Wednesday, February 24, 2010

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
  • Pack inlet and exhaust
  • Negative pressure relief vents
  • Wing illumination light
  • Static ports
  • Positive pressure relief valves
  • Forward outflow valve
  • Crew oxygen thermal discharge disc 
2. Left Forward Nose
  • L pitot probe
  • L ice detector probe
  • TAT probe
  • L AOA probe

Tuesday, February 9, 2010

Gas Turbine Engines

Gas turbine engines are widely used in different fields for generate energy. They are commonly used in aircrafts. If you watch a huge passenger aircraft, you can see the gas turbine engines are either hanging on the wing section or tail section. Those power plants gives enough energy to generate thrust which finally result the aircraft fly.

Figure: An Airbus A340's 4 engines are situated on the wing, 2 in each side.

Figure: A Tupolev 154 Aircraft where engines situated on the empennage 
How does a gas turbine engine work?
There are several sections inside of an engine. First one is the air intake and fan which direct the air to inside of the engine, then the compressor, which compress the air to a very high pressure while reducing its speed. Then air meets the combustion chamber, where kerosene (fuel) is spread as small particles and burned in a high temperature. 

Thursday, February 4, 2010

Visual Inspection

Visual Inspection is one of the most common NDT methods used to evaluate the condition and provide a better quality of an item. Visual method is easily carried out, inexpensive and usually does not require special equipment. It entails reflected or transmitted light from a test object being imaged with a light-sensitive device, such as the human eye.
Such a testing method requires proper vision, good lighting conditions and the knowledge of what exactly to look for.