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FAA Revamping Wings Program
The FAA Safety Team (FAAST) is changing the focus of its Wings-Pilot Proficiency Program from an awards-based program to a true proficiency program. The new system is expected to be in place in June. In a release on the FAAST Web site, spokesman James Pyles said the goal of the program is to instill a culture of constant education and re-education in pilots. "It encourages pilots to continue their aviation educational pursuits and requires education, review, and flight proficiency in the Areas of Operation found in current Practical Test Standards (PTS) that correspond with the leading accident causal factors in the United States," he said. That would be the stick. The carrot is that as long as a pilot keeps up with the curriculum, the requirement for flight reviews is suspended.
Under the program, pilots design their curriculum to fit their own requirements and continuously study and review the material. The educational activity is monitored by the FAA and, as long as it meets the requirements of the basic level. Of course, the program also encourages more advanced courses of study as a way of keeping pilots actively thinking about safety. If they drop out, though, the time table for flight reviews is reinstated.
Cessna 182 Hits Blimp Wire, Three Killed
Pilots in South Florida have said for years that it's been an accident waiting to happen, and now it has. Three people died Friday when the Cessna 182 they were in hit the cable used to tether a surveillance and propaganda blimp over Cudjoe Key in the Florida Keys. The blimp, known locally as Fat Albert, is normally flown at about 8,000 to10,000 feet, and the aircraft hit the wire at about 4,000 feet. Airspace surrounding the blimp is restricted. A camera trained on the blimp caught the impact on video. Fat Albert is one of squadron of lighter-than-air devices, more properly known as aerostats used by the federal government to detect suspected drug smugglers. Some also beam anti-Castro television signals to Cuba. Meanwhile, rescuers are also looking for the five occupants of a Piper Aztec that appears to have gone down off the coast of Fort Lauderdale.
The airplane was on its way from Fort Lauderdale Executive Airport to Andros Island in the Bahamas when it went off radar screens. Coast Guard Petty Officer Jennifer Johnson told the Associated Press that debris had been found, but no bodies or survivors. According to newspaper reports, the five onboard were planning a fishing trip in the Bahamas. |
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Finger-Pointing Continues in Brazil Crash
The operator of the Embraer Legacy 600 business jet involved in a midair with a Gol Airlines Boeing 737-800 over the Amazon jungle is blaming the accident on Brazilian air traffic controllers, according to the Associated Press. All 154 people aboard the 737 were killed when the jets collided over the Amazon jungle in late September; the seven aboard the Legacy owned and operated by New York-based ExcelAire survived. In a 154-page document sent to Brazilian federal police earlier this month and released to the AP on Saturday, the U.S. charter firm said an analysis of air traffic control transmissions and flight recorders in the Legacy "confirmed that both planes were freed by Air Traffic Control to fly at the same altitude [37,000 feet] and the same path, in opposite directions." Meanwhile, Brazil's Defense Minister, Waldir Pires, maintains that his country's air traffic control system is one of the safest in the world.
According to the AP, Pires said the collision was the fault of the ExcelAire pilots because the Legacy's transponder was not turned on or malfunctioned. Honeywell, which manufactured the business jet's transponder, has repeatedly told AVweb that there is no evidence that suggests that this equipment malfunctioned in the ExcelAire Legacy.
Piper Pares Down PiperJet Manufacturing Sites
Vero Beach, Fla.-based Piper Aircraft is reportedly considering Tallahassee, Fla.; Vero Beach, Fla.; Columbia, S.C.; Oklahoma City, Okla.; and Albuquerque, N.M. for its PiperJet manufacturing facility, according to the Tallahassee Democrat. The newspaper reported on Sunday that if Piper chooses the capital city for its new plant, the facility would be built on a 275-acre site at the Tallahassee Regional Airport, where it would have access to 700,000 sq ft of space. Further, the city said it would construct and lease the buildings to lure Piper to the area, the newspaper said. Meanwhile, Vero Beach officials are fighting hard to keep the work alongside Piper's existing headquarters there. Richard Aboulafia, vice president of aerospace forecasting and consulting firm Teal Group, told the Florida Sun-Sentinel that the PiperJet will likely be manufactured outside Florida because of that state's aggressive incentives to lure new companies.
If Piper selects Albuquerque to build the PiperJet, the Albuquerque Bizjournal says it is likely its new plant would be built at the Double Eagle II Airport, where Eclipse is erecting its manufacturing facilities. Piper has hired Boston-based consultant BDO Siedman to scout locations where it could build its jet single. Now that the list is pared to five cities, the next step will be to narrow this further down to two or three locations before Piper makes a final selection. |
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Seaplanes Stroll Down Lakeport Streets
Visitors to downtown Lakeport, Calif., were treated to an unusual site Thursday afternoon when two aircraft emerged from Clear Lake and taxied through the streets of downtown. The pilots and their aircraft were participating in a rehearsal for the Western States Seaplane Festival -- also known as the Clear Lake Splash-In -- that will take place September 22. The festival is billed as the "largest gathering of floatplanes and amphibious aircraft west of the Mississippi." This year, some of the aircraft will be parked on Main Street, where the public is invited to get close to a seaplane, talk with the pilots and participate in the festivities. Thursday's rehearsal "was designed to ensure that the considerable logistical concerns involved in the effort will go off without a hitch," according to festival spokesperson Damon Trimble. The pilots landed on Clear Lake and taxied up ramps normally used by boaters and fishermen.
From there, volunteers from the Lake County Airman’s Association guided the airplanes as they taxied through city streets along the same route they’ll use at the festival. According to Trimble, the rehearsal ensured that the aircraft’s wing span will clear phone poles, street signs and other obstacles on the downtown streets. Pilots Jennifer Martin and Ray Arceneaux donated their time and airplanes for the rehearsal.
Eclipse 500's European Debut
On Thursday, the Eclipse 500 first very light jet (VLJ) made its European debut at AERO 2007 in Friedrichshafen, Germany. According to Eclipse Aviation, this is the first time that the Eclipse 500 has been outside of North America. The twinjet left Eclipse's headquarters in Albuquerque, N.M., on April 14 and flew the North Atlantic route through Canada, Greenland, Iceland and the UK before landing in Friedrichshafen. “Europe is such a great market for the Eclipse 500 because of its superior performance and efficiency to anything else offered today,” noted Eclipse Public Relations Director Andrew Broom. “We already have more than 100 orders throughout this market, and we be lieve that once people in Europe and the UK see it and fly it, we can change the way they travel.” Over the next month, the Eclipse 500 will travel to several countries while attending trade shows and completing sales demo flights before arriving in Geneva, Switzerland, on May 22 for the European Business Aviation Convention and Exhibition.
The aircraft manufacturer says the Eclipse 500 is the "quietest turbine powered aircraft" and exceeds ICAO’s most stringent Stage 4 noise standard by more than 40 decibels. It said that noise testing proves that the Eclipse 500 is quieter than all multi-engine and most single-engine piston powered aircraft. "Additional testing by Pratt & Whitney Canada shows that the Eclipse 500’s PW610F engines are setting a green engine benchmark by registering a smoke number (SN) of less than five, while the regulatory limit for engine smoke emissions is a SN of 50," Eclipse said. |
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Gulfstream Jet Aids Climate Research
A Gulfstream V twinjet will be used to track and analyze large plumes of dust and pollution from Asia as they journey across the Pacific Ocean, according to New Scientist. The airplane is expected to start its first research mission this week to monitor the plumes, which affect cloud formation and are believed to contribute to global warming. The Gulfstream will fly at up to FL510 during the research missions, and onboard instruments will monitor plume movement and cloud formation, as well as capture dust, pollutants and cloud particles for more study. “This is the first time that an aircraft with very sophisticated instruments will be following these plumes all the way across the Pacific,” principal researcher Veerabhadran Ramanathan told New Scientist. “There is a gold mine of information out there waiting to be uncovered.”
The plumes peak in the spring when windstorms over Central Asia’s Gobi desert send huge masses of dust, soot and smog from China and other East Asian countries across the Pacific Ocean.
Stars Get Reality Check from Fellow Passengers
Paula Abdul either overestimated her star power or underestimated the sort of primeval code of conduct that rules when 100 or more people are packed in an aluminum tube, rebreathing each other's air. The American Idol judge's first mistake was to ask for first-class treatment on the successfully proletariat Southwest Airlines by demanding advanced boarding for a flight from San Jose to Burbank, Calif. Her next move was trying to cash in her star credits. When told that advanced boarding was reserved for the old, the very young and infirm, she reportedly said, “But I’m famous! I need to go on first!” according MonstersAndCritics.com's retelling of tabloid accounts. At that point, her fellow passengers reportedly dissolved into laughter with one quipping "You're no Sanjaya," referring to the talent-challenged contestant whose flamboyance carried him to a final 10 berth in the popular reality TV series. Abdul's final indignity was being forced to rub shoulders (not to mention elbows, knees and likely feet) with the less important people in her seat row because the airplane was full and her lame attempt to reserve the seat beside her was immediately overruled by a flight attendant.
But while Abdul's antics had her seatmates rolling in the aisle, Heather Mills' impromptu dance routine couldn't break the veil of doom that had settled over the flight she was on. Mills, the estranged wife of Paul McCartney is a competitor on Dancing with the Stars and, when the entertainment system on the Virgin Atlantic flight she was on from LAX to London broke, she thought she'd fill in. Mills foxtrotted from First Class to Economy and back with Dancing partner Jonathan Roberts, but her act was scant compensation for the planeload of passengers facing 10 hours without day-old news programming, TV reruns and six-month-old movies to distract them. "We weren't in a good frame of mind because of the broken entertainment system," one passenger is reported by London.Net to have said."When the dance routine, which moved from first-class to economy, finished, no one clapped because we were all in such a bad mood." |
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Pilot Error, Road Placement Cited In PA-28/SUV Collision
Deicing Trucks Hit Airplanes In Cleveland
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The greatest threat of collision at Cleveland Hopkins International Airport during early April's unprecedented spring snowstorms was
apparently from deicing trucks.
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On The FlyS-TEC received FAA STC approval on Wednesday for installation of its standard roll-axis servo in Cirrus SR22s with System Fifty Five X autopilots. The company says the new $4,000 servo will enhance roll response when using the airplane's autopilot…
Flight1 Aviation Technologies' Avidyne EXP5000 primary flight display PC-based courseware has been accepted as a FAA/Industry Training Standard (FITS) self-learning program…
Anywhere Map is now offering the HP Travel Companion 5915 packaged with its moving-map GPS system and an airplane interface adapter…
MS Aviation on Friday released its online private pilot training course that covers ground training, FAA knowledge test preparation and checkride preparation. The introductory price is $97.
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The Pilot's Lounge #112: Fire Your InstructorIf your instructor is not behaving in a professional, respectful manner, then you need a new one. And if you're a CFI with an unprofessional, disrespectful student, don't wait around for things to change. Click here to read Rick Durden's column.
step back and evaluate just exactly why it is going on and whether to instruct that student in particular or acting as a flight instructor in general. If a student has an instructor who seeks to reschedule more than about twice, it's time for a heart-to-heart with the instructor as there is probably a more serious underlying problem. The instructor is not putting the student's best interests first. If the instructor simply does not show up for a lesson because something more interesting came up, it's time for a pointed conversation. If it happens a second time the student should probably change instructors. (Breaking the CFI's kneecaps is considered an over-reaction and poor form.) There are times that the FBO/flight school manager will send the CFI off on a charter flight when lesson(s) are scheduled. Smaller FBOs especially have a heck of time juggling the demands of charters, flight students and personnel. When it has to be done, the FBO is absolutely obligated to call each student, apologize profusely, reschedule each lesson affected and, if it happens more than once, should offer some sort of compensation such as a free half hour of ground school. In the short run, students are an important source of revenue for that particular lesson. But they also must be considered important sources of revenue in the long run as renters, and potential airplane buyers, maintenance and fuel-business customers. Any FBO with even a smidgeon of business sense will treat students very well. From the student's standpoint, if an FBO does not call and apologize in such a situation, and work to reschedule the lesson, it's time to look for another FBO. If it's the only game in town, at the very least a complaint to the FBO manager/owner and to the local Better Business Bureau is appropriate. 3. The instructor has a duty to brief each lesson with the student prior to doing any flying. The student should have a chance to ask questions about anything that has come up since the last lesson. (In fact, the instructor should encourage students to write down questions that occur to them between lessons and cover them first thing, because instructors know that students who think about flying between lessons do a heck of a lot better than those who do not.) The instructor should explain what is to be covered in the upcoming lesson, tie it in to what has been done and what is to come and explain what the performance standards for each flight operation are so that the student can self-evaluate. For instance, the student should know what is the acceptable range for airspeed in a climbing turn or on approach to landing, if those are the areas to be covered. It gives an objective performance target and will make the post-flight evaluation simpler for both the instructor and student. The completion standards should be realistic. A three hour student is not going to meet the practical test standards for maneuvers. It's tough enough to learn to fly without frustrating the student with unreasonable expectations. 4. The instructor should be clean and well-groomed. It sounds silly, but I'm astonished at the number of instructors who aren't. It doesn't mean formal dress or coats and ties for men, and it certainly doesn't mean the silly practice of epaulets worn by fuzzy cheeked CFIs at some schools. It just means showing respect for someone who is paying a lot of money to learn to fly by dressing appropriately and having showered that day. [IMGCAP(3)] 5. An instructor should listen to the student. Listening to the questions asked is one of the best ways to tell if something has been missed in a student's education. It means listening to the student's concerns and fears, and remembering that flying can be scary as all get out to a new student. It means respecting what the student says and taking fears and concerns and worries seriously and addressing them professionally. It also means listening to how the student says something, as the tone or inflection of a question or comment can mean a great deal. After all, any aerobatic instructor will tell you that when you ask a new akro student how s/he is feeling after a maneuver, the answer will always be "fine." The word itself is meaningless. It's how the word is expressed that determines whether the lesson will continue or be cut short, or whether the sick sack is pulled out immediately and handed to the student. 6. The instructor is responsible for keeping the training airplane clean. No matter if the lessons are at a huge flight school where people are hired to clean the airplanes, it is still the duty of the instructor to keep the airplane looking good and the interior of the airplane free of trash and clutter. It may mean that the instructor is also going to have to wash and vacuum the airplane. Students are spending a pile of money to learn to fly; many are showing up at the airport in high-dollar cars that are kept spotless. If an instructor wants to keep making money and keep those students coming back for more lessons, the instructor has to keep the airplane(s) looking attractive. 7. A professional instructor does not give extra dual training, or delay soloing a student for a few hours, to make extra money. It is absolutely unethical. 8. The instructor has a duty to the student to take the time to discuss the flight in appropriate detail afterward. It is a part of the learning process to review each part of the flight and evaluate it objectively and honestly. 9. Whether or not the training program has a formal grading system, the instructor has a duty to evaluate or grade honestly. I've seen far, far too many programs where the instructor just grades everything "satisfactory" or "average" or "above average". That's lying to the student. The student is entitled to know how well he or she did on an objective scale linked to the completion standards for each flight operation, and that scale has to have been established prior to the flight. If nothing else, if the student crashes and the instructor is placed on the witness stand, how the heck is he or she going to explain an "above average" grade on slow flight when the student spun out of the turn from downwind to base leg? Honest grading and evaluating sometimes leads to one of the instructor's toughest jobs: telling a student, or a rated pilot who is in for a flight review, that the person's performance is absolutely unacceptable and unsafe and that the pilot should not be flying without further instruction. It is extraordinarily rare, but a CFI may have a student that the CFI feels cannot learn to fly. It is a part of the instructor's primary responsibility, that of the best interest of the student. The appropriate step is to have the student fly with another instructor, as the problem may just be the dynamic between the student and instructor. However, once the CFI has gotten a second opinion, the CFI may be faced with the unpleasant task of telling a student that the student should take up another line of endeavor. If it is a rated pilot, the instructor must be honest with the pilot regarding the objective evaluation and suggest a flight with a different instructor. If the pilot refuses, and the instructor feels that the pilot is unsafe, the next step is to go to the FAA and tell an inspector. In my life I have known two pilots who I honestly felt were so unsafe that they were a threat to themselves. In one case I expressed my opinion to the pilot (he blew me off); in the other I did not. In neither case did I go to the FAA. Both killed themselves in airplanes. To this day I feel that I did not live up to my obligation to either of them. 10. An instructor has a duty to be an advocate for the student. The need for that may not arise; however, if it does, the instructor should always stand up for the student in an honest fashion in dealing with the FBO management, FAA, insurers or others. It also means encouraging the student when a lesson has not gone well. Sometimes lessons do not go well, but that it does not mean the student cannot become a pilot. It may mean telling a spouse that the student is flying in a safe and responsible manner, if it is true. (Being an advocate does not mean lying for a student at any time). 11. An instructor has a duty to demand the best of the student, to keep the student working right up to the edge of their ability. It means recognizing that, by federal law, the Federal Aviation Regulations are "minimum standards," as are the standards set in the practical test guide. Therefore, the CFI has a duty to train the student to a level the CFI considers to be appropriately above that of the FAA minimum standards, because good CFIs know what the real world is like and the student must be prepared for flying in the real world, not just going for a checkride. 12. An instructor has a duty to never, ever enter into an intimate or sexual relationship with a student while the instructor-student relationship exists. On one level it is simply unprofessional; on another it is invariably counterproductive to the student's progress. The tutor-student relationship can generate a close relationship because of the psychological factors of trust involved, as well as the fact that the instructor seems to the student to know everything about the subject and thus can become very attractive to the student. Putting a personal relationship or sex into the instructor-student equation does nothing positive for the student and almost invariably has negative results. If the teaching relationship appears to be moving to something closer than a handshake at the end of each lesson, the instructor has a duty to call a halt to everything, sit down with the student and discuss precisely what is going on. If the two of them decide that the relationship should become intimate, then it is the duty of the instructor to find another instructor for the student. The instructor cannot disregard the duty to the student for the learning process. I have seen two situations where a student and instructor realized that things were progressing on a personal level. In both cases the student changed instructors. In both cases the student and instructor eventually got married (and, happily, still are). In both cases, the student finished her flight training and obtained her rating. Yes, wives have taught husbands how to fly and vice versa. However, the intimate relationship was established prior to the flight instruction relationship. (And, in many cases, the result was a strain on the marriage and problems with the rate of progress of the student in the training relationship.) 13. An instructor has a duty to set a good example at all times. The CFI can preach safety and checklists and appropriate behavior to students but then can destroy all of the teaching the first time a student sees the CFI operate an airplane contrary to the teaching. 14. Finally, an instructor has to recognize that occasionally there are personality conflicts between an instructor and student. While the situation is pretty rare and an instructor who has a professional attitude can overcome most minor difficulties, from time to time things simply do not click and the two cannot get along. Unresolved personality conflicts always adversely affect the student's progress. If the situation develops, the instructor should never take it personally, but should simply arrange for the student to fly with another instructor. Sometimes a student who is having a great deal of trouble getting along with his or her instructor may be reluctant to say so. The student will either not do well during training or may just quit flying rather than address the issue openly with the instructor or the instructor's boss. It is the instructor's duty to be sensitive to the situation and politely inquire, and then take appropriate action as a professional. (Often the situation means that the instructor does not particularly like the student; nevertheless, the CFI has an obligation to set up the student with another instructor and not speak ill of the student so as to avoid tainting the new CFI-student relationship.)
Expectations of Students[IMGCAP(4)] As I was making notes about what a student should be able to expect from a flight instructor, I realized that the tutoring relationship works both ways. The student has duties as well. The instructor has a right to expect certain things from a student. 1. Students have a duty to show up on time for their lessons, and to expect to pay for the lesson time that was set aside, even if they are late. The instructor has dedicated a certain period of time exclusively to the student and should not be penalized for the student's tardiness. 2. A student has an obligation to call and cancel a lesson as soon as the student knows it's necessary. If the cancellation occurs within some previously established period of time before the lesson, the student should pay the instructor's fee for the lesson, or at least a full hour of instructional time, because there is a significant risk that the instructor cannot fill that time on short notice and is otherwise not going to get paid. Not all things in aviation have gotten more expensive; flight instructor incomes have not kept up with the rate of inflation. If flight instructors were being paid today what they were paid in 1978, allowing for inflation, they would be making between $40 and $65 per hour of instruction. Therefore, having a student stand up the instructor hurts a person who is not well compensated to start with right in the wallet. 3. A student has a duty to pay for each lesson as it takes place, or to pay in advance. A flight instructor is not a bank and should not be making no-interest loans to students by having to wait to be paid for services rendered. Good grief, the student has to pay for the maintenance on his car when they pick up the car (and it's a lot more expensive per hour than a CFI charges), so the student should not quibble about paying for flight instruction when it is received. If a student does not pay at the time of a lesson, it should be paid prior to taking the next lesson. 4. The student has a duty to show up prepared for each lesson, having read any material assigned and ready to learn. The instructor is not a babysitter or someone who is to read the assignments to the student. (Unless the two of them agree to go about it that way and the student understands it is going to radically increase the cost of learning to fly.) 5. A student has a duty to ask questions about anything confusing, even if it seems off topic. It's an essential part of the learning process. Attempting to hide ignorance about a subject or concept is invariably wrong in a learning environment and tends to have a snowball effect. Ignorance about something is never, ever, a sign of weakness or stupidity; it just means that the student has not been introduced to it. (Ignorance is never an insult; it is just a lack of exposure to something.) Learning is the process of reducing one's degree of ignorance of the subject and is fostered by honestly asking questions about things one does not know or understand. The questions themselves also do a great deal to help the instructor tailor the teaching that will occur because it tells the instructor a lot about the boundaries of the student's knowledge and experience as well as how the student thinks and learns. 6. A student has a duty to tell the instructor when there is a level of discomfort with any aspect of the flight training process. From the most basic, "I think I'm going to be sick" in turbulent air, to, "For some reason I don't seem to get along with you and I'd like to fly with a different instructor," and all points in-between. The student bears responsibility for that side of the learning relationship and, in order to learn most efficiently, and not waste hard-earned money, must speak up when something is bothersome so the instructor can do something about it. An uncomfortable student does not learn well; any instructor worth his salt knows that; but, to my knowledge, most CFIs are not clairvoyant, so it's up to the student to speak up about discomfort. No matter how it is approached, learning to fly is hard work at any level, whether for a brand-new student pilot or someone finishing up the ATP rating. The student and instructor have duties and responsibilities to each other and themselves in the process to make it go as smoothly and efficiently as possible. By the way, when Tom went down the hall to express himself to the manager of the FBO, it worked. He was immediately assigned to a different instructor (and flew that afternoon). About two weeks later he passed his checkride. I've heard he's looking to buy an airplane. I've also heard that the manager is helping Tom find an airplane and has already introduced Tom to the maintenance director. I don't know what the manager said to the CFI, but I've heard he hasn't cancelled any lessons recently. See you next month.
Want to read more from Rick Durden? Check out the rest of his columns. -->
Corrosion ControlSome parts of the country are much worse than others, but we all have to know about corrosion. Click here to read this maintenance article. are surface-etch corrosion, pitting, and exfoliation, which we will describe later on. However, there are also forms of corrosion that can occur more rapidly, such as stress corrosion cracking, environmental hydrogen embrittlement, and fatigue corrosion. These latter forms are influenced by both chemical and mechanical aspects of the environment, and can cause catastrophic structural failures without a great deal of warning.
Oxidation[IMGCAP(4)] One of the most common gradual types of corrosion you will encounter is atmospheric corrosion, sometimes called oxidation. Whenever a metal is exposed to any gas that contains oxygen atoms along with atmospheric moisture, a reaction occurs. Two atoms from the metal join with three atoms of oxygen to form an oxide. How serious is this type of corrosion? It depends on what type of metal is involved. When an aluminum surface is involved, the corrosion by-product is aluminum oxide. Once the layer of aluminum oxide film is formed, it provides an easily penetrated barrier between the aluminum surface and oxygen elements. Further deterioration can continue under the oxide layer, but at a reduced rate. Unfortunately, the surface oxidation may mask a serious level of corrosion going on below. A number of different aluminum alloys are used on a typical plane, and they have differing susceptibilities to corrosion. Never trust an oxide film to protect aircraft components from further deterioration. There is a form of oxide film that forms very tightly bound to the surface of some metals. It creates what is called a passive film. Stainless steel and titanium are also examples of such metals. Once formed, further deterioration is stopped unless the film is broken. Unfortunately the film is all too flimsy to provide useful self-limiting. Pure aluminum is very resistant to corrosion but not strong enough to be used in any structural capacity. It is used on sheet metal as a very thin coating called cladding, but it is easily broken through to the less corrosion-resistant structural component of the sheet without extra care. Careless use of a machine buffer can even go through cladding, as can minor scratches. When an iron surface is involved, the corrosion by-product is iron oxide, which we all know as rust. Rust never sleeps, and the iron oxide forms a porous film that cannot seal out the oxygen. The reaction between the surface and the oxygen will continue until the metal is completely eaten away.
Surface Etch[IMGCAP(5)] General surface-etch corrosion is a very common type of corrosion encountered in the aviation field. This occurs when an unprotected metal surface is exposed to a corrosive atmosphere such as exhaust fumes, salt air, industrial contaminants, or acidic fumes (like those found in your aircraft's battery box). The exposed surface takes on a uniform, dull appearance caused by microscopic amounts of salts being formed. If these salts are not removed and the surface is not treated to prevent further decay, this type of corrosion will reach the next level, known as pitting, which can be deceptively destructive. When surface-etch corrosion is left to have its own way, pits will form in localized areas. In its early stages, pitting makes its presence known by producing small clumps of white powder on the surface. In its later stages, it can be detected by using a small flashlight to shine light through the holes in the surface of the metal.
IntergranularArguably, one of the most insidious forms of corrosion is intergranular corrosion. It is often difficult to detect, and can be enabled by the heat-treating procedure used during manufacture of the metal when the treatment is not done properly or there is a subsurface flaw that can cause substantial weakening of the part in service to where it can fail. In the heat-treating process, metals are heated to a temperature at which the alloying agents blend into solution with each other. After the solution has reached a uniform temperature throughout, the metal is removed from the furnace and immediately quenched to solidify the elements into extremely small grains. If the quenching process is delayed, even by only a few seconds, these grains will grow. When finally quenched, they may have grown to such a size that areas of dissimilar metals can provide cathodes and anodes for the formation of corrosion. If -- through a scratch, gouge, or pit -- an electrolyte is allowed to reach the boundary layer between the grains, the corrosive action can continue inside the metal. Another cause of grain enlargement, and hence, intergranular corrosion, can be found from imperfect electrical welding on steel or 6061 aluminum. Beneath the surface of a weld, small blisters may form during the welding process. The surface over these welding blisters is very thin and can be picked open with a knife or an awl. When the blister is opened you'll find a small depression containing the salts of this type of corrosion. Aluminum alloys 2024 and 7075, which contain appreciable amounts of copper and zinc, are especially vulnerable to intergranular corrosion if quenched improperly during heat treatment. Once intergranular corrosion reaches the point at which the metal is starting to delaminate, it is called exfoliation corrosion. The delamination of the metal occurs along the grain boundaries in the material. Here again, aluminum forgings and extrusions are especially prone to attack due to grain structure.
Galvanic and Intergranular[IMGCAP(6)] Galvanic corrosion, also known as dissimilar metal corrosion, can occur any time two requirements are met: Two or more dissimilar metals must be connected in a manner that provides a path for the flow of electrons, and their common surfaces must be covered with a form of electrolyte. It can be easily recognized by the buildup of corrosion at the joint between metals. Want to see a good example of this? The next time it rains, go out and look at your aircraft's wing. You'll find steel screws attaching aluminum inspection panels to an aluminum wing covered with water. A similar situation can be found where a stainless steel firewall is riveted to an aluminum fuselage skin. Throw in a couple of minor exhaust leaks and maybe a small oil leak or two to help trap and hold dirt, and you have a wonderful environment in which corrosion can occur. It almost sounds like the germ theory of disease. Another close relative of intergranular corrosion is stress corrosion cracking. It occurs when a metal under tensile stress is subjected to a corrosive environment, and may be caused by internal or external stress. As with intergranular corrosion, the stress can be caused by improper quenching after heat-treatment, or uneven deformation during cold working. Parts that have an interference-fit -- such as the bushings in a landing-gear strut housing -- can also cause it. Susceptibility to cracking increases with stress and if a crack does occur, it will grow rapidly because the corrosion attacks the end of the crack more so than the edges.
Oxygen-Concentration CellAnother sneaky form is oxygen-concentration cell corrosion. It has three basic forms. Oxygen concentration cell corrosion can develop anywhere where the oxygen in the air is prevented from diffusing into contact with the metal surface. Typical locations are under deposits on the metal, either organic or inorganic, and under faying surfaces such as riveted lap joints so common on aircraft. These concentration cells can also develop under gaskets, wood, rubber or other materials in contact with the metal surface. The low oxygen concentration forms the anode. Active-passive cells are the second type. Metals such as some stainless steels depend on a tightly bound passive-film adhering for oxidation prevention. If a deposit forms in the presence of water, an oxygen cell is created. The passive film is then broken beneath the deposit and corrosive attack and rapid pitting occur. Metal-ion concentration cells, the third type, usually consist of water and ions of the metal in contact. The higher concentration of metal ions forms the cathode, and can be found under faying surfaces where the solution is stagnant. A low ion-concentration will exist (anode) adjacent to the crevice created by the faying surface and corrode.
Filiform[IMGCAP(3)] Filiform corrosion is a special form of oxygen-concentration cell corrosion that occurs on metal surfaces having an organic coating system (such as paint). It is very easily recognized as a wormlike trace branching out in all directions under the paint film like varicose veins. Polyurethane paint does not breathe and is particularly good at promoting filiform. Fortunately, the new primer systems when applied properly largely eliminate the problem, but proper application is key. Filiform corrosion occurs at high humidity and with a slightly acidic surface condition as promoted by polluted air or industrial environments. It occurs at micro breaks in the paint system and diffuses under the surrounding area. Filiform is particularly damaging to aluminum, but can also occur on steel. Don't be misled into thinking this is somewhat self-limiting because it's under the paint. If filiform is not removed promptly, it can progress to intergranular corrosion, especially around fasteners and seams. If the corrosion traces cross, you will be surprised by how deep the problem is in the metal. Storage in an environment below 70 percent humidity, keeping surfaces washed to preclude acidic surface contaminants, and using properly matched paint/primer systems are all helpful.
Fatigue and FrettingFatigue corrosion is a double whammy of cyclic stress and corrosion, and no metal is immune from its effects. Damage is greater than either corrosion or cyclic stress taken separately. Fatigue corrosion occurs in two stages. First, the combined action of corrosion and cyclic stress causes pitting and crack formation. At this point even the removal of the corrosion will not prevent further damage from cyclic stressing (second stage) until fracture ultimately occurs by crack propagation, often from a simple pit in the metal. The fracture of a part undergoing corrosion fatigue (even a relatively small area) will occur at levels far less than the normally expected fatigue limit. This makes protection of parts subject to cyclic stress especially important, particularly in even mildly corrosive environments. Another common one on our list of bad guys is fretting corrosion. Have you ever noticed those "smoking rivets" on some airplanes? Congratulations! You have just identified fretting corrosion. It happens when two surfaces are held tightly together but can still move relative to one another -- even ever so slightly. This, of course, allows the surfaces, and in some cases the fasteners, to wear. These surfaces generally are not held close enough together to keep out oxygen. The oxide film is destroyed just as rapidly by the rubbing action of the two surfaces. If all that isn't bad enough, when this type of corrosion is started, the movement between the surfaces is too small to allow the powdery deposits to escape, and they act as an abrasive to further accelerate the damage. As far as corrosion is concerned, this type could be considered the active pilot's worst enemy. The more you fly your plane, the faster this type corrosion will progress. Loose and "working" rivets can be "reset" and the joint held tighter, but once the corrosion starts, it won't stop, so beware the "smoking rivet." Environmentally induced hydrogen embrittlement is the result of hydrogen damage rather than oxidation. Atomic hydrogen is present in many electrochemical reactions, and can very easily diffuse into clean metal and migrate to spots where it can react to later form cracks. This is particularly true in high-strength alloys that are statically loaded.
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. -->
AVmail: Apr. 23, 2007Reader mail this week about FSS closures, medical certificate duration, user fees and more. Click here to read this week's letters to the editor.
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Sun 'n Fun Podcasting Round-Up
As we pack up and head home from the 33rd Annual Sun 'n Fun Fly-In in Lakeland, Florida, let's take a moment to recap the six exclusive audio interviews we turned into webcasts during the show. Here's the checklist, in case there are any you've missed.
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| FBO of the Week | back to top | |
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FBO Of The Week: Augusta Aviation
Nominate an FBO | Rules | Tips | Questions | Winning FBOs
AVweb's "FBO of the Week" ribbon goes to Augusta Aviation at KDNL in Augusta, Ga.
AVweb readers Jim and Karen Lindemulder says the FBO owners went out of their way to help them. "Good Friday evening our Skylane experienced multiple instrument failures while flying over Georgia. Control vectored us to Daniel Airport for assistance, where we were met on the ground by the smiling faces of Sherrell and Steven Gay of Augusta Aviation. The Masters Golf tournament was in progress and every hotel and rental car was taken. There were no mechanics available at the late hour and we considered a ferry flight to another facility, but Sherrell could tell by my wife's face that we really needed a night on the ground. She made many personal phone calls and located the last room available 35 miles away and gave us their own truck to get there. When we returned in the morning, their mechanic had already checked out our plane and determined the pitot heater was not working well and allowed ice to form in the lines. We were gratefully humbled when we were told that there was no charge for any of the services, even though we did not buy fuel. We will definitely stop to see them whenever passing through!"
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! |
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Sun 'n Fun Video Round-UpRecommend a Video | VOTW Archive
This week, we're taking a brief hiatus from reader-recommended videos to point out two videos produced on-the-fly (and largely on-the-run) by AVweb's Glenn Pew over the last couple of days at the Sun 'n Fun Fly-In in Lakeland, Florida. We shot quite a bit of video at the show, so look for more original video content here on AVweb in the next few days. For now, here are a couple of short clips that set the tone for our adventures in vodcasting at the Fly-In:
Would you like to see more original video content from AVweb? Do you an idea that would make a great video? Let us know. |
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| The Lighter Side of Flight | back to top | |
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Short Final
After 10 years of flying a Twin Comanche, I upgraded to a Beech Baron. With the Beechcraft Pilot Proficiency Program in Lakeland, Fla. under my belt, I advanced the throttles on my first PIC flight into Orlando airspace. Me: Orlando Approach, Baron Eight Two Four just off Lakeland, five miles to the east, out of 1,200 for 3,500. Would like to coordinate a Class B entry en route to New Smyrna Beach, VFR. Approach [in a classic southern drawl]: Baron Eight Two Four, this is Tampa Approach, and if you don’t call us Orlando, we won't call you a Piper. Squawk two seven three zero and ident. |
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Meet the AVwebFlash Team
AVwebFlash is a twice-weekly summary of the latest news, articles, products, features, and events featured on AVweb, the internet's aviation magazine and news service.
Today's issue was written by Contributing Editor Russ Niles (bio) and Editor In Chief Chad Trautvetter.
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