Avcon Industries recently announced it has received FAA RVSM group approval for 20-series Learjets using a modification package that the company has been developing for the last two years.
Avcon has modified and flight tested a total of six 20-series Learjets equipped with the Avcon-developed components and JET FC-110 autopilots. The airplanes represent a range of Learjet 24s and 25s with approved wing configurations, including the Century III, Mark II, XR, SoftFlite and the original standard wing, according to the company.
Avcon is accepting orders for its RVSM package and reports it has open installation slots available through this November. The company has completed 11 installations so far and claims it has orders for another 50 booked or pending. The current retail price for the installed RVSM package is quoted as $156,975, in addition to the cost of required autopilot component inspections and repairs. The Avcon package requires between two and three weeks of downtime for structural and electrical modifications to replace the existing pitot and static system and to install the approved RVSM equipment.
“FAA group approval is a significant accomplishment for the Avcon team,” said Clark Stewart, CEO and president of Butler National Corp., Avcon’s parent. “The group approval demonstrates Avcon’s dedication to supporting classic aviation products and should significantly extend the useful life of the 20-series Learjets.”
Avcon president Larry Franke said the initial test airplanes “easily met” RVSM height-keeping requirements (±65 feet) for autopilot operation. The package developed by Avcon uses the Learjet 24/25’s original FC-110 autopilot, which must first be sent back to the manufacturer (now L-3 Avionics Systems) for bench testing and any needed modifications. The upgrade also adds an Innovative Solutions & Support autopilot interface unit and digital air-data units and altimeters and new Rosemount pitot probes.
According to FAA specifications, the autopilot must be able to maintain level flight in its “altitude hold” mode between FL290 and FL410. Due mainly to the slow sampling rate of the older autopilot, the FC-110 in some airplanes has had a hard time maintaining altitude to within 65 feet and has been known to porpoise under certain circumstances. Before the FAA would grant group approval status for the Learjet 24/25, Avcon had to show it solved this technological shortcoming.
There are about 500 Learjet 20-series aircraft in operation worldwide, many of them based in the U.S., where domestic RVSM will begin in the airspace from FL290 to FL410 next January 20.
Based in Newton, Kan., Avcon modifies business aircraft for special missions, including passenger-to-freighter conversions and aerial-photography equipment installations, and offers stability-enhancing airframe modifications for Learjet, Beechcraft, Cessna and Dassault airplanes.