About the Author:
James R. Chiles trained in a two-seater helicopter as part of his research for this book. His first book, Inviting Disaster, was named a Best Book of 2001 by Amazon.com and was made into a four-part series for the History Channel. He lives in Minnesota.
Excerpt. © Reprinted by permission. All rights reserved.:
Chapter One
Preflight
Of all birds, winged mammals, and insects, very few have mastered the skill of pausing in midair and going backward as well as forward, so anything capable of such flight is, ipso facto, a rare beast. The ruby-throated hummingbird, which can hover with sewing-machine-like precision and also fly more than 500 miles across the Gulf of Mexico without a rest, is one such improbability. Helicopters are another unlikelihood. Explaining how the parts work together to do the unlikely is best approached by treating the helicopter as terra incognita, exploring it from the headland of its cabin to the archipelago of its tail boom.
This particular helicopter is white, and composed mostly of high-strength steel and aluminum. It is thirty-one feet long and seats two people, typically a wary instructor on the left and a trainee on the right, but it is also suitable for aerial photography and other daily errands. Anyone renting a Schweizer 300 CBi for weekend travel will be traveling lightly, because there is no trunk for baggage. I required a formal introduction to the Schweizer, because I would be flying one. The instructor I secured from Hummingbird Aviation, John Lancaster, had been a professional skiing instructor for twenty years in Vail, Colorado. Skiing injuries and a love of flight prompted him to seek out a new, and statistically safer, profession. He learned to fly helicopters in Florida at the world's largest privately run helicopter school1 and came to Minnesota to share his knowledge. Typical students were those planning to fly for police departments, tourist outfits, or offshore oil companies. He favored shorts and sport shirts and, before getting down to business, displayed the cheery demeanor of a camp counselor. But he also had nearly a thousand hours of helicopter time and we were both mindful that I was not here to interview him; he was now my instructor. As when dealing with any rookie, his first job was to explain important parts of the ship.
Lancaster began my first lesson in the flight-school office by picking up a black-and-white toy police helicopter from a shelf and explaining basic principles of flight. Then he sold me a set of pilot books out of a glass showcase that looked to have been bought from a going-out-of-business sale at a jewelry store.
The helicopter he would train me to fly is of recent vintage but a lineal descendant of a 1956 model invented by the Aircraft Division of Hughes Tool. Beginning in 1964, the army used a military version called the TH-55 Osage* to drive thousands of new pilots through eighty hours of basic flying at Fort Wolters, Texas. The TH-55 was a light piston-engine helicopter and cost much less than a turbine-powered model to operate.
This session lasted an hour and was devoted to a four-page inspection checklist. It required a close look at every side of this helicopter, including the underside. It was so thorough that we might as well have been hunting for a small bomb that someone has tucked away on the aircraft. With this guidance, Lancaster said, I would know how to check out the machine for my own flights. It seemed to this novice that the whole machine is so small and so open to view that it can be taken in with a quick glance followed by a nod or a frown, but this is considered bad form.
Still, an open-minded, undistracted glance from thirty feet away is not a bad way to begin a preflight, Lancaster said. Sometimes it reveals immediately that something is out of whack, or missing, and a mechanic can be summoned sooner rather than later. We folded our arms and took it in, top to bottom. For all the publicity about helicopters black and deadly, this ranked no more than a "1" on the intimidation scale. It has the look of a dragonfly carrying saddlebags, which in this case are twin fuel tanks. It also doesn't look radically more elaborate than a car, so I had to wonder why it costs a quarter-million dollars if purchased new. With an instructor, each hour in the air costs $300 in rental fees. Since helicopter pilots need to fly regularly to stay on top of their skills, winning the license is comparable to buying a fancy boat: the initial expenditure is steep and leads to still more spending.
The Schweizer sits on tubular landing skids that hold it high off the ground, giving it a poised and alert look. Above the cabin is an elaborate-looking hub gripping three airfoils that droop slightly. Each airfoil is a "rotor blade," taken together they make a "rotor." The extreme engineering challenges that are posed by spinning such large weights atop a hovering aircraft came as a complete surprise to the early inventors. When in operation the rotor rotates nearly eight times every second. Unlike airplane wings, which have a more generous curve on the upper side than the lower side, the cross-section of each rotor blade at the end is nearly symmetrical.
Pointing to the rear is a slender, tubular tail boom with a second set of rotor blades at the end, much smaller than the big blades on the main rotor. The tail rotor looks like an afterthought, but it is a technological survivor despite many attempts by helicopter innovators to get rid of it. The tail rotor's side-thrust overcomes the powerful twisting force that would result if a helicopter had only one rotor atop its fuselage and nothing to oppose it.* Single-propeller airplanes would also have a torque problem were it not for the fact that their wings have enough leverage in flight to keep the comparatively small propeller under control.
Lancaster closed in to work the checklist. He squatted to point out the engine and its associated parts, nestled in a stout tubular frame under the cabin. It's an aircraft engine, built for dependability and costing much more than a car engine. It burns eleven gallons of aviation gasoline per hour.2 We drained a pint of blue fuel into a plastic jar, checked for water that could kill the engine, then poured it back into the gas tank. Lancaster rapped on the tank, starting high to low, stopping when the sound changed from boom to thump. This verified the actual fuel level. He warned me not to place all my faith in the fuel gauge inside the cabin.
Of all the mistakes helicopter pilots can make, leaving the ground with too little gas for the trip is among the most embarrassing and avoidable. Despite the early freewheeling style of helicoptrians of the 1950s, who felt they could land about anywhere, today it is not acceptable to plan on refilling at a convenience store. That leaves mostly airports, except for the very few cities in the nation offering public heliports. A modified helicopters have flown for six hours or more, but more typical is two to three hours of operation on a full tank.
We peered into the cabin to make sure the fire extinguisher and paperwork were where they belonged. The view of the outside world is impressive from the pilot's seat, which in helicopters is on the right side of the cabin. The reason is that most pilots are right-handed and this arrangement allows these pilots to control the cyclic lever, which requires the most finesse, with their favored hand. In many conventional airplanes the pilot's visibility is narrow, comparable to looking out from a foxhole with a low roof, but not so with helicopters. The control panel and instruments are kept to a minimum so they all can be packed onto a pedestal in the center. Everything else within sight is a plastic bubble or just open air, since pilots prefer to fly without doors whenever the weather permits. The seat belts are comparable to those in race cars.
Lancaster prompted me to check the engine oil, the transmission bolts, the emergency transmitter, the door hinges, and even the welds in the landing gear. We lit up the beacons and wiped the housings with rags. We wiggled cables, belts, rods, and ball joints. We looked at a frame holding the belts for the transmission; Lancaster recalled a case from the National Transportation Safety Board files where that frame broke and killed the pilot. Unlike gasoline-powered airplanes, where the propeller is bolted directly to the crankshaft, all helicopters must have reduction gears so that the rotor turns only a tenth as fast (or even less) as the engine. The reason is that slow-turning rotors are more efficient than fast rotors.*
"Reading through the NTSB cases makes for an instructive evening," said Lancaster, "but it can dampen your enthusiasm."
We proceeded along the tail boom to the rear of the aircraft. Lancaster stopped for a lengthy discussion about the health and well-being of the tail rotor, which from our first glance at a distance looked to be little more than a set of striped lawn-mower blades. It's not, said Lancaster. There are little rods and bearings that allow the tail-rotor blades to change their angle a little, or a lot, as the pilot steps on the tail-rotor pedals. It has its own gearbox and oil supply.
The tail assembly is so delicate and essential to flight that pilots have to order passengers to be mindful of anything that wind might scour from the cabin, in flight, when the doors are off. Murphy's Law dictates that the slipstream will carry any such object straight into the tail rotor rather than allow it to tumble ineffectually to the ground. While there are verifiable wartime stories of Huey pilots who slashed through branches, even four-inch limbs, with their main rotors on the way down to a landing zone, no sane pilot would plan on chopping or even brushing anything lightly with the tail rotor.
Now fully two pages into the checklist, we reversed course and worked back toward the nose, along the right side of the helicopter. Lancaster pointed out a little window built into the tail boom and prodded it with a finger. It's there for inspection of the tail-rotor driveshaft dampers. These are doughnut-shaped bearings that keep the tail-rotor driveshaft from wobbling, which was one of many problems to vex early helicopters. This brings up a principle applying to helicopter components and he...
"About this title" may belong to another edition of this title.