New systems added to re-engining conversion as developer prepares for certification

Spirit Wing Aviation is developing a glass-cockpit upgrade and autopilot to augment its re-engined Learjet 20 series conversion, and plans to offer the feature within 18 months.

The new systems will be available as follow-on additions to the baseline package, which is centred on replacing the aircraft's original General Electric CJ601s with the Williams FJ44-2C turbofan. The retrofit is set to be certificated by April 2005, pending successful completion of US Federal Aviation Administration flight tests of the baseline SpiritLear conversion that are now getting under way, says company president Calvin Burgess.

These tests follow the completion of extensive company flights that cleared a flutter problem encountered during the earlier stages. "We had problems along the way with flutter, and we found we had to rebalance the tail to stop an oscillation," says Burgess. Following the balance changes, all traces of the issue have disappeared, he adds, and "we've had it out to Mach 0.87 and it's been as smooth as glass".

The re-engining relocates the engine further aft by about 0.5m (1.6ft) compared with the CJ601 installation, reducing the local shockwave and associated drag. Although internal fuel volume is actually reduced because of the need to comply with rotorburst certification requirements, the improved engine and aerodynamic efficiency results in a 22% lower fuel burn and a 70% increase in range. With full reserves, this results in a range of 3,300km (1,785nm) with four passengers.

Spirit Wing has also announced an RVSM (reduced vertical separation minimum) upgrade, available independently or as part of the re-engining package. The upgrade will be available through three newly appointed conversion locations at West Star Aviation in Colorado, Banyan Aviation Services in Florida and General Dynamics Flight and Aerospace Research in New York.



Source: Flight International