It's cold. An arctic blast brought freezing temperatures overnight and it's just 7 a.m. now. Brrr! I've just met Greg Trzaska of Aero AT-USA at his home airport of Northampton (7B2), Mass. We stand shivering, warming our innards with the coffee and doughnuts my host has brought.
It's a clear, sharp, Northeastern winter's blue-sky day, and a great day to fly. Trzaska is one of five U.S. dealers for the Aero AT-4. If you don't recognize the handle, does the name Gobosh G-700S ring a bell? That's the cute, lively, low-wing flivver I first flew five years ago.
Back then, the G-700S was repped by Dave Graham and Tim Baldwin. They held a respectable market share with 26 sold in the U.S. by December 2010. Then, as with so many aviation enterprises, Gobosh succumbed to the EconoCollapse and by 2011 was no more.
Fastforward to early 2012: Three Denver entrepreneurs invested in a new import and sales enterprise to keep the G-700S—rebadged as Aero AT-4—healthy and happy in U.S. skies, and with a reduced base price of $105,000.
That's good news for Gobosh owners and flight schools, too, because the AT-4 is, literally, a born trainer as well as a comfortable medium-range cruiser.
The Aero AT-4, formerly the Gobosh G-700S, is the S-LSA version of the AT-3 in Poland. It has an increased wingspan, added winglets and a modified airfoil.
Beyond Skin Deep
The AT-4 is decidedly sporty with its sexy upturned winglets, big, one-piece bubble canopy, jaunty swept tail and wide, rugged tricycle gear. The interior serves up attractive, very comfortable leather seats and a roomy instrument panel. Greg Trzaska's pretty white demo is fitted with dual-screen Garmin G3X avionics. The G3X, introduced a few years back as a robust electronic flight instrument system (EFIS) for light-sport aircraft (LSA) and experimental owners, is a quality draw, all on its own.
The G3X crams a ton of functionality into its two seven-inch screens: synthetic vision with 3-D "pathways," the EIS, engine monitoring, built-in GPS, Air Data Attitude and Heading Reference System (ADAHRS), autopilot integration and, on Trzaska's demo, traffic alerts and XM satellite weather and radio.
The AT-4 is the special light-sport aircraft (S-LSA) version of the popular AT-3 offering from Aero Ltd. of Poland. Established in 1994, it was the first in its country, and sixth in the world, to certify an airplane to Europe's new JAR-VLA certification standard. After that came an European Aviation Safety Agency Certification Specification for Very Light Aircraft (EASA CS-VLA) Type C Certificate in 2005, and full Federal Aviation Administration (FAA) certification in 2010.
To conform to the lower stall speed requirement of the LSA spec, Aero increased the wingspan and wing area, modified the airfoil and added winglets and a larger elevator. As with many LSA, the AT-4 is built overseas, shipped in component parts, then assembled, rigged and test-flown in America.
Greg Trzaska handles those duties as well as providing expert liaison with the factory for an owner's needs, from replacement parts to troubleshooting to requesting an LOA (Letter of Authorization, see sidebar) for maintenance, mods or upgrades such as oil heaters or a special instrument panel. The responsive company even custom-cuts holes in instrument panels to customer wishes. Since he speaks Polish fluently, Trzaska is a natural to bridge the gap.
Veteran pilots appreciate airplanes built with tried-and-true general aviation (GA) techniques. The AT-4 is a quality entry in that vein: The all-metal airframe features a semi-stressed skin, with fairings and cowlings of carbon/kevlar composites. GA-standard anodizing and hardware cadmium plating throughout ensure lifelong corrosion protection, and the airframe is built using solid rivets.
The robust spring steel landing gear was chosen to deflect the slings and arrows of outrageous student flying and rough-turf grass strip ops common to club and flight schools in Europe.
All three wheels have attractive streamline fairings that augment the clean, stylish looks. The mains have dual brake calipers for brake redundancy. If the pilot brake system fails, the right-seater can save the day.
The nosewheel, full castering, is well set up and works like a treat with differential braking (when gingerly applied!) through the rudder toe pedals. I pulled a surprisingly tight 180-degree turn effortlessly on the narrow taxiway at Northampton—it truly turns on a dime. Taxiing with differential braking takes very little time to get comfy with, and just a couple seconds after adding power, that big, bird- feathers-like swept tail gives you rudder control, anyway. But, I'm getting a bit ahead of myself.
You Can Go Home Again
I enjoyed flying the Gobosh version with Dave Graham. He had described its handling characteristics as "lively," and that was right on. But, after those years away from its comfortable cockpit, I wondered: Would my initial impressions, 30-some LSA demos later, hold up? Would it still feel as comfortable, responsive and forgiving?
To find out, Mike Kuehlmuss, a German-born airframe and power plant mechanic (A&P) and certificated, chief flight instructor (CFI) for Northampton Aeronautics, took on the demo for me in Greg Trzaska's lovely new AT-4.
We warm up the 100 hp Rotax 912 ULS engine in that frigid air, but since there's an oil heater, reaching the customary 122 degrees takes surprisingly very little time. The engine vibes feel very smooth. Maybe the carbon/composite three-blade ELPROP has something to do with that.
I had remembered the 41-inch wide cabin to be a bit roomier, then Kuehlmuss tells me this particular version has a raised sidewall to accommodate Greg Trzaska's tall frame. Even so, we're dressed in bulky winter parkas and it's plenty comfortable.
The seats and rudder pedals aren't adjustable as on some LSA. Back and seat cushions are used to fit various-size pilots to the very comfy seats. Some nice features as we warm up: The dual throttle gives the PIC a left- or right-hand stick option. The console-mounted right throttle has an effective friction lock.
Keeping the Garmin G3X company are analog airspeed and altimeter, readout lights (fuel pump, canopy open, etc.), a compact Garmin SL40 radio and GTX 330 transponder, and PS Engineering PM 3000 intercom. There's an ELT on board, toggle switches, cabin heat and other knobs, all neatly organized. The center console sports an easy-reach handle for the split flaps and the pitch trim wheel falls nicely under your right hand.
Kuehlmuss lets me make the first takeoff. We surge down the asphalt strip. Rudder comes to life almost immediately and before I expect it, the AT-4 hops into the air. "More rudder," my host advises—this bird likes a lot of right foot on climbout.
The nosewheel shudders, although the airframe dies down quickly as we settle into a 60-knot best rate (Vx) climb. The G3X shows a respectable 750 fpm rate. Book for best rate is 856 fpm, which should be easily doable.
My first return-to-cockpit impression: "very comfortable, stable, well-balanced airplane." The rudder is firm but effective; turn forces are also a bit firmer than I had remembered, but the wing responds briskly to input. Roll rate is good; this is no truck. I crank a couple 45-degree bank reversals, then feel right at home with several Dutch rolls which aren't half bad.
First-impression verdict: The AT-4 has the same friendly chops as the G700S. Roll control forces, though a bit firmer than I remembered are equivalent to other top-line LSA, such as the CTLSi.
We shoot a couple of landings. In my customary fashion, I turn final too high because I'm afflicted with inherent glide ratio pessimism. Curse those hang glider landing memories! A strong slip with flaps easily takes care of the excess altitude. Over the fence in the low 50- knot regime, as Kuehlmuss instructs, feels just right, and before I know it, I'm easing back the stick to touch down.
The AT-4 floats nicely through rotation. Roll forces are lighter than at cruise as we bleed off airspeed into the 40s. The wing, flaps and winglets help hold on to the lift near the stall. The wheels find the runway without dropping out and we settle on, almost as if I knew what I was doing.
What a sweet bird for training! It's a comfortable cruiser, too: immune from inadvertent, ham-handed overcorrections near the stall, yet able to handle bumpy weather fine at cruise since the feel stiffens up a bit at the 105 to 110 knot-max cruise I saw during our flight.
And the view? Terrific with that bubble canopy and low-ish nose angle, which makes it a snap to take in the terrain above the cowl straight ahead.
A couple more landings prove the airplane's all-around good manners and forgiving personality. We pull stalls and it's a non-event: mush mush mush, lower the nose a touch and you're back flying.
Rudder is required in turns to counter slight adverse yaw but it's not what I'd call a rudder ship. Just a little push as you roll in and you're in Fat City. Unlike some LSA such as the CTLS, powered- back descents don't require left foot to keep yaw at bay.
My favorite features: The trim wheel is so easy to work. It's geared so effectively that very little movements take you right to the trim you want, while giving you good touch feedback. On some LSA, electric trim is so sensitive, trimming becomes a "chase the sweet spot" chore.
I also like where everything's placed, from pedals to stick to panel switches to (positive-locking) canopy latch. The AT-4 is refined, well-thought-out and enjoyable. And the G3X display: beautiful.
The airplane is stable in slow flight. You get a stall warning beep in the low 40s but you have to work to stall —another great training feature. You can mess up pretty badly and it won't bite you.
A lot of air vents with controllability for airflow make for good cooling potential on hot days. There's night lighting for GA missions, with dimmers. Nice. Kuehlmuss tells me he tapes off some of the cowl inlets when it's really cold so the engine doesn't suffer during descents.
The flap handle is a little stiff if you try to bring it in at top-of-flap-regime airspeeds. Slow things down and all's fine. After our final landing, we roll onto the grass for some photos. I appreciate how well the spring gear soaks up the bumps.
Quick wrap-up: The Aero AT-4 is a quality-made, durable S-LSA that deserves your consideration if you're in the market for a reasonably-priced, all-around friendly airplane.
Its decent useful load of 485 to 540 pounds (depending on equipment), means with full fuel (111 pounds) it's somewhat limited at 370 to 439 pounds, but for training ops in particular, and a moderate cruise mission profile, it's a workable range. And, Greg Trzaska notes, there's an optional 14.5 gallon external fuel tank for longer flights, although that further lowers useful load. The takeaway: AT-4 remains one of my top 10 friendliest, fun-flying S-LSA. hard helping somebody.
What Is An LOA?
|One cool and progressive thing about the Special Light-Sport Aircraft (S-LSA) category is how owners and mechanics can make major upgrades, repairs and alterations to their aircraft. These can include changes such as oil heaters, modified wing tips and changing the wheel to a different size. The key to making sure it all stays kosher with the FAA is the Letter Of Authorization (LOA).
Here's a quick tour of how it's done, as laid out by ASTM, (American Society for Testing and Materials), the independent body that establishes standards of airworthiness for LSA:
Any major repair, alteration, or maintenance refers to those for which instructions to complete the task are excluded from the maintenance manual(s) supplied to the consumer.
Minor repairs, alterations, or maintenance are those which are provided for in the maintenance manual(s).
The manufacturer must identify in writing the instructions for the modification, who is authorized to perform it, and that person's level of certification.
The manufacturer must provide directions to accomplish the task, detailed instructions and diagrams, methodology to test/inspect for proper completion, and an affidavit stating the modification, repair or alteration will not change the aircraft flight characteristics and applicable ASTM design and performance specifications.
The instructions must include ground and flight testing that complies with the original ASTM production acceptance testing standard, as appropriate, to verify the alteration was performed correctly and the aircraft is safe to operate.
Major repairs and alterations may only be accomplished on S-LSA by a light-sport aircraft repairman with a maintenance rating, a certificated mechanic with A&P ratings, or a certificated repair station.
The manufacturer must provide the level of certification required to perform the task and the technical data for such a repair or alteration and identify the training required, if any, to perform that repair or alteration.