1 / 51

Cessna Citation II Powerplant

Cessna Citation II Powerplant . Dr. Barnhart. Introduction. Powerplant systems include: Engines Lubrication Fuel distribution Ignition Engine instrumentation Engine power control Engine starting Engine synchronization. Powerplant General. 2 aft fuselage mounted turbofans

holli
Download Presentation

Cessna Citation II Powerplant

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Cessna Citation IIPowerplant Dr. Barnhart

  2. Introduction • Powerplant systems include: • Engines • Lubrication • Fuel distribution • Ignition • Engine instrumentation • Engine power control • Engine starting • Engine synchronization

  3. Powerplant General • 2 aft fuselage mounted turbofans • Pratt & Whitney JT15D-4 • 2,500 lbs. thrust- standard conditions

  4. Powerplant Sections • Intake • Compressor • Combustion • Turbine • Exhaust • Accessories

  5. Powerplant Intake • T(1) probe in inlet • Anti-iced by bleed air • Intake- becomes 2 concentric ducts aft of fan. • Outer duct- bypass • Inner duct- core engine air

  6. Powerplant- Fan • Fan assembly: • Nose cone (continuously anti-iced by bleed air when engine operating) • Fan stage • Single axial compression stage • 2 sets of stator vanes (anti-iced when “Eng Anti-ice- ON”)

  7. Compressor • 2 stages: Low press./High press. • Low Press.- Non-geared fan and booster stage- axial flow; compresses and accelerates air rearward. • Outer span of Fan- speeds a high volume of air at relatively low velocity into bypass duct. • Inner span of Fan- accelerates air to booster stg.

  8. Compressor ctn. • Booster stg.- extends to primary (core) air only and incr. air press. then directs it to high press. compressor. • Bypass ratio- diff. in air mass flow btn. Bypass duct and eng. Core- 2.7:1 in this eng. • Fan = 2/3 of total thrust at sea lvl.

  9. Compressor ctn. • High press. Compr.- single stage centrifugal compr. Which receives airflow under pressure from booster stg.- Increases press. Further & directs it rearward.

  10. Combustion • Annular- reverse flow chamber- 12 fuel nozzles, 2 igniter plugs- directs expanding/accelerating gas rearward to turbine scn.

  11. Turbine Section • Single high press. Stg. • 2 low press. Stgs. • HPT connected to HPC via shaft • HPT- extracts energy from combustion gasses to drive the HPC and accessory scn. • HPC/T together = High press. Spool- N(2)

  12. Low press. Turbine- LPT • 2 stg.- connected to LPC by shaft which runs inside the HP shaft • Low press. Turbine- extracts sufficient energy from comb. Gasses to drive LPC and Fan.

  13. Exhaust section • 2 sections- Primary duct and bypass duct • Primary- tapered cone and struts • Combination of primary exhaust and bypass flow produces a total propulsive force for the A/C.

  14. Accessory scn. • A gear assy. Encased and mounted beneath the compressor. • Driven by tower shaft and bevel gear. • Drives: • Oil pump • Hydraulic pump • Fuel control unit (FCU) and pump • Tach. generator- N(2)

  15. Powerplant Operation • Nacelle inlet directs air to eng. Inlet. • Outer fan span- compresses and accelerates a larger volume of air at low vel. To full length bypass duct. • Inner fan span- compresses/accelerates air to axial compr. Stg. • Air press. Increased by booster stage & directed to the HPC which accelerates air & directs it through a diffuser.

  16. Powerplant Operation ctn. • Diffuser- changes kinetic energy to static energy (velocity to press. By slowing) • Low volume of the core air flows through combustion chamber- fuel added- ign. Occurs. • Combustion process- produces expansion & acceleration • Remaining core compressed air- cooling and bleed functions.

  17. Powerplant Operation ctn. • HPT- extracts energy to drive HPC and accessory scn. • LPT- extracts energy to drive LPC (fan/booster). • Remaining flow- directed to exhaust scn;- joins w/ bypass flow to provide thrust.

  18. Engine Systems • Oil system • Fuel system • Ignition system • Instrumentation • Power control • Synchronization • Thrust reversing

  19. Oil system • Fully automatic- cooling/lub.of engine and accessory brgs. • Tank- integral part of compressor intermediate case- contains filler and dipstick assy. For servicing (ensure fully engage after svc. Or inspn.- check qty. 10 min. after shutdown. • Max. allowable consumption 1 qt. ea. 4 hrs. over a 10 hr. period. • Different Oil brands not normally mixed

  20. Oil system ctn. • Pump- engine driven (1 pressure, 2 scavenge elements)- mounted on accessory scn. • Oil cooling- FCOC- fuel cooled oil cooler- heat exchanger or radiator. • Filter- removes solid contaminants and combustion by products- no indication of bypass feature in cockpit.

  21. Oil system ctn. • Oil press.- eng. Oil press maintained by a mechanical relief valve. • Indication- sensed by dual transmitters. • Press. Transducer sends input to dual vert. tape gauges in IP.- gauge calibrated in psi- a pr. Sw. activates an L or R OIL PRESS LO light. On annunciator panel.

  22. Oil press. Ctn. • Oil press. Indicating sys.- powered from main DC elec. System.- Red OFF flag appears @ top when D.C. not avail. • Oil press. Sw.- also senses oil press.- if oil press at or below 35 psi- contacts close and L or R OIL PRESS LO light comes on.

  23. Oil Temperature • Sensed by a resistance bulb- transmitted to a dual-scale vertical tape gauge on center IP- calibrated in deg. C and require main D.C. power- Red OFF flag at top when D.C. not avail.

  24. Fuel System • Components: • Engine driven pump] • Fuel filter • Fuel control unit (FCU) • Step modulator • Flow divider • Emergency shutoff valve • 2 fuel manifolds • 12 fuel nozzles

  25. Fuel System ctn • Fuel pump- receives fuel at tank pump pressure & delivers high press. Fuel to FCU • Not a suction pump- must receive pressure- if eng. Pump fails- engine flames out- PERIOD!

  26. Fuel System- FCU • FCU- hydromechanical- 3 scns: 1. computing, 2. governing, 3. metering. • Computing section senses 5 parameters: • P(3)- compressor discharge press. • P(A)- Ambient press. • T(1)- compressor inlet temp. • N(2)- RPM • Throttle position

  27. FCU- ctn • Governing section- senses both N(2) rpm and throttle position then modifies the signals sent by the computing section to the metering system. • The result of this process determines the position of the fuel metering valve which controls the volume of fuel delivered to the combustion chamber.

  28. FCU- step modulation • A step modulator on the FCU increases fuel scheduling whenever the ignition system is operating ensuring engine acceleration performance. • Step modulation performance may be checked through ITT and N(1) for an increase when ignition is on

  29. Fuel System- Flow Divider • Flow divider- divides metered fuel between the primary and secondary manifold (supplies fuel nozzles). • Flow divider also prevents fuel flow to nozzles until sufficient fuel press. Present. • Primary nozzles- used during eng. Start and low power.- Both nozzles at high pwr. • Residual manifold- collects residual fuel during shutdown- fuel flows back to the respective tank on next startup.

  30. Emergency Fuel Shutoff Valve • Primary and secondary fuel from the flow divider pass through a N.O. shutoff valve • Valve activated mechanically by aft movement of the LPC shaft .070 inch. • Valve automatically shuts off fuel (i.e. failure of the LPC shaft- shaft would move aft); This prevents overspeed of N(1) turbines.

  31. Fuel Nozzles • 12 Duplex nozzles- produce a precise atomized spray pattern conducive to combustion • Primary- operates continuously when eng. On- secondary only for high power settings.

  32. Fuel indication system • Flow meter- senses metered flow downstream of the FCU; displays pph (100 – 2,000) on vertical tape gauges in main I.P. • Flowmeter power- main D.C. thus a red off flag indicated no D.C. avail.

  33. Ignition System • Dual high energy ignition system: • 2 engine mounted ign. Exciters (older models had one exciter box per engine • Shielded cables • 2 igniter plugs in the comb. Chamber provide redundancy only (only 1 is needed for normal operations). • Ignition divided into 2 phases: 1) automatic, 2) selective

  34. Ignition System ctn. • Automatic ign.- avail. During starting- terminated automatically when start sequence is terminated- also ign. Is automatic when eng. Anti-ice is ON. • Selective ign.- continuous operation selected by pilot • Remember- when ign. Circuit powered- step modulation is also activated

  35. Ignition System Control • Ign. Controlled by an IGNITION sw. for ea. Eng. On the pilot’s sw. panel. Sw. is labeled: ON and NORM. • *NOTE: Ign. Should be ON for T/O and Lndg. And during heavy precip., heavy turbulence, stalls, or emerg. Descents.

  36. Ignition System Control ctn. • In NORM- ing. Is automatic when START button is depressed AND associted throttle is moved from the cutoff position. • Power comes from the hot batt. Bus through the throttle microswitch. • Ign. And starter operation both terminated by the speed sensor switch on the starter generator.

  37. Ignition System Control- ctn. • When ign. Sw. in ON ign. Is continuous regardless of throttle pos. • In this case, left eng. Ign. Power is supplied by rt. X-over bus and the rt. Eng. Ign. Pwr supplied from left ext. bus. • CB’s on pilot’s CB panel. • Remember- Ign. Also activated when ANTI ICE is ON.

  38. Ignition indication • Ign. Operation indicated by a grn. Light near the ign. Sw. whenever pwr. Avail. To exciter. DOES NOT indicate exciter is operating or plug is firing

  39. Engine Instrumentation • Horizontal row of gauges @ top of center I.P. • From Left to Right: N(1) or fan rpm, ITT, N(2) or HPC rpm called “turbine”, oil temp., oil pressure.

  40. Engine Instrumentation ctn. • N(1)- supplied from a Tach generator located on top side of compr. Case. Driven by LPC rotor shaft. • Tach. Gen. output is then amplified and output displayed on the dual tape guage calibrated in % rpm- 3 digit lighted display also below ea. Gauge.

  41. Engine Instrumentation- ctn • N(1) is the primary thrust indicator for the JT15D-4- and is the ref. for all pwr. Settings. • Gauge powered via main D.C.- when elec. Pwr. Not avail. The lighted display inop. • Also, loss of D.C. means loss of the amplifier circuit. The vertical tape still receives tach. Gen. output and provides accurate information when engines are above 50% N(1).

  42. Engine Instrumentation ctn. • ITT- a computed synthetic readout. EGT is sensed by 6 thermocouples in the exhaust aft of the turbine. • Also, temp rise across the fan sensed by 4 T(1) probes (1 in front of fan and 3 @ aft end of bypass duct). • A trim resistor in the thermocouple system is test-cell adjusted.

  43. ITT ctn. • The ITT readout is the result of adding 3 times the temp. rise in the bypass duct to the trimmed value of the thermocouple output- provides an accurate indication of eng. Combustion temp. under all flight conditions. • Computed temp displayed on vert. tapes calibrated in deg. C. OFF flag when D.C. not avail.- pwr. Source same as for N(1).

  44. HPC rpm N(2) • H.P.C. rpm supplied via a tach. Gen. driven by the accessory scn- displayed in % rpm by dual lighted digital displays on the turbine gauge • Pwr. Failure results in loss of lighted display. • Red light under ea. Display will come on (and digital read will flash) when N(2) exceeds 96%. Pwr. Supply same as N(1)

  45. Engine Power Control • Via throttle or “power levers” travel from full aft or “cut off” to full fwd. or “max. thrust” position. • A cutoff stop prevents inadvertent selection of cutoff. A latch must be raised before eng. Can go into idle cutoff. • Thrust reversers “TR’s” are piggyback mounted on ea. Throttle- throttle is mechanically connected to a pwr. Lever on FCU • Friction adjustment on side of pedestal

  46. Engine Starting • 2 types of engine starts: • Ground- further divided into battery starts, generator assists, and External pwr. Starts. • Air- divided into starter-assist, and windmilling starts. • Starter operation covered in chap. 2 (elec.) • Perform all airstarts I.A.W. the airstart envelope (Fig. 7-11).

  47. Engine Synchronization (Sync) • Ea. Eng. Has both a fan and/or turbine has • master/slave rpm synchronizer controller • An actuator • A control sw. • An indicator light • Left eng. Is master- rt. is slave.

  48. Engine Synchronization (Sync) • System adjusts rt. Eng. Rpm to that of left- eliminates the out-of-sync. “beat” of engs. • Operates in a very narrow rpm band to prevent rt. Eng. Spool down if left fails • Manually sync. To 1.5% prior to engaging the system using N(1) fan or N(2) turbine. • System should be off for: pwr. Changes, T/O & lndg., and for single eng. Ops.

  49. Engine Synchronization (Sync) • Sync cntrol- 3 pos. rotary sw. labeled “ENGINE SYNC FAN-OFF-TURB” • OFF permits sync. Controller to position the actuator (in rt. Nacelle) to a “null” or center pos. • FAN or TURB selection permits sync. Of N(1) or N(2) as desired- Fan for pax. Turb. For pilots.

  50. Engine Synchronization (Sync) • When ENNGINE SYNC sw. is in FAN or TURB- the amber ENGINE SYNC light is on. • System activated by pilot following T/O • Tach. Generators (turb. And fan) supply signals to sync. Controller. Controller computes error diff. of selected inputs and transmits an output to actuator (rt.) which then adjusts rt. FCU to sync. R Eng. to left.

More Related