Bell Helicopter Textron’s vision for a brand-new line of rotorcraft known as the modular affordable product line (MAPL) has sharpened further now that a powerplant design advertised to meet its lofty efficiency requirement is appearing on the horizon. Studies under way at Honeywell show that a family of engines using technology incorporated into the HTS900 turboshaft, developed to power a high-performance variant of the Bell 407 known as the 407X, could meet Bell’s call for 20-percent lower operating costs in the MAPL line. Scheduled for certification in the second quarter of 2006, a low-speed, 6137-rpm version of the HTS900 began running last November. Bell planned to deliver the first ground-test engine to Bell this month.

“[The HTS900] is by no means the last example of investment in this market by Honeywell,” said the company’s Engines Systems & Service division vice president of propulsion, Barry Eccleston, who specifically identified the Bell MAPL project as potentially the next application for the engine.

Bell envisions three size variants for MAPL: the first, a five-passenger, single-engine 351; the second, an eight-passenger single called the 381; and finally, a twin-engine, eight-passenger variant dubbed the 382, expected to borrow much of the technology used on the new IFR-rated 429, scheduled to fly in about two years.

Bell hopes to bring all three MAPL variants to market by 2012. Designed to fill a gap between helicopters in the size range of the Robinson R44 and Bell’s own 206, the MAPL machines would cost between $500,000 and $1 million. Finding that customers overwhelmingly base their buying decisions on price, Bell intends to pursue a modular design, theoretically keeping manufacturing costs in check by using the same components on the various models.

While using basically the same systems architecture used on the still-in-production LTS101, Honeywell’s HTS900 will incorporate new compressor technology for improved performance, giving it more than 925 shp at takeoff on a standard day at sea level, according to Bob Miller, head of Honeywell’s light utility helicopter engines unit. Miller said the engine will burn 3- to 6-percent less fuel than any of its earlier engines while generating 42-percent more power at ISA+35 deg C.

Equipped with dual-channel FADEC, the engine also includes a next-generation impeller and new cooled gas producer and shroud assembly designed to deliver more power and at least 15,000 component cycle lives. Honeywell targets place TBO at 3,000 hours, a mark Miller said he expects to rise to 5,000 hours once the product matures.

Miller estimated that the engine would yield 48 percent lower DOCs per shaft horsepower than the original LTS101, introduced in 1975. The HTS900 will come in both the 6137-rpm version and a 9,598-rpm version for either single or twin-engine applications.

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