The Beaver and the Swans
How de Havilland's famous bushplane has helped protect a species.
- By James Wynbrandt
- Air & Space magazine, July 2006
(Page 2 of 3)
The swans’ anti-camo plumage is a great help to the census-takers. Occasionally a flash of brilliant white will warrant a closer look, usually to reveal itself as a bit of wind-whipped lake foam, sunlight reflecting off a rock, even a sun-bleached moose rack. But for the most part the adult swans are unmistakable and hard to miss, whether on a cobalt-blue alpine lake or nesting in the green reeds encircling a glacial pond.
The survey is alternately exhilarating and monotonous. In high-density areas, where it seems every one of the endless lakes has at least a pair, the project has the feel of a cattle roundup, as we cut and wheel one way, then another. But in some USGS quadrants, the terrain in the 15-mile square is unchanging and devoid of trumpeters, and an hour or two without a swan is enervating and mildly depressing, no matter how magnificent the scenery.
Fish and Wildlife Service crews and aircraft typically operate in remote areas, and sometimes eddying rivers, small lakes, or unimproved strips are their only airports. In this roadless environment, the air crews have adapted strategies ranging from packing extensive survival gear aboard to modifying both airframe and powerplant. The queen of the modified fleet is N754, the one-of-a-kind de Havilland DH2 Beaver that Conant flies.
N754 was modified in 1976, when Jerry Lawhorn, then the aviation manager of the Fish and Wildlife Service’s Alaska region office, worked with Volpar Inc. of Van Nuys, California, to customize the aircraft for aerial surveys. On one of the many days last August when we couldn’t fly because of low ceilings, Conant and I dropped in on Lawhorn at his home in Anchorage. A picture of N754 hung on the wall opposite the front door. In the living room, Lawhorn joked about the oxygen canister he had to carry around, referring to his “range between refueling.” Settling into a couch below a pair of bighorn sheep trophies, Lawhorn recalled spending hours riding along with survey pilots and watching how they operate so that he could explain to Volpar exactly what he needed for counting critters from the air. Lawhorn was no stranger to aircraft design. A pioneer in bush operations, he had designed and built his own airplane shortly after arriving in Alaska in the late 1940s.
For wildlife surveys, Lawhorn needed an aircraft that was simple to operate and had superb forward visibility. Most turbine-powered Beavers use a Pratt & Whitney PT-6 engine, but that engine’s exhaust stacks, exiting from the side, interfere with an observer’s view. Volpar had been converting Grumman Gooses from piston engines to 715-shaft-horsepower Garrett 331-2UA-203D turbines. Hoping for a military contract to do the same for de Havilland Beavers, the company was happy to work with Lawhorn to make a single example of what it hoped to produce in large numbers. Lawhorn was interested in the Garrett engine because its exhaust exits from the bottom and doesn’t interfere with the pilot’s visibility. That engine is what gives N754 its distinctive needle-nose nacelle. Except for narrow frame posts, the windshield provides unobstructed front-to-side observing. And on the instrument panel, switches, power levers, and handles have been repositioned for simplicity of operation.
“It had to be biologist-proof,” Lawhorn
said. Every Fish and Wildlife Service pilot-biologist has a baccalaureate in biological sciences, a minimum of 500 hours of flight time, and an instrument rating. Beyond that, some come with more experience in biology than in aviation.
An aircraft that has been as highly modified as N754—different engine, panel layout, and avionics from those aircraft holding the Beaver’s type certificate—would ordinarily have to go through a series of certification tests to win approval from the Federal Aviation Administration. But the airplanes that fly the aerial surveys come under the purview of the Department of the Interior, and they fly with waivers from the department’s Office of Aircraft Services.