Tanking The Bonanza

Aftermarket aux tanks are available for many legacy aircraft, such as this mid-’60s V-35 Bonanza, giving them enough range to make even longish legs reliably. Photo By Peter Bakema GFDL 1.2], Via Wikimedia Commons

The Beech Bonanza, whose incredible production run is closing in on 75 years, is a particularly fertile field for auxiliary fuel tank installations. The original Bonanza 35's 39-gallon wing-tank fuel system was soon outgrown as horsepower increased in either stock form or through modification. A factory-installed STC added a 20-gallon rear fuselage tank, available up to the 1954 E35. Some of these older airplanes have even had wingtip tanks installed for a total of five fuel sources. The F35 of 1955 introduced auxiliary wing bladders, used until the 1960 M35, after which the optional-but-always-ordered long-range tanks simplified fuel management.

You can forget about adding an aft-fuselage tank to an old Bonanza that wasn't built with one, so wingtip fuel is really the only way to go at this point. Even the 74-gallon factory tanks in the more modern Bonanzas aren't always enough, as we mentioned earlier. Two tip tank options exist; General Aviation Modifications (GAMI), Inc., in Ada, Oklahoma, now offers the 20-gallon tip tanks previously made by J.L. Osborne in Victorville, California, and D'Shannon Aviation, Inc., of Buffalo, Minnesota, sells its own wingtip tank system. Both work well, using electric pumps to move the fuel into depleted wing tanks.

The Osborne by GAMI system uses welded aluminum tanks, while the D'Shannon tanks are made of fiberglass, allowing the incorporation of a sight-gauge window to confirm fuel level in addition to the electric gauges. D'Shannon's tanks are canted slightly, reportedly improving roll control. If you're purchasing an existing modified Bonanza, either is worth consideration.

D'Shannon Aviation has had 50 years of experience with its Bonanza tip tanks, which now have a 20-gallon capacity; older installations offered 15 gallons per side. The latest engineering improvements tailor airflow for maximum efficiency, and an aileron-rebalancing kit is included. Reportedly, the tanks help with the Bonanza's dutch-roll characteristics. The kit price is $13,850, with installation time requiring about 50 hours, plus or minus; we were told that $1,450 of the cost of the kit is represented by the new AeroLED lights that come with it.

Osborne by GAMI tanks have a long history as well, dating back to the 1950s. They incorporate LED lighting, feature flush filler caps and quick drains, and are said to improve aerodynamic efficiency and stability. The kit price is currently $12,995 and will cost about $20,000 installed.

Adding tip tanks to a Bonanza can result in an approval to operate at higher gross weights. Both the D'Shannon and GAMI tanks' extra weight allowance varies by model and, in some cases, requires additional weight to be fuel in the tips. However, the matter of increasing takeoff weight may not be entirely tied to a tip tank installation. D'Shannon offers a Genesis STC to extend gross weight, allowing operation in Normal Category certification instead of the Utility Category carried by most Bonanzas. This resets maneuvering speed and other POH parameters.

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J BeckettWriter