Pia Internship Report

SUBMITTED TO HR DEPARTMENT – PIA

INTERNSHIP REPORT P.I.A Engineering

SUBMITTED BY FAWAD MUEED - ( Reg # 14592 -Permit No# 14 ) QAZI FAHAD AHMED – ( Permit No # 54 ) ABDUL QAYOOM CHANNA – ( Reg # 10SW184 )

Table of Contents

HISTORY OF PIA ............................................................................................................................................. 2 AIRCRAFT PRESSURIZATION .......................................................................................................................... 3 THE NEED OF CABIN PRESSURIZATION ......................................................................................................... 3 OUTFLOW VALVES ........................................................................................................................................ 4 AOA [ANGLE OF ATTACK ] SENSOR ............................................................................................................... 4 CABIN PRESSURE CONTROLLER: ................................................................................................................... 5 EMERGENCY OXYGEN SYSTEM ..................................................................................................................... 5 LASER GYROS................................................................................................................................................. 7 Attitude Indicator.......................................................................................................................................... 8 USES OF ATTITUDE INDICATOR ..................................................................................................................... 8 HORIZONTAL SITUATION INDICATOR ........................................................................................................... 9 Rotary Actuator........................................................................................................................................... 10 Variable Stop Actuator ................................................................................................................................ 11 AutoThrottle................................................................................................................................................ 11 AutoPilot Engager - Mode Control Panel ( MCP ) ....................................................................................... 12 Gyroscope ................................................................................................................................................... 13 Attitude indicator ........................................................................................................................................ 13 Exhaust gas temperature gauge ................................................................................................................. 15 TACHOMETER / RPM METER ...................................................................................................................... 15 HYDRAULIC GAUGES ................................................................................................................................... 16 FUEL GAUGES .............................................................................................................................................. 16 CONCLUSION............................................................................................................................................... 17

HISTORY OF PIA

When Pakistan was founded in 1947 it comprised two territories on either side of the expanse of India. It was in this unusual circumstance that Pakistan International was formed. Despite wars and economic trouble, the carrier survived to grow and prosper. Today it maintains a sizeable international route network, in addition to its services closer to home, with a modern and expanding fleet. PIA Engineering is an established Aircraft Maintenance and Repair organization that provides world-class solutions to the aviation industry. PIA's Engineering Base, head-quartered at Jinnah International Airport, Karachi, is acclaimed as one of Asia's best.

SAFETY & COMFORT 1 AIRCRAFT PRESSURIZATION Cabin pressurization is the active pumping of compressed air into an aircraft cabin when flying at altitude to maintain a safe and comfortable environment for crew and passengers in the low outside atmospheric pressure.

THE NEED OF CABIN PRESSURIZATION Flights above 3,000 meters (9,800 ft) in unpressurized aircraft put crew and passengers at risk of four illnesses Hypoxia, Altitude sickness Decompression sickness Barotrauma. Maintaining the cabin pressure altitude to below 3,000 meters (9,800 ft) generally avoids significant hypoxia, altitude sickness, decompression sickness and barotrauma. Air is pressurized by the engines. Turbofan engines compress intake air with a series of vaned rotors right behind the fan. At each stage of compression, the air gets hotter, and at the point where the heat and pressure are highest, some air is diverted. Some of the hot, high-pressure air, called bleed air, is sent to de-ice wings and other surfaces, some goes to systems operated by air pressure, and some starts its journey to the cabin.

OUTFLOW VALVES Outflow Valves are use to control the Cabin Pressure of the aircraft. The outflow valves vents air pressure from within the cabin. As the plane gains altitude, it incrementally closes to build pressure within the cabin. When the plane is at a typical cruising altitude of 35,000 feet, the cabin pressure controller keeps the output valve positioned to maintain cabin pressure -- also known as "cabin altitude"-- at the equivalent of 6,000 to 8,000 feet, depending on the aircraft. This is comparable to breathing the air in a mountainous area on the ground and easily tolerated by most passengers. As the aircraft touchdowns the caps of the OutFlow valves completely gets open to depressurize the Aircraft .

AOA [ANGLE OF ATTACK ] SENSOR Angle of Attack Sensors are used to sense the angle of Flight. It tells at what angle the aircraft is flying with. It is very necessary to get know the Aircraft’s Angle while flying, since if safety Angle of Flight [ that is 16 Degree ] is not maintained , Aircraft can Stall.

CABIN PRESSURE CONTROLLER: The cabin pressure control system (CPCS) is an electropneumatic system normally operated by a digital-electronic controller; a completely independent manual control is also provided. The air necessary to pressurize the cabin is supplied by the environmental control system (ECS) or by the emergency pressurization system. Two valves control the cabin pressure, regulating the discharge of the air from the cabin to the outside.

EMERGENCY OXYGEN SYSTEM Aircraft emergency oxygen systems are emergency equipment fitted to commercial aircraft, intended for use when the cabin pressurisation system has failed and the level of oxygen in the cabin atmosphere drops below a safe level. It consists of a number of individual oxygen masks stored in compartments above passenger seats, and some form of central oxygen generator. Aircraft oxygen is usually stored in high pressure system containers of 2000 psi, These containers are known as OXYGEN BOTTLES which are installed vertically in the Cargo department of the aircraft. They are filled to 1850 psi that is as per Boyle’s Law.

INERTIAL NAVIGATION SYSTEM An inertial navigation system (INS) is a navigation aid that uses a computer, motion sensors (accelerometers) and rotation sensors (gyroscopes) to continuously calculate via dead reckoning the position, orientation, and velocity (direction and speed of movement) of a moving object without the need for external references.

An inertial navigation system includes at least a computer and a platform or module containing accelerometers, gyroscopes, or other motion-sensing devices. The INS is initially provided with its position and velocity from another source (a human operator, a GPS satellite receiver, etc.), and thereafter computes its own updated position and velocity by integrating information received from the motion sensors. The advantage of an INS is that it requires no external references in order to determine its position, orientation, or velocity once it has been initialized. Gyroscopes measure the angular velocity of the system in the inertial reference frame. By using the original orientation of the system in the inertial reference frame as the initial condition and integrating the angular velocity, the system's current orientation is known at all times. This can be thought of as the ability of a

blindfolded passenger in a car to feel the car turn left and right or tilt up and down as the car ascends or descends hills. Based on this information alone, he knows what direction the car is facing but not how fast or slow it is moving, or whether it is sliding sideways. INS/IRS AT PIA The INS we studies at PIA, comprised of all the Data and Routes of the PIA Destinations. They are kept upgraded with all the New Routes ,if defined for any of their Aircraft. These INS use to help the Pilot to Auto Fly to the required Destinations. But before working on it , it has to be fed with the data of position the Aircraft will fly from or the Position the aircraft is at that moment. The data is fed in Latitude and Longitude. However, after feeding the Current Position, the Device itself checks the entered data is correct and the Aircraft is really at that Latitude and longitude.

LASER GYROS A ring laser gyro splits a beam of laser light into two beams in opposite directions through narrow tunnels in a closed optical circular path around the perimeter of a triangular block of temperature-stable Cervit glass with reflecting mirrors placed in each corner. When the gyro is rotating at some angular rate, the distance traveled by each beam becomes different—the shorter path being opposite to the rotation. The phase-shift between the two beams can be measured by an interferometer, and is proportional to the rate of rotation.

NAVIGATION Attitude Indicator An attitude indicator (AI), also known as gyro horizon orartificial horizon, is an instrument used in an aircraft to inform the pilot of the orientation of the aircraft relative to earth. It indicates pitch (fore and aft tilt) and bank or roll(side to side tilt) and is a primary instrument for flight ininstrument meteorological conditions. Attitude indicators also have significant application under visual flight rules, though some light aircraft do not have them installed.

USES OF ATTITUDE INDICATOR The essential components of the indicator are: 

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"Miniature wings", horizontal lines with a dot between them representing the actual wings and nose of the aircraft. The center horizon bar separating the two halves of the display, with the top half usually blue in color to represent sky and the bottom half usually dark to represent earth. Degree marks representing the bank angle. They run along the rim of the dial. On a typical indicator, the first 3 marks on both sides of the center mark are 10 degrees apart. The next is 60 degrees and the mark in the middle of the dial is 90 degrees.

If the symbolic aircraft dot is above the horizon line (blue background) the aircraft is nose up. If the symbolic aircraft dot is below the horizon line (brown background) the aircraft is nose down. When the dot and wings are on the horizon line, the aircraft is in level flight. Because it is the horizon that moves up and down and turns, while the symbolic aircraft is fixed relative to the rest of the instrument panel, trainees get confused; a standard corrective given by flight instructors is "Fly the little airplane, not the horizon. HORIZONTAL SITUATION INDICATOR The horizontal situation indicator(commonly called the HSI) is anaircraft instrument normally mounted below the artificial horizon in place of a conventional heading indicator. It combines a heading indicator with aVOR/ILS display, reducing pilot workload by lessening the number of elements in the pilot's instrument scan to the six basic flight instruments. Among other advantages, the HSI offers freedom from the confusion of reverse sensing on a localizer backcourse approach. On a front course approach, the HSI needle is set to the inbound track; on a back course approach, the HSI needle is set to the outbound rather than the inbound track, causing needle deflection that mimics a front course approach instead of displaying the normal reverse sensing.

On the HSI, the airplane is represented by a schematic figure in the center of the instrument - theVOR/ILS display is shown in relation to this figure. The heading indicator is slaved to a remote compass, and the HSI is frequently interconnected with an autopilot capable of executing an approach by following the localizer and glide slope

AUTOPILOT

An autopilot is a mechanical, electrical, or hydraulic system used to guide a vehicle without assistance from a human being. An autopilot can refer specifically to aircraft, self-steering gear for boats, or auto guidance of space craft and missiles. The autopilot of an aircraft is sometimes referred to as "George", after one of the key contributors to its development. Rotary Actuator A rotary actuator is an actuator that produces a rotary motion or torque. When Autopilot is engaged, Rotary Actuator controls the Elevator to Pitch Up or Down the Aircraft.The simplest actuator is purely mechanical, where linear motion in one direction gives rise to rotation. The most common actuators though are electrically powered. Other actuators may be powered by pneumatic or hydraulic power, or may use energy stored internally through springs. The motion produced by an actuator may be either continuous rotation, as for an electric motor, or movement to a fixed angular position as for servos and stepper motors. A further form, the torque motor, does not necessarily produce any rotation but merely generates a precise torque which then either causes rotation, or is balanced by some opposing torque.

Variable Stop Actuator This Actuator is used to control the yawing of the aircraft by controlling the movement of the Rudder while in the Autopilot mode. This is an Actuator that recives Electrical Signals, Process the signals and deliver it to the Motor that controls the Rudder Movement to take care of the yawing of the Aircraft.

AutoThrottle An autothrottle (automatic throttle) allows a pilot to control the power setting of an aircraft's engines by specifying a desired flight characteristic, rather than manually controlling fuel flow. These systems can conserve fuel and extend engine life by metering the precise amount of fuel required to attain a specific target indicated air speed, or the assigned power for different phases of flight. A/T and AFDS (Auto Flight Director System) work together to fulfill the whole flight plan and greatly reduce pilots' work load. There are two parameters that an A/T (autothrottle) can maintain, or try to attain: Speed and Thrust. In Speed mode the throttle is positioned to attain a set target speed. This mode controls aircraft speed within safe operating margins. For example, if the pilot selects a target speed which is slower than stall speed, or a speed faster than maximum speed, A/T will maintain a speed closest to the target speed that is within the range of safe speeds. In Thrust mode the engine is maintained at a fixed power setting according to the different flight phases. For example, during Takeoff, A/T maintains a constant Takeoff power until Takeoff mode is finished. During Climb, A/T maintains a constant climb power; in Descent, A/T retards the throttle to IDLE position, and so on. When A/T is working in Thrust mode, speed is controlled by pitch (or the control column), and NOT protected by A/T.

AutoPilot Engager - Mode Control Panel ( MCP )

In aviation, a mode control panel (MCP), is an instrument panel that controls an advanced autopilot and related systems, such as an automated flight-director system (AFDS). The MCP is so called because it contains controls that allow the crew of the aircraft to select which parts of the aircraft's flight are to be controlled automatically. In modern MCPs, there are many different modes of automation available. The MCP can be used to instruct the autopilot to hold a specific altitude, to change altitudes at a specific rate, to hold a specific heading, to turn to a new heading, to follow the directions of a flight management computer (FMC), and so on. The MCP is actually independent of the autopilot—it simply sets the mode in which the autopilot operates, but the autopilot itself (e.g., an AFDS) is a separate aircraft system. The MCP often interacts with both the AFDS or autopilot and the FMC(s).

GYRO

Gyroscope A gyroscope is a device for measuring or maintaining orientation, based on the principles of conservation of angular momentum.[1] In essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any orientation. This orientation changes much less in response to a given external torque than it would without the large angular momentum associated with the gyroscope's high rate of spin. Since external torque is minimized by mounting the device in gimbals, its orientation remains nearly fixed, regardless of any motion of the platform on which it is mounted. Attitude indicator An attitude indicator (AI), also known as gyro horizon or artificial horizon, is an instrument used in an aircraft to inform the pilot of the orientation of the aircraft relative to earth, Attitude indicators use a gyroscope (powered via vacuum pump or electrical motor) to establish an inertial platform. The gyroscope is geared to a display that has two dimensions of freedom, simultaneously displaying pitch and bank. The display may be colored to indicate the horizon as the division between the two colored segments (typically blue for sky and brown for ground), and is intended to be intuitive to use. The actual bank angle is calibrated around

the circumference of the instrument. The pitch angle is indicated by a series of calibration lines, each representing 5° or 10° of pitch depending on design.[citation needed] The Artificial Horizon has turning errors when turning through 090 and 270 degrees, and it has no turning errors when turning through 180 and 000 degrees. For example, when turning through 090 degrees the Artificial Horizon will show nose up and bank angle too low. When turning through 180 degrees it will show nose up and bank angle correct.

ENIGINE PERFORMANCE In the Engine Performance Group of Instrument Shop, we were taught about the several gauges of the Aircraft that are fitted in the Cockpit. That includes EGT [ Exhaust Gas Temperature Gauge ] , RPM METER, FUEL Gauges, Hydraulic Gauges and there test systems.

Exhaust gas temperature gauge An exhaust gas temperature gauge (EGT gauge) in an aircraft is used to monitor the exhaust gas temperature of an internal combustion engine or the jet Engine.

TACHOMETER / RPM METER The RPM meter of an Aircraft is installed in the cockpit, helps to display the Jet Engine’s RPM ( Rotation Per Minute ).

HYDRAULIC GAUGES Hydraulic Gauges use to indicate the Hydraulic Fluid level in the hydraulic pumps that use to control the Primary Controls of the Aircraft , i.e Ailerons, Rudders, Elevators , Flaps ,Spoilers . The picture shows the Hydraulic Gauges of Boeing 737 Aircraft.

FUEL GAUGES Fuel Gauges of the Aircraft use to indicate the Fuel Level inside the fuel tanks. An aircraft Fuel tanks are divided as the CENTRE TANK, and the 2 Tanks in Each wing. But this Tank positions may vary from aircraft to aircraft.

CONCLUSION Internship at PIA was a great experience for us. We had a first time Industrial exposure of Electronics and Electrical Components. Here at PIA ENGINEERING we spent 2 weeks at different shops namely Instrument Shop, Electrical Shop & Radio shop. We came to know about Aircraft Industry and gained a lot of knowledge of Aircrafts, their Maintenance and Repairing of their Delicate Components. Each shop is subdivided into groups and we were appointed in each group for 2 to 3 days. Where we experienced the professional working environment. Working under very professionals and High Tech Engineers there, we got answers to many of our questions and queries regarding our field of Electronics. Since we didn’t had the Manufacturing Area Exposure there at PIA Engineering, we observed the Repairing, Maintenance and Troubleshooting of many Aircraft Components there. We feel our self very fortunate to have an opportunity to do Internship at PIA as we had an exposure of highly precise, very expensive and high tech instruments.