Almanac: Engineering takes flight — Sibley’s Cessna modification makes plane Bush sense

By Jenny Neyman

Photos courtesy of Mike and Julie Sibley. Gerald “Sib” Sibley poses with a float plane. Sibley was an aircraft mechanic in North Kenai, pioneering a modification to Cessna 150s that made them more suitable for backcountry flying. He was a Bush pilot himself, taking frequent trips across Cook Inlet for fishing — as seen below — hunting and camping at his cabin on the Kustatan River.

Redoubt Reporter

There’s engineering, there’s skill, and then there’s physics. In aircraft mechanics, the first two can get an idea off the ground, but it’ll never soar without being grounded in the third.

That’s a lesson Gerald “Sib” Sibley knew well in creating his Cessna “tail-dragger” Bush plane modifications. The Kenai aviation mechanic wasn’t the only one to turn standard, nose-wheel Cessna 150s into planes better suited to taking off and landing in the backcountry, but he was the one to do it best.

“Some other outfits Outside did conversions to a tail wheel but they didn’t go off as good as the ones that Sib did. He had other ideas as far as the landing gear and how they needed to be configured, and he did them right,” said Warren Johnson, a longtime friend of Sibley’s, and owner of the hangar in North Kenai where Sibley operated his Peninsula Aircraft Service until he died in 2002.

Popularity of the tail-wheel planes in the 1980s was driven by economic and safety necessity. Prices for small, lightweight planes adapted to landings and takeoffs in all manner of off-airport conditions — beaches, gravel bars, mountain ridges and unimproved dirt strips — were rising along with interest in them. In Alaska, maintained airports were few and far between compared with all the villages, lodges, cabins, hunting and fishing grounds, and other destinations for Bush pilots.

“The other Bush planes were getting more and more expensive, and he realized the Cessna 150 was still a really affordable little airplane, so people were coming out with modifications to make them do better in the backwoods,” said Sibley’s son, Mike Sibley, of Kenai.

Just removing the nose wheel from a standard Cessna 150 and adding one to the tail was a modification that made the planes more versatile. That was a start, but Sibley knew there was further to go to improve performance and stability. He was a Bush pilot himself, having learned to fly in 1980. Before that he was a frequent passenger with friends on hunting and fishing trips into the backcountry. And as a mechanic, he was well versed in the toll Bush conditions could take on planes.

Merge that firsthand expertise with an incurable itch to tinker and you get Sibley’s approach to aviation engineering.

“He was a real good mechanic,” said Johnson, who knew Sibley for about 25 years and went to him for maintenance for his air taxi business — Kenai Float Plane Service. “He did what I needed — and that was more FAA-compatible, since I had to go by rules and regulations. But he liked getting into that experimental stuff, too. He was always pushing things kind of to the limit. He’d get an idea or some of our friends had ideas and he would run with it. He would keep making little changes and improving things.”

By the mid-1980s, Sibley had gotten nationwide notoriety for his tail-wheel Cessna 150 modification, which became known as the “Super Sibley” after an article was published in Plane and Pilot magazine in 1984.

Sibley’s modification decreased weight while increasing the plane’s power and stability. He removed the heavy nose wheel, moved the main wheels forward a couple feet and added a small tail wheel. He removed the factory-standard, 100-horsepower engine and put in a larger, 160-horse engine. Sibley also added longer propellers, larger fuel tanks and bigger, balloon tires.

“The weak point of a tricycle plane, which is a nose-wheel plane, is if you hit bumps with that front wheel your prop will go in the ground and you can bend the front fork really easy. It doesn’t do well in the soft sand and it doesn’t do well in the tundra,” Mike Sibley said. “So converting them to a tail-dragger does quite a few things — it lightens up the plane a little bit and it allows you to land and take off in a lot rougher conditions.”

Sibley converted and built 14 Cessna 150s, and they’re still going strong, even without the elder Sibley to look after them. Mike Sibley developed a hobby interest in airplane mechanics, especially working on his dad’s style of Cessna tail-draggers, and also doing plane painting.

Mike bought one of his dad’s Cessna 150s from his former flight instructor in 1995. He

Mike Sibley’s Cessna 150 was modified from a nose-wheel plane to a tail-dragger by his dad, Gerald Sibley.

flies it regularly with his group of pilot friends, primarily into the backcountry on the west side of Cook Inlet. One of his flying buddies, Bill Bryant, of Kenai, flies another of Sibley’s tail-dragger Cessna 150s, and used the elder Sibley as his mechanic. When Sibley died, Mike and Bryant started using Shawn Holly, of High Country Aviation, as their mechanic, and Holly quickly became another of their squadron of backcountry pilots.

“A lot of the planes that Shawn works on, he looks through the logbooks and sees my dad’s signature in there a lot. Dad used to take care of a lot of the planes around here. Bill was good friends with my dad, and Shawn got to know him, too, so it’s kinda neat to still have that connection,” Mike Sibley said.

The three recently participated in the Valdez May Day Fly-In and Air Show short takeoff and landing competition. They did well in the light touring division, with Holly taking first with his Cessna 170, beating Sibley in his dad’s Cessna 150 by a mere 3 feet. Bryant took fifth place.

Mike Sibley figures his dad would have been excited to see his planes in the competition, since it tests pilot skill and plane performance. The elder Sibley took both things seriously. Though he would tinker with modifications to expand the horizons of a plane’s capabilities, he had no use for pilots who purposefully pushed to the edge of those capabilities.

“These jerks that try to exceed the limits of the airplane are the ones that get killed,” Sibley was quoted in an Aug. 10, 1984, Peninsula Clarion article about the notoriety that came with the feature in Plane and Pilot magazine. “That and weather — flying in weather they’ve got no business being in — 90 percent of it’s just plain stupidity.”

Sibley didn’t have much patience for stupidity, but he could be counted on for help in just about any other situation. His sometimes-gruff exterior aside, he was a soft touch when it came to helping people out, Johnson said.

“He’s the type of person that would do anything for anybody, as far as give the shirt off his back to somebody if they needed it,” Johnson said. “He was just a roly-poly attitude, always in a good mood. Sometimes people would call him a grumpy old man. He would put that façade on every so often, but it wasn’t that he was. He was just all around a good person and easy to work with.”

Whether it was pulling a plane out of the bushes, patching up a busted part or tinkering with a new engineering idea, Sibley was often the one to which peninsula pilots turned, Johnson said.

“He was the type of person that he didn’t want to get rich off anything. If he made a buck he would put it into the next airplane,” Johnson said.

Sibley found all the riches he needed in his recreational pursuits, often hauling his friends, family and yellow Lab across Cook Inlet on his frequent hunting and fishing trips. The cabin he built on the Kustatan River was a common destination, one that still gets a lot of use by Mike and his friends.

“He wasn’t one that was doing a lot of going out and being with people around this area. He’d have a couple beers down at The Place or whatever, but that was all the mingling he did,” Johnson said. “He liked fishing and hunting, just being out of town. He’d get over there to his cabin for the solitude.”

Sibley was born Nov. 21, 1940, in Lansing, Mich. After spending 12 years in the U.S. Air Force he moved to Alaska in 1970 to pursue a career as an aircraft mechanic. He brought his family — then-wife, Joan, and sons Mark, Mike and Jim — first to Ketchikan, then Anchorage and finally to Kenai in 1975. He moved to Kenai to take a mechanic job but ended up starting his own business shortly after getting to town.

He quickly became a fixture in the aviation community. Mike remembers the short-field takeoff and landing competitions Sibley held on the Kenai beach south of Cannery Road. Sibley would put up a trophy and $500 in prize money to the pilot that managed the shortest takeoff and landing. The entry fee was $50 per try, with Sibley donating the proceeds to the Civil Air Patrol.

“It got really popular there for a while. It was a neat show,” Mike said. “Us kids would go out there and rake the sand and then they would leave tracks in the fresh sand and we could tell how far they landed or took off; we’d just measure the tracks, then erase them every time. It worked really well.”

Sibley held the competition for four or five years, Mike said, and later tried to start up another one in North Kenai but the popularity didn’t quite catch on. Mike remembers the beach competition getting fierce at times.

“There was a lady, Patty Chadwick, she was about 89 pounds dripping wet. She was a great pilot and she would beat all those guys because she was so small and light,” Mike said. “And they would throw all the money in the world in the hat trying to beat her and they never could. If I remember right, one year she took off in like 21 feet, and they could never beat that. That’s just physics.”

Sibley was found dead Jan. 4, 2002, in Johnson’s aircraft hangar, where Sibley ran his maintenance shop and lived in an apartment upstairs. It’s still classified as an unsolved murder. Mike said they figure Sibley overheard a burglar in the shop, came downstairs, surprised the thief and was killed. He was 61. Some tools were found missing, but no suspects have been charged. Johnson and Mike said they both still hope there’s a resolution to the case.

“He left behind a lot of buddies and memories. Everybody was really shocked because he did everybody favors all the time. He didn’t have any enemies. It was quite a tragedy,” Mike said.

“I hope that the powers that be one of these days comes up with some final answers,” Johnson said. “He was an excellent mechanic and a good pilot, and just a darn good person.”

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