Persistence and teamwork enabled Honeywell Aerospace to reach an inspection interval milestone for LTS101-850B-2 turboshaft engines used in MBB/Kawasaki (Eurocopter) BK 117-850D2 high-performance multirole helicopters. The extension increases the timeframe between mandatory engine inspections from 1,800 flight hours to 2,400.
Although the cost of this mandatory maintenance won’t change under the expansion program, increasing the time between engine inspections allows operators to spend their money less frequently, which helps to reduce costs in the long run.
When engines don’t require inspection as often, the helicopters also spend less time on the ground and more time in the air, which is an additional bonus for operators.
It wasn’t an easy feat to achieve. Doug Kult, product line director, Commercial Helicopter Engines at Honeywell said validation of the longer inspection interval took about 18 months to complete.
“We submitted a plan to the U.S. Federal Aviation Administration (FAA) through our designated engineering representatives and earmarked engines from different companies as they came due for their next inspection,” he added.
Honeywell engineering and product development teams thoroughly inspected LTS101 engines from BK 117Ds flown by Pacific Helicopters in Papua, New Guinea, as well as Helicopters Otago and Auckland Rescue in New Zealand. This provided a representative cross-section of engines operating in a variety of challenging environments, from utility work to search-and-rescue operations.
Three global maintenance providers — Airwork in New Zealand, Germany’s Motorflug and Intermountain Turbine Services in the United States — provided valuable engine service and installation on Honeywell’s behalf. After validating that critical engine components could support the longer inspection interval, Honeywell teams “pushed hard,” Kult said, to earn official FAA approval.
More than 440 BK 117s were built before production ended in 2004. The expanded inspection interval currently applies to the BK 117D, an upgraded variant featuring twin Honeywell LTS101-850B-2 engines, which offer improved performance and higher safety margins over BK 117s equipped with earlier LTS101 variants.
“It’s an extremely popular upgrade, with more than 55 out of approximately 180 earlier BK 117 ‘B’ models converted to the higher ‘D’ specification,” Kult said. “We look forward to keeping these helicopters flying for years to come.”
FAA validation may also be submitted for approval of the extended inspection interval by other global aviation authorities, such as EASA in Europe, and Honeywell is exploring similar interval extensions for other LTS101 variants.