Earlier this year, Paul Conner, a well-known figure in the canard homebuilt community, was killed in an accident in his SQ2000 plane not long after taking off from his home airport.
Because Paul was a highly-experienced pilot and builder, his death led to much soul-searching and introspection in the canard homebuilt community; if it could happen to Paul, it could happen to any of us.
Mark Zeitlin and several other owner/builders decided to conduct their own accident investigation in order to determine the cause(s) of the accident. Their report has been published here.
The report shows that, as is usual for many fatal accidents, several issues and events probably overlapped to result in Paul's tragic demise.

Took a work colleague for a trip around the Metroplex on Saturday. We flew from Dallas Executive down to Cleburne to see Jesse, who is the builder of my plane.
The air was a bit bumpy low down, but smoother above 6000 feet.
Jesse, being the sort of person who has to be building something, built a Cozy IV after he built the Long-EZ, and the Cozy lives at Cleburne, ironically, in the same hangar in which James Redmon first began building his Berkut. It's a small world...
The first thing I discovered is that fuel prices at Cleburne, TX are a bargain - only $2.85 a gallon for 100LL. I promptly took on 28 gallons, which should keep me flying for a while. While I fuelled up, Jesse took Ron for a ride in the Cozy IV, which impressed him, mainly because of the acceleration on the take-off roll. Ron has been training in the classic collection of under-powered certified aircraft such as the Cessna 152 and Cessna 172.
Jesse has almost finished repairing minor damage to the Cozy caused when it fell over on its tail outside the hangar. A gust of wind lifted the plane's wing, and because the canard was off for the Annual Condition Inspection, the plane was tail-heavy, and up into the air went the nose...Jesse was unable to catch it in time, and even his weight was not sufficient to bring the plane's nose back down before the winglets and wheelpants hit the ground hard. Fortunately, the lower winglets took the brunt of the damage, and they are (relatively) easy to repair. The wheelpants were also damaged, but Jesse has already fixed them and they look as good as new.
The main lesson to learn from that incident if you are a canard pusher owner with a 3-blade prop is - always park the prop with one blade at 12 o'clock. Because Jesse had the prop parked at that orientation, the prop was not damaged. If a single prop blade had been pointing towards the ground, he would have become the owner of an expensive wall ornament.
We flew from Cleburne over to McKinney, to meet up with James Redmon, who had been flight-testing new baffling inside his lower cowling, designed to equalise the CHTs on his engine. When we arrived, James had already completed a successful flight test, with the CHTs now within 10-15 degrees. He then proceeded to make me salivate by showing off his newly-arrived Garmin 396 GPS, complete with XM Radio and real-time weather. Damn my current lack of spare cash...
We then met up with Gerhard, who was busy replacing a cylinder on his Cessna 172. The 100 hour inspection revealed that compression on that cylinder was a stunning 5/80...clearly something was amiss there. Removing the cylinder showed cracks in the cylinder head, but more seriously, damaged valve guides. The engine was operating as a 5-cylinder Continental. The cylinder was being replaced with a new Millenium cylinder, and Gerhard was expecting the plane to be back in the air mid-week.
We then flew back to Dallas Executive, detouring over Greenville to climb up to 8000 feet to weave in and out of some of the fluffy stuff, and show Ron the general performance of the Long-EZ. Then back to Dallas Executive.
When I inspected the exhausts after putting the plane away, I noticed oil residue on the prop and inside the #3 exhaust pipe. I have always suspected that #3 cylinder was not entirely healthy - this may be an indication of sticking rings. We may need to take a look at this issue before Rough River.

Link: http://www.aopa.org/whatsnew/newsitems/2005/050907meigs.html

For those of you who haven't been following this issue too closely...a little while ago, the city of Chicago, frustrated by being unable to summarily close Meigs Field and convert it into a nature park, sent in bulldozers overnight to destroy the runways. This trapped a number of aircraft, which had to be specially flown out under FAA waivers.
The demolition was illegal under the terms of funding agreements between the city and the FAA. The FAA has now fined Chicago the maximum amount allowed by law, which is sadly inadequate. However, the city may still be liable for other punitive sanctions under the terms of other federal funding agreements, since some of those funds may have been diverted for non-aviation purposes.
This saga will continue to evolve. In the meantime, the destruction of Meigs Field remains as a black mark on the city and mayor of Chicago. Shame on them.

Here is a good overview of all of the weird and wonderful "extras" that the fuel company may add to refined autogas as it makes it's way through the distribution chain to your friendly neighborhood gas station:

Additives are gasoline-soluble chemicals mixed with gasoline to enhance certain performance characteristics or to provide characteristics not inherent in the gasoline. Typically, they are derived from petroleum-based raw materials and their function and chemistry are highly specialized. They produce the desired effect at the parts-per-million (ppm) concentration range. (One ppm is 0.0001 mass percent or 1mg/kg.)

Oxidation inhibitors, also called antioxidants, are aromatic amines and hindered phenols. They prevent gasoline components from reacting with oxygen in the air to form peroxides or gums. They are needed in virtually all gasolines, but especially those with a high olefins content. Peroxides can degrade antiknock quality, cause fuel pump wear, and attack plastic or elastomeric fuel system parts, soluble gums can lead to engine deposits, and insoluble gums can plug fuel filters. Inhibiting oxidation is particularly important for fuels used in modern fuel-injected vehicles, as their fuel recirculation design may subject the fuel to more temperature and oxygen-exposure stress.

Corrosion inhibitors are carboxylic acids and carboxylates. The facilities — tanks and pipelines — of the gasoline distribution and marketing system are constructed primarily of uncoated steel. Corrosion inhibitors prevent free water in the gasoline from rusting or corroding these facilities. Corrosion inhibitors are less important once the gasoline is in the vehicle. The metal parts in the fuel systems of today’s vehicles are made of corrosion-resistant alloys or of steel coated with corrosion-resistant coatings. More plastic and elastomeric parts are replacing metals in the fuel systems. In addition, service station systems and operations are designed to prevent free water from being delivered to a vehicle's fuel tank.

Metal deactivators are chelating agents — chemical compounds that capture specific metal ions. The more-active metals, like copper and zinc, effectively catalyze the oxidation of gasoline. These metals are not used in most gasoline distribution and vehicle fuel systems. But when they are present, metal deactivators inhibit their catalytic activity.

Demulsifiers are polyglycol derivatives. An emulsion is a stable mixture of two mutually insoluble materials. A gasoline-water emulsion can be formed when gasoline passes through the high-shear field of a centrifugal pump if the gasoline is contaminated with free water. Demulsifiers improve the water-separating characteristics of gasoline by preventing the formation of stable emulsions.

Antiknock compounds are lead alkyls — tetraethyl lead (TEL) and tetramethyl lead (TML), manganese compounds — methylcyclopentadienyl manganese tricarbonyl (MMT), and iron compounds — ferrocene. Antiknock compounds increase the antiknock quality of gasoline. Because the amount of additive needed is small, they are a lower cost method of increasing octane number than changing gasoline chemistry. Gasoline containing tetraethyl lead was first marketed in 1923.The average concentration of lead in gasoline gradually was increased until it reached a maximum of about 2.5 grams per gallon (g/gal.) in the late 1960s. After that, a series of events resulted in the use of less lead: new refining processes that produced higher-octane gasoline components, steady growth in the population of vehicles requiring unleaded gasoline, and EPA regulations requiring the reduction of the lead content of gasoline in phased steps beginning in 1979. The EPA completely banned the addition of lead additives to on-road gasoline in 1996 and the amount of incidental lead may not exceed 0.05 g/gal.

MMT was commercialized in 1959 and was used in gasoline alone or in combination with the lead alkyls. The Clean Air Act Amendments of 1977 banned the use of manganese antiknock additives in unleaded gasoline unless the EPA granted a waiver. MMT continued to be extensively used in unleaded gasoline in Canada at concentrations up to 0.068 g/gal. (18 mg/L). In 1996, after several waiver requests and court actions by the manufacturer, the courts ordered the EPA to grant a waiver for MMT. Its use is limited to a maximum of 0.031 g/gal. (8.2 mg/L). California regulations continue to ban the addition of manganese to gasoline.

MMT's future in the U.S. is clouded: Its use in gasoline is opposed by environmental groups and the automobile manufacturers. Gasoline containing MMT leaves significant red-orange deposits on spark plugs, catalytic converters, oxygen sensors and combustion chamber walls. The additive manufacturer has developed a large body of data to support its claim that MMT in gasoline does not reduce performance or increase emissions. The auto manufacturers have expressed concerns about shortened catalyst, oxygen sensor, and spark plug life and interference with the performance of the new on-board diagnostic system (OBD; see Chapter 5, Gasoline Engines). The auto industry conducted a large vehicle test of MMT that showed increased exhaust hydrocarbon emissions and increases in other emissions in some vehicles at high mileages in vehicles designed to meet low-emission limits. There have been reports of plugging in high-density honeycomb (brick) catalyst systems with MMT. The additive manufacturer takes exception to the autos’ test results and concerns over catalyst plugging. Some new vehicle owner’s manuals recommend against using gasoline containing MMT. Very little MMT is being used in U.S. gasoline at this time (2003). The controversy over MMT continues.

In many parts of the world, lead antiknocks are being eliminated from gasoline used in vehicles that do not have catalytic exhaust emission controls. This gasoline frequently is referred to as lead replacement petrol. Because many of the refineries in the world do not have the processing capability in place to meet octane number needs without an antiknock additive, MMT is being using in lead replacement petrol. The use of MMT helps protect engines susceptible to exhaust valve recession. Alternatives to using MMT for octane enhancement are the use of oxygenates, alkylates, and aromatics until processing can be constructed. The auto industry also opposes the use of MMT in this gasoline because of concern that this lead replacement petrol will find its way into emission-controlled vehicles. Lead replacement petrol is usually dispensed through wide nozzles to prevent misfueling.

Ferrocene (dicyclopentadienyl iron) has been around for nearly 50 years. It has not been widely marketed as an antiknock, although it has seen limited use in Europe. When combusted, it forms ferric oxides (also known as jeweler's rouge), a fine abrasive. Early studies of ferrocene showed excessive piston ring, cylinder bore, and camshaft engine wear at the concentrations investigated. Recent studies by the auto industry at lower iron concentrations have shown premature spark plug failures at the current recommended concentration of 30 ppm (9 ppm Fe). Concern also has been expressed that the ferric oxide will act as a physical barrier on oxygen sensors and exhaust catalyst surfaces and possibly cause catalyst plugging in modern vehicles. In the U.S., ferrocene cannot be used in reformulated gasoline because of a ban on the use of heavy metals. Further, it cannot be used in conventional gasoline without first obtaining a waiver from EPA, which requires extensive vehicle emission testing.

Anti-icing additives are surfactants, alcohols, and glycols. They prevent ice formation in the carburetor and fuel system (see Carburetor Icing). The need for this additive is disappearing as older-model vehicles with carburetors are replaced by vehicles with fuel injection systems.

Dyes are oil-soluble solids and liquids used to visually distinguish batches, grades, or applications of gasoline products. For example, gasoline for general aviation, which is manufactured to different and more exacting requirements, is dyed blue to distinguish it from motor gasoline for safety reasons.

Markers are a means of distinguishing specific batches of gasoline without providing an obvious visual clue. A refiner may add a marker to its gasoline so it can be identified as it moves through the distribution system.

Drag reducers are high-molecular-weight polymers that improve the fluid flow characteristics of low-viscosity petroleum products. As energy costs have increased, pipelines have sought more efficient ways to ship products. Drag reducers lower pumping costs by reducing friction between the flowing gasoline and the walls of the pipe.

Link: http://www.chevron.com/products/prodserv/fuels/bulletin/aviationfuel/7_ag_intro.shtm