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The FAA has opened comments until Aug.10 for changes to GA flight training rules that would affect a broad spectrum of pilots, including those pursuing private and commercial certificates. Its Notice of Proposed Rulemaking includes a long-anticipated proposal to use glass-cockpit, fixed-gear aircraft for commercial flight training instead of traditional complex aircraft with retractable gear. The FAA states in the NPRM it plans to update the definition of a technically advanced airplane to include those with primary and multi-function flight displays and integrated two-axis autopilots, which would encompass the features that are now standard in most new single-engine piston airplanes. The agency cited comments from the flight training industry that legacy complex airplanes have become outdated and difficult to maintain. It also pointed to reports from the General Aviation Manufacturers Association, noting that "Cessna has not produced a piston engine retractable gear airplane since 1985 and Piper has produced only 28 piston engine airplanes with retractable gear since 2008 (16 being the Piper Arrow model)."

Other proposed changes would lift restrictions on flight instructing. Light sport pilots would be able to use training hours provided by a sport pilot-only instructor toward a private pilot certificate. In addition, instrument-only flight instructors would not need category and class ratings on their CFI certificates to provide instrument training, which would clarify legal questions that have been brought to the FAA.Adding to recent changes in flight simulator time allowed for instrument training, the proposed rules also include instrument currency, and would allow rated pilots to more easily use FAA-approved simulators for maintaining their currency, while not requiring that an instructor is present to provide dual training. Organizations including AOPA have pushed for the updates to training regs, saying they would make training less costly while accommodating new technology."AOPA has long advocated for many of the changes in the NPRM, and we believe they will benefit the general aviation community," the association stated Thursday. "Many of the proposals in the NPRM will save pilots time and money while making it easier for them to maintain or expand their skills." AOPA plans to submit detailed comments on the proposed changes.

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Aero Electric Aircraft Corp.'s solar-electric Sun Flyer airplane made its first public appearance at Centennial Airport in Colorado Wednesday. The proof-of-concept model, in development as a low-cost, environmentally friendly trainer, will be the test aircraft for its FAA certification, AEA said. The company also announced during a rollout event it is partnering with the University of Denver's Daniel Felix Ritchie School of Engineering & Computer Science to research uses for electric propulsion, including unmanned aerial systems. Meanwhile, Spartan College of Aeronautics and Technology – which had ordered the first 20 Sun Flyers for a future training program – said Wednesday it will reserve five additional airplanes.

The Sun Flyer, a two-seat, low-wing trainer, features solar cells on the wings, lithium-ion battery packs and an electric motor that AEA says is quieter than conventional aircraft motors and is emission-free. Designed for flight schools, the aircraft will come with a tailored training program that AEA is developing in partnership with Redbird Flight. Flight tests for the Sun Flyer are expected to begin soon and continue through the end of 2016.

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The Airbus Perlan Mission II team, which aims to fly a pressurized glider to a record of 90,000 feet, is continuing its flight-test program in Minden, Nevada. Airbus CEO Tom Enders visited the site last weekend, and went for a flight in the glider with the project's chief pilot, Jim Payne. "Experiencing the Perlan 2 glider in flight was truly remarkable," said Enders. "Airbus Perlan Mission II is all about pushing the boundaries of innovation, refining our understanding of our environment and climate change, and inspiring a new generation of aerospace pioneers. We're honored to see this dedicated team of volunteers carry our name on a journey that will eventually take them to the edge of space." The high-altitude tests also will provide insight into the potential for wing-borne travel in the thin atmosphere of Mars, according to the team.

The Perlan II glider first flew last September, in Oregon, and moved to a higher-altitude site in Nevada in December. The team has been gradually increasing the altitude and speed reached on each flight. They plan to relocate to the Patagonia area of Argentina this summer, where conditions will enable them to begin test flights to higher altitudes, ultimately reaching the 90,000-foot goal later this year. The glider's true flight speed at that altitude will be more than 400 mph. The crew will breathe pure oxygen provided by a rebreather system, similar to what astronauts use in space.

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AVweb's search of aviation news around the world found announcements from Vector Aerospace, McKinney Air Center,LifeStyle Aviation and Flightglobal. Vector Aerospace Corporation, a global independent provider of aviation maintenance, repair and overhaul (MRO) services, announced the grand opening of a new engine test cell at its Summerside facility in Prince Edward Island, Canada. It joins three existing test stands at Summerside, two dedicated to turboprops and one to turbofans. McKinney Air Center earned the top spot in the 2016 Pilots' Choice Awards survey. Now in its seventh year, the survey is open to all of FltPlan's 157,000-plus registered users. In addition to U.S. FBOs, the survey ranks FBO chains, Canadian, Caribbean, and Mexican FBOs, ATC Centers, ATC Towers, and airport-based U.S. Customs & Border Protection facilities.

LifeStyle Aviation announced the expansion of their popular DiamondShare aircraft access program to include the all-new Diamond DA62 and the Diamond DA40 NG and DA42-VI modern aircraft. The company is highlighting the availability to purchase the new seven-place DA62 as well as the expansion of the DiamondShare Program during an East Coast Demo Tour. Flightglobal's second annual Flight Safety Symposium takes place from Sept. 13-14 at the Radisson Edwardian Hotel, Heathrow Airport in London. This unique symposium showcases the importance of the continued improvement in global aviation safety through a three-conference-in-one format showcasing a range of issues within the industry from SMS and 'Just Cause' to Safety II and the regulation issues.

The Weekender's SocialFlight calendar turned up some busy events with lots in store for vintage enthusiasts, all taking place on Saturday.

Join fellow pilots for a grassroots fly-in to Massey, Maryland, where you can tour the Massey Air Museum and share your best chili recipe and/or hors d'oeuvre item. Good weather brings over 100 aircraft, especially taildraggers, biplanes and antiques landing on the ample, firm grass runway.

Smith Mountain Lake in Moneta, Virginia, will celebrate its 50th anniversary with an antique car show, antique airplane static display, RC demos and plenty of other activities.

The Arkansas Wing of Angel Flight South Central will host a fly-in at Searcy Municipal Airport in the Bulldog Helicopters Hangar. Presentations willinclude non-towered airport operations, ATC operations, ADS-B avionics, maintenance and Angel Flight operations.Register for this event online so the host can provide a free barbecue lunch.

Brewton Municipal Airport in Alabama will host its sixth annual fly-in, with plenty of activities for all including airplane rides, military aircraft displays, hot air balloons, ultralights and rotorcraft, plus live music and food vendors.

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Regardless of whether your aircraft is metal, composite, or tube and fabric, quite a few homebuilts these days use composite fairings. Nowhere is this more true than the engine cowl—it's just not an easy shape to fabricate out of other materials. Unfortunately, for tightly-cowled installations, heat from proximity to exhaust pipes (or a turbo) can be a problem. It's not uncommon for builders to find blistered—or even burnt—cowlings during Phase I testing, or after an engine swap or other firewall-forward modifications. If you are making your own cowl, use of a high-temp epoxy is an option, but for those of us working with kit-supplied cowlings, some kind of a heat shield may be required.

What's My Clearance?

To find out what kind of clearance between cowl and exhaust pipes is typically necessary, we went straight to the exhaust master himself—Larry Vetterman. Although Vetterman is now retired, his 27 years of experience manufacturing exhaust systems for Experimental aircraft have made Vetterman exhausts the gold standard among homebuilders. Vetterman flies behind his own pipes in an RV-7A.

To begin with, it's important to understand the heating and cooling of the pipes themselves. "What builders need to realize is that the pipes are hottest in two areas," says Vetterman. "First, because of valve overlap, the flame front in the pipes is about two inches from where the pipe flange bolts to the cylinder head. In cruise flight, this area of the pipe will actually be cherry red. You can see this in the discoloration of the pipes—when you look at the flange, you'll see that it stays a normal color at the cylinder but turns brown about two inches downstream. Incidentally, this is where your EGT sensors should ideally be located. The second location of high heat is the branch on crossover systems, since this is getting a double whammy of exhaust.

"On the other hand, we need to appreciate that the exhaust system is one of the best heat sinks on an air-cooled engine. The mass airflow coming past the cylinders continues to pick up heat as it passes the exhaust pipes." So, in addition to the thermodynamics of the exhaust gases cooling as they expand towards the pipe exit, cooling airflow causes the exit end of the pipes to be significantly cooler than the flange end. Therefore, one of the first steps in dealing with excess heat down by the pipes is to make sure your baffles up top are well sealed to improve that mass airflow cooling.

And, if you've considered using automotive-style exhaust pipe wraps to manage under-cowl heat, think again says Vetterman. "Wrapped exhausts are a serious issue. I've seen numerous examples of pipe failure caused by wrapping. When I asked a metallurgist several years ago what was happening, he explained that if the surface of the pipe exceeds 1250 F, you see serious degradation of the metal as the chromium and other additive elements used to give Type 321 stainless its high temperature properties oxidize." In addition, wrapping the pipes is likely to put additional heat stress on the engine since their function as a heat sink is compromised. Vetterman has seen no evidence that wrapping improves power or speed.

Finally, although this article is focused on keeping your cowl from getting toasted, Vetterman points out that it's extremely important to also protect fuel lines and control cables in the vicinity of hot exhaust pipes with heat shields mounted directly to the pipe.

Determining Actual Clearance

So, what kind of clearances does Vetterman recommend? "For unprotected fiberglass, I would recommend not less than 1 inches of clearance. For fiberglass with either foil or silver paint, you can reduce that to inch." The addition of an insulator like Fiberfrax will provide additional protection.

These numbers of course represent a rule of thumb and Vetterman stresses the importance of airflow in keeping things cool. In that sense then, an area of static airflow is of greatest cause for concern. In determining your own cowl's hot spots, it also helps to find someone else with a similar installation and compare notes. If you want to be truly scientific, you could use something like Omega temperature labels (www.omega.com) and make a temperature map.

In order to determine the exact cowl clearance from the exhaust pipe at any particular point, roll a bit of modeling clay into a cone slightly greater in height than the estimated clearance. Stick the cone to the pipe in the region of interest, and carefully assemble the cowl. Give the cowl a light tap in the region of the cone, then remove. The cowl will have made an impression on the clay which you can then "plumb" with a stick pin to determine the precise clearance. You may want to subtract another 1/8 to 3/8 inch from this measurement to allow for vibration of the cowl, engine or pipes themselves.

Level 1 Protection/Rare: White Paint

At a minimum, simply painting the interior of the cowl white or silver will help to reflect radiant heat, as well as highlight oil leaks. Some builders fill and smooth the interior of their cowls just as they would an exterior surface, since a smooth surface facilitates easy clean up and is aesthetically pleasing. However, this is not necessary, and it does add weight and build time.

Before painting, it is recommended that you at least seal the entire inner cowl with a nice fuel-proof coat of laminating epoxy. (Laminating epoxy is much less viscous than structural epoxy and therefore easier to apply; I recommend West Systems 105 Resin and 206 Hardener.) This helps keep oil and gas from soaking into pinholes or core material, which can add weight and compromise the strength of the cowl. And as Vetterman points out, if you need to repair the fiberglass in the future, it will be impossible to do so if it has been contaminated with oil. Some builders thin the epoxy with acetone, but I don't find this necessary—simply paint on a single thick coat with a brush and wipe the excess off with a rubber squeegee. Let cure and follow with your choice of paint. Even if you plan to put down additional heat barrier layers, you'll still want to seal everything with epoxy as a kind of base coat.

Level 2 Protection/Medium-Rare: Adhesive-Backed Foil

The next level of protection is adhesive-backed aluminum foil. Both Aircraft Spruce & Specialty Co. and Van's Aircraft, Inc. sell foils. (Van's is happy to sell many of their products to all homebuilders, not just those who have purchased their kits.) The Van's product is 30 inches wide and adheres very well; I highly recommend it. You'll want to make templates for the area of application (better to waste template material than foil) and to get an idea of how many linear feet of foil you'll need to order. I find the 1/16-inch thick closed-cell foam often used for packing material these days perfect for templates, since it is slightly rigid, but still conforms nicely to compound curves—like the foil itself.

The foil cuts easily with either scissors or an X-Acto knife and straightedge. It is extremely sticky, so make sure you have it positioned exactly where you want it before laying it in the cowl. This is another reason to put down a layer of epoxy—the adhesive backing sticks best to glossy surfaces. I prefer to work from the middle outward, as this seems to minimize the number of creases on compound-curved surfaces. Use the felt edge of a window-tint application tool, available from a car parts store, to smooth the foil as you go. Once finished, mix up some laminating epoxy and paint the edges of the foil with an acid brush. This will prevent oil seeping under the foil as well as the foil lifting.

Level 3 Protection/Well-Done: Ceramic Blanket

If your clearances are minimal, you'll want to consider adding an insulator. Aircraft Spruce sells a variety of insulating blankets. We encourage you to do your own research, but try not to get carried away with high-tech multilayered blankets that promise to deflect space shuttle-magnitude heat rays. For most builders 1/16-inch Fiberfrax is more than adequate (1/8-inch is also available). Fiberfrax is a ceramic blanket that can be laid under the aluminum foil to greatly slow heat transfer.

As with the foil, first make templates of the region you want to protect. Cut out the Fiberfrax, and attach it to the cowl with Pliobond contact cement. Use regular Pliobond—VOC compliant isn't nearly as effective. Now, using your original template, cut a sheet of aluminum foil whose edges extend one or two inches beyond the Fiberfrax. This extension will serve to anchor the foil around the perimeter of the Fiberfrax. Peel the backing and lay this directly over the foil, again working from the center outward. Finish up by sealing the edges with laminating epoxy.

Level 4 Protection/Charbroiled: Firewall 2000

The nuclear option of heat barriers is a product like Firewall 2000, a quarter inch of insulator sandwiched between aluminum foil on one side and stainless steel on the other. Unless you have a glowing turbo an inch from your cowl, avoid the "bigger is better" temptation. This is pretty substantial stuff. It is quite heavy at 9.5 ounces per square foot, versus less than 1 ounce per square foot for either 1/16-inch Fiberfrax or Van's adhesive-backed aluminum. Due to the sandwich construction, it doesn't conform to compound curves as well as the thinner materials, and it relies on rivets or glue to be held in place. In addition, due to the open edge construction, you'll definitely need to anchor the perimeter with aluminum tape to keep the blanket from getting oil-saturated.

Where to Start?

While some builders apply foil to the entire inside of their cowl, this probably isn't necessary. Unless you have extremely close tolerances from the get-go (i.e., less than 1/2 inch), I'd probably take the first step of epoxy seal/white paint, then go fly. During Phase I, you'll be pulling the cowl off quite a bit anyway to make sure everything is secure, and if you are toasting the cowl, the paint will tell you pretty quickly. However, once you've got your base layer of epoxy and paint, applying the Fiberfrax and aluminum won't take more than a few hours and will add less than a pound of weight, so don't be afraid to take a preventative approach. Given how much many builders hate fiberglass work (and how expensive cowls are), this is one case where an ounce of foil is worth a pound of Bondo.

The finished cowling is shown in the opening photograph of the article. The entire inner cowling was sealed and painted, followed by application of Fiberfrax and aluminum foil in areas of close proximity to exhaust pipes.

Good luck, and stay cool!

This article originally appeared in the May 2014 issue of Kitplanes magazine.

Read More from Kitplanes, and learn how to receive your FREE copy of The Annual Homebuilt Buyers Guide!

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Wrapping up a marathon 10 days of travel this week, I was happy to get my mitts on and actually fly a real airplane. Not a drone operated from some air-conditioned trailer a half a world away or something powered by batteries that lack capacity or, more likely, something that exists only in a PowerPoint presentation. This blatant and unprovoked commission of aviation occurred at Cub Crafters in the hilly plains of south central Washington.

Cub Crafters, as you probably know, has carved a unique niche for itself in the GA market. Owner Jim Richmond started with a Cub restoration business, plying the Alaska trade where the Super Cub remains a stalwart in the commercial bush flying business, prized for its generous payload and robust construction. Cub Crafters' business quite naturally evolved into actually manufacturing new, certified aircraft and although most of us may think of the company as a builder of light sport airplanes--the Carbon Cub--the factory is a proper Part 23 manufacturing facility. They certified and continue to sell the Top Cub. Cub Crafters President Randy Lervold had invited me to come have a look at their newest product, which will be announced in June. I spent some time flying it and although a press embargo restricts me from revealing any details, I think the airplane will create quite a stir when it's unveiled. You'll be able to get a good look at it at AirVenture and I suggest you take the time to do so.

Having spent a day and half flying the airplane and touring the factory, I had a moment or two to consider this question: Are the modern tools available to designers yielding better airplanes than ever? And are production techniques more efficient than ever? Although the answer is not a universal yes, it's a general yes. As I mentioned in a blog on Diamond's new DA62, that airplane is as uncompromised as it's reasonable to expect from any manufacturer. Diamond didn't corner cut to hold a particular price point and my impression of the new Cub Crafters airplane is that the company followed a similar strategy. Like Diamond, they appear to have focused everything they've learned in 30 years in the airplane business and married it with modern design technology to build a thing that's about as competent and unblemished as is possible to do in 2016.

During my interviews with Lervold and CC's marcomm guy, John Whitish, I tried to gain some sense of the investment required to bring a new model to market and despite my insistent bracketing around specific numbers, they politely demurred. Suffice to say that when I opened the bidding at $2 million, I got a polite laugh and it's not because I've overshot the estimate. And rules number one and two in aircraft development are that it always costs more and takes longer than anyone plans. Just the paper shuffle alone for a certified product requires multiple thousands of pages of documentation and if you page through all that data, you'd be hard-pressed to measure value for the customer in terms of a higher-quality--or a safer--product delivered. That's not to say that neither Part 23 nor the ASTM standards for light sports aren't rooted in sensible design and manufacturing processes, because they certainly are. It's the level of niggly detail that runs the costs up and delays the project, preventing the companies from pulling in revenue on that big investment they've made. That's one reason why the long-awaited Part 23 revision is being anticipated as a potential market changer. I've said before that I'm skeptical of the expectations for the Part 23 revision, although I think it will at least help hold the line on the rate of cost escalation.

Ignoring the costs for a moment, the actual design quality of airplanes is, I think, better than ever. Lervold told me structural efficiency of new airplanes continues to improve because digital design tools exist to build structures that are just strong enough, without throwing in extra tubes or brackets where they aren't needed. I'm sure in the days when the original Cub was designed using slide rules, the builders added extra structure as a safety margin ... just because. Lervold told me one other thing that has nearly revolutionized flight test revisions is the simple POV camera, like a GoPro. These can be attached to any point on the airframe to film a tufted surface in flight to see what the air is actually doing rather than guessing at it. It's literally like a flying wind tunnel. This makes design tweaking faster and more effective and, I'm convinced, delivers that last measure of performance confirmation that defines the difference between acceptable and exceptional.

On the shop floor, CNC technology certainly offers labor-saving efficiency and it allows companies to pull in-house what they used to outsource. Lervold showed me a complex machined fitting for the control stick that was certainly done on CNC. Shipping that stuff outside gives all the margin to the outside vendor and that's not a formula for profitable success. The established trend in most low-volume, high-mix manufacturing is insourcing.

A few years ago, when manufacturers were trying to produce cheaper LSAs in hopes of stimulating volume, Jim Richmond told me the company looked at trying to build an $85,000 light sport. They concluded that it was a path to big losses and now Cub Crafters plies the upper end of the LSA price strata and with good success. They're building about 60 airplanes a year and have capacity for more than that. The company is growing modestly and is expanding its footprint on the Yakima Airport. In a market that seems determined to continue withering, that's encouraging. The company's new airplane, I predict, will find enough buyers to keep the trend perking.

Legendary Ram Engines || Sale: You Choose Your Discount!

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Tomorrow || May 14, 2016 || Come See Aircraft Spruce in Peachtree City, GA

At the AUVSI show in New Orleans, a new company called SkyeIntelligence was showing a trick drone with self-following capability. You simply launch it, and it follows your every move. AVweb shot this short news video on the product.

Fly Safe & Spend Smart! || Incredible Savings on Evolution Display Systems from Aspen Avionics

Hurray, hurray, the month of May,
Airborne folly starts the day,
You forget how significant a Convective SIGMET really is,
But memories revive in a rite of spring that begins by acing this quiz.

Click here to take the quiz.

California Aircraft Expo || Palo Alto || May 13-14, 2016