Sonex boosts gross weights

The change, driven in part by expected expansion of the light sport category under pending Modernization of Special Airworthiness Certification rules, follows a series of analyses and flight tests. The new weight limit applies to earlier A-Model aircraft as well as the more recent Sonex-B and Waiex-B.

“We expect these changes to be very popular and greatly expand the appeal of the Sonex and Waiex to today’s homebuilder,” wrote Sonex owner and President Mark Schaible. “Due to the aerobatic load limit capability of the two aircraft models and the impending MOSAIC changes to the Light Sport Aircraft rules, we took the opportunity to study this change to our specifications. We are pleased to report that stall speed testing has proven the aircraft still qualify for Sport Pilots to fly under the existing rules.”

Flight testing thus far has included aircraft powered by 100-horsepower AeroVee Turbo and Rotax 912 engines. Sonex listed performance specifications for the 120-horsepower Jabiru 3300 engine with the new weight limit, including a cruise speed of 170 mph, but noted they are estimates. The company is awaiting flight test results from customers who are using the Jabiru.

Sonex and Waiex owners who are currently flying their aircraft and want to make the change to a higher maximum weight can do so by adhering to the operating limitations of their aircraft. Because a change in gross weight is considered a major change, owners would have to go through the standard process for experimental amateur-built aircraft. The specifics of the process are included in each aircraft’s operating limitations.

In most cases, the company said, aircraft owners would have to work with an FAA flight standards district office for approval of a flight testing area. The owner can move the aircraft into flight testing status with a logbook entry, complete the necessary testing, document new performance data, and return the airplane to normal operation with another logbook entry.

Sonex noted that changes to its aircraft over time necessitate specific testing procedures for each model. “Operating limitations have changed somewhat over the years, so what works for one aircraft may not work for another,” the company said. “Each individual will have to follow the procedure outlined in their particular operating limitations.”