SF340 Hydraulics

  1. The hydraulic system supplies pressure for the operation of what? 10-1
    Flaps, Landing gear, Brakes, and Nose wheel steering
  2. Are Hydraulic lines routed to their respective systems inside the aircraft? 10-1
    No, they are routed externally in “hydraulic tunnels”
  3. What pressurizes the main hydraulic reservoir? 10-2
    Emergency accumulator circuit
  4. What is the back up to the emergency accumulator for pressurizing the reservoir? 10-2
    Spring loaded piston
  5. What would cause a HYDR CWP light to illuminate with all gauges normal? 10-2
    High temperature has been noted in the main reservoir (116ºC)
  6. What supplies hydraulic fluid to the Hand Pump reservoir? 10-2
    Overflow fluid from the main reservoir
  7. What does the Hand Pump reservoir supply fluid to? 10-2
    Hand Pump
  8. What does the main reservoir supply fluid to? 10-2
    • Electric hydraulic pump
    • Overflows to the Hand Pump Reservoir
  9. What is the normal source of pressure for the hydraulic system? 10-2
    Electric pump
  10. What electrical bus supplies power to the electric pump in AUTO? 10-2
    Left main bus
  11. What electrical bus supplies power to the electrical pump in OVRD? 10-2
    Left essential bus
  12. Why is it important to verify the BUS TIE CONN light illuminates during left engine shutdown while taxiing? 10-2
    Hydraulic pump is powered from the left main bus
  13. With a failure of the electric hydraulic pump can the main accumulator be pressurized? 10-2&3
    Yes, with the hand pump
  14. What does the Main Accumulator supply pressure to? 10-3
    • Nose wheel steering
    • Flap actuation
    • Gear retraction and extension
    • To pressurize the brake accumulators
  15. At what pressure does the Pressure relief valve vent pressure? 10-3
    3750 psi
  16. Is there protection for an overpressure of the hydraulic system? 10-3
    Yes the pressure relief valve
  17. Where does the Pressure relief valve return fluid to? 10-3
    To the main reservoir
  18. Where does the Fluid from the hand pump get returned to after use? 10-3
    Main reservoir
  19. What is the most likely problem if a HYDR CWP light is illuminated and hydraulic quantity, main accumulator and inboard accumulator pressure all indicate low? 10-3
    A leak in the inboard brake
  20. What is the normal operating pressure in AUTO mode? 10-4
    2100 psi-2900 psi
  21. What is the operating pressure when the pump is in OVRD? 10-4
    3000 psi
  22. What causes the electric pump to automatically activate? 10-4
    • Pressure in the main accumulator decreases below 2100 psi
    • Landing gear is extended or retracted
  23. What can the Hand Pump pressurize? 10-4
    All accumulators except the Emergency accumulator
  24. The selector valve facilitates pressure of what? 10-4
    Main, Inboard brake, and Outboard brake accumulators
  25. Can the landing gear be hand pumped down with a total electrical failure? 10-4
    No, the gear requires left battery bus power to operate the selector valve
  26. Can the flaps be hand pumped with a total electrical failure? 10-4
    No, flap operation requires left battery bus to be powered
  27. With an outboard brake accumulator leak, can the main accumulator be pressurized by the Hand Pump? 10-3&5
    No, the Main accumulator will equalize to the leaking brake accumulator
  28. Which accumulators have check valves? 10-5
    Emergency, Inboard and Outboard brake accumulators
  29. What is the pressure of the nitrogen pre-charge in the accumulators? 10-5
    1650 psi
  30. What pressure is read on the gauges if hydraulic qty in the accumulator decreases to zero, leaving just the nitrogen pre-charge pressure? 10-5
    Zero psi on the gauges in the flight deck. The actual accumulators should read 1650psi in the nose well
  31. What is the purpose of the Nitrogen charged accumulators? 10-5
    To absorb pump pulsations and surges caused by large fluid demands
  32. What pressure triggers a HYDR CWP light to illuminate? 10-2&5
    Pressure less than 1850 psi, or High Temp
  33. Which accumulators will trigger the HYDR CWP light to illuminate with pressure below 1850 psi? 10-5
    Main and Emergency accumulators
  34. What is the Purpose of the Emergency accumulator? 10-2&5
    • Emergency extension for up lock release
    • To pressurize the Main reservoir
  35. What is the indication for a hydraulic filter that is clogged and bypassed? 10-5
    Clog indicator button pops up on the filter housing
  36. What is being pressurized by the Hand Pump when the selector is in the FLAPS LDG GR position? 10-5
    The Main accumulator
  37. How many hydraulic accumulators are on the Saab 340? 10-5
  38. Why do the brakes have 2 accumulators? 10-5
    One for inboard and one for outboard brake systems in case of a leak in one system brakes are still available
  39. What does the Emergency landing gear extension use hydraulic pressure for? 10-5
    To release the up locks and allow the gear to free fall
  40. Can the flaps be extended AND retracted with only the Hand Pump? 10-5
    Yes, by pressurizing the main accumulator
  41. Where can the 1650 psi Nitrogen pressure be checked? 10-6
    Nose wheel well, right side of the aircraft
  42. Where are the hydraulic filter bypass pins located? 10-6
    Nose wheel well on the left side of the aircraft
  43. What does an illuminated HYDR CWP light indicate? 10-7
    • Pressure in the main or emergency accumulators less than 1850 psi
    • High temp in the main reservoir (116ºC)
  44. Does the HYDR CWP light illuminate for low quantity? 10-7
  45. Does the HYDR CWP light illuminate for high pressure? 10-7
  46. Where is the Hand Pump handle stored? 10-8
    Behind the First Officer seat on the bulkhead
  47. Is the electric hydraulic pump protected by a resettable circuit breaker?
Card Set
SF340 Hydraulics
Colgan Air Saab 340 Chapter 10 - Hydraulics