Aircraft Systems Field Investigations
Aircraft Systems Field Investigations
Overview
This area of your fieldwork investigation covers aircraft systems investigative techniques. For the purpose of this course, aircraft systems are categorized as propulsion systems, aircraft systems, and cockpit instruments. Propulsion investigation encompasses reciprocating engines, turbine engines, and propellers. Aircraft systems are generally categorized as electrical, hydraulic, pneumatic, fuel, mechanical, fluid transfer, and miscellaneous systems.
Aircraft system investigation can be a long and tedious process, especially depending upon the level damage and ability to recover sufficient wreckage debris specific to each system. Barry Holt, Western Region Senior Technical Investigator with the Transportation Safety Board of Canada and David Fisher, Manager, Air Safety Investigations with Commercial Aircraft, Bombardier Air Safety Investigation wrote an interesting piece titled Managing a Complex Aircraft Systems Investigation (PDF)/isasi.org their challenges investigating the landing gear collapse upon landing, of Jazz Aviation Flight 8481, which occurred on November 6, 2014. Also representative of the complexities of investigating systems failures in complex accidents, were the wreckage retrieval and investigation of Trans World Airlines (TWA) Flight 800 and COPA Airlines Flight 201.
TWA 800, a 747 heading from JFK to Charles DeGaulle International Airport, Paris, France, broke up with explosive forces midair on July 17, 1996, spreading wreckage debris over a vast area of the Atlantic Ocean near East Moriches, New York and killing all 230 occupants. TWA flight 800 was operating under the provisions of 14 Code of Federal Regulations Part 121 as a scheduled international passenger flight from John F. Kennedy International Airport (JFK), New York, New York, to Charles DeGaulle International Airport, Paris, France. The airplane itself was destroyed by the explosion, breakup and impact forces, and fire.
According to the National Transportation Safety Board (2000, p. xvi):
The probable cause of the TWA flight 800 accident was an explosion of the center wing fuel tank (CWT), resulting from ignition of the flammable fuel/air mixture in the tank. The source of ignition energy for the explosion could not be determined with certainty, but, of the sources evaluated by the investigation, the most likely was a short circuit outside of the CWT that allowed excessive voltage to enter it through electrical wiring associated with the fuel quantity indication system. Contributing factors to the accident were the design and certification concept that fuel tank explosions could be prevented solely by precluding all ignition sources and the design and certification of the Boeing 747 with heat sources located beneath the CWT with no means to reduce the heat transferred into the CWT or to render the fuel vapor in the tank nonflammable.
COPA Airlines 201 was another example of midair break-up and widespread wreckage over nearly eight miles in a vast jungle. According to the accident report, there was an intermittent failure of the main attitude indicator due to a short circuit. The flight crew didn’t notice the issue, and adjusted the aircraft attitude based on the malfunctioning attitude indicator. The aircraft was in cruise at FL250 when it went into an uncontrolled high speed dive and broke up several thousand feet above the ground.
Key to understanding the basic principles of systems is transferring fluid/air/energy from the source to the application. The source or supply is the initiating component such as fuel tanks, hydraulic fluid, reservoirs, and batteries or generators. An initiating power source, such as a pump, serves to propel the fluid, air, energy through the system. These systems then distribute the matter to the application source via wires, cables, plumbing, pulleys, etc. Finally, the application is where the intended function occurs. Investigators start with this basic understanding of systems to assess where the specific system components potentially failed. The investigation becomes more complex as investigators drill down to the component level, to isolate specific failures and to determine whether the failure occurred pre- or post-crash and whether the failure contributed to the accident.
Most modern aircraft are a combination of complex systems that must function properly for safe operations. All systems have methods of transferring power, energy, or fluid from where it is stored to where it is needed. Basic systems investigations can be done in the field, but normally, laboratory testing is required to confirm system operation and condition at the time of impact.
References
National Transportation Safety Board (2000). In-flight breakup over the Atlantic Ocean Trans World Airlines flight 800 Boeing 747-131, N93119 near East Moriches, New York July 17, 1996. Retrieved from https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR0003.pdf.
Review the following industry resources to expand your understanding of the topics explored in this module:
· In Aircraft Accident Investigation, read:
· Chapter 10: Reciprocating Engines
· Chapter 12: Turbine Engines
· Chapter 13: Aircraft Systems
· Chapter 14: Cockpit Instruments
· Chapter 15: light Bulb Analysis
· Boeing 787 Electrical System/newairplane.com (Links to an external site.)
· Boeing Batteries and Advanced Airplanes/newairplane.com (Links to an external site.)
Note: See Chapter 9, Volume 1, and Chapters 10 and 11 in Volume 2: Aircraft Electrical Systems.
· See Chapter 9, Volume 1, and Chapters 10 and 11 in Volume 2: Aircraft Electrical Systems
· See Chapter 12, Volume 2: Hydraulic and Pneumatic Power Systems
· See Chapter 14, Volume 2: Aircraft Fuel Systems
· Boeing 777 CBT #56 Fuel System – Overview and Operation/YouTube (14:23)
Part 1 – You must submit at least one artifact per fieldwork area. Choose from the instruction page (the fieldwork area, sample file type and artifact) that you would like to work on.
Part 2 – Artifact Feedback and Collaboration
Discuss the type of artifact(s) you feel will best demonstrate achievement of the Aircraft Systems field investigations objectives. In addition to your discussion points, feel free to post a sample, outline, diagram, video clip, etc., of your artifact. You are welcome to post your full artifact for peer feedback, but artifacts themselves will not be graded by your faculty until you submit your completed artifact portfolio in Week 8. This assignment will be graded as a discussion, based on your concepts, explanations, and rationale for the artifact, and on peer collaboration. The intention of your portfolio artifact is to show mastery of the objectives for Aircraft Systems Field Investigations:
· Analyze accident investigation techniques associated with aircraft systems.
· Support the importance of cockpit instrument analytic techniques for accident investigation.
· Demonstrate the time influence of structural accident findings and recommendations to aviation safety.
Access the Virtual Crash Lab to collect evidence of any aircraft system settings/damage, and discuss potential sources/causes and repercussions of system failures. This may include fuel, hydraulics, landing, navigational (ailerons, rudders, etc.) electrical, etc. You may not be able to directly see all system components, but you can photograph sections of aircraft and detail in your notes, what investigators should consider. It may help to include a brief introduction of your work, but all photos or photo groupings should include detailed notes to explain what you have photographed and why it is pertinent to aircraft systems evidence. Ensure photo and notes evidence is specific to systems only. Aspects of your evidence collection and note annotations may be used in your final portfolio and/or Case Study.
