Piper PA-46 Malibu and Mirage Engine Conversion

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92 • APRIL 1994 PHOTOGRAPHY BY ALTON K. MARSH AND BARRY GROSS and some of those were very lean pro- duction years-Piper Aircraft's PA-46 Malibu already has undergone one significant round of factory modifica- tions. This was when Piper switched from a 310-horsepower Continental TSlO-520-BE engine to a 350-hp Lycoming TIO-540-AE2A, cleaned up the instrument panel, and freshened the interior design. The re-engined Malibu was renamed the Mirage. The Mirage is faster but at the expense of higher fuel consumption and greater empty weight. Now the aftermarket is eying the pre-Mirage Malibu. Not surprisingly, power and speed are the focus-tur- bine power (Piper tried it), liquid- cooled power (RAM wants to do it), and just plain more power. Henry Van Kesteren, a longtime fixed-base operator who now has a modification shop at Albert Whitted Municipal Air- port in St. Petersburg, Florida, has opted for the latter approach. His Continental TSIO-550C-powered Malibu conversion has been approved by the Federal Aviation Administration under a supplemental type certificate, and he has sold and delivered the first example, the air- plane you see pictured here. Van Kesteren has taken a middle- of-the-road approach with his con- version, achieving something that has the performance characteristics of both the Malibu and the Mirage. The twin-turbocharged, twin-inter- cooled 550C engine is rated at 350 hp, but in Van Kesteren's Malibu conver- sion, it is manifold pressure limited to 310 hp, the same as the 520-BE engine it replaces. Maximum power in a standard 520-powered Malibu is achieved at 38 inches manifold pres- sure and 2,600 rpm. The 550 delivers the same 310 hp at 35.5 inches and 2,600 rpm. If the larger engine is limited to the same maximum power output as the one it replaces, what then is the advantage of the conversion? The answer lies in the percentages. The 550 achieves its 310 hp at about 88.6 percent of maximum rated power. At 310 hp, the 520 is delivering every- thing it's got-100 percent. Reduce power to 75 percent for cruise, and with a 520, you'll have 232 horses pulling for you. The 550 delivers 262 hp at 75-percent power. The bottom line: Even with the 310-hp limitation, there's more usable horsepower available from the 550. Because there is no such thing as a free power lunch, the bill for the 550's extra punch is in fuel consumption. It takes fuel to produce power and more fuel to produce more power. At the same percentage of power, the 550 consumes about 24 percent more fuel than the 520. That affects endurance and range. Of course, with the 550 you have the option of reducing power to achieve the same horsepower and fuel flow as a 520, thereby preserving orig- inal endurance and range perfor- mance. In fact, it's likely that the 550 is a bit more efficient than the 520 given its "volumetric efficiency" and other esoteric features understood only by people gifted with internal combustion insight. But why buy more power if you're not going to use it? The 550 Malibu likely will be flown the same as a Mirage: Bump up the •Even with the 310-hp limitation, there's more usable horsepower available from the 550. throttle to a go-fast setting on shorter trips when endurance or range are not concerns, and go for lower power settings and lower fuel consumption on those continent-crossing trips. The differences between the 550 and 520 are all internal. The 550 has a longer piston stroke and thus a differ- ent crankshaft and piston skirts, and it uses a single-stage engine-driven fuel pump rather than the more expensive two-stage pump on the 520. Like the 520, the 550 has dual alternators and vacuum pumps and a 2,000-hour time between overhauls. The 5.5-psi pressurization differential is unchanged with the conversion. Engine dimensions, weight, and con- figuration (where the accessories are mounted) are the same, so it's a rela- tively easy conversion to perform. No changes are required to the cowling, and weight and balance is unaffected. The manifold pressure gauge is altered to reflect the lower maximum limit of 35.5 inches. Van Kesteren's first 550 conversion is a 1985 Malibu. The previous owner, AOPA PILOT • 93 94 • APRIL 1994 Larry Lee, flew it in the 1992 around- the-world air race and also installed some new interior appointments developed by his company, Plastek, including attractive Mirage-style pull- down window shades. Van Kesteren bought the airplane after it was involved in a minor land- ing accident. He repaired the damage (a collapsed gear), performed the engine conversion, and installed Spoilers, Incorporated's hydraulically actuated spoilers in the wings. The air- plane has been sold to Lyle Kallis, a contractor in Red Deer, Alberta, Cana- da, near Calgary. Kallis and a friend, along with Van Kesteren, stopped by AOPA in Frederick, Maryland, on their way back to Canada to give us an opportunity to fly the airplane. No question, a Malibu is beautiful in almost every respect. It stands higher and wider than any other sin- gle on the ramp and many twins, as well. Its big-airplane character is accentuated by the airstair door and the fact that you pass through the passenger cabin-albeit hunched over-to get to the cockpit. The Malibu's attributes-cruise performance, pressurization, the long and wide cabin, and its commanding presence-are responsible for its resurgence in the used airplane mar- ket. After the rash of Malibu/Mirage in-flight structural failures between May 1989 and March 1991 and the National Transportation Safety Board / FAA investigation that fol- lowed, used Malibus dropped as much as $50,000 each in value. How- ever, the federal investigation did not find fault with the airplane's struc- ture, and today, prices for used Mal- ibus are back almost to normal levels.