Engine.pdf

RESTRICTED (i) 2 TETTRA SCHOOL TRAINING NOTES Mi-17 V5 HELICOPTER ENGINE ‘AEO & GP-X’ Compiled By: Wg Cdr Romeo Singh WO Lal Chand...

RESTRICTED (i) 2 TETTRA SCHOOL TRAINING NOTES Mi-17 V5 HELICOPTER ENGINE ‘AEO & GP-X’ Compiled By: Wg Cdr Romeo Singh WO Lal Chand Sgt RC Dubey Checked By : Wg Cdr KP Vishwas Chief Instructor REVISED: DEC 2014 DESIGNED FOR TRAINING COURSE USE ONLY DO NOT QUOTE AS AN AUTHORITY RESTRICTED RESTRICTED (ii) RESTRICTED  RESTRICTED (iii) VISION “2 TETTRA School continues to put forth the belief that imparting In-Depth Knowledge on the Helicopter and its systems through Quality Training is the future of our Fighting Force that Empowers the Air Warrior and Benefits the Organization. Thus meeting the mission statement of IAF “To Train Air warriors to deliver Air Power for the Nation” RESTRICTED RESTRICTED (iv) RESTRICTED  RESTRICTED (v) FOREWORD 1. 2 Tettra School since its inception in 1980’s has grown to be the best and largest Tettra school of the IAF. For the last three decades, 2 Tettra has been imparting Technical Type Training to all the Air- warriors who are engaged in the Operation and Maintenance of Mi-8, Mi-17, Mi-171V and Mi-17V5 helicopters. 2. Innovation and improvement is a walk of life at this school. The school has now successfully digitized the entire training notes enabling their continuous refinement and updating. To keep pace with the paradigm shift in the training methodologies and the dynamic changes in Aviation Technology the updation of training notes is a continuous process. 3 The new e - training notes are compiled to make them comprehensive and yet simple for better assimilation by trainees. High resolution photographs and schematic diagrams are included for better understanding of systems. Practical activities and questions are also added in each chapter for ready reference. 4. I am sure that the new e-training notes will act as a ready reckoner for the Air-warriors of Mi-17V5 fleet to acquire comprehensive knowledge of various systems of the helicopters. This will contribute directly in enhancing safe and efficient flying environment. (Vasant Navad) Gp Capt Commanding Officer Date: 01 Jul 16 2 TETTRA School, AF RESTRICTED RESTRICTED (vi) RESTRICTED  RESTRICTED (vii) INDEX Mi-17 V5 HELICOPTER CHAPTE PAGE CHAPTER R NO. NO. 01 BK-2500-03 Engine General 1 02 Engine Construction 6 03 Low Pressure Fuel System 18 04 Lubrication And Breathing System 26 05 Engine HP Fuel System 37 06 Air Starter CB – 78 89 07 Dust Protection Device 93 08 KO-50 Kerosene Combustion Heater 96 09 Engine Anti – Icing System 105 10 Engine Electronic Fuel System (BARK-78) 107 11 Time And Monitoring Counter SNK-78 112 12 Auxiliary Power Unit (SAFIR-5K/G-MI) 116 13 Cranking Of Main Engine 136 14 Engine Controls 137 15 Engine Efflux Shield 143 RESTRICTED  RESTRICTED (viii) AMENDMENT RECORD Date Amendment Page No. Authority Signature RESTRICTED  RESTRICTED CHAPTER-1 VK-2500-03- ENGINE 1. Description. Mi-17 V5 helicopters is equipped with two VK-2500-03 turbo shaft engines (Refer Fig 1.1). The VK-2500 (Vladimir Klimov-2500) turbo shaft engine differs from TV3-117VM engine in maximum power at operating conditions due to increase of compressor turbine inlet temperature and gas generator (GG) rotational speed. Depending on the setting of the engine take off power, the engine is produced in three versions VK-2500-01, VK-2500-02, VK-2500-03. VK-2500-03 turbo shaft engines power the Mi-17 V5 helicopter. These engines differ from the TV3-117VМ engines in higher contingency power (up to 2700 SHP) as well as in retention of takeoff, rated and cruising power within a wide range of outside air temperature and altitude due to increase of maximum turbine gas temperature and increase of gas generator maximum RPM. The engine may be operated both with a DPD and without it. Fig. 1.1. MAIN PARTS AND COMPONENTS OF VK-2500-03 ENGINE 01 Exhaust 09 Fuel regulating pump 02 Second support breather pipeline 10 Thermocouple 03 Oil tank breather pipeline 11 Fuel oil ejector 04 FT speed governor drive 12 DTA-10 transducer 05 Air blow off valve 13 Air starter 06 Fuel filter 14 Hot air valve 07 Compressor casing 15 Ignition unit 08 External gear box 16 MSTB-2.5 RESTRICTED  RESTRICTED (2) 2. Design Features VK-2500-03 (a) New materials of higher temperature resistance in gas generator turbine. (b) Change of cooling flow of gas generator turbine. (c) Thermocouple harness is shifted to a zone of lower temperature (before free turbine first stage NGV). Thermocouples Т-102 in TV3-117MT (Qty-14) are replaced with thermocouplesТ-80Т (Qty-12). (d) New oil pump block of high-reliability and long service life. (e) ERD-3VM EEG and RТ-12-6 temperature control unit replaced with BARK-78 EEG with functions of: (i) Temperature regulator (ii) Gas generator RPM limiter (iii) Free turbine over-speed guard (f) Installation of engine operating time counters SNK-78-1. Engine Operating Parameters 3. The engine operation is ensured at: (a) Engine inlet air temperature - from- 60 to +60 ºС (b) Relative humidity - up to 100 % (c) Flight Speed - from 0 to 400 Kmph (d) Pressure altitude - 0 to 6000 m. (e) Speed and direction of wind - not more than 10 m/s during ground start (tail and side) possible gusts up to 15 m/s 4. Acceleration Time (a) Partial Acceleration - 6 sec (b) From idle to takeoff power - 8 sec (c) From cruising I to takeoff power - 4 sec. 5. Engine Power Ratings (a) In All Engine Operative (AEO) conditions: (i) Take off power (TOP) (ii) Maximum continuous power (MCP)/NOMINAL (iii) Cruise power I (iv) Cruise power II (v) Idle power. (b) In One Engine Inoperative (OEI) conditions: (i) 2.5-min contingency power (CP) - 4 times per service life (TBO). (ii) 30-min contingency power once in service life (TBO). RESTRICTED  RESTRICTED (3) 6. Engine Basic Parameters ROTATIONAL MAX. MAX POWER OUTPUT SPEED % (Rotor) INDICATED SFC, CONDITION SHP EGT GG FT MR RPM G/HP.H Contingency (OEI) 2700 103.5 98±1 93 ±1 735 _ 2.5 min Contingency (OEI) 2700 103.5 98±1 93 ±1 735 _ 30 min Take off* 2000 97±0.5 98±1 93 ±1 600 220 Max cont* 1700 95.3 ±0.5 100±2 95±2 565 _ Cruise I* 1500 94.2 ±0.5 100±2 95±2 545 _ Cruise II* 1200 92.3±0.5 100±2 95±2 520 -- Idle 200 max 70 min 65-5 55-70 540 170 * - Parameters corrected to International standard atmosphere (ISA). Main engine parameters are with the DPD not installed. The parameters mentioned above do not account for losses caused due to engagement of helicopter services. NOTE (a) 100% gas generator rpm - 19537.48 rpm (b) 95.4 % MR speed corresponds to 15000 rpm or 100% of the free turbine rpm. (c) In the event of ACMU failure at take off for any power set up the max observed engine SHP shall not exceed 2650 HP, observed rotational Ngg shall not exceed 103.5%. 7. SHP of Engine at Various Power Condition (without DPD and Air Off-Take not used) POWER MAINTAINED POWER MIN.SHP (HP) AT SEA LEVEL AT ISA, UP TO CONDITION 0 AT t C ALTITUDE, Km WITH CONCURRENT OPERATION OF BOTH ENGINES TAKE OFF 2000 +45 3.8 NOMINAL 1700 +35 5.0 CRUSIE-I 1500 +40 5.5 WITH ONE ENGINE INOPERATIVE 2.5MINUTE(CP) 2700 +30 1.5 30MINUTE(CP) 2700 +30 1.5 NOTE. In case the engine control system BARK-78 fails at take off power condition the max permissible observed Ngg (without DPD) amounts to 103.5 %. RESTRICTED  RESTRICTED (4) 8. Various Important Engine Parameters Values No Parameter Min Normal Max Wind speeds allowable for engine start (shutdown), km/h (Knots) Headwind - - 90 (50) 1. RH crosswind - - 36 (20) LH crosswind - - 54 (30) Tailwind - - 30 (16) OEI Ratings (CP-Contingency Power) 2. 2.5 minute CP (max 04 times in service life) - - 2.5 min 30 minute CP (Only once per service life) - - 30 min AEO rating limits (TOP-Take Off Power) 3. 6 min TOP (Limited to max time equal to 12% - - 6 min of service life) 15 min TOP (Limited to max time equal to 3% 6 - 15 min of service life included in 12%) Maximum continuous power (MCP) rating - - Nil Cruise rating - - Nil Idle rating - - 20 min NOTES (i) CP rating is indicated by LH(RH) ENG Contingency Power annunciator. (ii) Idle time is restricted to 20 minutes, at the end of which throttle shall either be increased to full power or the engines switched off. Repeated operation of OEI 2.5 min CP rating or TOP rating is permitted after an 4. interval of 5 min at a lower rating. Engine Gas Temperature in °C 2.5 min CP rating - - 735 30 min CP rating - - 735 5. TOP rating - - 705 MCP rating - - 670 Cruise rating - - 640 Idle rating 540 6. Permitted TGT fluctuations - - ± 25 °C Gas Generator RPM (Ngg) at ratings 2.5-min CP rating - - 103.5 % 30-min CP rating - - 103.5 % 7. Take Off Power (TOP) - - 102 % Max Continuous Power (MCP) - - 99 % Cruise - - 98 % Idle 70 % - 82 % Permitted Ngg fluctuations at ratings (steady state) 8. Max Continuous Power (MCP) - - ±0.25% Cruise and lower ratings - - ±0.25% Main Rotor RPM Maximum for 20 sec at a time (maximum 10 - - 103% occurrences during service life) 9. Maximum 30 sec during transient power 88% - -- changes In OEI condition for a maximum of 10 sec at a 75% -- RESTRICTED  RESTRICTED (5) Values No Parameter Min Normal Max time (occurrence is limited to 4 times per service life) During autorotation landing for a maximum of 5 sec at a time (occurrence is limited to 4 70% - - times per service life) Free Turbine Guard System (FTGS) FT RPM - - 118%±2 NOTE. (i) In case Rotor rpm exceeds 108% or if time of overshoot exceeds, free turbine must be replaced. (ii) In case of FTGS activation free turbine must be replaced. Permitted Ngg split between engines At Cruise and MCP (Rotor RPM Control neutral) - - 2% 10. Activation of EEG TGT limiting control loop - - 3% NOTE At transients and power settings lower than Cruise Ngg split is not specified. Engine Oil Temperature °C Before start -40 - - 11. To set power rating higher than Idle 30 - - At continuous cruise and higher ratings 30 80 - 140 150 2 Oil Pressure at ratings, kg/cm 4 (at oil temp 12. Idle 2 - or equal to 81%, the guide vanes are getting open in accordance with a linear relationship. At N gg corr = 100%, α vgv is equal to 0 deg, and when Ngg corr grows up to 103%, the guide vanes come to rest against the stop corresponding to α vgv =-3deg. 183. The guide vanes reversal is effected by two hydraulic power cylinders (63) and (66), one of them (cylinder 63) being built into the fuel regulating pump. Hydraulic power cylinder (66) incorporates limit switch (66), which produces a command signal for closing compressor air bleed valves (64) when the cylinder displaces the guide vanes into a position corresponding to α VGV =22 deg, i.e. at Ngg corr=84 to 87%.The guide vanes control mechanism is located within the fuel regulating pump. 184. Operation of Main Fuel System When Engine is Shut Down by Free Turbine (Refer Fig 5.36). At all engine operating power conditions, the high pressure fuel is delivered from chamber M of fuel regulating pump constant pressure differential valve (53) to el. Actuator (78).When the free turbine protection system RESTRICTED  RESTRICTED 83 comes into operation, el. Actuator 78 connects chamber M of constant pressure differential valve (53) with the spill line, which leads to an increase in the pressure differential (53) across the diaphragm of constant pressure differential valve (53). Constant pressure differential valve (53) moves to the right and causes the fuel upstream of the frontal valve moves to the right and causes the fuel upstream of the throttle valve to spill, thus reducing the fuel pressure in the fuel regulating pump to a value required for shut-off valve to get closed. Shut-off valve (43) gets closed and stops the fuel flow into the combustion chamber. 185. Operation of Main Fuel System at Engine Shut Down (Refer Fig 5.36). The engine shutdown is affected by shifting the shutdown valve (44) lever of the fuel regulating pump to the shutdown position. In this case, the fuel line upstream of shut-off valve (43) gets connected to the spill line and shut off. 186. Operation of Main Fuel System during Engines Concurrent Running of Helicopter Power Plant (Refer Fig 5.36). The control over the performance of the engines is effected by means of:- (a) The engine throttle levers (22), with the help of which engine control levers located on the fuel regulating pumps, may be set to any position within a range from the idle to the maximum power. (b) The twist grip, which is structurally combined with the collective pitch control lever. The twist grip enables fuel regulating pump levers to be moved through 50 deg over the fuel regulating pump dial with the main rotor pitch remaining unchanged. (c) The collective pitch control lever, which moves levers through 70 deg over the fuel regulating pump dial when the rotor blade angle is increased from Φ MR =1 deg to Φ MR=14 deg. 187. The gas generator speed governor (60) is re-adjusted in relation to an angular position of fuel regulating pump engine control lever, thus pre-setting the engine power available. For the values of the predetermined gas generator RPM (i.e. the engine power available at H=0, T air inl=+15 ºC).At the idle power condition, when the engine control lever (22) is set against the idling stop, the power plant lacks power to rotate the main rotor at the operation speed (Nmr= 95%).Although the rotor blades are fully fined of (Φ MR=1 deg), the main rotor runs at Nmr< or equal to 65%, and the power condition of the engines is controlled by the gas generators speed governors (60). 188. When moving the engine control lever (22) to increase its angular setting (i.e. when turning the twist grip clockwise), the gas generator rotational speed grows with the resultant increase in the main rotor RPM. The rotor pitch remains therewith at a minimum value (Φ mr =1deg).At α ECL equal to approximately 48 º, the gas generator rotational speed and, consequently, the installed power increase to a level sufficient to rotate the main rotor at Φ mr=1 deg at the operation speed. Starting from that moment, the main rotor rotational speed is maintained constant within Nmr=95 ±2% with the aid of the main rotor speed governors, which are in control of the power plant operating power condition. RESTRICTED  RESTRICTED 84 189. With the twist grip turned fully clockwise, the engine control levers (22) of speed governors of the gas generators are set to maintain the operating condition of Ngg=92%, which is higher than the power consumed by the main rotor since the main rotor pitch still remain at its minimum. The excess installed power is cut off by main rotor speed governor (28) and the actual gas generator rotational speed is set below 92%. A gas generator rotational speed drop below pre-set values leads to a closure of the governor valve and cut-out of the gas generator speed governor (60). 190. The effect of the governors on each engine will be different since the settings of the main rotor governors (28) of the power plant RH and LH engines may not completely coincide, whereas the free turbines are rotating at exactly identical RPM controlled by the main rotor. The governor having a lower setting will trim more fuel, which will result in the engines operating at different power conditions. To eliminate this shortcoming, the fuel regulating pump incorporates power synchronizer (33), which by varying the compressors delivery pressures, affects the fuel flow into the engine (running at a lower power), that has a lower compressor delivery pressure, thus increasing the engine power condition. This will bring about some initial increase in the main rotor RPM and, consequently, in the free turbine RPM of the engine operating at a higher power, that is with a higher compressor delivery pressure. To restore the main rotor RPM, the main rotor speed governor (28) of the engine operating at a higher power will reduce the engine power condition. 191. Thus the counter-process occurs, which helps to equalize the compressor delivery pressures with the aid of the main rotor speed governor (28) of the engine operating at higher power and the power synchronizer (33) of the running at lower power. As the air-gas flow ducts of both engines have some differences within the tolerable limits, the gas generators rotational speeds at equal compressors delivery pressures during the engine concurred operation may different. 192. Power synchronizer (33) is series-connected in between throttle valve servo chamber and main rotor speed governor (28).It is worth noting, that the power synchronizer (33) of the engine operating at a higher power does not participate in controlling the fuel flow. 193. Hence, the operating condition of the power plant in point 3 that is the so- called clockwise correction condition, is characterized by the following parameters: (a) Main rotor pitch Φ mr=1deg. (b) Engine control levers angular position α ECL = 50 deg. (c) Setting of GG speed governor (60) at OAT =15ºC, set Ngg = 92%. (d) The power plant operating condition is controlled by the main rotor speed governor (28) having a higher setting. The operation of the second main rotor speed governor (28), having a lower setting, is corrected by the power synchronizer (33). (e) The gas generator speed governors (60) of both engines do not take part in the operation since the actual gas generator rotational speed is 3 to 5% below the governors setting. (f) The main rotor rotates at Nmr =95±2%. 194. A further increase in the engine control lever (22) setting angle is achieved by advancing the collective pitch lever, which is simultaneously with increasing the RESTRICTED  RESTRICTED 85 power consumed by the main rotor.At αECL=70 deg the setting of the gas generators speed governors (60) becomes equal to the main rotor at this point, characterized by rotor pitch Φ mr= 4 deg, is still less than that set by the engine control levers (22), and the power plant operating condition is controlled by the main rotor speed governor (28) in the same way as the clockwise correction power condition. 195. As the main rotor pitch further increases (αECL>70 deg and up to αECL=120 deg), the difference between the power pre-set by the gas generator speed governor (60) and that consumed by the main rotor is reduced. When the main rotor pitch becomes Φ MR = 12 deg, the power consumed by the main rotor comes to equal the takeoff installed power. A further increase in the pitch leads to a drop of the main rotor rpm from 93 to 92%, which is controlled by the BARK-78(gas generator loop) or by the gas temperature controllers. 196. Should the Engine electronic governor gas generator loop fail or get cut out, the engine power condition will be controlled by the gas generators speed governors (60). The engine automatically gains the takeoff power condition which is characterized by gas generator rotational speed exceeding that at the takeoff power condition by approximately 1.5%.In the course of increasing the pitch of the main rotor, the rotational speed of the main rotor is maintained within the pre-set limits by means of corrector. 197. The adjustment of the gas generator speed governor (28)at αECL > or equal to 70 deg to a max setting ensures at all operating conditions (with respect to speed, height and O.A.T.) the excess of the power available over that consumed by plant, except for the limited takeoff power and takeoff power, are controlled by the main rotor speed governors (28), whereas the rotational speed is automatically maintained within 95±2%. 198. At the same time, corrector of main rotor speed governors (28) setting functions as a unit limiting the over speeds and speed drops of the main rotor during abrupt changes in the rotor pitch. When the rotor pitch is being decreased or increased within a range of α ECL>70 deg, the setting of the gas generator speed condition will be changing only after an increase (or decrease) of the main rotor rotational speed, caused by the main rotor speed governors, has occurred. 199. Such a delay in the control process inevitably leads to high over speeds (or speed drop) of setting of main rotor speed governor (28) simultaneously with a decrease in the main rotor pitch, and, as the result, the main rotor speed governors (28) produce a command signal to reduce the fuel flow before the main rotor rotational speed has increased. Similarly, as the rotor pitch increases; main rotor speed governors (28) increase the fuel flow before a reduction in the main rotor speed occurs. 200. Thus, the implementation of the correction of the main rotor speed governors (28) setting allows to reduce substantially the main rotor dynamic over speeding (or speed drops).Presence of the power synchronizers (33) in the main fuel system may lead to a main rotor uncontrolled over speeding, should the engine develop certain faults. For example, if a failure occurs in the free turbine-to-main rotor speed governors (28) kinematics coupling, the main rotor speed governor (28) will produce a command to increase the engine power condition to a value limited by the limit RESTRICTED  RESTRICTED 86 power condition governor or the gas temperature controller. In this case, due to the present of power synchronizer (33), the second engine RPM exceeding the permissible limits, with the main rotor pitch remaining unchanged. Main rotor speed governors (28) are unable to reduce the fuel flow into the engine due to the fact that of them is not rotating and the other has been cut off by power synchronizer (33). 201. To prevent occurrence of the above, the fuel regulating pump incorporates slide valve (25) effecting the power synchronizer cut-out. As the main rotor comes to rotate at Nmr = 107±2%, slide valve (31) of the fuel regulating pump of the engine with the intact kinematics drive cuts out the power synchronizer (33), following which the main rotor governor(28) with the intact kinematics drive will reduce the engine power condition to idle power. The second engine continues to run at the max power. 202. In case the power synchronizers (33) have been disconnected, a further control of the power plant is effected by the collective pitch lever, the main rotor speed therewith being maintained within a range of 95±2% either ;manually by turning the twist grip counter clockwise or by manipulating the engine throttle levers. As a rule, the engine throttle levers and adjustment of the main rotor speed governor (28) with the aid of the helicopter’s electrical actuator (78) are used during an engine test and in some special cases in flight (e.g. when flying with one engine failed due to a discontinuous of the fuel supply). 203. Should one of the engine fail at operating conditions corresponding to α ECL> or equal to 70 deg due to the fact, that at the initial moment the main rotor pitch remained unchanged, the free turbine rotational speed decreases which results in a closure of the main rotor speed governor (28) valve and automatic acceleration of the running engine to the limited take off power. 204. Important Data on High Pressure Fuel System MI-17 V5 Helicopter 1 Inlet fuel filter filtration capacity 160 micron Fixed swash plate reciprocating plunger 2 HP Fuel Pump type, out put pressure 60 kg/ cm2 max. Maintains constant pressure differential Constant pressure differential 3 of 3±0.5 Kg/cm2 across metering needle valve orifice. Permits fuel flow into primary line at a 4 Shut off valve of Primary manifold fuel pressure of 3-0.5 Kg/ cm2. Gas generator rpm at which fuel 5 15-20% flows into primary manifold Supplies compressed air from air starter into main fuel manifold during starting. It 6 Pressurising air valve cuts off when fuel pr. in primary manifold reaches 5-6 Kg/ cm2 Permits fuel flow through the main fuel 7 Distributor valve manifold when pressure in primary line reaches 32±1 Kg/ cm2 Fuel flow through primary Both during starting and at all operating 8 manifold conditions. 9 Fuel flow through main manifold After idle and all power conditions RESTRICTED  RESTRICTED 87 Governing of fuel flow ---- up to 45% rpm Auto start control unit. ---- 45% till idle run Acceleration Time Control Unit. 10 ---- with throttle fully open Main rotor governor. ---- above idle rating up to take off Main rotor governor. ---- at idle, take off and cp BARK-78. Working range of IM-47 temp 11 705-735 deg C control unit. IM-47 interlocking/cut out control Disengages IM-47 in case compressor 12 slide valve rpm drops below 69%. Closes between 84-87% compressor 13 Air bleed valves rpm. Does not allow fuel pr to drop below 12 14 Minimum pressure valve Kg/ cm2 15 Free turbine circuit operating rpm 118±2% of free turbine rpm. Range of movement of VGV’s 27+1.5 deg to –6.5±0.5deg. 16 ---- up to 81% rpm 27+1.5 deg (i.e. closed) ---- 84% rpm 22 deg ---- 100% rpm 0 deg ---- 103.5% rpm -3 deg. Constant pressure valve out put 17 15+1 Kg/ cm2 pressure. Operates at 107±2% of main rotor rpm Power synchronizer emergency 18 which corresponds to F/T rpm of cut out slide valve 112±2%. Main rotor trimmer adjustment 19 91±2 to 97+2% main rotor rpm. range Throttle valve control lever dial 0 to 120 deg graduations 20 ---- idle rating 0 to 3+7 deg ---- throttle grip fully open 50 deg ---- take off 70to 120 deg RESTRICTED  RESTRICTED 88 205. Multiple choice questions (a) If air starter disenga gment rpm is beyond specified limit, then adjustment is carried out on:- (i) No.1 screw (ii) No.2 screw (iii) No. 4 screw (iv) No. 5 screw (b) The position of twist grip and CPTCL setting, while starting the engine (i) opened and 1º pitch respectively (ii) opened and 5-7º pitch respectively (iii) closed and 1º pitch respectively (iv) closed and 5-7º pitch respectively (c) While adjusting the screw no.1 max rpm adjusting screw of VK-2500- 03 aero engine, one turn in either direction gives a variation of: (i) 0.5% of rpm (ii) 1.0% of rpm (iii) 2.0% of rpm (iv) 1.5% of rpm (d) During engine starting the pressurized air from AI-9B engine is supplied into the main fuel manifold of the duplex burner The unit which control air valve :- (i) Pressurizing air valve (ii) Air starter cut out slide valve (iii) Air starter cut out solenoid valve (iv) Distributor valve 206. Short Question (a) Which are all the units supplied with gas generator and free turbine control pressure transmitter fuel? RESTRICTED  RESTRICTED 89 CHAPTER 6 AIR STARTER CB-78 1. General. The function of the air starter (Refer Fig 6.1) is spin up the gas generator rotor in the course of a dry motoring run, a wet motoring run and an engine start. Air starter is fitted on EGB rear side beside FCU (Refer Fig 6.2). The air starter comprises the following assemblies:- (a) Air valve (b) Control unit (c) Turbine (d) Reduction Gear (e) Air Filter 2. Description. The air valve is an actuating mechanism intended to admit and shut off the compressed air coming from the SAFIR APU into Air Starter Turbine. The air valve comprises the following major assemblies:- (a) Casing (b) Inner casing (c) Piston (d) Rod Fig. 6.1. AIR STARTER RESTRICTED  RESTRICTED 90 Air starter Fig. 6.2.LOCATION OF AIR STARTER 3. As the piston travels a distance of 0.6 + 0.2 mm from the closed position, the mechanism of electrical contacts intended to provide an indication of the air valve open position comes into operation. When the pressure in the air chambers becomes balanced out, the piston acted upon by the spring closes the air valve. Control unit is intended to effect control over the operation of the air starter air valve and is located in the upper portion of the air starter. The control unit is secured to the casing of the air valve by means of studs. The control unit comprises of the following main components and assemblies:- (a) Control unit (b) Casing (c) Solenoid valve (d) Pressure Limiter with Rod. 4. The turbine comprises the following elements:- (a) Aluminum turbine casing with exhaust port. (b) Aluminum nozzle guide vane assembly. (c) Bladed aluminum disk. (d) Steel turbine shaft. 5. The reduction gear is of the planetary, two stage type. The reduction gear consists of the following elements:- (a) Aluminum reduction gear casing. (b) Planetary mechanism steel gears (c) Titanium carrier (d) Steel torsion shaft 6. The reduction gear is mounted on ball and roller bearings. The lubrication system of the reduction gear is of the centralized, forced, splash type and employs RESTRICTED  RESTRICTED 91 the engine oil. The oil required for lubrication of the reduction gear is provided in the starter itself. The quantity of oil filled in the starter is 120 cc. 7. The air filter is mounted in the line delivering air from the SAFIR engine to the control unit. 8. Operation. The compressed air is delivered from the SAFIR engine to the inlet of air starter air valve(Refer Fig 6.3). Two vents serve to bleed the compressed air into atmosphere, thus ensuring the supply of hot air to the air valve. At the same time the air from the chamber is supplied along pipe line via an air filter to disc valve of the control unit and then further via the passages made in air valve casing to inner chamber of air valve piston. The forces of the air pressure acting on both sides of piston are balanced out and spring keeps the piston in the closed position. 9. On depressing the main engine start button the power is supplied to solenoid valve of the control unit which extends rod and moves disc valve to the right. The passage delivering air into the inner chamber of piston gets closed, whereas the passage bleeding the air from the inner chamber of air valve through bleeder jet to atmosphere gets open. Bleeder jet ensures delayed opening of piston and progressive rise of the air pressure upstream of turbine. The pressure in the chamber drops and piston, acted upon by air pressure supplied from the SAFIR engine, moves to the right and opens the air flow to the turbine. 10. Rod with the thrust ring moves together with piston in the guide casing. Rod closes the contacts, located in air valve inner casing, thus energizing the air starter ‘ON’ text message on MFD. Under the action of the compressed air, turbine rotates and transmits a torque to the engine rotor via planetary reduction gear and EGB. The compressor turbine upstream air pressure is conveyed along a pipe line to chamber of the control unit. If the air pressure upstream of the starter turbine comes to exceed a predetermined value, the pressure in front of labyrinth seal bushing builds up which causes rod to overcome the force of spring and to shift. As a result, the some air from chamber in front of air valve is admitted into the chamber behind the piston, through a port having a larger sectional area than the bleeder jet. The pressure in chamber behind the piston starts increasing causing piston to move, to reduce the air flow into the turbine, which leads to reduction in the air pressure upstream of the starter turbine. 11. The air pressure drop upstream of the starter turbine leads to a pressure drop in front of labyrinth seal bushing. As a result, a spring moves pressure limiter rod towards masking the port delivering air into chamber behind the piston. In this case piston comes to rest in new equilibrium position. The air starter disconnection is effected by de-energizing of solenoid valve. In this case, spring presses solenoid valve rod into the solenoid valve, whereas disc valve gets pressed out by its own spring, thus allowing air to flow into the chamber behind the piston. At the same time, the passage, relieving the air pressure from chamber through bleeder jet, gets closed. The air pressure in chamber behind the piston becomes equal to that upstream of piston and spring causes piston to return to the closed position, thus shutting off the air flow to the starter turbine. 12. The air starter cut out signal is delivered from the following units. (a) Fuel regulating pump micro switch. RESTRICTED  RESTRICTED 92 (b) APD-78 control unit (on completion of the starting cycle) (c) Start disconnect button. 13. If in the course of an engine starting the air starter turbine rotational speed reaches a limiting value for some reason, the centrifugal switch de-energizes the solenoid valve power supply circuit which leads to the closure of the air valve. Fig. 6.3. AIR STARTER RESTRICTED  RESTRICTED 93 CHAPTER-7 DUST PROTECTION DEVICE 1. Introduction. Dust and foreign particles, when drawn into the air intake of a gas turbine engine causes compressor blade wear. This wear beyond a certain limit, leads to loss of power or compressor surge. Helicopters particularly, are prone to the adverse effects of sand / dust laden air kicked up due to rotor downwash during taxing, take-off and landing. 2. All Mi-17 series helicopters have the provision for fitting a DPD(Refer Fig 7.1) which is capable of cleaning the air to the extent of 70 to 75 %. With the device fitted, icing condition in the intake is aggravated. For that reason DPD anti-icing system is incorporated in engine. 1. FAIRING (OUTER AND INNER) 3 5 2 4 1 2. SEPERATOR (DUST TRAP) 3. COLLECTOR TRAY 4. EJECTOR 5. STAY (MOUNTING) Fig. 7.1. PARTS OF DPD 3. Principle of Operation. The engine is protected from dust by separating the heavy dust particles from the clean air. This is done in stages using two different principles (Refer Fig 7.2). (a) First Stage. Air with dust particles is forced to follow a circular path before it enters the air intake. Due to the effect of the centrifugal forces the heavier dust particles are swung to the outer edge of the air column. Purified air occupies the inner column. The two air columns are separated with the cleaned air being allowed to continue on its path, over the compressor blades. The phenomenon is illustrated in the diagram. RESTRICTED  RESTRICTED 94 (b) Second Stage. The dense dust laden column of air is trapped and subjected to further purification within the trap where particulars are deflected further by means of baffles inclined at an angle to the main air stream. Clear air escapes through the space between the baffles to join the first stage purified air stream while dust particles concentration is scooped up and diverted out to the atmosphere. (c) Third Stage. The dumping into the atmosphere is aided by rarefaction induced in a pipeline by a jet nozzle using compressed air. OPERATION OF DPD STAGE 1 STAGE 2 P2 AIR FROM COMBUSTION STAGE 3 CHAMBER Fig. 7.2. OPERATION OF DPD 4. DPD Anti Icing System. The anti-icing system of the dust protection device is of combined type, some units are warmed with hot air, while the other units have an electric heating system. Both the air warming and electric heating anti-icing systems are energized in synchronism with the switching on the anti icing system. The ambient temperature at which the anti-icing system gets energized is from +5o C below with engines operating. 5. Hot air bled from the engine combustion chamber heats the following parts:- (a) Trap, whose four rings and ribs are hollow in construction with hot air passing through and let out via strategically placed holes. (b) Circular air intake manifold lip. 6. The hot air flow rate is controlled by a thermo regulator and selected by an electrically operated flap valve. 7. Electric heating is used for the following elements:- (a) Front panel of dome shaped fairing. (b) Rear panel of dome shaped fairing. (c) Dust removing pipeline casing 8. Effect on Engine Performance. The operation of DPD involves losses. The dome shaped fairing and the trap, though streamlined, causes an obstruction to the air flow path in the air intake. The resulting inlet duct pressure loss ultimately RESTRICTED  RESTRICTED 95 shows as a power loss. In addition power losses occur due to air bleed from the engine for activating the DPD wherein air is supplied to the nozzle of the ejector. A further loss would occur during icing condition when hot air is supplied for the DPD thermal anti-icing. 9. Power Loss due to DPD. Following power losses occurred due to DPD (a) DPD installed 40 SHP (b) DPD installed and ejector on 100 SHP (c) DPD installed engine and DPD anti-icing on 240 SHP (d) DPD installed engine and D P D anti-icing on and ejector on 300 SHP RESTRICTED  RESTRICTED 96 CHAPTER 8 KO- 50 KEROSENE – COMBUSTION HEATER 1. Introduction. The helicopter is equipped with KO-50 kerosene combustion heater for heating and ventilation system for supply of heated or atmospheric air into the cargo compartment and crew cabin in order to maintain normal temperature conditions. 2. Purpose. KO-50 Kerosene combustion heater is designed for heating and ventilation of the crew cabin and passenger compartment of the Mi-17 V5 helicopter. Besides, the heating and ventilation of the passenger compartment and crew cabin it is also designed for:- (a) Heating the pilot’s feet. (b) Blowing the windshields and blisters of the pilot’s cabin. (c) Heating of drain cock of drain tank. 3. Location. The main unit of the system is represented by Kerosene combustion heater KO-50 (with a heating capacity of 50,000 K Cal/hr), located outside the helicopter (starboard side) under a streamlined cowl, on top of the starboard entrance door as shown in Fig 8.1 (refer fig. 8.2 also). KO-50 Fig. 8.1. LOCATION OF KO-50 RESTRICTED  RESTRICTED 97 Fig. 8.2. KO-50 4. Main Data The main leading particulars are as follows: (a) Rated calorific capacity : 50,000 K/Cal/hr (min) (b) Fuel used : ATF K-50 (c) Max fuel pressure at pump inlet (748-A) : 0.5 to 2.2 Kg/Cm2 (d) Fuel consumption (max) : 8.7 Kg/hr (e) Rate of air blown through (max) : 1760 kg/hr (f) DC power supply : 27 + 10 % Volt (g) Power consumed by the heater at supply: 2.5KW voltage of 27 V (max) (h) Operating altitude (max) : 5 KM (j) Weight of the heater (including blower and component) (max) : 47.5 Kg 5. Main Components of the Heater. The kerosene combustion heater comprises the following components assembled in a single unit and interconnected with pipes and wires. The components are as follows (Refer Fig 8.3).:- (a) Blower (fan) with electric motor D-60. (b) Heater (combustion chamber and air heater) (c) Fuel pre-heater. (d) Thermo switches Qty – 3. (e) Pneumatic relays Qty –2 (f) Temperature regulator control unit (electronic unit) 4087-3C. (g) Temperatures Sensors Qty – 2. (h) Temperatures pickups Qty – 2. (j) Temperature setter (Range 0o to 30o C) RESTRICTED  RESTRICTED 98 (k) Ignition Unit (l) Glow plug (m) Injector with by pass. (n) Fuel control box; It consists of the following:- (i) Fuel filter 774 (ii) Pressure regulator 773H-2C (iii) Main fuel valve 772. (iv) By pass fuel valves 772 Qty – 2. (v) Low rate jet (vi) High rate jet. Construction of KO-50 Heater And Purpose Of Its Components 6. Blower. It is intended for feeding air through the heater as well as supplying the air to the combustion chamber. 7. Combustion Chamber. It is intended for combustion of fuel air mixture. The combustion chamber is assembled from a cone and shell having a welded bottom. It is made of heat resistant steel. 8. Air Heater. Air heater is provided for preheating the cold air fed by the blower before sending to the passenger compartment and crew cabin. It is also made of heat resistant steel. Fig. 8.3. COMPONENTS OF KO-50 1, 2 & 14 Thermo Switch 3 & 12 Temp Sensor 4. Pre Heater 5. Heater 6. Blower 7. Fuel Control Box 8. Temp. Pick up 9. Pneumatic relay 10. Ignition Unit 11. Electronic Unit 13. Ignition Cable 9. Fuel Pre-Heater. Pre-heater is provided for preheating kerosene up to 70 + o 5 C prior to starting the KO-50 heater to ensure ease in starting. 10. Thermo Switches. There are total three thermo switches installed at the outlet of the kerosene combustion heater and are provided for three different purposes. RESTRICTED  RESTRICTED 99 (a) Thermo switch 2416-17.5 is intended to discontinue the fuel supply to the kerosene Combustion Heater when air temp at the heater outlet reaches 200o C. (b) Thermo switch 2416-4 is intended to switch off ignition when the temperature of heater air attains 40+25o C or 40-10o C. (c) Thermo switch 1374A-5 is intended to automatically cut off blower, when the air temp at the heater outlet attains 50+5 oC or 50-20oC. This thermo switch allows the fan to run for several minutes after the KO-50 heater is switched off. This provided for expelling the kerosene vapors from the combustion chamber and faster cooling of heater. 11. Pneumatic Relays. They are intended for either switching ON or switching OFF the main fuel valve 772. Until unless the fan is ON the pneumatic relay diaphragm will not get pressed and no electrical supply will go to the fuel valve. Thus the valve will not get actuated. The operation of the pneumatic relay also ensures that the exhaust pipe of the heater is clean and free from carbon deposit. 12. Temperature Regulator Control Unit 4087-3C. It is an electronic unit designed for converting the resistance of two temperature pickups, two temperature sensors and two temperature setter into electrical signals, fed to the bypass fuel vales 772. It is incorporated in the automatic temperature control circuit that maintains air temperature inside the crew cabin and passenger compartment of the helicopter within 10o to 30oC as pre determined by the temperature setter. Depending upon the temperature in the compartment, at the heater inlet and outlet, the control unit sends respective signals to the bypass fuel valves 772 which control flow rate of fuel through injector. 13. The automatic temperature control unit functions in conjunction with the following:- (a) Two temperature pickups P-9T (item 2622) (b) Two IS-264A-2 temperature sensors. (c) 2400B temperature setter. (d) Two bypass fuel valves 772. 14. Temperature Pick Up 2622. There are two temperature pickups installed inside the cargo compartment ceiling left side, one at the rear near clamshell door and other at the front near main entrance door. These are installed in the automatic temperature control circuit and come into action when the heater is put into automatic mode. They pick up the temperature from the compartment and send signal to the automatic temperature control unit via resistance and automatically control the temperature in the passenger compartment and crew cabin. 15. Temperature Sensor IS-264A-2. There are two temperature sensors installed at the inlet and outlet of the kerosene combustion heater. Temperature sensors operate in the automatic air temperature control system and are installed in the flow of heated air blown from the 2437 kerosene combustion heater. They sense the temperature of the KO-50 heater from the inlet and outlet and send the signal to the electronic unit through resistance. RESTRICTED  RESTRICTED 100 16. Temperature Setter 2400B. It is located inside the crew cabin. It is intended for setting a pre determined air temperature inside the flight and passenger compartment within the range from 10o to 30oC. 17. Ignition Unit. It is located inside the KO-50 heater compartment and provided for transformation of 27 V low voltages into a high voltage which is required for glow plug operation. 18. Glow Plug SD-96. It is intended to ignite fuel air mixture. 19. Injector. It is intended for injecting the kerosene into the combustion chamber and for bypassing some portion of fuel through the bypass fuel valve to the starboard external tank, when the kerosene combustion heater is switched ON for low calorific capacity. 20. Fuel Control Box 2621. The box is located inside the KO-50 combustion heater compartment. It is intended for filtering the fuel, maintaining pressure upstream of the injector within 1.6+ 0.1 Kg/Cm2, for opening and closing the fuel supply into the combustion chamber and also bypassing some portion of fuel from the injector. Fuel control box consists of two covers made from steel sheet. 21. Fuel control box accommodated the following components(Refer Fig 8.4).:- (a) Fuel filter 774 (b) Pressure regulator 773H-2C (c) Main fuel valve 772 (d) By pass valves 772 – Qty two (e) Low rate jet (f) High rate jet 22. The pipe line that supplies the fuel from the pump 748A to the injector comprises fuel filter, pressure regulator and main fuel valve interconnected by pipes. The bypass line comprises two bypass fuel valves, high rate jet and low rate jet interconnected by pipes. 23. Fuel Filter. It is intended for cleaning the kerosene from the impurities. 24. Pressure Regulator. The purpose of pressure regulator is to keep the fuel pressure at its outlet within 1.6+ 0.1 Kg/Cm2 the pressure at its inlet being within 2+0.5 Kg/Cm2. It is fitted inside the fuel control box in the main fuel flow path after the fuel filter. 25. Fuel Valve 772. There are three fuel valves fitted inside the fuel control box, one is in the main fuel line after the pressure regulator and another two are fitted in the bypass line after the injector. These are the solenoid operated fuel valves RESTRICTED  RESTRICTED 101 intended for opening and closing the fuel supply pipelines after receiving the signal from the respective units. FUEL CONTROL BOX 2 1 3 1.PR.REGULATOR 2.FUEL VALVE 3.FUEL FILTER 4.LOW RATE JET 5.HIGH RATE JET 6.FUEL VALVES (BY PASS) 6 5 4 Fig. 8.4. VARIOUS COMPONENTS OF FUEL CONTROL BOX 26. Jets. They ensure the control of fuel flow. They are fitted into the inlet port of the bypass fuel valves. They differ from each other in sizes. The diameter of the high rate jet is 0.47 + 0.01 mm and the low rate jet is 0.36 + 0.01 mm. 27. Modes of Operation. KO-50 kerosene combustion heater can be operated in three modes. These are:- (a) Heating mode (automatic & manual) (b) Ventilation mode (c) Re-circulation mode(Refer Fig 8.5). 28. Heating Mode. In this mode of operation, the fan incorporated in the heater which is run by the electric motor, draws air either from the atmosphere via the air intake provided in the cowl or from the cargo compartment (in re-circulation or partial re-circulation) via air intake in the fuselage starboard side. Both the intakes can be opened or closed by operating the shutter manually from the cargo compartment. HEATING AND VENTILATION SYSTEM MI-17 H/C MODES OF OPERATION 1. VENTILATION MODE 2. HEATING MODE AUTO MODE MANUAL MODE RECIRCULATION MODE Fig. 8.5. MODES OF OPERATION RESTRICTED  RESTRICTED 102 29. In heating mode fuel and air is supplied into the combustion chamber and ignition is provided by the glow plug. Combustion takes place inside the combustion chamber and exhaust gases discharge through the exhaust pipe. Majority of the air which passes through the air heater, absorbs heat from the combustion chamber wall and also simultaneously cools down the walls of the combustion chamber. The heated air is supplied from the heater into the distributor in which the air is divided into two streams i.e. flowing into the cargo compartment and into the crew cabin. 30. In the heating mode the heater may be operated either through automatic or manual control. For this purpose a selector switch is provided in the cockpit instrument panel. With the heater operating in the automatic mode air temperature is maintained at a constant level depending upon the position of the temperature setter, mounted on the instrument panel of the co-pilot. Manual control provided for heater operation at maximum (full) and medium ratings (with regard to heating capacity). For this also, a selector switch is provided in the cockpit instrument panel. Selection of the switch is as follows:- TOP : Priming CENTER : Full rating BOTTOM : Moderate rating 31. Ventilation Mode. Operation of the KO-50 heater in the ventilation mode ensures cooling of the air heater and ventilation of the H/C cabins in summer season. In this mode only fan is made to run by the motor. For the operation of the fan, a separate switch is provided in the cockpit instrument panel. In this mode of operation, no fuel is supplied and no ignition is given to combustion chamber. ‘Auto- manual’ selector switch is in neutral position. 32. Re-Circulatory Mode. Re-circulatory mode is a form of heating mode only. The difference is that, in the case of re-circulation mode, the air intake (which draws the air from the atmosphere) is kept closed by the shutter. In this mode air is drawn from the H/C compartment through another intake and re-circulated through the heater for the purpose of faster heating. 33. Precautions while Operating KO-50 Heater. KO-50 heater should be switched ON at and outside air temperature of +5 oC or below on ground and in flight with the engine running at any rating, except auto rotation. In flight the KO-50 heater should be started in re-circulation mode and also up to an altitude of 4 km only. Prior to starting the heater, it is necessary to drain the fuel from the drain tank. Starting KO- 50 Heater 34. Starting KO- 50 Heater in Automatic Mode (a) Put the CBs ON. (b) Set the selector switch (auto-manual) to automatic mode. (c) Set the control knob of the temperature setter to dial division of 30 oC. (d) Press the button ‘KO-50 STARTING’ 35. After depressing the starting button of the KO-50 heater, all the operation i.e. preheating the kerosene, supplying the fuel to the combustion chamber, giving RESTRICTED  RESTRICTED 103 ignition, and maintaining the pre set temperature in the cockpit etc takes place automatically. Only, the control knob of the temperature setter is to be set to the desired temperature. 36. Starting in Manual Mode (Full Rating) (a) Put the CBs ON. (b) Set the selector switch (auto-manual) to manual mode. (c) Set the selector switch (priming-full-moderate) to full rating. (d) Press the button ‘KO-50 STARTING’ 37. Starting in Manual Mode (Moderate Rating) (a) Put the CBs ON. (b) Set the selector switch (auto-manual) to manual mode. (c) Set the selector switch (priming-full-moderate) to moderate rating. (d) Depress the button ‘KO-50 STARTING’ 38. Operation in Ventilation Mode. Set the selector switch FAN on the air heater control panel to the ON position. For accelerated cooling of the air heater, it is recommended to keep the fan running for three to ten minutes. 39. Operation of Heater in Re-Circulation Mode. Should it be necessary to accomplish cabin air heating at a higher rate, with the air heater operating in the automatic or manual mode at an outside air temperature below –13oC, close the shutter which allows outside air flow into the air heater and open the shutter for drawing in air from the H/C cabins, for that purpose set the handle to FROM CABINS POSITION. 40. Warnings. If the air heater operates at full rating, and the air temperature in the cabin at the air heater inlet is from –13oC to +15oC, it is allowed to run the system in the re-circulation mode for not more than 10 minutes. 41. It is not allowed to start the heater in the re-circulation mode, when the air temperature in the cabin at the heater inlet is in excess of +15 oC. 42. Fuel and Air Flow Path. Kerosene is fed from the service tank under a pressure of 0 to 0.3 Kg/Cm2 through solenoid valve to the fuel pump 748 A which raises the pressure up to 2+0.5 Kg/Cm2. Thereafter, the kerosene flows through fuel filter to pressure regulator. At the outlet of pressure regulator, pressure is held constant within 1.6+0.1 Kg/Cm2.From there, the fuel is supplied through main fuel valve and kerosene pre-heater to injector and further to the combustion chamber(Refer Fig 8.6). 43. Simultaneously the air is fed from the running blower through the combustion air pipe connection to the combustion chamber. Thus, the kerosene air mixture is formed and ignited. The heated gases formed in the combustion chamber flows through the insulated flues of the air heater to outlet pipe connection and dissipate its heat via steel walls to the cold air drawn and supplied from the atmosphere by the blower through the air heater flues. The direction of flow of air, exhaust gases and kerosene is shown by arrows in the above figure. The heated air is supplied to the crew cabin and passenger compartments. RESTRICTED  RESTRICTED 104 Fig. 8.6. BLOCK DIAGRAM OF FUNCTIONING OF KO-50 HEATER 44. Caution (a) Change the heater operation rating from automatic to manual control and vice versa only after switching off to neutral position and after the heater is closed down for 10 to 15 minutes to accelerate the cooling of the heater. (b) It is prohibited to operate the heater at nominal heating if the heater inlet temperature exceeds 13oC (c) Do not start the heater if there is any fuel / oil leak. (d) After each abortive start, it is necessary to blow off the heater before attempting the next start. 45. Multiple Choice Questions (a) It is not allowed to start the KO-50 heater in recirculation mode when the temperature in the crew cabin or outside (i) More than 5ºc (ii) More than 15º C (iii) More than 20º (iv) More than 25º C (b) Never operate the KO-50 heater in heating mode with automatic temp control if:- (i) the loading hatch is opened (ii) the entrance door is opened (iii) the engine cowling is opened (iv) both (i) & (ii) (c) Kerosene pre heater is intended for heating the kerosene up to:- (i) 70±5ºC (ii) 75±5ºC (iii) 70±2ºC (iv) 65±5ºC RESTRICTED  RESTRICTED 105 CHAPTER 9 ENGINE ANTI-ICING SYSTEM 1. General. The engine anti-icing system serves to protect the engine air intake and DPD from ice formation when operating in extreme cold weather conditions. The engine anti-icing system uses the hot air tapped from the combustion chamber outer casing. The anti-icing system can be operated manually or automatically. When air is bled for anti-icing the engine gas temperature rise by 25 to 50 0 C and the compressor RPM increases by 1% to 2%.The anti-icing system comprises of:- (a) Ice Detector- DSL-40T. It is mounted in cooler fan inlet duct. It automatically puts ‘ON’ the anti-icing system as soon as the ice formation starts in air intake of the engine. (b) 1919 T – Hot Air Valve. It is an electrically operated valve and serves to supply and shut off hot air flow from the combustion chamber to the engine inlet duct. (c) Temperature Control Device. It serves to limit the hot air flow from the combustion chamber to the inlet duct during anti-icing in order to reduce the engine power loss. (d) Visual Ice Indicator. It is installed on the cockpit port side blister and serves to indicate ice formation to the pilot visually. 2. Operation. When the system is put ON (manually or automatically), the hot air valve opens to allow hot air from combustion chamber to flow via temperature control device to enter the right horizontal strut of the 1st support housing. Further the hot air flows for the anti-icing of different assemblies as follows(Refer Fig 9.1).:- (a) Hot air along a system of channels and holes flows to heat the fairing and horizontal struts. The vertical struts are heated by lubricating oil. (b) Along the annular chamber of the first support housing and through the hollow lower trunnion of the VIGVs, the air enters into the VIGVs. The hot air after heating the VIGVs escapes through the perforations on their trailing edges and mixes with the airflow. (c) An external pipe carries the hot air to the air intake duct for its heating. (d) From the left horizontal strut, through an elbow connection, air is taken for the heating of air conduit of the main fuel pump. (e) When DPD is installed, part of the hot air flows via two elbows to the dust separator for its heating. The DPD fairings (Rear and front) are heated electrically. RESTRICTED  RESTRICTED 106 Fig. 9.1. ENGINE ANTI ICING 3. Multiple Choice Questions (i) Radio isotope ice detector RIO-3 is located at the:- (a) port engine air intake (b) starboard engine air intake (c)SAFAIR air intake (d) cooling fan air intake (ii) The anti-icing of DPD is carried out by:- (a) hot air (b) electrically (c) lubrication oil (d) hot air & electrically (iii) Visual ice detector is fitted outside the:- (a) port sliding blister (b) starboard blister (c) air intake (d) cooling fan intake (iv) Air blow off valves operates (a) Manually (b) Automatically with high pressure fuel (c) Electrically. (d) Pneumatically with air pressure. RESTRICTED  RESTRICTED 107 CHAPTER-10 ENGINE ELECTRONIC GOVERNOR (BARK-78) DESCRIPTION AND OPERATION 1. Description In the modified circuitry the engine power is controlled (limited) by means of the BSK-17В-5 on-board monitoring system providing data display on the MFD (by page selection) as respective text messages for the crew. 2. BARK- 78 is included into adjustment system of the engine VK-2500-03 and designed to adjust fuel consumption by making control actions to actuator IM-47 of fuel control unit to: (a) Keep preset rotation frequency of turbo compressor rotor at emergency, take-off and idle power modes (turbo compressor revolutions limiting channel). (b) Limit the engine operation mode by limit values of gas temperature (Gas temperature limiting channel). (c) Switch off the engine by applying signal to actuator of engine stop IM- 3А in case of exceeding rotation frequency value of the FT rotor over preset limit of 118±2% (free turbine revolutions limiting channel). Note: In case of its own failure or failure of sensors and actuators, the control/limitation of Ngg is done by the Ngg governor. 3. BARK-78 consists of the following main functional devices: (a) Power source (b) Input (c) Output device (d) Device of connection with Test Equipment (TE) 4. Power source is designed to convert power supply voltages of the airborne mains into voltages providing operation of all devices of BARK-78 as well as sensors, actuators and warning annunciates. 5. Input device is designed to receive electric signals from sensors and indicators of the engine and the helicopter, the controls located in the crew cabin, as well as standardization of those signals and protection from input overvoltage and pulse jamming. 6. Computing device checks reliability of parameter values received from sensors, provides calculation and synthesis of control actions on actuators, self- check of computer serviceability, operability of memory storage devices, integrity of programme code, serviceability check of output circuits of actuators, data exchange with SNK-78 and TE. RESTRICTED  RESTRICTED 108 7. Output device is represented by unit of power shaping amplifiers converting output signals of computing device into control signals of actuators and displays and signals for SNK-78. 8. Device of connection with TE provides exchange of data between computing device of BARK-78 with TE. Engine Automatic Control System (ACS) 9. The engine ACS comprises of two units, NR-3VMA-T mechanical fuel control and BARK-78 electronic engine governor (EEG). 10. Functions of BARK-78 (a) Maintaining the rotational speed of the gas generator rotor at the idle power setting with an accuracy of ±0.5% depending upon the OAT and OAP. (b) Maintaining the (Ngg takeoff) rotational speed of the gas generator rotor at the takeoff power setting with an accuracy of ±0.15% depending upon the OAT and OAP. (c) Maintaining the (Ngg CP) rotational speed of the gas generator rotor at the CP power setting with an accuracy of ±0.15% depending upon the OAT and OAP. Ngg cp = Ngg takeoff + ΔNgg 0. Where ΔNgg 0 value is the value specified in engine log book. (d) Limitation of maximum EGT at takeoff and contingency power. (e) Output commands for engine shut down and illumination of the FREE TURBOVSP L(R) ENG annunciator as the free turbine reaches the maximum tolerable RPM. (f) Readjustment of gas generator RPM and TGT limitation control loops for CP rating in OEI conditions, provided the following conditions are present simultaneously.  A signal from the CP switch is available.  The Ngg - Ngg(next engine) > 7% and Ngg > 80 % conditions are fulfilled. Note. When the Ngg - Ngg(next engine) ˂ 5% and Ngg ˂ 80 % conditions are fulfilled or when the CP signal is removed, the EAMU should provide for re- adjustment of Ngg and Tgas limitation circuits to the takeoff power setting program. (g) Hold of CP constant value to an altitude of 1500m in ISA and ISA + 30ºС conditions. RESTRICTED  RESTRICTED 109 (h) Hold of TOP constant value to an altitude of 3800 m in ISA and ISA + 45ºС conditions; (j) Output information to SNK-78 to store a total operation time, a time of operation at TOP and CP. (i) Generates signal to record the take off power when Ngg (T/O) (cal.)-Ngg (actual) ≤ 0.7% Or Tg (T/O) (max) - Tg(T/O) (actual) ≤ 15º c. (ii) Removes signal of recording the take off power when Ngg(T/O) (cal.)-Ngg(actual) > 0.7% and Tg (T/O) (max) – Tg (T/O) (actual) > 15º c. (iii) Generates signal to record the CP power when Ngg (CP) (cal.)-Ngg (actual) ≤ 0.7% Or Tg (CP) (max) – Tg (T/O) (actual) ≤ 15º c. (iv) Removes signal of recording the CP power when Ngg (CP) (cal.)-Ngg (actual) > 1 % and Tg (CP) (max) – Tg (T/O) (actual) > 20ºc. (k) Supply the control signal to the MKT-163 actuator as soon as Ngg obtains a value 5% less than the designed limitation threshold of the Ngg take off value. (j) Removes the control signal from the MKT-163 actuator in the following cases: - (i) As soon as the rotational speed of the gas generator rotor is reduced below the Ngg takeoff designed value by 7 %. (ii) As soon as the built in system reveals failure of the unit, transmitters and actuators that makes impossible for the unit to perform its functions. (iii) As soon as power supply is disconnected. (l) Reducing the response threshold of the free turbine protection in the corresponding NFT measurement channel to the level of (96±2%) on receipt the “FT1 test” or “FT2 test” signal fed from the FT TEST switch. 11. BARK-78 Sensors. Following are the sensors for BARK-78(Refer Fig 10.1): RESTRICTED  RESTRICTED 110 12. Temperature Bulb P-109. This sensor is used to measure the air inlet temperature. Functions on the principle of metal (Platinum wire) with temperature.. It is located inside air conduit of fuel regulating pump of fuel regulating thermo corrector. 13. Air Pressure Sensor IKD-27 DA. It senses the atmospheric pressure. It is located on crew cabin belly frame No. 3 H and 4 H. 14. Compressor Rotor Speed Sensor DChV-2500. It senses the compressor rotor rpm. It works on the principle of magnetic flux change. It is located on external gearbox portside near DTSN-70. 15. Free Turbine Over Speed Sensor DTA-10. It senses the free turbine rotor rpm. There are two pair of DTA-10 is located inside engine exhaust stack cone (one set is standby) fitted 180 ° opposite to each other. 16. Micro Switch in 5 H Panel. This micro switch closes during the full closing of twist grip and signal is fed to BARK-78. EEG ensures the engine is in idling mode. 17. Thermocouples T-80. There are qty-12 thermocouples fitted in the engine after the compressor turbine to sense the exhaust gas temperature. BARK-78 Actuators (Refer Fig 10.1) 18. IM-47 Actuator. This actuator is intended to effect control over the throttle valve thereby fuel flow is restricted to engine on receiving signal from the BARK-78. It is located inside the FCU. 19. Electronic Actuator IM-3A. It serves to bypass the high pressure line fuel into spill line when an electrical signal sent to the solenoid of the electrical actuator to shut off the engine. Fuel is spilled from the right chamber of constant Pressure Differential Valve (CPDV). The actuator is mounted on a bracket secured on the left hand side of the engine first support assembly. 20. MKT-163 Actuator. It is intended to make maximum fuel flow unaffected whenever it receives signal from EEG. It is installed on NR-3VMA-T fuel pump between Zero pressure differential diaphragm and differential valve (Left chamber of diaphragm and right chamber of valve) (Refer Fig 10.2). 21. Operation of MKT-163. When the engine RPM reaches 5 % less than the maximum rpm, BARK-78 sends a signal to MKT-163 which opens a passage from the line connecting left chamber of diaphragm and right chamber of Differential valve to spill line. This reduces the pressure from right side of ATCU Differential Valve. Diaphragm with spool moves to right side thus masking the drain port of throttle valve servo chamber. When original rpm is reduced to 7 % below the maximum rpm BARK-78 removes signal from MKT-163 actuator. MKT-163 actuator only comes to action when CP switch is ON. RESTRICTED  RESTRICTED 111 Fig. 10.1. BARK-78 SENSORS AND ACTUATORS Fig. 10.2. LOCATION OF MKT-163 RESTRICTED  RESTRICTED 112 CHAPTER-11 TIME AND MONITORING COUNTER SNK-78 1. Composition, Designation and Operation. SNK-78 is designed to provide objective registration of the engine operating time at different operating modes and registration of unauthorized turn-offs from operation of control and monitoring automatic unit BARK-78 and to calculate and register equivalent operating time and engine operation cycles. 2. SNK-78 consists of the following main functional assemblies: (a) Power source (b) Input/output device (c) Computing device (d) Power independent memory device (e) Indicator (f) Button “Read” (« ») (g) Connection device with test equipment TE. 3. Power source is designed to convert supply voltages of airborne mains into voltage providing operation of all devices of SNK-78. The counter gets energized, when the helicopter power system is turned down and gets off, when the helicopter power is turned down. 4. Input/output device is designed to receive electric signals from sensors and indicators of engine and helicopter and digital data from BARK-78 provide standardization of these signals and protection from input over voltages and pulse jamming, transmit received signals to computing device, form output signals of confirmation of data receive when operating with BARK-78 (БАРК-78). 5. Computing device SNK-78(СНК-78) is made on the basis of microcontroller realizing functions of digital computer. 6. Power independent memory device is designed to store fixed values of the engine operating hours, keep recorded data in cut-off condition within 20 years min., and allow 10,000 cycles of rerecord min. Indicator is designed for operative provision of data on fixed values of the SNK-78 (СНК-78) operating hours as well as for checking serviceability and current operational mode of the SNK-78 (СНК- 78).Indicator consists of 8 matrix light diodes of green illumination. 7. Technical Specifications 1. Overall Dimensions – 195x140x37 Mm (Max.) 2. Weight – 1.0 Kg (Max.) 3. Time of Continuous Operation - 10 H (Max.) 4. Power Consumed – 5.0 Wt (Max.) RESTRICTED  RESTRICTED 113 5. Power Supply of SNK-78 should be Provided from Storage Battery or Helicopter Power Supply System with DC Voltage from 24.0 To 29.4 V. 6. Units of SNK-78 of the Left and Right Engines are installed on Ceiling of the Cargo Compartment between Frames Nos.3 and 4 Rightward. 8. Operating Conditions The ambient working temperature--------- from minus 60 to plus 60o c. Note: Prior to starting the engine at a temperature of below minus 40 oc the OTMC should be subject to external warming up by a hot air with a temperature of plus 60o c. The atmosphere pressure ------- not lower than 26.7KPA 9. SNK-78 automatically does the checking of the following modes: - (a) Self test mode. In case of any fault displays the message “Not work”. (b) Preparation for operation mode. Various messages and its meaning are as follows:- (i) 0000 denotes No signal from Ngg speed sensor. (ii) **** denotes setup parameter correction signal is coming but not in proper form. (iii) XXXX denotes failure of BARK-78. (iv) ~~~~ denotes failure of exchange channel. (v)...... (Running dots) denotes everything is OK but Ngg is Below 60 %. (vi)  - denotes everything is OK and Ngg is above 60 %. 10. Button “Read”(Refer Fig 11.1 item no 6) is designed to control operational mode of the indicator. Short-time (less than 2.5 Sec) pressing of button “Read” change the SNK to SDM mode (Serviceability Display Mode).In case of repeated pressings within 20 sec the following parameters should be indicated in turn: - (a) Overhaul operating life of the engine (mode A) (b) Operating hours at take-off power (mode B) (c) Operating hours at emergency power (mode C) (d) Operating hours at increased gas temperature (mode D) – For manufacturer and need not to make log book entry). (e) Operating hours with turned off electronic regulator CMAU (mode E) (f) Equivalent operating life of the engine (mode G) (g) Cyclic operating life (mode H) (h) Number of the engine starts (mode I) 11. Long-time (more than 2.5 Sec) pressing of button “Read” change the SNK to Test mode. In case of repeated pressings within 20 sec the following parameters should be indicated in turn: - RESTRICTED  RESTRICTED 114 (a) T - EGT. (b) N – denotes Ngg. (c) S - Three digits (D1 D2 D3) (i) D1 = 0 if SNK is not recording. (ii) D1 = 1 if SNK is recording (iii) D2 = 0 if no weight on wheel signal. (iv) D2 = 1 if weight on wheel signal is receiving. (v) D2=2 if BARK is operating and no weight on wheel signal is ON. (vi) D2= 3 BARK is operating and weight on wheel signal is received. (vii) D3 = 0 if engine is shut down (viii) D3 = 1 if engine is running. (ix) D3 = 2 if engine is running in take off mode. (x) D3 = 4 if engine is running in Contingency Power. (d) J – denotes No.of times engine operated BARK-78 OFF. (e) # - Fault analysis mode. 12. SNK-78 is designed to count and store engine-operating time on various power settings, and to monitor operability of BARK-78. In general sense the EOTC is a real time operating digital computer with I/O devices for interface with sensors and EEG. 13. EOTC provides registration of parameters as follows: - (a) Total operating time (at Ngg of 60% and more). With presence of WOW signal counting of total operating time is provided with coefficient of 0.2. (b) Operating time at TOP rating (in presence of TOP signal from EEG). (c) Operating time at CP rating (d) Operating time at increased TGT (e) Operating time with EEG OFF. (f) Equivalent and Cyclic Operating time (at Ngg of 60% and more) (g) Number of Engine start. 14. EOTC operation starts with switching ON corresponding EEG. The registered parameters are stored in non-volatile memory. EOTC maintenance set includes a computer and I/O interface providing download of registered data. 15. Operating Time Recording Accuracy (0-500000) Hrs (a) Total Equivalent, ACMU De-Activate---- At Least One Minute Per Hour Of Operating. (b) Take Off, CP and Increased EGT (MODE B,C &D)-------------At Least One Sec Per One Minute Of Operating Time. RESTRICTED  RESTRICTED 115 (c) Cycles (0-10000) ---------Not More Than One Unit Per Each 100 Cycle Fig. 11.1. ENGINE OPERATING TIME COUNTER (EOTC)-SNK-78 1. Connection to BARK-78. 5. Reverse portion. 2. Connection to ERD-3VM 6. Button read 3. Reference no. 7. Bonding 4. Display unit. 8. Mounting points. RESTRICTED  RESTRICTED 116 CHAPTER-12 SAFIR-5K/G-MI APU 1. Performance Characteristics and Limitation. The existing fleet of Mi-17 and Mi-17 1V helicopter in IAF inventory use the AI-9V APU. The new induction MI- 17 V5 helicopters equipped with SAFIR 5K/G APU. The SAFIR APU has the following advantages over the AI-9V APU. (a) More fuel efficiency. (b) Enhanced life. (c) No restriction in number of bleeds. (d) Can support both bleeding and electric supply (load up to 3 KVA). (e) Increased continuous operating time. (f) Increased in permitted operating altitude. (g) More reliable operation. (h) Higher electrical power output. (j) Efficient cooling 2. Comparison between AI-9V and SAFIR 5K/G MI is described in the table below:- Sl No Feature AI-9V APU SAFIR 5K/G-MI 1. Origin Russia (Ex-USSR) Czech Republic 2. Type Gas Turbine Gas Turbine 3. Electrical Power Output 3 KW 20 KW 4. Continuous Operation 30 min 6 hrs 5. Altitude limitation 4 Km 6 Km 6. Dry Weight 70 Kg 69 Kg L-888 mm, W-530 7. Overall Dimensions Not specified mm, H-490 mm 8. Life in starts (TBO/TTL) 900 2000/6000 9. Life in bleeds (TBO/TTL) 3000 No limitation 10. Life in gen mode (TBO/TTL) 150 No limitation 11. Life in calendar (TBO/TTL) N/A 08/24 years 12. Life in hrs (TBO/TTL) N/A 750 hrs/ 2250 hrs 13. Specific fuel consumption 80 kg/hr max 55 Kg/hr max 14. Oil consumption 150 cc 100 cc 15. Amount of air bleed 0.4 kg/sec 0.4 kg/sec Not less than Not less than 16. Bleed air temperature 0 0 160 C 160 C Centrifugal single Centrifugal single 17. Type of compressor stage stage Single stage axial Twin stage axial 18. Type of Turbine flow flow 19. Stilling chamber Yes No 20. Air separator Nil yes 21. Starting fuel system Yes No 22. Maximum RPM 39150 ± 475 55300 RESTRICTED  RESTRICTED 117 Sl No Feature AI-9V APU SAFIR 5K/G-MI Simultaneous air bleed and Permitted up to 23. Not permitted power supply 3 KW 24. Max EGT 8800 C 950 ± 100 C 25. Normal EGT 7200 C 650 ± 200 C 26. Starting time 20 sec 36 Sec 27. No of ignition plug 01 02 28. Torch igniter 01 Nil 29. No of thermocouples 02 03 30. Type of fuel regulating pump Mechanical Electrical 31. Oil tank capacity 2.5 ltrs 1.6 ltrs 32. Oil Scavenge pump 01 Nil 33. Magnetic plug Nil 01 34. Oil solenoid valve Nil 01 35. Low oil level float switch Nil 01 36. Max oil temp 1650 C 1400 C 37. Max oil pressure 1.2 ± 0.3 kg/cm2 1.5 kg/cm2 38. Oil Cooling media Atmospheric air Fuel 39. No. of lifting points 01+02 01+01 03 consecutive 03 consecutive with with at least 1 min at least 3 min interval. Followed interval. Followed 40. Max allowable no of starts by shut down for by shut down for not less than 20 not less than 15 min cooling period min cooling period. or 1500 C EGT. 3 consecutive bleeds of 45 sec followed by at least 1 min of idling. Total continuous 41. Max allowable air bleeds operation shall not No limit exceed 10 min and must be followed by engine shutdown and 15 min cooling period. 3. SAFIR 5K/G МI is installed on the helicopter as a source of compressed air for air starters of the main engines. Reserve generator of APU provides power supply of the airborne mains with AC of 115 V/200 V voltage with 400 Hz frequency for 6 h. Pressure of air taken for starting the main engines will change depending on environmental conditions. 4. Operational Limitations (a) Operating temperature range is from minus 55°C to +60°C. (b) Above sea altitude from 0 to 6,000 m. (c) Relative air humidity from 20 to 100%. (d) Speed of side wind from 0 to 20 m/sec. RESTRICTED  RESTRICTED 118 (e) Three sequent starts of APU (including false starts) are allowed with 1 min. interval. (f) Next start is allowed to be performed after 20 minutes break minimum. (g) Restart of APU should be performed after its turn-off at exhaust gas temperature is below 150°C max. (h) Continuous operation of APU in reserve generator mode is limited by exhaust gases temperature of up to 650°C, and when flying, in short Time (within 30 sec) the temperature of up to 670°C is allowed. (j) When starting the main engine electric power intake is limited by 3 KVA. 5. Working Limitations. The APU turn-off should be performed automatically after achieving the following parameters: (a) Maximum gas temperature when starting - (950 ± 10) °C (b) Maximum gas temperature in operating mod - (720 + 20) °C (c) Maximum rpm of APU rotor (112.6 ±1) % - 55,300rpm (d) Minimum rpm – (75 ± 1) % 6. Parameters of APU operation can be checked by pointers of multifunction display (MFD) indicator in APU mode. Ignition Unit Gas Generator Reserve Generator Anti Surge Valve Fig. 12.1. SAFIR APU 7. APU Technical Data 1. Generator type P/N 20040-100 2. Rated voltage 115/200 V 3. Rated frequency 400 Hz 4. Maximum power 20 KVA 220 kPa (2.2Kgf/cm2) 5. Over-pressure of air off take minimum RESTRICTED  RESTRICTED 119 6. Temperature of air off take 165 С minimum 7. Amount of taken air 0.4 Kg/ Sec 8. Fuel consumption 55 kg/h max 9. Oil consumption 100 сm3/h maximum 10. Continuous time of operation, 6 hrs maximum Full dry mass of APU aggregates in 11. 69 Kg