Plane & Pilot
Tuesday, July 29, 2014

20 Things You Never Knew About Your Airplane (Or Someone Else’s)

A few little known thoughts. Ever heard of the Cessna 620? Why T-tails? A Seneca Tri-Motor?

6 Back in the decade surrounding the 1980s, T-tails became something of a trend. Piper embraced T-tails big time, mounting them on their Cheyenne III and IV, Arrow, Lance, Seminole and Tomahawk. Beech adopted them on the Duchess and Skipper, and Bellanca featured a T-tail on its short-lived Aries T-250. Trouble was/is, T-tails aren't ideally suited to all airplanes. Mounting the horizontal stabilizer high on top of the vertical tail can create as many problems as it solves. T-tails typically demand a beefier empennage structure, but can allow the elevator to fly in undisturbed air at low speeds and high angles of attack. On some models, a high tail simply doesn't have the pitch authority it needs, and takeoff and landing distances are extended. Sure enough, Piper reverted to a conventional tail on the Arrow and Lance/Saratoga, and Beech dropped the Duchess and Skipper altogether.

7 Owners of manual-gear Mooneys tend to be fanatical about their compact, little speed demons. It's a fact that the bicep-powered, Johnson-bar, Mooney- gear systems were among the fastest in the industry. A really competent pilot of a 1965 or earlier M20 could lever the wheels into the wells so fast, an outside onlooker could be fooled into thinking the gear had simply disappeared. With the benefit of gravity, extension was even faster. In fact, the Mooney's manual retraction mechanism was the only one certified by the FAA without a backup extension system. Perhaps ironically, Mooney abolished the manual gear system because it was too hard to get up, not down. Back in the '60s, some lightweight pilots complained that manual retraction was simply too physically demanding, and Mooney was forced to switch to an all-electric system that still managed three seconds up and two seconds down—still the fastest in general aviation.

8 Whatever your opinion of the V-tail Bonanza in-flight tail failures, the mechanics of the failures have long since become well known. The last failure occurred in Northern California in April 2002, but the vast majority of the 200-plus accidents have been intimately dissected and analyzed. The FAA finally addressed the problem head-on in 1986 and determined that the leading edge of the ruddervaters was failing when subjected to high loads. The V-tail's leading edge wasn't attached to the fuselage, so any significant load could cause the forward rudder to fail and deflect, precipitating failure of the entire tail and loss of the airplane. The major cause of the accidents that resulted was exactly what made the Bonanza such a wonderful airplane to fly—the delightfully light control response, far superior to that of most airplanes of the time. The answer was a simple cuff to anchor the leading edge to the aft fuselage, so it couldn't deflect with high G-loads.

9 Aerostars were almost universally regarded as the fastest piston production airplanes with any number of engines. Designer Ted Smith was nothing if not eccentric, however. His ultimate piston twin reflected his quirks. Practically everything on the Aerostar was electric, including the fuel selectors. The airplane was fitted with three fuel tanks, 62 gallons in each wing and 41.5 gallons in a fuselage tank mounted in the forward section of the baggage compartment. The fuel selectors had three positions—on, off and crossfeed—and like everything else, they were electrically powered. Turn on the master, flip the selectors to on and you'd hear the telltale "wooo" of the selectors as the valves opened. This would allow the airplane to feed fuel from the center tank to both engines by head pressure. When the center tank reached the same level as the wing tanks, fuel would begin feeding from the wing tank to its respective engine, and the center tank would continue to feed both engines. Problems arose if you were running on double crossfeed and had a total electrical failure. That shut the center tank out of the system completely. If you couldn't get the fuel system back to the normal "On" position, that 41.5 gallons became unavailable. That's why the flight manual had a large red warning in the fuel system section that read, "DO NOT RUN ON DOUBLE CROSSFEED."

10 Just as the relative merits of high wing/low wing have been argued for years, pilots continue to disagree about the benefits of wood versus metal in light-aircraft construction. Wing integrity has been heavily debated between the all-metal and wood wing crowd. Wood wing proponents argue that wood has no memory and therefore doesn't "remember" past overstresses, whereas aluminum can only be stressed so many times before it fails. No less an authority than the late Scott Crossfield, aeronautical engineer, designer and X-15 test pilot with more rocket time than anyone else back in the 1950s, agreed wholeheartedly. "The wing on the Bellanca Viking was built of Sitka spruce, and it was practically indestructible when properly maintained. Wood makes a better surface for shaping airfoils because it may be perfectly contoured to the desired airfoil section without screws, rivets, butt skin lines or other interruptions. Wood airplanes do demand to be kept inside, but they're worth it."


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