AE 2355 AERO ENGINE LAB MANUAL

INTRODUCTION

AIRCRAFT RECIPROCATING ENGINE COMPONENTS AND CONSTRUCTIONS

The general aircraft engine used in any aircraft for thrust generation consist of the following basic components.

CRANK CASE: The crank case of an engine is the housing that houses the various components surrounding the crankshaft. Therefore it is the basic foundation of the engine. The crank case performs the following functions:

It contains bearings in which crankshaft revolves. It provides a tight enclosure for lubricating oil. It supports various internal and external mechanism of power plant It provides a support for attachment of cylinder. It prevents the misalignment of the shaft and its bearings.

BEARINGS:Bearing is any surface that supports or is supported by another surface. The

bearings in any aircraft engine are designed to minimize the friction and wear resistance. They must reduce the friction of moving parts and also take the thrust loads, radial loads or combination of both.

CRANK SHAFT: The crankshaft transforms the reciprocating motion of the piston to rotating motion for turning the propeller. It is a shaft composed of one or more cranks located at definite places between the end. Since the crank shaft is the backbone of the engine it is subjected to all forces developed within the engine and hence should be strongly constructed.

CONNECTING ROD ASSEMBLIES:Connecting rod is the link which transmits forces

between the piston and crankshaft of an engine.It transmits the reciprocating motion of the piston to the rotating movement of the crank shaft.The principle type of connecting assemblies are the

Plain type Fork and handle type Articulated type

PISTON: The piston is a plunger that moves back and forth or up and down within the engine cylinder barrel. It transmits the force of the burning and expanding gases in the cylinder through the connecting rod to the engine crank shaft. As the piston moves down the cylinder, during intake stroke, it draws in the air fuel mixture. As it moves up, it

compreses the charge. Ignition takes place and the expanding gases cause the piston to move towards the crank shaft.The piston forces the burnt gases out of the combustion chamber during the next stroke.

CYLINDERS: The cylinder of an IC engine converts chemical heat energy of the fulel to mechanical energy and transmits it through the connecting rods to the rotating crank shaft. The cylinder assembly used for present day engines usually includes cylinder barrel, cylinder head, valve grid, valve seats, rocker arms, cooking fins

VALVES: In general a valve is a device for regulating or determining the check on the flow of a liquid or a gas by a movable part which opens or closes into a passage.The main purpose of a valve in IC engine is to open and close parts which are into the combustion chamber of the engine namely intake and exhaust ports.The valves are associated with valve guides,valve seats and valve springs.

PROPELLERS: They are essential aircraft parts that provide the necessary thrust for moving the aircraft.The propeller is connected to the engine by means of a shaft.The propeller consists of two or more blades and a central hub to which the blades are attached. Engines and their components are designed and built to provide many years of service.For an aircraft to remain in an airworthy condition the following conditions have to be fulfilled.

Periodic inspection Repairs Overhauls and replacements

TROUBLE SHOOTING: It is the step by step procedure used to determine cause of a given fault and then select a quick and best solution.

STRIPPING OF PISTON ENGINE

AIM: To dismantle a piston engine and study its particular components.

TOOLS REQUIRED: Special tools for notching crank shaft. Universal socket for spark plug Selected spanner no: 6-19 Ring spanner no: 6-22 Adjustable spanner

Plier, cutter and screwdriverValue depression toolCrow foot spanner

PROCEDURE: Remove spark plug and rocker curves. Remove starter and accessories. Turn the engine over such that cylinders are upper most. Remove controls completely with universal joints. Remove airscoop, plug leads, distribution covers. Remove induction system with carburetor. Unscrew push rod ball socket from rockers. Take out push rod and push rod covers. Remove cylinder baffle plate. Remove cylinder. Remove piston rings. Extract gudgeon pin, air clip. Withdraw gudgeon pin and piston. Remove magnetos. Remove gearbox with timing gear cover. Turn the engine cover on its stand. Remove starter. Remove adaptor, thrust bearing cover and top cover. Detach big and bearing caps. Withdraw connecting rod. Remove main, intermediate bearing caps. Lift crankshaft. Unscrew idle gear hub bolt. Draw off gear wheel. Remove magneto drivers. Unscrew camshaft gagging the gear. Remove camshaft rear bearing bush. Withdraw camshaft. Remove tappet and guides. The parts are kept for visual inspection.

RESULT: Thus the stripping of piston engine is carried according to instructions in the manufacturer’s maintenance manual.

VIEWING PROCEDURE OF CRANK SHAFT

AIM: To view the crankshaft and check out its dimensions.

TOOLS REQUIRED: Surface table V-blocks Dial indicator Vernier caliper Micrometer Magnifying glass

PROCEDURE: Check for cracks by contact current method. Check for corrosion, pitting etc.. Check for ovality and taperness using micrometer. Check external dimensions of crank pin and journals. Carry out rip check before measuring internal dimensions. Check for central journal errors due to ovality. Check the crank web for parallelism. Check crank pin for parallelism. Error allowed is 0.0016” per unit length. Check if propeller shaft has a tapered end in the hub. Check propeller shaft for threads and keyways for burrs and beveling. Check oil seal retainer and sealing for burrs and correct seating. Carry out static and dynamic hardness tests.

RECTIFICATION: Score,taper and ovality can be removed by grinding. Slight score and pitting can be removed by grinding or dressing with

carborundum or polishing with emery paper.

RESULT: Thus the crankshaft is viewed and its dimensions are checked with the manufacturers’ maintenance manual.

VIEWING PROCEDURE OF CONNETING ROD

AIM: To perform maintenance and inspection on connecting rod.

TOOLS REQUIRED: Surface plate Micrometer Dial gauge

Vernier caliperTelescopic gaugeTapered sleeveArborsPlug gauge

PROCEDURE: Check the connecting rod conditions,the big end caps for

cracks and other surface defects by hot oil and chalk method. Check the rod for notches and abtrasion. Measure small end dia and compare with external dia of gudgeon pin. Check the nip in the big end bearings. Measure and check the diameter with internal dimensions of

cylinder bore gauge. To carry out the nip check,assemble connecting rod shell and

cap as per assembly sequence and tighten the bolts. Tighten to 840 pounds inch and check diameter of big end bearing. Check connecting rod for alignment. Check connecting rod bolts for elongation and nuts for threads. Check for hardness.

RECTIFICATION: During the NIP check, if 0.004” doesn’t go inside machine

the big end cap. If 0.006” goes inside replace the bearing cap. Fitting and searing can be removed by stoning and

polishing if not too deep.

RESULT: Thus the connecting rod is viewed and its dimensions are measured as per instructions in the manufacturers’ maintenance manual.

VIEWING PROCEDURE OF PISTON ASSEMBLY

AIM: To carry out inpection on the piston assembly.

TOOLS REQUIRED: Cleaning basket

Feeler gaugeScale 12”

Telescopic gaugeMicrometer

Vernier caliper

PROCEDURE:

CLEANING: Check for completeness of the piston assembly and clean it by dipping in

petroleum solvent using cleaning basket. Examine the piston surface thoroughly for excessive pitting, cavaties or

surface distortion. Check the piston rings, grooves, piston pinholes and holes base for

any damage. Check side clearance between piston rings and piston (0.004”-0.0025”). Check end clearance on wedge type piston rings. Check inside diameter of piston pinhole (0.03”-0.004”). Check clearance between piston skit and cylinder and piston dia top

and bottom(0.021”). Check outside diameter of piston pin against inside diameter of

hole in piston(0.0002”-0.001”). Measure fit between piston and plug and check outside diameter

of plugs(0.0002”-0.001”). Examine two interior surface of piston pin hole for corrosion and fitting.

RESULT:The maintenance and inspection of the piston assembly has been performed

according to manufacturers maintenance manual.

VIEWING PROCEDURE OF CYLINDER ASSEMBLY

AIM: To perform the task of maintenance and inspection of cylinder assembly.

TOOLS REQUIRED: DIP basket Stud removing tool Spark plug insert tool Hand vice drill bit Drift and bore gauge

PROCEDURE:

CLEANING: Clean the cylinder head with petroleum solvent.Dip it in petroleum agent using cleaning basket.

VISUAL INSPECTION: Inspect the cylinder head visually using a magnifying glass. Inspect the cylinder for

Loose damaged studs.(replace new ones) Loose spark plug (insert new oversize ones.) Loose cracked valve guide. Damaged mounting ports, rocker box cover Cracked or damaged fins

DIMENSIONAL CHECKS: Check internal dimensions of intake and exhaust valves. Check diameter and roundness of guide bore with gauge. Check wear and tear in rocker arm bush. Dimension checks are done in processes.

CYLINDER BARREL:

TOOLS REQUIRED: Cleaning basket Feeler gauge Dial gauge Bore gauge

PROCEDURE:

CLEANING:Clean the barrel using petroleum solvent dipping it on the cleaning basket.

VISUAL INSPECTIONS: In cooling fins, check for nicks and notches. In barrel, check for cracks (result in rejection) In skirt, check for cracks, bends, and breaks. In mounting flange, check for nicks, cracks and warping. Inside the barrel inspect for corrosion and scoring.

DIMENSIONAL CHECKS: Maximum clearance between piston skirt and

cylinder is 0.021” Maximum taper of cylinder wall in 0.018”. Maximum ovality is 0.018”.

RESULT: Thus the inspection of the cylinder assembly is carried out as per instructions given in manufacturers maintenance manual.

REASSEMBLY OF PISTON ENGINE

AIM: To re assemble the piston engine after inspection checks.

TOOLS REQUIRED: Special universal socket for spark plug Set spanners 6’-19’ Ring spanners 6’-22’ Adjustable spanner Pliers and cutters Screwdriver different sizes Hammer Value depression tool Crow foot spanner

PROCEDURE: Insert the tappet and the guides in the crank case. Fix the camshaft after positioning bearing bush. Fix the magneto drive gear. Fix the idle gear and screw the hub bolt. Fix the crankshaft and position the bearing caps. Fix the connecting rod and the bearing caps. Position the top crankcase and then tighten all bolts and nuts. Fix the gearbox with timing gear cover. Fix the magnetos. Fix the position in the connecting rod. Assemble the piston rings on the piston groove and insert the cylinder

over piston and tighten all cylinder large nuts. Fix the cylinder baffle plates. Position the push rod covers and push rods. Fix the rocker shafts. Fix the induction system and carburetor. Fix the air scoop, plug heads with distribution cover. Fix the carburetor controls with universal rods. Fix the starter and other accessories. Fix the spark plug in cylinder head bush and tighten to connect torques

and connect the plug leads. Fix the rocker covers.

RESULT: Thus the piston engine in reassembled as per maintenance manual instruction REMOVAL AND INSTALLATION OF FIXED PITCH PROPELLER

AIM: To remove, inspect and reinstall the fixed pitch wooden propeller.

PROPELLER PARTS: Propeller retaining nut Hub assembly Propeller Rear cone

TOOLS REQUIRED: Retaining nut wrench Propeller puller Hub butting drift 14’-15’ set spanner

PROPELLER REMOVAL AND DISMANTLING: Take out the device pin which locks the propeller retaining nut

to the crank shaft by removing split pin. Remove propeller-retaining nut from the crankshaft using iron bar. Take out the propeller from the crank shaft after disengaging

hub assembly using a puller. Remove the cone and spar from the crankshaft. Dismantle the propeller hub assembly by removing split pin. Separate the front and rear hub plates by removing both with

the help of bushing drift.

ASSEMBLY AND INSTALLATION PROCEDURE: Fix the rear and front hub plates on the propeller properly. Tighten the nuts to correct torque, engage split pins. Place the spacer and cone on the crankshaft. Engage the propeller with the hub assembly on the crankshaft. Engage the propeller-retaining nut and tighten to correct torque. Align the holes of retaining nut with crankshaft holes. Engage clevis and cotter pins. Now make necessary entry in the aircraft engine.

RESULT: Thus the fixed pitch propeller is installed in the piston engine aircraft as per the maintenance manual instruction.

DISASSEMBLY OF TURBOJET ENGINE

AIM: To dismantle the turbojet engine in a proper sequence.

TOOLS REQUIRED: ¾ *1/4 BS or 12-13 set spanner

10-11 set of ring spanner8-9 set of ring spannerC-spannerCommon screw driverBall peen spannerplier and side cutter

PROCEDURE: Loosen the fine nuts using appropriate spanner and r3emove the inlet

case from the accessory case. Loosen the 10 nuts using no 10-11 set of ring spanner and detach air

casing from compressor case. Remove 15 bolts using no 8-9 set spanner. Detach compressor casing

from diffuser. Loosen retaining nut with C-spanner and remove centrifugal impeller. Remove front roller bearing and the sleeve. Remove 2 ignition connection and fuel turners from the combustion

chamber outer case. Now take out the turbine along with the shaft from the rear side. Take out the combustion chamber. Loosen the bolts and nuts from the exhaust pipe flange and detach the

exhaust pipe from the combustion chamber. Loosen the clamps of the propelling nozzle and disconnect the nozzle

from the exhaust pipe. Keep all the removed parts separately in the cleaned tray in sequence so

that there is no possibility of mixing with each other. Wherever blanking is required,blank it and place identification slips.

RESULT: Thus the turbojet engine in dismantled and the components are studied.

ASSEMBLY OF TURBO JET ENGINE

AIM: To assemble a turbojet engine in a proper sequence.

TOOLS REQUIRED: ¾ *1/4 BS or 12-13 set spanner

10-11 set of ring spanner8-9 set of ring spannerC-spannerCommon screwdriverBall peen spannerplier and side cutter

PROCEDURE: Remove all blankings and clean them thoroughly. Attach air intake case front accessory by tightening all the 5 nuts using

12-13 set hammer Attach air intake case rear to the compressor case by tightening all the

nuts using 10-11 set ring spanner Now assemble the compressor in the front and turbine at the rear of the

shaft by inserting the shaft in front of the diffuser case. Enclose the combustion chamber outer case over the flame tube and

tighten all the 15 bolts. Encage 2 ignition and 5 fuel burners connection and tighten the nuts. Encage the exhaust pipe to combustion chamber outer case flange and

tighten all the bolts and nuts. Attach the propelling nozzle to the rear side exhaust pipe and together

with the clamp.

RESULT: Thus the turbojet engine is assembled as per the maintenance manual instructions.

FIXED PITCH PROPELLER BALANCING

AIM: To ensure the propeller is balanced horizontally and vertically.

TOOLS REQUIRED: Propeller stand with knife-edge support. Correct size mandrel

PROCEDURE: Insert the mandrel in the propeller shaft hole. Place the mandrel in the knife-edge. Rotate the propeller and to vertical position and ensure it remains in this

position without moving. The vertical balance is corrected by attaching a metal weight to the

lighter side of the hub. The amount of weight is determined by applying putty at a point normal to the horizontal line. After balancing, the putty is weighed; a metal plate is cut approximately equal in weight to the putty. The weight of the metal is adjusted for the weight of the screw and the solder.

The plate is attached to the hub at the location normal to the counter shrunk screw. Finally varnish is applied.

The horizontal balance can be adjusted on a wooden propeller by adding or removing solder from the balance tip.

RESULT: Thus the propeller is balanced both vertically and horizontally.

CHECKING OF PROPELLER PITCH BALANCING

AIM: To ensure the propeller blade twist is intact.

TOOLS REQUIRED: Surface table Degree marked protractor with mounting stand

PROCEDURE: Attach the propeller on the hub stand and place it ont the surface table. Now position the protractor head near the propeller hub station with

surface table. Now check the angle of the blade near to the hub station. The propeller stations are at a distance from the hub and tip varies from

propeller to propeller. The blade angle is checked from the hub to the tip by moving the

protractor in all directions of the blade stations and also referred the maintenance manual for the particular airplane adjustment.

The propeller track also checked with the help of weight gauge on the surface table.

RESULT: Thus the propeller pitch is checked at various stations and compared with values in maintenance manual.

PISTON ENGINE AIRPLANE STARTING PROCEDURE

AIM:

To start the given airplane engine according to the maintenance manual instructions.

PRESTARTING INSPECTION: The inspection is done to determine the general conditions of aircraft and engine:

EXTERNAL CHECKS: Head the airplane against wind direction. Remove all protective covers and control locks. Position chocks in front and near main wheel. Position carbon-di-oxide fire extinguisher midway between

the port wing tip and cockpit. Position technicians at port and starboard wing tips to

give clearance before starting. All panels and cowlings should be in place, flaps open. Check fuel for water content and oil for grade. Turn the propeller 5-8 times to remove hrdralisation. Check for correct type pressure and shock strut extension.

INTERNAL CHECKS:Slide the canopy open.Enter the cockpit and take a convenient position.Check instrument panel for completion and correction.Apply parking brakes to up position.Retract flaps to fully up position.Take clearance and switch on the battery.Open throttle approximately to 1/4th position.Turn the booster pump “ON”Move mixture control to fuel rich position until steady flow.Return mixture control to idle cut off position.Move throttle fully back and switch off booster pump.

STARTING PROCEDURE: Take clearance from marshall. Move throttle forward to 1/4th travel. Set magneto switch on.

Press the starter button on to engage. Watch the propeller rotation as soon as the engine picks up. Move the mixture control slowly and smoothly to fuel rich. Release the finger pressure from starter button. Continue to run the engine at 1000-1200 rpm to warm it up. Check oil pressure gauge if minimum oil pressure is not

indicated within 30 seconds, stop the engine and determine the trouble. If oil pressure cylinder head temperature and oil temperature

readings are satisfactory,continue to run the engine. Run the engine at different ratings not exceeding 1500rpm. Note the rpm, oil temperature and cylinder head temperature.

SHUT DOWN PROCEDURE: Run the engine at idle rpm till CHT decreases continuously. Take clearance from marshal to cut off the engine. Move mixture; throttle to cut off the position. When the engine stops, turn off the booster and ignition pump. Disconnect the battery and check the fuel or oil leakage. Carry out the documentation.

RESULT: Thus the starting procedure and pre-flight inspections are performed in aircraft engine and studied.