AVwebFlash - Volume 14, Number 30b

July 24, 2008

By The AVweb Editorial Staff
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» Ask for your complimentary copy of Trade-A-Plane at booths 1121-1124 at EAA AirVenture
Destination Oshkosh back to top 
Sponsor Announcement

Next Week: AirVenture 2008!

Over the next few days, AVweb's crew will be packing up our gear, heading for various airports, and winging our way to Oshkosh, Wisconsin, ready to bring you daily news (including a full AVwebBiz next Wednesday) from the EAA AirVenture grounds all next week. The show promises to be an exciting one, with several aircraft making their debut, new products galore, a diverse lineup of unique aircraft on the flight line at Aeroshell Square, the unveiling of the Rocket Racing fleet, the latest experimental electric aircraft, the world's best airshow pilots, and much more. Staffers from Kitplanes and other Belvoir publications will be pitching in to help AVweb bring you the fastest, most complete, and in-depth coverage possible. Watch for frequent blog updates, daily videos and podcasts, and of course our daily AVwebFlash newsletter to bring all the news from the show straight to your desktop. And if you are in Oshkosh next week, check in with AVweb on your handheld device to be sure you are not missing a thing.

New engine announcements are expected, Burt Rutan is returning to the forum tent with Sir Richard Branson for an update on their space-tourism ventures, the V-22 Osprey will appear at the show for the first time ever, and the Goodyear Blimp and the F-22 Raptors will make return visits. Kitplanes editor Marc Cook will be on site to contribute ongoing coverage and analysis as the FAA's brand-new updates regarding the 51-percent rule get a thorough looking-over. Plus, the winner of AVweb's Aeroshell Aerobatic Team drawing will be going for an unforgettable ride. (Not entered to win yet? Click here!)

Aircraft Spruce at the Annual EAA AirVenture Oshkosh 2008!
Join the Aircraft Spruce team at AirVenture in Oshkosh, Wisconsin in Booths 1022-1029 on July 28th to August 3rd, 9am-5pm. Take advantage of some of your favorite products on sale, complimentary ground shipping (does not apply to hazardous or oversize products) and a helpful staff to answer all questions. Don't forget your complimentary copy of the new 2008–2009 Aircraft Spruce Catalog! Call Aircraft Spruce at 1 (877) 4-SPRUCE or visit online.

» Visit Aircraft Spruce for your catalog and show specials at booths 1022-1029 at EAA AirVenture
Things to See at the Show back to top 

Lancair Evolution Prototype To Fly Demos At EAA AirVenture

When the first Lancair Evolution showed up at Sun 'n Fun earlier this year, still in its plain white undercoat, the design attracted plenty of attention. Pressurized and turbo-powered, the four-seat kit aircraft promised high performance, with 385-mph speed. Now prospective buyers will be able to find out for themselves how it performs. The company is bringing the newly painted prototype to Oshkosh, where it will be available for demo flights. Lancair also said this week it has delivered the first Evolution kit, and the buyer will participate in the two-week builder assist program at the company's facility in Redmond, Ore. Also, Forward Vision said this week its EVS-100 synthetic vision system will be offered as an option for the Evolution.

Estimated cost for the completed aircraft is up to about $1 million. Click here for exclusive AVweb video from the Evolution's visit to Sun 'n Fun in April.

Austro Diesel Engine At AirVenture

Diamond Aircraft will be exhibiting the new AE 300 Austro engine next week at EAA AirVenture in Oshkosh. The Austro is a jet-A-burning, 170-hp, next-generation turbo-diesel engine that soon will be available on the DA42 Diamond twin. The AE 300 offers 26 percent more power than the engines currently on the DA42, says Diamond, for better takeoff and climb performance, better single-engine performance and more speed. Diamond has been working with MB Tech (a Mercedes Benz daughter company) and Bosch to develop the engine, and they expect European certification within a few months. The "next-generation" features include a clutch-less gearbox, a cast-iron crankcase, integral oil/coolant heat exchanger and improved turbocharger air induction and cooling systems.

Diamond has been working hard to get the engine certified and online since their regular diesel supplier, Thielert Aircraft Engines, ran into delivery issues recently. The company will also have a flying prototype of its D-Jet on static display, along with its full-scale D-Jet mock-up.

Aircraft Financing to Fit Your Needs
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» Talk with AirFleet Capital about financing your purchase at booth 1133 at EAA AirVenture
Vandals & Victims back to top 

Vandals Pull Piper Twin Apart, Damage 10 Others

Vandals spray painted, slashed tires and smashed instruments on and otherwise tampered with at least 11 aircraft, including a Citation 550, in a spree that caused hundreds of thousands of dollars worth of damage at Monmouth Executive Airport, near Belmar, N.J. last week. It's speculated that the vandals used a vehicle to tear the tail and part of the wing off a twin-engine Piper. "It appears that a motor vehicle, with a cable attached, may have been used to accomplish this damage," Wall Township Police Lt. John Gavin told the Coast Star.

In fact, the violently disassembled Piper may be beyond repair, according to a spokesman for First in Flight, the airport business that reported the devastation. The vandalism is currently being investigated by the Wall Township Police Department. In addition, the Monmouth County Prosecutor's Office, the FBI, and the FAA will also help in the investigation.

Vintage Aircraft Wings Recovered From Metal Thieves

Thieves were apparently in search of scrap metal when they made off with two irreplaceable vintage aircraft wings from a storage yard used by the Wingspan Aviation Heritage Foundation in Mesa, Ariz. When the theft was discovered, about a week ago, foundation director Robert Kropp went to the media in hopes of uncovering information about the wings' fate -- and he got lucky. An anonymous tipster led Kropp and police directly to both wings, hidden in two separate remote locations in the desert. "I really feel like I found a winning lottery ticket in the street," Kropp told The Arizona Republic. "I'm just absolutely elated. Without the media exposure, it was gone, baby, gone." The wings, from a 1940s-era Lockheed T-33 trainer and a 1950s Lockheed PV-2 bomber, were found intact and police dusted them for fingerprints.

The wings now are secured in a locked location, and the foundation plans to reattach them to their aircraft as soon as possible and improve security. "It was a big learning curve to see how insidious these metal thieves are," Kropp told the Republic. "I really was so fortunate."

Sensenich: Right on the Nose ... Again!
For more than 75 years, Sensenich has been the industry's fixed-pitch prop leader. No surprise Sensenich leads the way again with new composite propellers for light sport and homebuilt aircraft. Proven on 5,000 airboats over the last eight years, plus Rotax- and Jabiru-powered planes, the new lightweight, precision composite props are now available for Continental- and Lycoming-powered planes. Call (717) 569-0435, or click here to learn more.

» Find the right Sensenich Propeller for your aircraft at booths 4145-4147 at EAA AirVenture
News Briefs back to top 

Five Teams Prepare For CAFE Challenge

The General Aviation Technology Challenge, hosted by the CAFE Foundation and funded by NASA, has announced the five teams that will take part in this year's event, coming up Aug. 5 to 9 in Santa Rosa, Calif. The competition aims to promote the development of "green" and efficient GA aircraft. CAFE will award $300,000 in prizes for achievements in noise reduction, fuel economy (mpg), safe handling, and speed. The five teams will be: "Team Pipistrel" flying a Pipistrel Virus 912, team leader Frank Vance Turner; "Team Aerochia" flying a modified Diamond DA20-A1, team leader Geoff Stevenson; "Team Wilkinson Aero Sport" flying a Dynamic WT9, team leader Neil Wilkinson; "Team Lambada" flying a UFM-13 Lambada, team leader John A. Dunham; and "Team Flight Refine" flying a Flight Design CT, team leader John Robert Basham. All of the competing aircraft are two-seaters, and four of the five are light sport aircraft. One will fly on biodiesel fuel.

The flight competition will be staged at the CAFE Flight Test Center at Charles M. Schulz Sonoma County Airport beginning on Aug. 5, 2008, and conclude with a cross-country "Green Prize" race on Saturday Aug. 9. A static display of the winning aircraft and their scores will be open and free to the public at Charles M. Schulz Sonoma County Airport's CAFE Foundation Flight Test Center on Aug. 10 from 9 a.m. to 1 p.m.

Another Chance For Seawind Amphibian?

The Seawind amphibian may yet make it to the long-elusive certification finish line, if the company can raise the next round of funding it needs. The airplane drew a loyal following for its kit version, which is no longer in production, but efforts to achieve certification have run into numerous delays. When the only flying prototype and its pilot were lost in a flight-test accident last year, that seemed like the end of the story. Now Seawind President Richard Silva says that he's been encouraged by an "overwhelming" outpouring of support from the Seawind pilot community, and he's ready to move forward with the certification project. He said he needs to raise $2 million to complete certification and it will cost $2 million to ramp up production. "We did not give up, and we have our production facility secured. If it is at all possible, we will resume operations, and the Seawind will be coming back," he said this week.

The company still holds its production assets and a 82,000-square-foot facility at Saint-Jean Airport in Quebec. Check the AVweb Web site tomorrow for an in-depth podcast interview with Silva by AVweb editor Russ Niles.

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» Ask Avemco Insurance what policies are right for you at booths 1159-1160 at EAA AirVenture
News Briefs back to top 

GA Pilots Complete Around-The-World Flight

"It was a great adventure," said Thierry Pouille, president of Air Journey, this week, after his small group of GA pilots completed the company's first-ever 10-week-long, 25,000-mile trip around the world. "We're all back -- and we're doing it again!" Pouille said the company will definitely offer the tour a second time in 2009. The six aircraft on this year's trip -- a PC12, two TBMs, a Cessna Conquest, a Cessna Mustang and a Duke Turbine conversion -- all completed the journey without any major mechanical problems or other setbacks, he said. "It takes a lot of organization and preparation and office support," Pouille said, to make the trip run smoothly and on time. "But it's been a fantastic experience." Since AVweb last checked in with the group, they have flown up the east coast of Asia via Taipei, Taiwan; Seoul, South Korea; and Vladivostok, Russia; then across the Bering Sea to Anchorage, Alaska. The pilots stopped in Juneau for a cruise and ended their journey in Seattle, then each aircraft headed for home.

If such a trip sounds appealing, be prepared to spend $68,750 per person for the 2009 trip, plus an airplane registration fee of $16,500 and various other expenses. For more details from earlier legs of the trip, click here and scroll to the "Around The World" stories.

Foreign Flight Students To Lose Work-Study Option

Work-study visas that allow foreign flight students to train and work in the U.S. will no longer be granted, effective June 2010, according to a new policy issued by the U.S. State Department. The current J-1 visa program allows foreign students to train in the U.S. and work as flight instructors to build flying time. Eight U.S. flight schools make use of the program, and some of them could lose up to half of their revenue once the program is eliminated, according to AOPA. "While this only impacts a small number of students, we are deeply disappointed that the State Department believes that flight training programs no longer further the public diplomacy mission of the United States," said Craig Spence, AOPA vice president of aviation security. "This country has long been a world leader in flight training, and we want to see that continue."

Lower costs and broader availability attract foreign students to the U.S. from Europe and elsewhere. The Department of State has stated that it does not have the expertise and resources to fully monitor flight training programs and ensure their compliance with national security concerns. AOPA said it will work to change the State Department policy before it takes effect in two years. The National Air Transportation Association also said it is currently in discussions about this issue with the Department of Homeland Security, flight training providers and the Small Business Administration.

On the Fly ...

A Cessna 402B twin crashed into a municipal construction site in Ocean Ridge, Fla., on Tuesday. The pilot was hurt but there were no other injuries...

The NTSB is investigating a near-midair between an Embraer ERJ-145 and a Learjet LR60 at Chicago O'Hare International Airport on Monday...

Training for pilots of Bombardier Challenger jets should emphasize the importance of the proper takeoff stabilizer trim setting, says the NTSB...

British pilots took the lead in the Red Bull Air Race in Rotterdam; the series now moves to London for Aug. 2-3.

Dr. Blue Says, "Don't Be Stupid — Carry a PLB!"
Flying, hiking, camping, riding your ATV or bike — accidents happen that can become a life-threatening situation. Be prepared with a Personal Locator Beacon (PLB). It's as easy as pushing a button. PLBs from Aeromedix.com include the ACR MicroFix 406 MHz for pilots and SPOT, the world's first handheld Satellite Messenger, for when you're enjoying activities in unpopulated areas. Click now to visit Aeromedix.com for complete details.
Reader Voices back to top 

Question of the Week: Security at Your Airport

This Week's Question | Previous Week's Answers


With more and more "personal jets" in the offing, we're starting to wonder if this is the start of a new era for GA or just another short-lived trend. Last week, we looked to AVweb readers for predictions, asking how many single-engine jets you think will be available in ten years' time.

Nearly half of you (45% of those who responded) said there would be at least two casualties among the six that have already been announced. Only 3% predicted that all six would capture and hold a solid market niche.

For a complete (real-time) breakdown of reader responses, click here.
(You may be asked to register and answer if you haven't already participated in this poll.)


AVweb has recently run two stories in which aircraft were tampered with or parts were stolen. Programs like Airport Watch work well when there are people around. We'd like to know how you rate the night security at your airport.

Click here to tell us how secure your airport is.
(Click to answer.)

Have an idea for a new "Question of the Week"? Send your suggestions to .

This address is only for suggested "QOTW" questions, and not for "QOTW" answers or comments.
Use this form to send "QOTW" comments to our AVmail Editor.

AVweb's Newstips Address ...

Our best stories start with you. If you've heard something 200,000 pilots might want to know about, tell us. Submit news tips via email to newstips@avweb.com. You're a part of our team ... often, the best part.

Join NAA and Help Shape the Next Century of Flight
It's a great time to join the National Aeronautic Association (NAA), the nation's oldest aviation organization. At $39 a year, NAA membership is a terrific value for any aviation enthusiast! Members receive the Smithsonian's Air & Space magazine, plus access to aviation records and much more. To become an NAA member, sign up online or call (703) 416-4888 and press 4.
New on AVweb back to top 

Battery Basics

Here's how to get the most out of all that money you paid for your last new battery.

Click here to read this maintenance article.

Aircraft starting batteries have a tough life; much more so than their automotive counterparts. They are left idle for days or even weeks at a time, then asked to start a 500 cubic-inch engine in cold weather with three gallons of oil the consistency of molasses in the sump. To make matters worse, aviation batteries have significantly lower capacity than an auto battery, and multi-weight oil can help only to a degree.

Twenty-four volt batteries provide some help in high-current-demand situations such as speeding up electric retractable landing gear, but in terms of battery cost compared to 12 volts, a 24-volt system leaves a lot to be desired on cost vs. benefits.

When left idle, batteries self-discharge about one percent or so a day due to the side effects of components (antimony) used to keep battery-grid structures from shedding and damage during use. This self-discharge process has a long-term, deleterious effect on the battery if not corrected by frequent recharging. The term is sulfation, and when left unchecked it means the gradual self-destruction of the battery. Recharging and the replacement of lost electrolyte, a natural process in wet-cell batteries, staves off permanent sulfation.

When a battery is allowed to remain in a state of sulfation, either from lack of use or from lack of recharge, it tends to lose both capacity and life. Initially reversible sulfation hardens with time and it becomes less and less reversible. As sulfation flakes off and falls to the base of the case, it can short out the cells.

By Definition

First, let's look at volts and amps, two often-confused terms. We will use the common (but not perfect) water analogy.

The rate of flow through a pipe (amps) is governed by two things: the pressure (voltage) and the size of the pipe (wire diameter). A third factor also has influence -- pipe length. The longer the pipe the more resistance (ohms) and pressure (voltage) drop.

Increasing pressure (pipe size) increases the potential flow. More flow, more work. Greater pressure or voltage allows delivery of more fluid (amps) in a given diameter pipe (wire).

Excessive pressure and flow can cause a pipe too small for the application to burst (a wire would overheat and melt). Thus, there must be a balance of pipe (wire) size for a given flow (amps) and length combination. That's why starting batteries need such large wires leading to the starting motor. There are hundreds of amps required at 12 or even 24 volts (not much pressure) to deliver the large quantity of amps to spin the starter. (Volts times amps equals watts, or power, in a properly sized circuit for DC electricity. AC can get a little more complicated.)

You can have more volts and fewer amps or fewer amps and more volts to equal the same power, given the wire size is appropriate for the application. We are over-simplifying here, but our goal is to give the basic concepts for understanding a battery, not a course in DC electronics.

A Basic Wet Cell

The battery is a simple device, allowing the chemical storage of electricity. In some batteries, the chemical fuel -- once exhausted -- means a throwaway.

In batteries such as a wet cell (liquid electrolyte), the process is reversible, and you can restore an exhausted battery by adding electrical energy and restoring the chemical potential.

Batteries like this have been around for well over a hundred years, and the classic model is still the basis of operation of the majority of today's starting batteries, but the times are slowly changing.

If you wanted to make a battery, all it would take is suspending a few strips of lead in a solution of sulfuric acid (see drawing at right). To charge the battery, a piece of lead is connected to become the positive terminal and the other the negative terminal. Connect an outside source of voltage, say 3 volts. Bubbles will form and rise in the acid, coating the positive terminal with a brown coating called lead dioxide, yielding a positive potential. Your cell has a voltage of about 2 volts DC. Connect a small bulb to the terminals and -- voila! -- light.

The discharge process converts the lead dioxide of the positive terminal and the lead strip of the negative terminal to lead sulfate. Water is also released, diluting the acid. Connect the outside charging source and charge again. Connect six 2-volt cells in series and you have a 12-volt battery.

Capacity is roughly a function of the amount of lead. Typically, the lead plates are alloyed with antimony for plate ruggedness and resistance to vibration. The down side is antimony promotes shedding of the active plate material. As a battery begins to discharge at peak rates for more than a few seconds, significant amounts of lead sulfate immediately begin to form, slowing the reaction as you crank.

Starting batteries have thin plates with fiberglass separators to provide the maximum active surface area for the greatest burst of current. It's also why a short rest (20 minutes is better) will allow an apparently dead battery to spontaneously recover a bit, sometimes for one last shot to start. The remaining unsulfated lead is being contacted by the electrolyte through diffusion. Wet-cell batteries are least efficient when you demand maximum discharge.

When a battery is charged, and especially when excess voltage is applied, some of the water in the electrolyte is converted to gaseous hydrogen and oxygen and then vents. As this condition continues, electrolyte is lost to the atmosphere, thus the normal requirement to replenish the water in the cells ... preferably with distilled water, please. Aircraft battery caps also have internal stoppers to help prevent loss of electrolyte in unusual attitudes.


In automotive use, "maintenance free" generally means a wet-cell battery with simply more electrolyte and different chemical additive. An exception to this is the true maintenance-free battery from Optima, and a few other specialty companies, which will run from $150-200 -- and worth it.

Aviation-type maintenance-free batteries for certified airplanes -- available from Gill and Concorde -- are also called sealed, valve-regulated batteries and are truly maintenance free from adding liquids. Terminals still require periodic cleaning. They can be damaged by overcharging with excess voltage (over 14.7 volts for a long time).

They may be installed at any angle, have superior resistance to self-discharge, and can discharge more completely under high loads, such as with an alternator failure.


Being chemical beasts, the ability to supply current is not really linear. The greater the draw in amps, the less efficient the typical wet cell battery. For example, a battery that has a 25 amp-hour rating of 60 minutes will not sustain a 50 amp load for 30 minutes, but substantially less time due to the inefficiencies of the plate design.

A battery has an internal resistance of fractions of an ohm, but it's meaningful. The greater the amp drain per unit of time, the more energy is lost as internal battery heat due to that small resistance. As batteries age and/or sulfate, this resistance goes up.

Bottom line: The discharge curve is very sharply sloped. Every battery has an optimal maximum rate for current draw. This concept is important to understand because in an "alternator-out" situation, you will get much more than double the battery time if you cut the current drain on the battery in half when running electronics.

Capacity Testing

Capacity Testing is a greatly ignored annual requirement, because most shops don't have the proper equipment. You must have an annual capacity test performed on your starting battery. It's part of the Instructions for Continued Airworthiness that should come with any new battery.

Our conversations with the FAA indicated they interpret the rules that the capacity test is mandatory for Part 23 certified airplanes and recommended for CAR 3 certified airplanes. That's a rule interpretation we don't understand and don't agree with. Do yourself a favor and do the test -- it's your neck.

The test must show that your battery is capable of sustaining 80 or 85 percent of the amp-hour rating of your battery (depending on the type of test protocol performed). See each maker's ICA for the specifics -- they do differ.

If you want the best chance of passing this test (and longest-lived battery), then the best bet is to use a multi-stage battery charger that reaches up to 14.5 volts, but not more, at the conclusion of the charging cycle.

We recommend the BatteryMINDer from VDC Electronics. They have a line of 12 and 24-volt chargers optimized for aircraft batteries. With battery costs rising, it makes economic sense to use a proper charger -- it will make the battery last significantly longer.


Once you've discharged a storage battery, promptly recharge it. In the simplest terms, if you apply a voltage to the battery that's higher than the voltage the battery produces, you reverse the chemical action that produced the electricity. This converts the lead sulfate and water back to lead, lead dioxide and sulfuric acid.

If the process were 100-percent efficient -- which it isn't -- you'd have to put back exactly as much electricity as you drew from the battery when you were discharging it to return it to a fully charged condition. In real life, lead sulfate, lead dioxide and lead are materials with different densities and different rates of expansion and contraction with changing temperature. When one replaces another, small pieces can flake off the plates and fall to the bottom of the cell. Then too, the chemical reactions that occur during charging take time to occur.

If you try to charge a battery faster than it can accept a charge, some of the electrical energy goes to producing additional lead dioxide that will flake off and fall uselessly to the bottom of the cell. Some will also break down the water portion of the sulfuric acid electrolyte into gaseous hydrogen and oxygen and vent out the caps. An undesirable but unavoidable consequence of recharging causes some of the electrical energy you supply to a battery to be lost as heat.

As a rule of thumb, you have to supply about 120 percent of the electrical energy you've taken from the battery to recharge it. It should be supplied in a controlled manner specific to the battery if you are to achieve maximum battery life.

Ideal Charging

One of the best ways to charge a battery is at a constant current rate in amps equal to 20 to 40 percent of the battery's capacity in amp-hours (Ah) until the battery reaches an optimal voltage for its type. The level of charge at this point is equivalent to about 75 percent of the battery's capacity. This first phase of charging is called bulk charging.

Once the bulk charging is complete, the charging device should maintain the charging voltage at a constant value and allow the charging rate in amps to drop steadily. When the battery accepts current at only about 1 percent of its capacity (e.g., a 25-Ah aircraft battery accepting 0.25 amps), it can be considered fully charged. A current of 5 percent of capacity represents about an 85 percent charge. This phase, which can take several hours, is called the acceptance phase of the charge cycle.

Once a battery is charged, a float cycle helps to hold it in that condition. A float cycle is simply a voltage maintained slightly above the battery's rested, open-circuit voltage (13.1 volts nominal for a 12-volt battery). This float voltage doesn't really charge the battery but helps maintain a charge to compensate for internal losses in the battery. If your charger is trickle charging at more than 13.2 volts, it is slowly cooking the battery -- don't leave it on all the time.

This phase charging is what a "smart" charger does. A typical alternator/regulator charging system is not as sophisticated in recharging a battery, nor is the typical automotive battery charger.

A quick start takes very little charge out of a battery, so sophisticated charging is not critical. Batteries that sit idle, though, need more capable battery chargers for long life to reverse any sulfation that always take place when a battery sits.

Never recharge a battery that's low on electrolyte (plates showing to air). Add distilled water before starting the charging cycle, not after. Only fill it to the bottom (or a bit below) of the split rings, not to the top, or else the electrolyte will overflow during the charging cycle. Tap water is not good since it contains minerals that tend to accelerate adverse reactions. Adding more battery acid is even worse, and usually kills the battery in a matter of days.

Checking the Charge

A hydrometer is a simple instrument used to measure the state of charge of a battery. It does this by measuring the specific gravity -- the weight as compared with water -- of the electrolyte. You can get a suitable hydrometer at a local auto parts store, but be sure that it only requires an ounce or two of electrolyte for a reading. That's about all you'll get from an aircraft battery. Also, get a numerically calibrated one; do not buy a pith-ball type.

Checking the charge is simply a matter of taking a sample of electrolyte from a cell and reading the value where the fluid line meets the hydrometer's floating scale. Write the number down. A specific gravity reading between 1.300 and 1.275 indicates a high state of charge; between 1.275 and 1.240 is a medium state of charge, and between 1.240 and 1.200 is a low state of charge.

A battery in a low state of charge has 50 percent or less of its capacity left and needs recharging. Check all the cells; then compare the readings. Usually, if there's a spread of more than 0.050 between the worst cell and the average of the others, the battery is on its way out.

When testing a battery with a hydrometer, observe temperature factors; the temperature of the battery can make a big difference in the readings. When its temperature is between 70 and 90 degrees F, the readings can be used as-is. Outside of this range, a correction chart is needed. Some hydrometers have this chart printed on floating scales; others have the chart on or in their packaging. Also, hydrometer readings are taken after the battery has been off the charger for a couple of hours minimum; overnight is even better for accuracy.

How Batteries Fail

Batteries, as we've noted, are relatively simple beasts, although some complex things happen to them during their operation. Battery failures, for the most part, are also relatively simple to understand.

The flaking and separation of lead sulfate -- and, to a lesser extent, lead dioxide -- from the plates that occurs even in normal operation can eventually cause a sludge in the bottom of the battery that actually short-circuits the plates. That can't be helped, but this process is exacerbated by overcharging and by excessively high charging rates. Even worse is when a battery is left badly discharged (more about this in a minute).

Gassing and subsequent loss of electrolyte is another possible failure mode. It's caused largely by overcharging the battery and by neglecting to check electrolyte levels from time to time. Check the vent caps once a month for electrolyte level. If you find that every couple of months you need to add water to the battery, have the airplane's charging system checked. It shouldn't be gassing that much, and the charging voltage may be set too high -- i.e., over 14.3 or 28.6 volts -- or the regulator is malfunctioning. If the charge voltage is too low, it can sulfate the battery.

The most common cause of battery failure is sulfation. It occurs when a battery is left in a discharged state, in which much of the plate area is covered with a fine deposit of lead sulfate. This deposit grows into larger, harder crystals of lead sulfate that clog the spongy surface of the lead plates, acting as insulators. The crystals don't readily break up, and so the battery loses effective plate area, and therefore capacity.

It's a very poor idea, in terms of longevity, to discharge a battery down to less than 50 percent of its capacity. In fact, a battery that remains in a low or discharged condition for a long period of time will be permanently damaged.

Simply put, it's not so much what needs to be done as what should not be done, to get the most out of your investment.

A special note: If you buy an aviation battery in a dry-charged state via mail order and plan to buy automotive acid locally, don't. Auto acid is not the same specific gravity and will reduce battery life.

More aircraft repair and prevention articles are available in AVweb's Maintenance Index. And for monthly articles about aircraft maintenance, subscribe to AVweb's sister publication, Light Plane Maintenance.

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AVweb Insider Blog: GA Has Its Own Version of the Airline Mess ...

In the latest installment of our blog, AVweb Insider, Paul Bertorelli opines on why GA is asleep at the switch when it comes to doing something about the escalating price of oil.

Read more.

Q: What's the Difference Between a $10,000 Annual and a $2,500 Annual?

Mike Busch and his team of seasoned maintenance professionals are saving their aircraft-owner clients thousands of dollars a year in parts and labor — not to mention hours of hassle — by providing professional maintenance management for owner-flown singles and twins. Learn how they do it.

» Attend one of Mike's six Savvy Aviator technical sessions at EAA AirVenture Forums Plaza at Oshkosh
click here for the forums schedule
Your Favorite FBOs back to top 

FBO of the Week: TAC Air (KGMU, Greenville, SC)

Nominate an FBO | Rules | Tips | Questions | Winning FBOs

AVweb's "FBO of the Week" ribbon goes to TAC Air at GMU in Greenville, South Carolina.

AVweb reader John Hey hadn't stopped at GMU for six months, but he tells us "they still remembered me":

Great, cheerful, and competent service — even though I had just saved $30 using their self-service pump. Call ahead, and they get you a great discount on the nice Phoenix Motel one block away with the best free full Southern breakfast ever!

Keep those nominations coming. For complete contest rules, click here.

AVweb is actively seeking out the best FBOs in the country and another one, submitted by you, will be spotlighted here next Monday!

Understanding Your Airplane's Mechanics Could Save Your Bank Account
Light Plane Maintenance is the monthly magazine for aircraft owners who aren't satisfied with just flying. Aircraft repair can be simple when explained in concise, step-by-step details. If you want to truly learn about the workings of your airplane (and save a few dollars, too), Light Plane Maintenance is for you. Order online today and receive LPM's Top 40 Maintenance Tips as a gift.
AVweb Media: Look, Listen, Laugh and Learn back to top 

Exclusive Video: F-16 Intercepts Jet & Turboprop Legally Flying Through MOA

Original, Exclusive Videos from AVweb | Reader-Submitted & Viral Videos

Last March, AVweb told you about a close encounter between two private aircraft, a Pilatus PC-12 and a Beech Premier and an F-16 in an Arizona Military Operating Area (MOA). AOPA has obtained the radar video and audio from the incident, and AVweb Video Editor Glenn Pew has put them together in an enlightening package.

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Try disabling ad blockers and refreshing this page.
If that doesn't work, click here to download the video directly.

Reader-Submitted Photos back to top 

Picture of the Week: AVweb's Flying Photography Showcase

Submit a Photo | Rules | Tips | Questions | Past Winners

Each week, we go through dozens (and sometimes hundreds) of reader-submitted photos and pick the very best to share with you on Thursday mornings.  The top photos are featured on AVweb's home page, and one photo that stands above the others is awarded an AVweb baseball cap as our "Picture of the Week."  Want to see your photo on AVweb.com?  Click here to submit it to our weekly contest.


Even as we type this installment of "POTW," we're packing our bags and checking our flight plans for EAA AirVenture in some town called Oshkosh, Wisconsin. We'll be on-site in just a couple of days, and we look forward to meeting all kinds of interesting folks at the show. If you see us wandering the grounds in our AVweb gear or happen to hop a ride with us from place to place, strike up a conversation! We'd love to hear what you think about the show, our site, and the world of general aviation!

("POTW" will be on hiatus during the show, but we'll return with more of your pictures in two weeks. Don't forget to send 'em, though, or we won't have anything to share!)

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Used with permission of Bruce Van Beek

AeroShell Aerobatic Team in Action

Bruce Van Beek of Sioux Center, Iowa serves up this fantastic image of the AeroShell Team doing what they do best.

Believe it or not — and, to be honest, we're not sure we would! — the fact that our top photo this week features the AeroShell Aerobatic Team is completely unrelated to the fact that we're giving away a chance to right with these guys during their Monday morning practice at Oshkosh. (But, of course, we will take the opportunity to link to the page where you can enter our drawing.)


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copyright © Helen Tempest
Used with permission of Jon Butts

"Holding the Bank, Gents"

Jon Butts of Whiteley, Hants (U.K.) is back in the #2 spot this week with another photo from the "Cirrus Six" formation flight. This one is from the sharp eye of Helen Tempest (Ultimate High Flight Training & Entertainment).

Jon teases, "Not a bad picture for a marketing manager, eh?" — and we have to give Helen her due; it is a terrific shot.


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Used with permission of Brian Petzel

Can't Fly THAT Direction!

Brian Petzel of Rockford, Illinois encountered these "huge storms southeast of St. Paul ... directly on my route home!" While they may have proven a hindrance to Brian's travels, they certainly made for a compelling photo when combined with the setting sun over St. Paul's Downtown Airport.


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copyright © Daniel Valovich
Used with permission

Tandem Experts

Daniel Valovich of Hot Springs, Arkansas is back — just in time to remind us that it's not only the Navy and Air Force that make air show appearances.


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Used with permission of Bill Wozniak

B-2 Fly-Over at the 2008 MLB All-Star Game

Bill Wozniak of Fair Lawn, New Jersey sees us off this week with an interesting juxtaposition ... .


Don't forget to visit AVweb's home page for more photos in our weekly-updated slideshow.

Click here to submit your own photos to "POTW."

A quick note for submitters:  If you've got several photos that you feel are "POTW" material, your best bet is to submit them one-a-week!  That gives your photos a greater chance of seeing print on AVweb, and it makes the selection process a little easier on us, too.  ;)

A Reminder About Copyrights:
Please take a moment to consider the source of your image before submitting to our "Picture of the Week" contest. If you did not take the photo yourself, ask yourself if you are indeed authorized to release publication rights to AVweb. If you're uncertain, consult the POTW Rules or or send us an e-mail.

More AVweb for Your Inbox back to top 

AVwebBiz: AVweb's Business Aviation Newsletter

HAVE YOU SIGNED UP yet for AVweb's NO-COST weekly business aviation newsletter, AVwebBiz? Reporting on breaking news, Business AVflash focuses on the companies, the products and the industry leaders that make headlines in the business aviation industry. Business AVflash is a must read. Sign up today at http://www.avweb.com/profile/.

Names Behind the News back to top 

Meet the AVwebFlash Team

AVwebFlash is a weekly summary of the latest news, articles, products, features, and events featured on AVweb, the internet's aviation magazine and news service.

The AVwebFlash team is:

Timothy Cole

Editorial Director, Aviation Publications
Paul Bertorelli

Russ Niles

Contributing Editors
Mary Grady
Glenn Pew

Features Editor
Kevin Lane-Cummings

Click here to send a letter to the editor. (Please let us know if your letter is not intended for publication.)

Comments or questions about the news should be sent here.

Have a product or service to advertise on AVweb? A question on marketing? Send it to AVweb's sales team.

If you're having trouble reading this newsletter in its HTML-rich format (or if you'd prefer a lighter, simpler format for your PDA or handheld device), there's also a text-only version of AVwebFlash. For complete instructions on making the switch, click here.

Aviate. Navigate. Communicate.