Source: 2014 Q2 Beartracks, Jared Yates
On a recent visit to Alaska, I had the good fortune of meeting up with Dan Shilling at Merrill Field in Anchorage. Dan graciously spent a few hours showing me his airplane and talking about how he built it, and how he uses it in Alaska.

Dan built his Bearhawk from scratch, over 8 years and 3300 hours of build time. As of now it has around 260 hours of flight time spread over 6 years. Dan was born in Alaska and is a minister by trade, and has always been interested in flying. He took his first lessons while living in Colorado early in his career. When he built his Bearhawk, one of his first priorities was minimizing his out of pocket expense. This explains why he was able to have about half as much money invested in his project as I do, but also about twice as much build time. It seems as though the cost and time variables are often interchangeable, a relationship that conveniently allows a builder to chose his priorities and proceed accordingly.
Dan shares a trait that I have found in many Bearhawk builders that I have met: he’s an excellent scrounger and seems to get a thrill from bargain hunting. For example, here is the story of how he got his spinner. “I scrounged the spinner for free off of a wrecked Maule. The spinner is the only thing that remains from that Maule. It had wrecked on a beach landing, and it was being sling lifted out of the area by helicopter. It was a pretty heavy load for the helicopter being used, and a bad gust of wind got hold of the plane and was about to cause a second crash when the helo pilot punched it loose into the ocean. I don’t know why the spinner had been removed since it was also damaged, but it now is a modified BH spinner. I hammered and hammered on that bent up thing to straighten it out.” Anyone can call up Aircraft Spruce and order a spinner, but how many folks can tell a story like that?
From the firewall back, Dan’s Bearhawk is much like the others that I have seen. He used the Polyfiber covering process with Polytone on the fabric and Aerothane on the rest. In Alaska, hangar space is practically unobtainable, so his airplane sits outside all year. I couldn’t help but note the unfortunate irony that the majority of airplanes in Alaska are not hangared, even though the weather and exposure there are about as bad as they could be anywhere. He installs wing covers in the winter, though they are a little bit tricky to get over the vortex generators. The condition of his finish speaks to the durability of the Polyfiber system; while it is not perfect, I thought Dan’s was one of the better looking birds on the ramp.
Notable deviations from plans include straight-bottom front doors (no mouse doors) and a skylight. The front doors don’t open quite as wide as those with a mouse door, but as he points out, they open plenty wide enough for him to get in and out of the airplane. Dan also incorporated a lever-actuated elevator trim system that is similar to the Patrol, though the lever points forward instead of to the side. By choosing this arrangement, he was able to eliminate the hump in the center of the fuselage and use a single, flat piece of plastic for the skylight. He added a hoop of metal to the top of the flap handle that makes it much easier to reach when the flaps are fully retracted. Dan’s tailwheel assembly and spring are right off of a Cessna 180, or as Dan said, “Right off of that Cessna 180 parked right there.” Don’t be concerned, the owner of the 180 was involved in that decision. After all, Dan is a minister, remember?
On the 180 the bolts that clamp the tailwheel to the stinger had worked loose and enlarged the holes (see the safety update in this issue for a similar concern on the Bearhawk). Dan drilled the holes to the next bolt size up and the setup works great, though he’d like to consider upgrading to a wider tire for soft ground operations. The smaller tire tends to plow in those conditions, and while a wider tire is available, it also requires a wider fork, which is an expensive upgrade.
On the day of our visit, Dan did not have the back seat installed. Since he usually flies solo or with one other passenger, he prefers to not carry around the extra weight of the seat. He keeps a survival kit and minimal camping gear in the back, and has had to stop for an impromptu overnight on at least one occasion. Dan uses his Bearhawk mostly for local flights around his part of Alaska, though he also uses it to visit is parents in a fairly remote area near Fairbanks. A trip that would require 10 hours of rough driving only takes a little more than two hours in his Bearhawk.
I was also impressed with Dan’s creative flight control lock. Control locks are certainly not something to take lightly– they should be designed well to mitigate the possibility of trying to fly with them installed. But for an airplane that sits outside all the time, they are a necessity. He uses large diameter (12 inches or so) externally-mounted padded disks to lock the flaps and rudder in place, but for the elevator and ailerons he devised a lock that clamps the control stick to the long carry-through tube that goes under the front seats. He said that if he were to do it again, he would change the design from its current pivoting arrangement. As it is now, he must remove the pivot pin for flight, since he’s concerned about interference in the full-aft stick position. He also realizes the very remote possibility that inflight turbulence could allow the lock to swing up into place and engage. His improved design would be to incorporate the same type of fitting on the rear two corners of the triangle that he used on the front of this one.
So what about the engine? Auto engine conversions are a polarizing topic in the homebuilding community. They often present an initially appealing price that can easily be overshadowed by a much longer build time and complicated research and development phase. Engines are the sort of thing that are designed for a specific use, and the designers of car engines certainly don’t have small airplanes in mind as they make design choices that balance power, weight, longevity, maintainability, fuel economy, and ease of mass production. It is not uncommon to hear about a builder who has started with an auto conversion and eventually replaced it with a Lycoming or Continental.
Someone must not have told Dan all of that, because his engine looks like it was supposed to be there, and it has been working great for the last 260 hours. When I asked him why he chose the Subaru over the Lycoming, he said that he was interested in minimizing cost, and that he was interested in the challenge of doing something different. He started with a junkyard engine, though he eventually replaced the junkyard engine with a newly-rebuilt engine of the same type. The cost of the rebuilt engine was on the order of $3500. It sits “backwards” compared to how it would sit in the car, with the belt-driven accessories on the back end. The new front end is connected to a New-Zealand made Autoflight PSRU that gears the prop down to about half of the engine RPM. The intake is on the top end, and he made a custom aluminum manifold that saved considerable weight and bulk over the original. The car exhaust manifolds were cast iron, so he removed those and fabricated a pair of muffled 3-into-1 pipes out of mild steel. The radiator sits parallel to the white engine mount tube in the right side of the picture, and he had it custom-made for this application. An oil cooler sits just in front of the radiator, with the small blue lines connected to it. The prop is a 3-blade 80-inch Ivo that has electrically-adjustable pitch. I looked at the prop hub and raised an eyebrow when he told me this, since the blades are clamped rigidly to the hub. It turns out that instead of rotating a rigid blade assembly like the Hartzell does, the Ivo contains a spanwise rod that warps the prop blade to change the pitch.

Dan doesn’t have any way to know exactly how much horsepower he is getting out of the Subaru. He knows that his static thrust is around the same as a Lycoming O360 Bearhawk, but that’s at full throttle and around 4400 of the 5400 static RPM that the engine could safely produce. This is an issue that he’s still tinkering with, and his next step will be to try trimming the prop blades to lighten the load on the engine and allow it to turn up to a higher RPM. Static thrust only tells part of the story anyway, so short of comparing climb rates, cruise speeds, and takeoff rolls, it’s hard to say exactly how the Subaru is performing. It is getting the airplane around Alaska just fine, which is certainly worth something. From my discussion with Dan, it sounds like his flight performance is on par with what I see in my 360-powered Bearhawk, though he notes that his firewall-forward weight is probably more comparable to a 540.
From the pilot’s perspective, operating the Subaru is a little bit different. For example, when Dan checks his oil level before each flight, he also checks his coolant level. In the cockpit, there is only one lever, which controls the throttle. The prop control is a three position switch just under the VSI. The left bank of switches includes an electrical master and two electric fuel pumps. This is certainly an electrically-dependent airplane, and Dan has designed the electrical architecture accordingly. He has two PC680 batteries under the front pilot seats. If his alternator quits working, he immediately gets active notification in the cockpit by means of a loud buzzer and flashing light. At that point he has around 45 minutes to find a place to land. The two electric fuel pumps deliver about 60 PSI for the injection system, which is controlled electronically by a system used in other aviation and racing applications. That system also controls ignition and ignition timing. The panel includes an extra gauge or two, such as coolant temperature and fuel mixture. The rheostat to the right of the prop switch is a mixture control that provides sort of a “trim” function to the computer.
Just to the right of the rheostat you can see the horizontal LED bar that shows the mixture condition. We prepared the airplane to fly, and I was impressed with Dan’s passenger briefing. He pointed out the location of his survival gear, a reminder of his prudent preparation for the remote areas that he flies over. So by now you must be thinking, how does it fly? I can’t tell you that, because we didn’t have a chance to fly it. Dan did start it up on the ground and ran it for a few minutes. It started readily, and ran very smoothly. The coolant flow is thermostatically controlled, so it comes up to temperature quickly.
Throttle response was very fast with the lightweight prop. We didn’t get to fly because the winds were very gusty and variable. Dan seemed very motivated to take me for a ride, but I was impressed to see that in spite of that motivation, he decided to stay on the ground when he realized how strong the winds were on the ATIS broadcast. I strive to live by the old adage “the superior pilot uses his superior judgment to avoid situations that demonstrate his superior skill.” In this regard Dan is certainly a superior pilot, and I suppose that one doesn’t fly for very long in a place like Alaska without having good judgment and respect for environmental conditions beyond his control.
I asked Dan about the reliability of his engine, since that has been one of the talking points in the argument against auto conversions. He recalled two situations where he had to land prematurely, but in both cases he was able to get the airplane safely on the ground at an airport. In one case he had a coolant line break soon after takeoff. His more-experienced pilot friend Mark (owner of the aforementioned Cessna 180) was at the controls during the early test hours and as the line broke he could smell the leaking coolant. He stayed in the traffic pattern and landed without incident. After finding the broken radiator hose, Dan recalled that he had probably scored the hose during fabrication. The second premature landing was a case of bad fuel. This manifested itself as a partial loss of power and a rough running engine, but Dan still had enough engine power to make it back to land. Honestly it seems to me like these sorts of problems can just as readily happen to any airplane, and I don’t think it would be fair to say that Dan’s powerplant has been any less reliable than a Lycoming or Continental.
In closing I would say that Dan has an excellent machine that fits his mission. While the auto engine added a year to his build, it also yielded a firewall-forward cost around $9,000, not counting the subsequent replacement engine. His airplane shows the flexibility of the Bearhawk, and how it allows builders to prioritize cost and effort to find just the right balance for each individual case. Auto engines are certainly not for everyone, but neither is scratch building! If you find yourself in Alaska, I’d suggest contacting Dan to try to get together for a visit. He’s an interesting fellow and loves to talk about the airplane that he has every reason to be proud of.