AOPA 172 Sweepstakes: Fire in the belly

Today’s owners can get more speed, range, and power out of their Skyhawks by installing an STCed engine upgrade. That’s what we’ve done for your AOPA Sweepstakes 172. The 160-horsepower engine is gone, replaced by a new 180-horsepower O-360 provided by Lycoming. The 172XP STC kit was provided by Air Plains Services of Wellington, Kansas, which has been selling and installing engine and airframe modifications since 1977.

“We’ve probably sold 2,600 [kits] in the years since we’ve had the STC,” said Carolyn Kelley. Her husband, Mike, founded the company; Carolyn runs the office, manages the finances, and handles sales and inquiries. In addition to the 172XP STC, Air Plains offers STC kits for the Cessna 180, 182, and 182RG, each of which pumps up the performance to 300 horsepower.

The technicians at Yingling Aircraft in Wichita installed the airplane’s kit. Air Plains dispatched its mechanics to install the engine baffles. Air Plains builds new air boxes in its manufacturing shop, and each kit also includes new baffles and powder coating with baffle seals.

Air Plains installs about a quarter of the kits it sells. When installed by Air Plains, labor is about 70 hours, including flying three hours to break in the new engine, weighing the airplane, and completion of the paperwork associated with the STC.

The remaining 75 percent of conversion kits are shipped throughout the world. “In 2011 we sold almost 30 to 40 of the 172 conversions” to Australia, Carolyn Kelley said. “We have it in places you’ve never heard of—a tiny island above New Guinea called Palau. We have them all over Europe, and we have some of our conversions in Tanzania, South Africa, South America, lots in Canada, and Costa Rica.” Air Plains sells 20 to 40 172 STCs each year.

Hutchinson Aerospace and Industry provided the engine isolator mounts that will keep the sweepstakes airplane’s engine secure and cut down on vibrations. Hutchinson acquired Barry Controls in 2000; you may be more familiar with the term “Barry mounts,” as many still call them.

Hartzell Engine Technologies donated the Skytec starter and Plane-Power alternator included in the kit. “We use those on all our upgrades, because they have a two-year warranty,” Kelley said.

The engine comes with a new Sensenich propeller and a gross weight increase STC. That supplemental type certificate can only be sold to customers who have purchased the horsepower STC from Air Plains. For model years 1963 through 1968, it’s a 200-pound gross weight increase; for later model years, it’s 250 pounds.

We sought out a Concorde battery for your sweepstakes airplane, and the company obliged with a donation. The sealed acid batteries have a reputation for long life and good value.

There’s a lot more going on under the cowling, but you’ll have to wait until a future issue of AOPA Pilot to find out the details. Here’s a hint: greater fuel economy and less maintenance.

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