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Showing posts from July, 2017

Marshaller

It is not marsheller or marschaller. It is Marshaller with 2 a and 1 e and without c. This is an addition to communication between ATC and Pilot. It helps to reduce the work load of an ATC operator. The dress code for a marshaller are: 1. Reflecting safety vest 2. Helmet with Acoustic earmuffs 3. Marshalling wands (Handheld illuminated beacon) The main function of a marshaller is to guide the pilot during parking after landing and taxing to the runway for takeoff. Excessive noise can cause hearing loss in marshallers, either imperceptibly over years or after a one time acoustic trauma. Therefore in many modern airports, the Marshallers are replaced by VDGS (Visual Docking Guidance System). Necessary indications: keep turning slow down stop start engine shutdown engine/ cut engine identify gate  continue to taxi straight ahead turn right turn left hold position/ stand by process to next marshaller or as directed by next marshaller or tower fire self brak...

Auxiliary Power Unit

Auxiliary Power Unit is an essential part of an aircraft. The primary function of this unit is to start the engine. In smaller aircraft the APU used is an electric motor. However, in the modern aircraft the APU used is an air turbine  motor. Basic parts of an air turbine motor APU are: 1. Power section  Power section like other gas turbine engine consist of compressor, combustion chamber and turbine. It consist of a single stage centrifugal compressor, combustion chamber and 2 stage axial flow turbine.  As the APU main switch is turned on, the inlet from the right side of the APU system allows the atm air to enter to the system. The inlet air is compressed by the centrifugal compressor which is turned through a shaft coupled with a starter/ generator. The starter/ generator is powered by GPU or Battery cart. The input from a GPU - 115V of 400kh AC current or input of 28V DC current is converted into 270V DC current using Start power Unit and finally the start conv...

Thrust Reversal

Thrust Reversal consist of 2 words. Thrust and reversal. This is a process adopted to reduce the aircraft velocity during landing. It is a type of braking system. The braking system in an aircraft consist of: 1. Landing Gear brakes. 2. Ground Spoilers 3. Thrust reversal. So while talking about the thrust reversal, the type of aircraft has an important role to play. For the propeller driven aircraft  the reverse thrust is achieved with the appropriate change in the blade angle. However for a jet engine the reversal of the thrust come in basically 2 major types: 1. Reversal by the use of hot exhaust. 2. Reversal by the use of cold bypass air. Classification in terms of mechanism used are: 1. Target (bucket) type  Operated With hydraulics in turbojet engine 2. Clamshell (Cascade) type  Operated with Pneumatics in Low bypass turbofan engine 3. Coldstream type The cold stream reverser system is activated by an air motor in High bypass turbofan engine ...

Daily Inspection (DI)

General Inspection: Ventilating Ram air inlet duct for cabin air. Pitot Heads and static Vents Drain holes and inspection of derbies on the fuselage  Antennas (underside) Wheel nose tire Nose oleo and Piston Cover Pitot Before going in depth about the further steps in the inspection, we need to know the areas of the planes that are used as a nomenclature to represent certain parts of the aircraft. They are: A1 , A2 , A3, A4, A5 A1 Internal  Ensure Gust lock- flaps 0 and brakes set A2 External Main wheel assembly brake   A2 Internal Battery and flashlght firstaid kit- seal check   A3 External Inspect stabilizers, rudder, elevators, trim and geared tabs A4 External Inspect fire extinguishing indicator discs for evidence of extinguisher discharge. Inspect wing strut Inspect wing fuel vent outlet Engine: Inspect engine intake deflector and screen Check for oil level inspect propeller blade   A5 External Inspect...

Inspection basics of an aircraft

Inspection of an aircraft is not an easy job. Though all the steps for the process is given on the inspection manual. The fact that any minor mistake can lead to human casualties is in itself a thing to get nervous about. There are many varieties of inspection in any aircraft. One of the various class of aircraft inspections are: 1. A - check 2. B - check 3. C - check 4. D - check Other inspection involve: 1. 100 Hours check 2. DI (Daily Inspection) 3. PDI (Pre- flight Daily Inspection) 4. HLI (Heavy Landing Inspection)

Fan, Propeller, Turbine

Fan: Fan moves air. It receives certain energy from engine or drive shaft --- which results in movement of the air through the motion of the fan blades. Propeller: Propeller moves the aircraft or machine.  Turbine: Turbine uses energy of a moving air into mechanical energy.

Oil Filter

There are many types of oil filters used in aircrafts. However, spin on filter is one of the most common. In this system the untreated oil is pumped to the filter assembly and enters through a Filter. This filter blocks the path for debris in the oil while letting the oil pass through. But this is an idle case assumption. Some other conditions that may apply are: 1. During pump restart:         When the pump restarts then if there is not any kind of blockage then the filter will be drained. Thus use of anti drain membrane is necessary to block the flow of the oil when there is no differential pressure. 2. During excess pressure:         During normal operation filter jam may occur at any time. This will result in reduced flow of oil to the various system. This can be a dangerous for the engine operation. Thus use of a Bypass valve comes at play here. When the pressure of the oil passing through the filter i...

Lock wire/ safety wire

This a crucial process that needs to be applied to the nuts and bolts that are prone to vibration. Many reports of the aircraft before the application was due to loosening of nuts due to vibration. With the help of this process the nut is applied with certain amount of tension even after it has been fully tight. This prevents the loosening due to vibration. It is a positive locking device that prevents fastners from lossening. Another significant importance of such device can be that it gives a visual assurance that the nuts are tightened rigidly in place. However, the most important part of this device is the twist direction. This lock device should be in such manner that the nut is under tension in the direction of tightening.

PT6A-27

General Engine specification Blog1. It is a turboprop engine- free turbine . This is an engine used in airplanes like DHC-6 Twin Otter 300  Harbin Y-12 Beechcraft This a Pratt and Whitney Canada Engine. One of the most famous and successful company to produce turboprop engine. Compressor  It consist of 3 stage axial compressor and 1 stage centrifugal flow compressor. Combustion  Annular reverse flow (right to left according to diagram above) combustion with 14 simplex burner (Glow plugs) Turbine 1 stage free power turbine and 1 sage gas generator power turbine.(Left to right according to diagram above) Other specs: Fuel type: aviation kerosine Overall pressure ratio- 6.3:1 Air mass flow: 5.3 lb/s Power to weight ration: 2.14 hp/lb 

Hub slippage

The Tire and hub system in aircraft just like any other wheel, work in combination with each other to provide a smooth translation motion of the aircraft. However the forces acting on the aircraft and a car or a bike is where the difference starts. Aircraft wheel has to bear a lot of load during its rotation as compared to a car. This is why the hub slippage is most common in aircraft and not a car or a bike. This is a phenomenon where the hub and tire slip under the immense pressure exerted by the aircraft load. This phenomenon does not occur on all tires. Some of the tires that allow such phenomenon are: 1. All Helicopter tube tires 2. Tires having inner tube. 3. The tire pressure being less than 150 Psi. The hub slippage is detected by painting a red paint on the hub and tire. The pain being a strip of width of 1 inch and length of 2 inch. After every take off and landing the wheel is inspected for slippage. If the alignment of the paint on the hub and the tire exceed more th...

Aircraft tyres

The similarities between the wheels of a car and an aircraft end with the geometry being circular. The aircraft tires are different from the build material to the air inside it. Most of the modern aircraft tires consist of 50% rubber, 45% fabric and 5% steel by weight. The Aircraft tires are basically two types : 1. Bias Ply type 2. Radial Ply type These are the tires with different layout of the individual fabrics that goes on the tire. The tires used in the modern aircraft have many features that separates these tires from any normal tires. These features are: 1. CHINE These are a protrusion from the tire that directs the water backward when the plan has to land or takeoff from a wet runway. 2. Grounding Most of the large aircraft need to discharge the thermostatic charge after landing. This is done with the help of on point that connects aircraft to the ground- aircraft tires, thus the tires need to conduct electricity. Hence discharging any static charge from the aircra...

Bleed air

Bleed air is a certain portion of air from the compressor. The high pressure and high temperature air from the compressor is channeled to various part. Many vital parts of the aircraft depend upon the bleed air from the engine for the proper operation. The bleed air basically acts as a power source for other systems. The systems include: 1. Anti ice system 2. Engine starting 3. Hydraulic system 4. Air conditioning system 5. Water system The aircraft has normally 2 bleed airs inlet in the compressor at the 5th and 9th Stage. The inlet pressure and temperature are 40Psi and 250 degrees Celsius respectively.
The idea of flight has captured me. The feeling of being above everyone and fly among the clouds. Sry this is dramatic, but this is the thing from a 12 years old me. I feel writing things down makes u understand more. And if u have an audience u speak a better version of anything u speak. So lets speak about aero. And start a journey to the skies. i hope we dont crash.