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AS350: Bringing the LTS101 Back to the AStar

By James T. McKenna | June 1, 2007
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»Bringing the LTS101 Back to the AStar

Exasperation among AS350 operators with Turbomeca’s support of the aircraft’s powerplants drove Honeywell Aerospace and Soloy LLC to partner in bringing the LTS101 back to the AStar.

Soloy got into the AS350 power business in 1990, when it bought the AS350 AllStar supplemental type certificate developed by Rocky Mountain Helicopters to retrofit the Allison (now Rolls-Royce) 250-C30 on the light single in place of Turbomeca’s Arriel or Lycoming’s LTS101.


The LTS101-powered AStars, marketed primarily in North America, developed a bad reputation due to reliability problems with the Lycoming. Among the aggravated operators was Elling Halvorson of Grand Canyon Helicopters, who reportedly once swore never to touch an LTS101 again after he was afflicted with its early problems. Halvorson ironically became an owner of Soloy at a time when that company was expanding its pursuit of the AS350 power market and Honeywell, which had bought the LTS101 line from Lycoming, was fielding much more reliable versions of that engine.

Soloy and Honeywell partnered on development of an STC to install the LTS101-700D-2 on AS350B2s and take back business from Turbomeca, whose Arriel 1D1 powers most AStars. Eurocopter also partnered on that project. Aircraft modified in that way are dubbed the AS350SD2.

The STC followed an 18-month development program. The partners say the LTS101-700D-2 upgrade gives the modified AStar a 14-percent increase in sea-level standard-day takeoff power (with an 18-percent gain in hot-and-high conditions), compared with Soloy’s previous conversion, which installed a LTS101-600A-3A in the AS350B2.

Honeywell designed the LTS101-700D-2 to the same power level as the Arriel 1D1, but with improved specific fuel consumption and reliability. Honeywell officials said the engine’s gains come from the use of a new, cooled gas-producer turbine that ups gas producer disk life from 6,500 to 15,000 cycles, and an updated reduction gear that has proved its performance in other LTS101 models.

Soloy also offers the AS350 Super D mod developed by Eagle Helicopters. Based on the original AS350D, it puts the Honeywell LTS101-600A-3A on the AS350D and AS350B. It uses all original Eurocopter AS350D parts and components.

Soloy’s AS350SD1 is based on the original AS350BA and also uses the LTS101-600A-3A. The advantage of the SD1 over the Super D, Soloy said, is the use of its own, exclusive drive train components, which support a future upgrade to the SD2 with minimal impact to configuration.

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