Functional methods

As we saw in the beginning, 2nd Section of technical diagnostics is about functional methods. They consist of:

• Evaluation of long term and short term statistical data such as, the temperature of the part/machine, Pressure of the hydraulic systems, fuel/air consumption etc… By analyzing such parameters, engineer can predict the economical use of the part/machine and prognosis future failures, so that it will be possible to remove it and put a new part/ or totally stop using the machine before a catastrophe.

• By analyzing the physical and chemical parameters such as the spectral analysis of oil in order to detect foreign particles (for example, small particles of metals can be found in oil system when a ball bearing is destroyed, and that can lead to a failure of the whole machine)

• Vibration diagnostics: where engineer analyses the vibration of machine and evaluate faults and trends. An experienced engineer watches the frequency spectrum of the vibration without even touching the machine, say where exactly problem is, and propose options to cure that defect.

Figure: An NDT engineer preparing instrumentation for a vibration analysis of a gas turbine engine

Aircraft Visual Inspection

Figure: Boeing 777 aircraft Commercial aircrafts are frequently inspected visually. There is a primary inspection called "walk around check" both in the line and the base, transit checks, daily check, weekly check, A check, B check etc… Line is the more about the quick checks while aircraft is in the park or in between flights. Base is mostly the hanger, where hard checks, repairs take place. A qualified engineer walk around the aircraft and inspect structural items visually. Engine is also checked during the walk around checks. There engineer watches for oil leaks, structural damages in the engine, inlet of the engine for composite parts fixtures to the structure, fan/first stages of the compressor, last stages of the turbine for deterioration or damages , or any unusual changes of the engine. In this example shows how, engineer/Pilot carry on a walk around inspection of a Boeing 777 aircraft. Figure: Walk around inspection of a Boeing 777 1. Left Mid Fuselage...

Eddy current Theory

Eddy current theory is based on electromagnetic induction. That means, a variable magnetic field can induce an electric current on a conductor which is separate to the source of the magnetic field, and also vice versa, which is an electric current generates a magnetic field. Similar theory is used for the magnetic particles inspection as well. Electromagnetic induction is used in many applications such as, Transformers, Electric motors, Generators, etc... In the field of Non destructive testing (NDT), we manipulate with this theory which I mentioned above, and try to find surface defects or/and shallow internal defects of ferromagnetic materials.

GKN A350 spar program update

"Automated fiber placement to replace established tape laying/drape forming process for the composite rear spars on the new midsize commercial passenger jet" Headquartered in Redditch, Worcestershire, U.K., GKN Plc’s Aerospace Division continues its strong growth, based to a large extent on its expertise in the production of composite structures. Even the 50 percent of the business that is not focused on composites is based primarily on materials technologies, such as complex titanium aero-engine components and cockpit canopies with vacuum-deposited surfaces to enhance stealth performance. This should not come as a surprise, because GKN’s first use of materials technology to gain market share was in the 1860s, when it dominated the railroad supply business by being the first company in the U.K. to make steel by the cost-effective Bessemer process. The company produced more than 56 million lb (25,400 metric tonnes) of steel per year by 1871. Fig. 1: The inner rear spar demo...

Technical Diagnostics and NDT

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