Everyman's Airplane

Skyhawk Mods and Ends

May 1, 1992

BY MARC E. COOK

That the world's most popular civil airplane should have a slew of modifications ought to surprise no one. Part of man's quest for identity has to do with personal expression, which becomes even more of a factor when one happens to own the most common airplane.

STOL kits

Avcon Conversions, Incorporated (telephone 800/872-0988), offers a leading- edge cuff kit for $649 that includes drooped fiberglass wing tips and aileron and flap-gap seals for $200 plus installation.

Bush Conversions of Udall, Kansas (telephone 800/752-0748), provides a STOL kit for the 172 that includes a recontoured leading edge for $800 plus installation. Flap-gap and aileron seals are also available for $240. Both Avcon and Bush claim better low-speed handling and slower approach speeds with the STOL kits.

Horton, Incorporated's (telephone 800/835-2051) STOL kit is comprised of a cambered leading-edge cuff, a pair of stall fences on the upper surface of the wing, and a pair of drooped wing tips. In addition, aileron and flap- gap seals are installed. The company claims an improvement in low-speed handling and the potential of reducing approach speeds by as much as 16 knots. Prices start at just under $1,500 for the installed kit. The modification is available for most model years of the 172. Flap and aileron kits are available separately for less than $500 installed or $230 in kit form.

The Robertson STOL kit is now being sold by Uvalde Flight Center (telephone 512/278-4481); the kit includes a modified leading-edge cuff, stall fences, and drooped ailerons, in addition to a handful of other aerodynamic tweaks, and is said to provide the 172 with tremendous short-field capabilities. Installed, the system costs a hefty $6,200 for later model (1973 and on) 172s that already have the Cessna leading-edge droop; for earlier models, the price is $7,500.

Tailwheel conversions

In addition to the STOL kits, both Avcon and Bush Conversions can help you take your 172 from tricycle gear to a taildragger. This involved kit includes a new tailwheel assembly, reworked landing-gear box structure, and tailcone beef-ups. Both companies claim better soft- and rough-field performance, as well as slightly improved climb and cruise for the modification. Avcon's kit runs $2,795, and Bush's lists for $2,250 to $3,200, depending upon which model 172 you're starting with. Count on $2,000 or so for installation labor for either kit.

Another source for the tailwheel Skyhawk is ACT (Aircraft Conversion Technologies, Incorporated [telephone 916/645-3264]), in Lincoln, California. Available for the 172A through 172P models, the conversion runs about $8,200 installed or $3,200 in kit form. The company claims an 8- to 10-knot cruise- speed increase and a 100-fpm-better climb.

Engine conversions

Certainly one way to get better cruise and climb from the 172 is the old fashioned way: Add more horsepower. After all, Cessna did it several times in the 172's lifetime — the Powermatic versions (175 hp), the so-called Reims Rocket (210 hp), the Hawk XP (195 hp, upgradable to 210), and the Cutlass (180 hp in both fixed-gear and retractable forms). The aftermarket has picked up on this formula of more is better, and two basic types of power-upgrade kits can be found — one that essentially replicates the Cutlass, and another, principally for older 172s, that swaps out the Continental O-300 or Lycoming O-320 for a Lycoming, O-360 and a constant-speed R propeller.

Air Plains Services of Wellington, Kansas (telephone 316/326-8904), will happily swap your O-320 for the 180-hp engine and Sensenich propeller for $18,500, which includes a factory-new powerplant. If you don't have that kind of clout, you might want to buy just the kit for $3,495 and hunt out your own O-360; this choice includes all the paperwork and hardware and propeller for the conversion. Among the advantages of the additional 20 or 30 hp, according to Air Plains, is a 13- to 16-knot cruise-speed increase, 300- to 400-fpm- better climb, and a gross weight increase of 200 to 250 pounds.

(Another modification offered by Air Plains allows owners of 1977 to 1980 Skyhawks to swap out the camshaft-and-lifter-eating O-320-H2AD engine for a -D2J model. This kit runs $750.)

Avcon Conversions has both constant-speed prop and fixed-pitch versions of the 180-hp upgrade available for all models of the 172. Prices range from $1,500 to $2,600 for the kit, and installation time falls in the 20 to 55 man-hour range, depending upon airframe model and engine choice. Although the constant-speed-propeller version of the kit can be $2,000 to $3,000 more expensive (because of the propeller, governor, and related hardware), Avcon says it will outperform the fixed-pitch retrofit across the board. Along with the engine swap comes a maximum gross weight increase of 150 to 200 pounds, depending upon the model.

Bush Conversions modification will allow you to add the 180-hp engine to most models of 172; some of the swaps allow use of a constant-speed prop while others use a fixed-pitch prop. Conversion kits range from $1,100 to $2,850. Gross weight increases are also available.

Penn Yan Aero Services of Penn Yan, New York (telephone 315/535-2333), also provides a 180-hp upgrade for the Lycoming-powered Skyhawks. This modification, which can be purchased installed or in kit form, runs $16,200 to $19,300 installed with a factory-new engine and your old motor in exchange; the price difference takes into account the lower value of the -H2AD engine core.

As with Air Plains, Penn Yan can swap out that -H2AD engine for a new 160-hp -D2J or -D3J variant, for $16,000 exchange, and will trade the 150-hp O-320 for a 160-hp version for an installed price of $11,000 to $14,000, depending upon the model.

Fuel systems

Of course with the extra horsepower available for the 172, it makes good sense to increase the stock airplane's fuel capacity. (It's not a bad idea even for the unmodified airplanes.)

Aircraft Conversion Technologies can add as much as 7 gallons to each of the 172's main tanks; kit price is $1,795 uninstalled, exchange, or $1,995 outright.

Flint Aero, Incorporated (telephone 619/448-1551), offers 12-gallon wing tanks for the 172 that use electric pumps to move the extra fuel into the existing main tanks. The basic kit starts at $2,900 and is installed in the outer wing panels.

Air Plains Services will install the aforementioned Flint tanks in your airplane for approximately $4,200.

O&N Aircraft Modifications (telephone 717/945-3769) has an 18-gallon baggage compartment tank for the 172F through 172P models. The kit alone costs $1,350, or you can have O&N perform the installation for a total price of $2,150; the company says it can install the tank in one to two days.

Speed kits

You don't have to add horsepower to a Skyhawk to make it more fleet than the average bird, because there are several companies that provide kits whose sole purpose in life is to make the aerodynamically dowdy 172 a bit slicker. (In addition, the aileron and flap-gap seals by the companies listed above in the STOL category are said to boost cruise and climb slightly.)

Aircraft Speed Mods, Limited (telephone 919/354-6630), though specializing in the Cardinal, offers airframe slick-ups for the 172. (The following modifications are also available through C2 Enterprises [telephone 701/727-9554].) In addition to providing fiberglass replicas of late-model Cessna wheelpants, the company sells brake fairings and will soon introduce a nosewheel-pant mod called Fancy Pants. Other go-fast tidbits like ADF loop and fuel-drain fairings are available. Prices start at $12 each for the drain fairings and run up to $225 per wheelpant and to $517 for the Fancy Pants kit. The exact performance gains vary by individual airplane; gains of up to 16 knots over a stock airplane sans wheelpants are possible, according to the company.

Maple Leaf Aviation of Brandon, Manitoba, Canada (telephone 204/728- 7618), also sells aerodynamic kits for the 172, consisting of similar components as those listed above. Kit prices start at $40 for the ADF loop cover and move upward to $225 for the Cessna-type wheelpants and $500 for the modified nosewheel fairing. In addition, the company sells an exhaust pipe fairing that is said to increase cruise speed and improve engine cooling; it sells for $195 uninstalled.

There's obviously quite a variety of modifications available for the 172, and we have just touched on a few of them — there are also instrument panel upgrades, shoulder harness retrofits, and myriad other interior and exterior improvements available. All of which should give the 172 owner the opportunity to make his airplane as individual as his time and budget will allow.