Gross Weight Increase Approved for Sonex and Waiex!

Sonex is excited to announce the approval of a higher maximum gross weight for all Sonex and Waiex aircraft powered by engines of 100hp or greater. Following a series of engineering studies and flight tests, Sonex and Waiex owners may designate a max. gross weight of 1220 lbs. for aircraft with 100hp or more. This represents a 70 lb. increase vs. the previous 1150 lb. limit and is applicable to both A-Model (Legacy) and B-Model aircraft.

"We expect these changes to be very popular and greatly expand the appeal of the Sonex and Waiex to today’s homebuilder," said 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."

Owners of complete and flying Sonex and Waiex aircraft wishing to make this change can do so in-accordance with their individual aircraft’s operating limitations. Changing the gross weight constitutes a "major change," and would be handled in the same manner as any other major change to an Experimental Amateur Built aircraft (installing a different prop or engine, floats, etc.). The operating limitations issued to the aircraft will include a process for incorporating a major change. For most operating limitations issued in the past 20 years or more, this will involve contacting the FAA FSDO to get a flight test area approved, then moving the aircraft back into Phase 1 flight testing via an aircraft logbook entry. The owner/operator would then test the aircraft up to the new gross weight, document the new performance characteristics (stall speeds, climb and glide rates, CG compatibility, etc.) for a minimum of 5 hours. Once the flight testing is completed, the owner/operator would then make another logbook entry, per the guidance found in the operating limitations, to move the aircraft back into phase 2 normal operations.

It is very important to follow the guidance found in each specific aircraft’s operating limitations with regard to incorporating a major change. Operating limitations have changed somewhat over the years, so what works for one aircraft may not work for another. Each individual will have to follow the procedure outlined in their particular operating limitations.