Friday, August 29, 2014

Blog #3; Addition to Chapter 21 and AD #13, Review http (link) in citation for an interesting review on tolerated fatigue damage

         
 Articles

           Article 1: If you wish to view a great free article; copy the following link, paste it in your browser and enjoy. http://www.skybrary.aero/index.php/Ageing_Aircraft_-_Structural_Failure

           Article 2: Enclosed is a pretty impressive article on how we live with structural fatigues and damages to our aircraft. Follow along with the author Jaap Schijve by highlighting:  http://ac.els-cdn.com/S0142112308001461/1-s2.0-S0142112308001461-main.pdf?_tid=49af11ea-2fe1-11e4-b9f1-00000aab0f01&acdnat=1409360717_363e7907ce7a35b3b440ca7e8ffd8204. Its going to ask you to purchase but if you log on to ERAU, you will be able to view in the Hunt Library. 
     
Reference

Schijve, J. (2008, April 28). Fatigue damage in aircraft structures, not wanted, but tolerated?. International Journal of Fatigue, 31(6), 998-1011. Retrieved from http://ac.els-cdn.com/S0142112308001461/1-s2.0-S0142112308001461-main.pdf?_tid=49af11ea-2fe1-11e4-b9f1-00000aab0f01&acdnat=1409360717_363e7907ce7a35b3b440ca7e8ffd8204

SKYbrary.aero. (2014, April 1). Ageing aircraft - structural failure. Retrieved from http://www.skybrary.aero/index.php/Ageing_Aircraft_-_Structural_Failure

Blog #3; Chapter 21 review and Air Detective Tip #13



            For this week blog, I have been tasked with choosing one of the chapters out of my text book titled: Aircraft Accident Investigation, second edition, written by Richard H. Wood and Robert W. Sweginnis. Also, I have to discuss air detective tip #13 and post a relevant article on my subject.  For this task I have chosen to discuss chapter 21, Operations and Maintenance. This chapter is very interesting because the analytical aspect and comparisons of my subject, Structural Failures.
             
            This chapter is broken down into three subjects and the authors surmised, Wood and Sweginnis (2006), “MAN-MACHINE-MEDIUM approach” (p. 165).  Each of these areas covers different analytical aspects of an aircraft mishap investigation. Under the first part “MAN,” it takes a deep look into the certification/qualifications of all aircrew that were aboard the aircraft at the time of the accident. “MACHINE,” breaks down the facilitated maintenance plan of the aircraft, the state of the aircraft and where it was worked on before the accident.  Finally, “MEDIUM” is split into two areas of concern, operations; who and how the pilot flew and operated the aircraft, while maintenance covered the initial status of the aircraft before the accident (Wood & Sweginnis, 2006).  

Operations
             
            At first, the inspector needs to gather all the information off of the important documents. These documents would include licenses, medical certifications and if applicable, logbook. Since these are labeled as perishable items, they need to be collected as soon as possible. Other items for collection could include but not limited to: flight manuals, plans, check-lists, charts and maps. All of these collected items could help paint a picture for the investigator as to how the pilot was physically, overall experience and if he or she was actually qualified to operate and fly that aircraft (Wood & Sweginnis, 2006).

Procedures
             
            Every company has a set of protocols that spells out what and how the pilot will be operating the aircraft. With this they are able to track, follow and train their pilots to ensure that they stay current in Federal Aviation Agency (FAA) guideline. But, not all companies follow these regulations and might have become indolent. As a mishap investigator, areas of focus need to be in the following areas: training and competency, flight data, communication and summation of the flight history that took place (Wood & Sweginnis, 2006).
           
            Training and Competency.  Everything is dependent on how the aircraft was actually operated. If the pilot was operating the aircraft for company transport or commercial paints a good picture. All pilots should be current and in compliance with both company training regulations and Federal Aviation Agency (FAA) training requirements. Investigators should look up previous grade sheets from simulator training and instructor pilot remarks. While doing this, the instructor could be asked for a better understanding of the pilot’s overall competency to operate the aircraft. Without the help of the instructor, most companies do not keep logs or records of all their pilots’ competency reports (Wood & Sweginnis, 2006).
             
            Flight Data.  Determining the load plan of the aircraft needs to take place. Investigators can collect the flight manifest of the passengers and cargo on the plane and statements from the ground crew who actually loaded the aircraft. By doing this, the gross weight (GW) and center of gravity (CG) can be calculated. Once calculated, it can be determined if it’s a causal factor of the accident, it would back up why the aircraft crashed shortly after takeoff. If not, one can assume that the load plan was within limits (Wood & Sweginnis, 2006).  

            Now that the load plan is determined, the file flight plan from the FAA can be copied. Air-to-ground communications can be factored as to where the plane was going, deviations from the flight plan, and what GPS system was utilized. A step by step approach can be determined of the course of action the pilot lead the aircraft on (Wood & Sweginnis, 2006)

            Communication.  Transcripts from the FAA can be obtained to determine any causal factors. Different frequencies could have been utilized and so a review of all relevant ones will be necessary. Also a copy of the tape can be obtained to see if any other noises or data was transmitted before/after the transcript took place. It might be strange to think that all this in necessary but to a trained ear, it can paint a clear picture of the situation. But, the FAA has all their tapes on a 15 day cycle and so you have to request hastily otherwise the tape could be recycled. Tapes and transcripts allows for a pretty accurate timeline because every time the pilot keyed their microphone, its recorded based on time (Wood & Sweginnis, 2006)

            Flight History.  Under the active operation investigation, a detail flight history of the accident is created to be submitted into the report. All the facts gathered from the beginning of the flight to the accident are logged in chronological order with the help of all other investigators. This detailed flight history is only of actual facts and not the detailed analysis that one might think it’s used for (Wood & Sweginnis, 2006). 

Maintenance

            The maintenance of the aircraft is paramount when determining the causal factors of the mishap. A thorough investigation of the life of the aircraft is going to be conducted to figure out if it complied with the strict requirements of the FFA and manufactures maintenance protocols. With this, applicable service bulletins and directives will need to be gathering from the manufacture and FAA. Going through the aircraft data book will depict the maintenance that was conducted on the aircraft in a detailed chronological listing (Wood & Sweginnis, 2006).

Aircraft Specifics

            Aircraft Titles.  A title search is paramount just like requesting a Carfax on a used car. This will determine if the aircraft has changed hands over time. The title and serial numbers are the only important data to research because registration numbers changes over the course of its age. The FAA can assist with the search to determine the aircraft's lifespan and can look up if all service directives and bulletins have been complied with because that is a mandatory reporting procedure to the FAA (Wood & Sweginnis, 2006)

            Data Books.  Next all of the data books, service records and logs will need to be collected and gone through. This will determine if required airframe inspection and maintenance intervals were complied with. Engine logs will have entries of all hourly inspection intervals conducted, rework, repair and modifications performed. Shop service records or aircraft discrepancy books will have all the daily maintenance performed on the aircraft logged. Here any major structural, hydraulic, or corrosion discrepancies will be annotated and either be job complete, awaiting parts or awaiting further re-work. These work orders will paint a clear picture of the airworthiness, overall condition and life of the aircraft (airframe). In my previous blog, I covered the general inspections of the type of materials utilized and the effects of corrosion degradation. Included with the data books are also going to be the most up to date weight and balance of the aircraft too (Wood & Sweginnis, 2006)

            Reports.  Mandatory reporting of serious malfunctions, discrepancies or defects must be reported to the FAA, in the United States. In the Service Difficulty Reports (SDR), which is maintained by the operator with a filed copy to the FAA, is logged on the aircraft specific serial number.  In accordance with Wood and Sweginnis (2006), “In the United States, the FAA maintains two computer files that are accessible and potentially valuable to the aircraft accident investigator” (p.168). The two files are Accident/Incident files which covers if the aircraft was in a reported accident and the SDR files covers any logged incidents or component failures. SDR files are viable even though only an average of 15% gets reported (Wood & Sweginnis, 2006).

            Maintenance Outsourcing.  As the aviation industry continues to grow, maintenance outsourcing has been a problem because owners of the aircraft usually don’t perform their own maintenance. If the respected aircraft needed some type of maintenance to be performed such as an engine overhaul, the aircraft would be brought to that respected profession. From the beginning till now, licensed Airframe and Power-plant (A&P) mechanics have performed the maintenance on any type, model or series of aircraft. If in individual possessed an A&P license, it was good for their entire life time and that is where the problems began because there is no way a mechanic can stay current on all aircraft (Wood & Sweginnis, 2006)

            Aircraft mishap began to occur and still occur due to maintenance outsourcing. It’s a traceable accident that the FAA has kept an eye open for. Items such as wrong parts installed, incorrect maintenance procedures/inspections, and rush maintenance are to blame. To help with the overwhelming issue the FAA foresaw, all major inspections and overhauls must be accompanied by the operator of the aircraft to ensure that the stringent maintenance procedures are adhered too, otherwise the FAA will hold the operator responsible for any complaints or accidents. The FAA released a statement back in 2004, that the authors Wood and Sweginnis (2006) stated, “Air carriers do not lose responsibility for their independent contractors’ regulatory violations simply because the independent contractor is independently certificated by the FAA” (p. 169). Since this is a global issue, agreement on maintenance standards should be standardized on who will be providing the certification, inspections and overall enforcement of all maintenance. Outsourcing is here to stay and will not be going anywhere, anytime soon (Wood & Sweginnis, 2006)

Air Detective Tip #13

            Basically, the air detective tip #13 is in direct correlation to chapter 21 that I surmised above. It gives a detailed checklist of all the items that an investigator will need to collect from the accident site, FAA and National Transportation Safety Board (NTSB). The investigator will need to read, interpret them and secure them so that no others could possibly be tampered with.  These items collected will help figure out what the cause of the accident might have been and could possibly lead up to preventing further accidents from this cause (Lawin). 

References

Lawin, R. (n.d.). Air detective tip 13 for aircraft accident investigation. Retrieved from https://erau.blackboard.com/bbcswebdav/pid-15078061-dt-content-rid-29793014_4/institution/Worldwide_Online/SFTY_UG_Courses/SFTY_330/Air_Detective_Tips/AirDetectiveTip13_0911.pdf 
Wood, R., & Sweginnis, R. (2006). Aircraft accident investigation. (2nd ed., pp. 165-169). Casper, WY: Endeavor Books.




Thursday, August 21, 2014

Week 2 Blog; Why did I chose this topic, brief history and the beginning of my research

      The question as to why I choose this topic? I decided to do a research paper on structural failure because it is an area that I have been working in for most of my adult life. It’s an area that I like to study and because of that, I am a sought after Marine in this field at work. In a squadron, I am considered a resident expert and thrive to constantly be on the top of my game.

                                                  History of Aircraft Structures

      Structural failures are an interesting topic because without a sound structure, flight wouldn’t be possible and where would we be today? When breaking down the aspects of heavier-than-air flight, aerodynamic lift has to be generated and this is usually accomplished by wind rushing over a wing. To get us where we are today, early inventors experimented with such contraptions as kites, gliders and airplanes. Without the wind, kites and gliders are rendered useless since their main sustainment of lift is wind. Airplanes on the other hand utilize a means of propulsion to propel them through the air causing wind to generate lift as it rushes over the wings (Bell, 2014).

      The history of the general construction of an aircraft and associated components throughout history has been comprised of various materials. Aviation pioneers had to utilize wood as the main component in making their aircraft as they were testing their theories. Heavier-than-air flight was achieved by the Wright Brothers in 1903, when their powered aircraft carried a man aloft and it was only comprised of wood truss structure and thin fabric covered wings. Over the next few years, engine development greatly advanced with more powerful and reliable models that in 1910, Hugo Junkers; a German inventor developed a metal constructed aircraft. This aircraft, called the J-1was constructed with metal trusses and the skin wrapped metal as well. The combination of both a powerful engines and metal construction eliminated the need of stacked wings and a monoplane was developed without the need of wires and wing braces (Federal Aviation Administration, 2012).

      By 1926, semi monocoque construction took hold, resulting in stronger and bigger aircraft. The principle behind this construction is instead of having a skeleton structure that the skin was attached and stretched over, only partial structures would be utilized with reinforcing bulkheads and much of the load would be carried with the skin. These reinforced bulkheads would help carry the associated stresses of flight. Using this structure allowed the aircraft to remain light, with powerful engine that eventually lead to the development of plastics (Flannigan, 2010).

      Now plastics are not strong enough to support the structure of an entire aircraft that researchers found out but could be used for smaller components and hence, glass fibers was developed to be better known as fiberglass. Owens Corning, in 1935 developed the first fiberglass that when combined with a product such as a plastic polymer could create a lightweight and strong structure. This development is still used today in an industry known as FRP, Fiber Reinforced Polymers (Jones, 2013).

      World War II created supply and demand for military aircraft to be lightweight and through further development, Radomes were developed. Radomes are utilized to shelter major electronic components as the structure of the radome is fiberglass and has a transparent quality for radio frequencies. With this breakthrough, the composites industry took a giant leap from scientific research working in laboratories with models and scientific studies, to being full scale production. In 1946 the first composite boat hull was develop and now both the marine and aviation industries benefited from their further research. In the industry today, composites lead the way with the development of carbon fiber, Aramid, Kevlar and graphite composites (Federal Aviation Administration, 2012).

      Structural failure contributors Structural failures have been long associated with the individual metal components or complete structures of an aircraft. An aircraft when assembled already has weakness incorporated into them that the manufacture might not associate with. These components will begin to weaken at these points when imposed stresses are acted upon each part during operation. The following are stress prone areas that have the most concentration of structural failures (Bell, 2014):

      1. Manufacturer design flaws or machining errors that leave the small imperfections, e.g. holes, burrs, voids, notches and in the forming processes, tight fillet radii.

      2. Metal extruded parts might have the same associated flaws during their manufacturer processes that could leave inclusions, pitting, voids etc.

      3. From production to service life, corrosion is ever so prevalent that companies pay workers to combat the ongoing spreading of corrosion. Different types of corrosion that cause structural failures are: Uniform attack corrosion, localized corrosion (pitting, crevice, and filiform corrosion), galvanic corrosion, environmental cracking, flow-assisted corrosion, and fretting corrosion.

      4. In-flight

                                                  What does all that mean?

• Uniform Attack Corrosion: Most common associated form of corrosion that occurs when a chemical reaction to the entire surface of the metal component occurs. The entire exposed surface will corrode to the point of failure. This form does cause the most corrosion of metal components, but it easily overcome since it predictable, preventable and manageable.

 • Localized Corrosion: Targets specific metal components in one of three types: pitting, crevice and filiform corrosion.

 • Pitting: Pitting is formed by cavities or small holes in the metal that create a galvanic environment making it hard to detect.

• Crevice Corrosion: Just the same as pitting corrosion but with the inhibitor of mirco-environment sitting stagnant. This micro-environment can be found where gaskets, clamps and washers are utilized.

• Filiform Corrosion: Water is the culprit with filiform corrosion. It’s caused when painted or plated surfaces begin to erode and water intrudes behind them.

• Galvanic Corrosion: When two dissimilar metals are mated together with each other to cause a corrosive electrolyte. Of the two metals, each takes a separate roll of anodes and cathodes. To create a galvanic corrosion environment, three conditions must be met:
  
      1. Two dissimilar, electrochemically metals must be present.
  
      2. Metals must be electrically contact as whatever point.
  
      3. An electrolyte must be present and exposed to the metals.

• Environmental Cracking: Environmental conditions against the metals.

• Flow-Assisted Corrosion: Erosion from flight or being susceptible to the environment when rain and wind wear down the outer layers, exposing the metals.

• Fretting Corrosion: Constant repeated wear from the aircraft's weight or vibration from flight. When looking at all of this as a big picture, an investigator during a mishap investigation would be using pretty much any air detective tip to help solve and determine what caused the mishap in the first place.

      When a structural mishap occurs, investigators will be looking at all aspects of every piece left of the aircraft. If corrosion was evident, one might suspect the overall maintenance of the aircraft could have been in jeopardy. The SHELL concept could be a great detective tip to utilize because the investigator could compare the Liveware (human) and the factors associated with the aircraft. The accident in general could have been associated with the maintenance malpractice of the maintainers concluding the interface of the pilots not knowing that their aircraft was susceptible to structural failure.

                                                    References

Bell, T. (2014, January 14). Types of corrosion: What are the different types of corrosion?. Retrieved
      from http://metals.about.com/od/metallurgy/a/Types-Of-Corrosion.htm

Federal Aviation Administration (2012). Aviation maintenance technician handbook. (Vol. 1, pp.
      21-75). Oklahoma City, OK: United States Department of Transportation, Federal Aviation
      Administration, Airman Testing Standards Branch. Retrieved from http://www.faa.gov
      /regulations_policies/handbooks_manuals/aircraft/amt_airframe_handbook/media
      /amt_airframe_vol1.pdf

Flannigan, P. (2010, January 19). Semi monocoque, mono-what?. Retrieved from
      http://www.aviationchatter.com/2010/01/semi-monocoque-mono-what/

Jones, T. (2013, August 10). Owens corning records , 1938 - present . Retrieved from
      http://www.utoledo.edu/library/canaday/findingaids1/MSS-222.pdf

Thursday, August 14, 2014

Blog Creation

This Blog was created to bring you, the reader, into the light of aircraft mishaps that are caused by structural failures. I will be exploring different aspects of aircraft structures and their associated risk factors of each material associated with making them, such as; composites, fiberglass and metals structures. Through detailed research, I hope to captivate you and that you will enjoy my posts through the following weeks. Thank you, Chris