On July 17th, 2019, Cessna revealed it was putting plans for its upcoming Hemisphere large business jet on hold, saying that it was doing so because of on going issues with the Safran Silvercrest engines that were due to power it.
CEO of Cessna’s parent company Textron Aviation Scott Donnelly said:… we determine that the engine has not yet demonstrated the performance required for the aircraft design and we have put the programme on hold”..
The Hemisphere was intended to be Cessna’s largest business jet. It was designed to be a wide cabin business jet that could carry up to 12 passengers. The maximum range was due to be 4,500nm.
Problems with the Silvercrest engines that should have powered the Hemisphere first surfaced in 2016, as air wasn’t flowing through the engines in the originally expected way. This was eventually traced to the axial-centrifugal high-pressure [HP] compressor, and Safran said that it would test a fix for the issue in the summer of 2019.
The company says that the redesign of the new compressor was frozen in June 2018, with the parts sent to production during the summer of that year. The compressor was rebuilt early in 2019, with testing beginning in April.
Those ground tests were completed in June, with Safran saying that the results exceeded expectations.
However, the firm does also state that the full performance of the engine hasn’t been demonstrated yet but plans to do so later in the year.
But the further performance testing seems to fall in line with its own schedule, which it outlined in 2018. “Within the framework of the development approach that we defined with Textron and Netjets in 2018, we were committed to validate this year the operability of the HP compressor through rig tests that have been completed in June in line with the timetable agreed with our customers,” says Safran. “On this matter, the results of the ground test which was completed per schedule in June have exceeded expectations.”
Despite Safran apparently sticking to the timetable it agreed, Cessna still felt that it had a way to go before proving the engine would work to its originally announced specifications.
But it is not ruling out the engine completely. During the announcement that the Hemisphere would-be put-on hold, Donnelly said the aircraft could be revisited in future, but that would depend upon “the state of the market, proven engine performance and a competitive landscape at that time.”
For Safran’s part, it promises to keep Cessna updated on the progress of the Silvercrest, saying that the next stage of tests on the new HP compressor are planned that will further confirm improvements, and complete the overall engine performance and durability validation.
“We will continue to update Textron on the product completion thus providing them with an opportunity for a reassessment of the situation,” says Safran.