compartment:
Primary Alternator: B&C 60amp BC460-H
Primary Voltage Regulator: B&C LR3C-14
Standby Alternator: B&C 20amp BC410-H
Standby Voltage Regulator: B&C SB1B-14
Standby Alternator Current Sensor: B&C SBK-14
ANL Current Limiter Base: B&C C903-3
40amp Current Limiter: B&C C904 40A
Ammeter Shunt: B&C S870-20
SureStart Ignition Booster: Champion Aerospace SS1001
Starter: Sky-Tec 12V
Battery: Odyssey PC680
Battery Contactor: B&C S701-1
Starter Contactor: B&C S702-1
Ground Block: B&C 24 Tab Forrest of Tabs
Hall Current Sensor: Grand Rapids Current Sensor
Misc.
Insulated Terminal Kit: B&C 1TK-1
Terminal Insulation Boots: B&C MS25171-2S
Ratcheting Crimping Tool: Meterk Tool
Lug Crimper: TEMCO Hammer Lug Crimper
Various Copper Eyelets: SELTERM UL Listed Lugs
Shrink Tubing: Dual Wall Adhesive Shrink Tubing
Wire Lacing: Breyden Lacing Tapes
Silicon Lined Ties: Grip Lock Ties



This is a poor picture of the P1 Plug. The left side with the white
wires is the female end and was prewired by Aerotronics. I ran
the wires to the right side and assembled the male end of the plug.
The two plug ends mate to create the connection from the (mostly)
firewall component to the instruments and switches on the panel.



Instead of mounting the current limiter and ammeter shunt to the firewall,
these were installed on a table behind the instrument panel on the
cabin side of the firewall.



Leads from the current limiter and ammeter shunt to the circuit breaker panel.






Battery contactor connections. 2AWG wire
to the starter. And 4AWG wire to the alternator.



Various connections including firewall penetrations, remote oil and
fuel sensors, battery contactor to starter contactor, etc.



Short run from the battery negative (2AWG) to the
24 tab airframe ground. 4AWG black wire from the ground
block to the engine ground. Ground block attaches
to a firewall mounting tab on the airframe.



The green donut surrounding the battery positive
is a hall current sensor from the battery



On the left; standby voltage regulator. On the right; SureStart Ignition Booster



EGT & CHT sensor wires above the standby voltage regulator.



I did not use any plain zip ties. All wires were grouped together with
polyester wire lacing. Wire groups were secured to engine mount
tubes with Grip Lock Ties



Wire lacing can be tedious and time consuming, but I think the outcome
is well worth the effort. It shows pride in workmanship, and I just like the way
it looks. Once you learn how to tie, it's actually pretty easy. Just tie
2 half hitches as shown here, pull tight, then lock it in with a
single square knot.



The panel was originally designed for a dual electronic ignition
system, therefore creating a need for two batteries and battery switches.
As I am now going with a dual magneto system, I eliminated one of the
switches, as seen here. This is good. If I every want to convert to dual
electronic ignition, my panel can accommodate.



Eliminated the hot bus for the dual EI.
Also installed a warning light for the standby alternator
which comes on if the primary alternator fails.



The aftermath

  Dec 13, 2019     The Air Induction System       Category: Engine

About a year ago Don Rivera, founder of Airflow Performance, hosted a Fuel Injection 101 course that I attended. I am using their fuel injection system on my IO-540. Don offered a perspective that stuck with me, ""Engines are just air pumps"". Good airflow entering the engine is just as important as a good exhaust system that can carry spent air out of the engine.


Below is the standard ""square"" air box on most Bearhawk's.


I set out to streamline the air induction system for my Bearhawk and create a round ram type inlet, like this.


My air induction begins with the Airflow Performance FM-150 fuel controller. Airflow Performance offers a 95 degree elbow from the bottom of the sump to the back of the controller. This allows the orientation of the controller to be altered from vertical to horizontal. A control cable bracket is also installed between the elbow and the sump. A direct connection between the elbow and the back of the controller creates a conflict with the cap screws and the sump.

I used washers to get an idea how thick of a spacer would be needed to push the controller forward in order to clear the sump.


Airflow Performance sent me a 3/8"" phenolic spacer.


I picked up this airbox from James Aircraft and began test fitting it between the front of the fuel controller and the bottom of the nose bowl.


The bottom of the airbox would need modified (squared off) to clear the bottom of the engine cowling.


I made a cradle for the bandsaw to make the cut.




Finished fiberglass over the cut area.
Also began a foam mold to form the back plate of the air box.


A cast of the fiberglass back plate over the foam mold.


Trimmed the filter to fit into the back plate.




Test fitting the modified airbox to the backing plate




Intake side of the airbox with the filter installed.


Next, it was time to install the aux air door.


Looking at the completed aux air door. A control cable will be attached to the steel arm at the bottom of the door.


I used a 3"" aluminum tube to connect the airbox the the lower nose bowl. Fiberglass was cast around the tube. A mold release was used to keep the glass from sticking to the tube.






View from the inside. The tube serves as a coupling.



The final version. Tube trimmed. Fiberglass built up and shaped with filler. There are two #6 flush head screws that are countersunk at 3 and 9 o'clock inside the tube. Nut plates were embedded in the fiberglass.


In this video I discuss the engine cowling, including my air induction system.

  Nov 27, 2019     Engine Cowling       Category: Engine

Time to install the engine cowling... When building the Bearhawk, there are two sets of manuals. The AviPro Aircraft ""Builder's Assistance Manual"" for the kit, and Eric Newton's ""Bearhawk Builder's Manual"" for scratch builders that was written in 2008. Both manuals discuss the design and installation almost identically. Eric Newton's scratch builders manual is a little more thorough on most everything, including the engine cowling. But both are referenced for varying aspects.



Completed view of the engine cowling and nose bowl installation.



The installation of the engine cowling begins with orienting the nose bowl to the back of the prop/spinner flange.


The goal is to establish a gap between the nose bowl and the prop/spinner flange of no more than 1/2"", and no less than 1/4"". I cut a 3/8"" sheet of plywood to use as a spacer. If I were to do it again, I would cut the spacer a bit larger than the diameter of the prop/spinner flange. I cut mine the same size as the flange and had to keep adjusting it.


The spacer is clamped to the flange. The top half of the nose bowl is temporarily attached (wood screwed) from the back of the nose bowl to the plywood spacer. I found the center of the nose bowl and used a digital level for true level.


Then the bottom of the nose bowl is clecoed to the top of the nose bowl. Now the basis for the rest of the engine cowling is established


I did not take pictures of the four 1 1/2"" x 3/4"" channels used as structural members for the engine cowling. However, I did discuss these on my YouTube Channel in this episode https://youtu.be/sKC-FsJj_Z4 (at the 2:10 minute mark)

The first section of the engine cowling is the top panel. This panel is .032 aluminum, the rest of the engine cowling will be .025. Notice the extruded hinge on both sides for the cowl doors.


Cutting the opening for access to the oil filler and dipstick


Access door. Still need to install the latch.


Using poster board to establish the size of the bottom cowl. The bottom cowl will be permanently affixed to the bottom of the nose bowl and the bottom two C channels and will become one piece to maintain structural integrity and for ease of assembly / disassembly.




Completed bottom cowling


Bottom Nose Bowl and Bottom Cowl are now one piece.


Using poster board to establish the cowl doors


Once the door panels were cut and attached to the top hinges, I used ratchet straps to snug in place for the final fitting.




I wanted a latching system for the doors that keeps the door nice and snug. I like these old school Piper cowling latches for their retro style and function. However, these are a little bit of a challenge to install. Not many resources or instructions are available. So I looked at many examples at Oshkosh and at local fly-ins.


The spoons used in Piper latches will be integrated into the C channels. I created a jig and practiced on a spare C channel.




Here you can see the cut out I made to accommodate the spoon portion of the latch


This is actually upside down, but this is what the installed version will look like.


Using the same jig to establish the mounting location


Holes drilled and material will be removed where the outlines have been drawn


Completed installation. What you don't see is the aluminum angle that is mounted to the inside of the door. That angle runs almost the entire length of the door to keep the panel rigid and creates the leverage needed to cinch the panel down.


Completed installation of the nose bowl and engine cowling. Very tight!

  Nov 20, 2019     Engine Baffling and Plenum       Category: Engine

After completing the baffling provided in the RV-10 Firewall Forward Kit, I installed the traditional Air Flow Fabric in order to seal the gap between engine cowling and the baffling. Ultimately I was not happy with all the seams, gaps and crevices with the Air Flow Fabric. Swiss cheese comes to mind. Yes, 99% of piston GA engines use a flexible fabric to seal and cool the engine, but I was intrigued with a few carbon fiber plenums I encountered. And considering IO-540's in tight Bearhawk engine cowlings are reported to run hot, I decided to take a stab at fabricating my own carbon fiber plenum.


The finished product...




With the Air Flow Fabric installed... that I later removed and replaced with a carbon fiber plenum.


Preparing to cast the plenum. Installed aluminum angles around the perimeter of the baffles to create a lip to attach the plenum. Removable panels will use Sky Bolt receptacles.


Poster board cut to size and secured with anti stick silicon release tape. The poster board was later coated with a PVA release agent and topped with a mold release wax.






Another poster board used to size and cut the carbon fiber. Three sheets total.


Masking tape around the perimeter keeps the CF from fraying.


Masking off the entire engine to protect it from the epoxy resin.


Three pre-cut CF sheets applied with epoxy resin between each sheet.




Insulated the gap between the aluminum angles and the plenum perimeter with high temperature felt, commonly used with BBQ grills. Sky Bolt receptacles were also installed.


Split the carbon fiber plenum into 4 integrated panels. The two outside panels allow quick access to the top spark plugs.


The finished product. I particularly like the two inlets that were boxed to direct air to the top of the cylinders (high pressure)

  Nov 13, 2019     Hanging the Engine       Category: Engine

Previously I discussed some difficulty with the engine bracket and isolators. Once resolved, the engine swung into place and was mounted in less than 20 minutes. Whew!















Next, I mounted the Hartzell prop governor.


Random pic of the custom Vetterman dual stainless steel exhaust. http://www.vettermanexhaust.com/ Clint Busenitz does a wonderful job building these exhaust systems specifically for the IO-540 Bearhawk.

  Nov 13, 2019     Boot Cowl       Category: Fuselage

I have two desired outcomes with the boot cowl.

1). To have access to the back of the instrument panel from the inside top, after the windscreen is installed. This will also allow the hinged panel to tilt rearward for greater access.

2). To have access at the sides of the boot cowl for access to rudder pedals, fuel lines, brake lines, etc.







An outline of the windscreen location provides the basis for the top access panel. Very nice mock up of the final version.







Lower Boot Cowl split to create an access panel. Installed a backing strip that I riveted to the top inside portion of the boot cowl, with nut plates on the bottom.



A view of the installed boot cowl from a distance.

  Aug 29, 2019     Engine Isolators - What a Debacle!       Category: Engine

(UPDATE 8/30/19... Several have asked and offered advise for installing the engine and isolators to the Type 2 bracket. I successfully completed the engine installation after consulting several certified engine service manuals on the same engine and Lord J-9613-12 isolators. All were consistent in detailing the sequence and that each AN-7 bolt should be fully torqued before moving to the next. This proved very effective made the installation a non event.)


It WAS a debacle... It's easy to describe the issue now after ""going to school"" on engine mounting brackets, engine case ears, isolators and isolator bolt lengths. But this whole experience was a huge time suck and slowed my build progress down more than I would have expected.


The following video describes the entire engine mounting situation and explains why it took so long to hang it... Get ready for an education on mounting an engine!







Lord Part# J-9613-12





In the following two pictures I am demonstrating the isolators in the wrong orientation. In the video I describe the correct orientation for these isolators.

  Aug 29, 2019     Gear Legs On ~ No More Rotisserie!       Category: Landing Gear

It's been a long summer and quite awhile since I updated my build blog... I had a business trip in June, family vacation to California in early July, then a week in Oshkosh at the end of July.


Now that the fuselage has been painted, it's time to get some legs under her. It is bitter sweet to remove the convenience of the rotisserie, but real progress to finally have the gear legs mounted. Finally starting to look like an airplane!

Each of the main gear struts is comprised of a cylinder containing a high compression spring and a capped shaft. The spring must be compressed into the cylinder, locked in place with a snap ring, then the cylinder is filled with ATV fluid. This creates the hydraulic dampening system for the Bearhawk landing gear.

In my opinion, the most underrated component on the entire Bearhawk line is the ingenious landing gear system. This gear is not ""springy"" and creates a sense of sticking to the runway on landings.


Following the Bearhawk Builder's Assistance Manual I installed the spring accordingly.





I used this 3/4"" impact socket to compress the spring into the cylinder. Piece of cake!



After the springs were installed and the snap ring was in place, I filled each cylinder with synthetic ATF fluid to complete the shock assembly.



Gear strut and gear leg connection. Brake caliper was installed immediately thereafter.



Adjustable rod ends connect the gear struts to the fuselage. Later, I will disassemble and adjust to 72"" tire center to tire center at normal flying weight, not to exceed 74"". I will replace the jam nuts with thinner AN-8's.



I borrowed a jig from another fellow Bearhawk builder to drill my cotter pin holes. The cotter pin prevents the wheel nut from backing off.

  May 20, 2019     Fuselage Fabric Covering, Fabric Filler, Prime & Paint       Category: Paint / Decals

I used the Stewart Systems fabric covering and waterborne paint products. And could not be happier! It took me about six weeks to cover and fully paint the fuselage.

I used the blanket method for covering the fuselage. I began on the bottom, then the sides, the vertical stabilizer, and finally the top. The transition from the leading edge of the V-Stab to the top was a little tricky, but again the Stewart Systems videos are exceptional for detailing the fabric covering and painting process. https://www.youtube.com/channel/UCrlV5GMsw4S6zTn9bzjFwkA

I was prepared to accept a marginal paint job considering my experience and conditions. So to say I am happy with the results would be an understatement. The top coat came out PERFECT!

I have to attribute much of the success of this paint job to the equipment I chose to use. Stewart Systems say that 95% of bad paint jobs come from poor or inappropriate equipment. So I selected everything they recommended including a high output air compressor that could keep up with long run times and maintain consistent pressure at the gun, high flow fittings and hoses, high performance air dryer, and a high performance HVLP paint gun with an inline pressure gauge.

I cannot say enough about the Stewart Systems for fabric and paint!



The Blanket Covering Method






Installing the Tapes


1 coat brushed and 3 coats sprayed EcoFill






Covering the Gear Legs






1 cross coat EcoPrime






Masking for 2 tone








1/4"" pin stripes were painted between the 2 tone. More difficult, but better looking.