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Beryl D'Shannon Bonanza tip tanks

It started out with a phone call to Beryl D'Shannon Aviation to inquire about vortex generators for AOPA's Beech A36 Bonanza. The call ended with our seriously contemplating the addition of tip tanks to what was already a well-equipped (read heavy) A36. How did this happen?

A little background: We were aware that D'Shannon's vortex generator kit would provide the A36 with a 100-pound increase in maximum gross takeoff weight - the reason for the call in the first place. By allowing pilots to carry more fuel and/or cargo that extra boost would come in handy on many of the trips that AOPA staff members take. A side benefit was improved low-speed handling. However, D'Shannon's marketing manager, Scott Erickson, pointed out that the company's tip tank STC would provide a 183-pound increase in the airplane's max gross weight and allow us to carry an additional 30 gallons of fuel, thereby greatly increasing the airplane's fuel/payload capability. Furthermore, the proposed gross weight increase could be utilized whether the tip tanks had fuel in them or not - free useful load, in other words. The tanks are available for nearly every model of Bonanza; however, gross weight increases, if applicable, vary by model.

It seemed like a win-win situation because many trips in the Bonanza were well beyond the nonstop range provided by the standard 74-gallon main fuel tanks. The tip-tank kit lists for $5,500 plus about $1,750 for installation. Hardly chump change, but when you consider the benefits, the addition of the tanks begins to make sense.

We figure that the total time of a fuel stop is at least 45 minutes, especially when you factor in the climb back up to altitude. If it's IFR and another clearance must be obtained, the time (and frustration) factor weighs in more. With a corporate-owned airplane, the time employees spend in the airplane also is a consideration. Arriving one hour earlier increases productivity and offsets the cost of the tanks still more. Most important, the addition of tip tanks should also increase the safety of travel in the Bonanza. The majority of accidents take place during the takeoff and landing phase. If you can eliminate a fuel stop, you've limited your exposure to the most dangerous aspects of a flight.

There's also the reduced wear and tear that added stops place on the airplane: landing gear cycles, hot starts, tire/brake wear, climbs, etc. After weighing in all of the known factors, we determined that the tanks would pay for themselves in less than 1.7 years or 750 hours. In reality, the break-even point should occur sooner because the reduced cycles should extend the life of the engine and other components to some degree, and we could sell the original wing tips.

With all of the figures behind us, a date was made to have D'Shannon's roving installer, Doug Kelly, come to AOPA's Frederick, Maryland, headquarters to hang the tip tanks and plumb the associated fuel lines. The fiberglass tanks come ready to be painted and can be installed by your shop if you prefer. Installations generally take about two days. A fuel pump is installed in each wheel well that transfers fuel from the tip tanks to the mains - you cannot burn fuel directly from the tips. Inside the cockpit there are two switches that control the right or left fuel transfer pumps. A fuel gauge and sending unit are available for $300. We opted instead for the clear window on the inboard side of the tank that allows the pilot to see how much fuel is sloshing around in the tank. The pumps must be turned off manually after the transfer is done. We'd prefer to have an automatic shutoff as some other tip tanks have. To help remind us to turn them off, the local avionics shop installed a small blue light that illuminates when one or both pumps are on. If your airplane is already wired for strobes as ours was, integrated strobe light bulbs will cost an additional $255. To offset some of the costs we sold the old wing tips for $1,300.

After seven months of operation, the tip tanks have proven very useful to us on several occasions because of the increased useful load, time-saving range, or ability to tanker lower-priced fuel. Nonstop trips to Oshkosh, southern Florida, and even home from Wichita are possible with the tip tanks filled. Since the net gross weight increase is roughly the same as the weight of the fuel in the filled tip tanks (180 pounds), the airplane has the same full-fuel payload (650 pounds) as it had prior to the installation - except, of course, that there are two hours' more fuel on board. Take the fuel out of the tips and the airplane has 830 pounds of payload-carrying ability. In other words, you can carry an extra adult. D'Shannon says that the canted tip tanks provide additional lift, which allows the airplane to behave the same at 3,833 pounds as it did at 3,650 pounds without the tanks.

Handling of the airplane is nearly identical, thanks to the STC's addition of some extra counterweights to the ailerons that preserve the Bonanza's excellent roll feel. Stall behavior is the same, and stall speeds are not noticeably different. The main difference comes in turbulence when the tips are full - the extra fuel weight causes the wings to flex slightly. If any fuel is in the tips or if the airplane is operated at a weight more than the original 3,650-pound max gross weight, it reverts from a Utility category airplane to the Normal category and the maneuvering speed lowers to 134 knots indicated from 141 KIAS.

We compared the range/payload figures of our tip-tanked A36 with a typically equipped 1998 Raytheon Beech Baron 58 and found that it could fly as far as the twin at 75-percent power and even carry a few more pounds of payload. It seems that we have a very useful airplane again. For more information, contact Beryl D'Shannon Aviation, Post Office Box 548, Wayzata, Minnesota 55391; telephone 800/328-4629 or 612/404-9000; or visit the Web site ( - Peter A. Bedell

AvBlend update

AvBlend has a new look. The familiar blue and silver, 12-ounce, cone-top can has given way to a new design. In addition, the oil's main ingredient, Lenckite, is now spelled LinKite. The contents of the can are the same, but the cosmetic changes are one of the byproducts of a recent buyout of the company by Bruton Smith, a well-known name in the auto-racing industry. Another byproduct of the deal is the disbanding of the distributorship of AvBlend. Now the product is available only direct from the factory through a toll-free number (888/AVBLEND).

AvBlend is an FAA-approved light mineral oil that is claimed to soak into metal, loosen carbon deposits, keep your engine clean, and leave a thin film that prevents rust and corrosion in your engine and eliminates "dry" starts. Unlike many popular automotive additives, AvBlend contains no solids such as Teflon. Although the cost versus benefit of the product has yet to be proven in

a large-scale study, there is overwhelming evidence that the product does no harm. However, at $20 a can, treating an engine with AvBlend at each oil change can get quite expensive, especially for those large-displacement engines requiring two cans at every oil change.

A lot of controversy surrounds oil additives, and with good reason - so much of the evidence is biased and/or anecdotal. The makers of AvBlend are doing all they can to refer customers to several in-depth studies and testimonials, but how is the average pilot going to know whether an extra $20 per oil change for a can of AvBlend will benefit an engine's life expectancy?

We have been testing AvBlend in one engine of a twin for nearly four years and more than 400 hours. Our results are positive although anecdotal; a survey of one engine is hardly scientific. Although we can't vouch for the advertising claims that the elixir "restores performance to engines with accumulated hours," "lowers fuel consumption," and "produces cooler oil and cylinder head temperatures," we can safely say that the benefit of the doubt in our limited experience lies in favor of AvBlend.

Over the period of the first two oil changes (at approximately 50 and 100 hours cumulative after the first application) we noticed that oil consumption by the Continental IO-520 improved from a quart in three hours to a quart in five hours. Howard Fenton, president of Engine Oil Analysis of Tulsa, Oklahoma, surmised that perhaps the product migrated up the channel-chromed cylinders, cleaned out the gummy residue in the ring lands, and allowed the rings to expand and seal better against the cylinder walls. Fenton performed his own objective blind oil analysis test of the product in 535 oil samples and came up with positive results for use of the product, especially in Lycoming engines with valvetrain problems (see " Pilot Briefing," June 1997 Pilot). Fenton himself admitted that AvBlend appeared to have cured a valve-sticking problem in the Lycoming on his personal Grumman Tiger.

Our test twin's oil analyses continued to show normal results although the AvBlend-treated engine showed slightly lower readings for wear metals like aluminum, iron, chrome, and particularly copper. In February 1997, the nonAvBlend-treated engine required a top overhaul, while the treated engine continued to chug along. One and a half years and 210 hours later, the AvBlend-treated engine received a top overhaul as well. (Even purveyors of AvBlend will not lead you to believe that the product is a miracle in a can that can save an engine on its last gasp.) Upon teardown, most components appeared normal for an engine of its age and hours.

Was it the AvBlend that allowed the engine to continue running more than 200 hours beyond the other? Nobody knows for sure. We will continue to use AvBlend in this engine and closely monitor its progress. For more information, contact AvBlend, 806 Transco Road, Mooresville, North Carolina 28115; telephone 888/282-5363 or 704/892-7717 for orders; or call 877/282-5363 for technical information. Or visit the Web site ( - PAB

Briefly Noted

Sporty's Pilot Shop has introduced its latest video in the Air Facts series, titled Personal Minimums. The $24.95 video discusses minimums prescribed by the federal aviation regulations and details how they may not be appropriate or comfortable for every pilot. To order, call 800/SPORTYS or 513/735-9000. - PAB

Unless otherwise stated, products listed herein have not been evaluated by AOPA Pilot editors. AOPA assumes no responsibility for products or services listed or for claims or actions by manufacturers or vendors. However, members unable to get satisfaction regarding products listed should advise AOPA. To submit products for evaluation, contact: New Products Editor, AOPA Pilot, 421 Aviation Way, Frederick, Maryland 21701; telephone 301/695-2350. Links to all Web sites referenced in this issue can be found on AOPA Online (

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