B737 Engine

  1. N1-Rotor System Components:
    • ducted fan
    • 3 stage compressor
    • 4 stage turbine
  2. N2-Rotor System Components:
    • 9 stage compressor (first 4 stages feature variable stator vanes)
    • single stage turbine
  3. Why are VARIABLE BLEED VALVES installed?
    • at low rpm, LP-compressor delivers more air than the HP-compressor can utilize
    • bleed excessive air into the fan duct
    • increase the engines stall margin
    • improve acceleration characterisic
    • VBV are closed with T/O thrust set
  4. duties of 1st and 2nd stage engine fuel pumps
    • 1st: positive flow to fuel/oil heat-exchanger
    • 2nd: high press. fuel for MEC
  5. MEC
    • meters fuel
    • hydromechanical unit using heated servofuel for adjustment of variable stator vanes and -bleed valves
    • regulates N2
    • influenced by PMC
  6. Components of Engine Oil System:
    • Oil Tank
    • engine driven oil pump
    • oil filter
    • two independent pressure sensors (for oil press. indication and LOW OIL PRESSURE light)
    • Scanvenge Pump
    • scanvenge filter (OIL FILTER BYPASS light)
    • temperature sensor (Oil temp. indication)
    • Fuel Oil heat exchanger
  7. What is Fan air is used for?
    • generator cooling
    • airconditioning precooler
  8. Bleed Air from 5th or 9th stage is used for?
    • Anti-icing
    • Airconditioning
    • Pressurization
  9. Can 5th and 9th stage bleed air be used simultaneously?
    • No, when 5th stage bleed air is insufficient for pneumatic users, MODULATING AND S/O-VALVE opens 9th Stage
    • reverse flow to 5th Stage is prevented by a Check valve
  10. How is the Thrust Reverser controlled?
    • electrically controlled
    • hydraulically operated
  11. Thrust reverser components:
    • 3 hydraulic actuators
    • translating sleeves
    • blocker doors
    • fixed cascade vanes
  12. Thrust reverser locking mechanism:
    • upper actuator is mechanically locked, unlocks hydraulically
    • all 3 actuators are synchronized by the SYNCHRONIZING SHAFT, locked by the SYNC LOCK (electrically pwrd)
    • AUTO RESTOW CIRCUIT: if other two locks fail: opens isolation valve, commands directional ctrl valve into stow position
  13. What is need for reverser operation?
    • Hydraulic to operate reverser sleeves
    • Electric for reverser ctrl
  14. Where is EGT sensed?
    between High- & Low pressure turbine
  15. Engine Vibration Monitoring system components
    • core sensor
    • fan sensor
  16. Minimum Engie start Pressure
    • 30 PSI at MSL
    • (-0,5/1000ft)
  17. describe engine start sequence:
    • start switch GRD
    • @25% N2 & N1>0 -> engine start lever IDLE
    • (selected igniter starts to work, Eng. and MEC SO-Valve open)
    • FUEL VALVE CLOSED light (fwd ovhd) extinguishes
    • inital FF can be observed
    • Observe EGT-rise with light up
    • @45% N2 Engine start switch holding relay deenergized
    • start switch returns to OFF
    • STARTER VALVE OPEN light (eng. instr. panel) extinguishes
    • Igntion terminates
    • duct pressure (fwd ovhd) returns to init. value
  18. Engine Start Switches CONT
    • selected igniter(s)
    • continuous ignitions
  19. Engine Start Switches FLT
    • both igniters, regardless of ignition sel. sw. pos.
    • continuous ignitions
  20. PMC
    • electronic device
    • adjusts fuel according to desired power setting
    • influences N2
    • maintains constant thrust
    • nearly constant N1 corresp. to thrust lever angle
    • starts operation above 46% N2
  21. Why are VARIABLE STATOR VANES installed?
    • optimum efficiency
    • are automatically positioned depending on pwr-setting by MEC
    • increase the engines stall margin
    • improve acceleration characterisic
  22. Engine Idle Ctrl
    uses air/gnd sensor to switch between low (22%) and high (32%) idle
  23. What is special with a BATTERY START?
    • only when APU inop, no ext pwr available
    • no duct pressure indication
    • right igniter usable only (pwrd by AC STBY BUS)
    • Engine Idle Ctrl off, enige accelerates to high idle
    • (will spool down to low idle as soon as first gen on bus)
  24. fast EGT rise, high FF (500kg/h):
    • HOT START, Engine Start Lever CUTOFF
    • before reaching limit EGT
    • TLB entry if EGT limit busted
    • Maint. action req.
  25. normal FF, no EGT rise after Eng Start Lever placed to IDLE
    • WET START, most propable is an ignition failure
    • check CBs
  26. Idle-N1 and/or -N2 not reached, normal FF, EGT rise
    • HUNG START, due to less air and normal FF, EGT is higher than normal
    • Do not mistake for a HOT START
    • Maint. action req.
  27. How to recognize an Aborted Engine start
    • no N1 or n2 rotation
    • no EGT ind. within 10 sec thrust lever placed to idle
    • EGT rapidly approaching limit
    • no oil pressure with enighe stabilized @ IDLE
    • ABORTED ENG. START Procedure has to be done if Eng. Start lever has allready been set to IDLE
  28. PMC light illuminated
    • do not attempt T/O with only one PMC light illuminated
    • acc. MEL flight possible with both PMCs OFF (lower nose compartement)
    • T/o perf. is reduced, use "PMC OFF T/O"-Procedure
  29. if oil pressure drops into yellow band
    • in flight: no action req.
    • on gnd: do not attempt T/O with oil press. in yellow
  30. eng oil temp in yellow band for more than 15min
  31. OIL FILTER BYPASS light illuminated
    • may be a hint for defective eng. bearing
    • retard thrust lever
    • if light remains on -> SHUTDOWN
  32. High engine Vibration value?
  33. Thrust reverser deployment suspected in flight?
    immediate eng. shutdown
  34. Requirements for eng. start?
    • Start air source (>30PSI)
    • DC power: starter valve and engine fuel S/O-Valve
    • AC power: Igniters
  35. Engine Starter cycle limits?
    • do not exceed 2 min during each attempt
    • a minimum of 20s is needed between 1st and 2nd attempt
    • a minimum of 3 min is needed between 2nd and 3rd attempt
  36. Eng Start switch fails to stay in GND, do not attempt to restart until N2 reaches...
    20% N2
  37. Engine Idle Values (N1, N2, EGT)
    • N1: 22.8%
    • N2: 60.3%
    • EGT: ~500°C
    • Oil QTY more than 1,5 USG
    • positive oil pressure indication
  38. Engine Idle N1 (GND)?
    N1: 22.8%
  39. Engine EGT after Start?
    EGT: ~500°C
  40. Engine Idle N2 (GND)?
    N2: 60.3%
  41. Engine Idle N1 (FLT)?
    • N1: 32%
    • (maintained until 4s after TD)
    • prevents compressor icing
    • expedites reverse thrust
  42. Engine Oil Consumption?
    • 0.4 ltr/h
    • (0.1 USG/h)
  43. Normal Engine starting sequence?
    2 - 1
  44. Normal FF after Engine Start?
    300-400 kg/h
Card Set
B737 Engine
B737 Engine