1. Class #4 Aircraft Instruments

2. Content Flight Instruments Engine Instruments
Miscellaneous Instruments
Gleim
JEPPESEN CHAPTER 2 SECTION C
PHAK Chapter 7

3. Flight Instruments (P85)

4. Pitot-Static Instruments (Jep 2-52)
What are the three instruments that are in the Pitot-Static system?
Airspeed Indicator, Vertical Speed Indicator (VSI), Altimeter

5. Airspeed Indicator The only true pitot-static instrument
Measures both Ram air (or pitot air) from the pitot tube and static air from the static port.
Airspeed indicator subtracts static pressure, supplied from the static ports, from the total pressure provided by the pitot head (tube). This difference is called Dynamic Pressure, and measures the aircrafts forward speed IAS.

6. Airspeed Indicator
Measures an indicated airspeed through the air not over the ground. (speed of the relative wind)

7. AIRSPEED

8. Airspeed Indicator
Diaphragm inside the instrument measures pressure forces from the pitot tube. If you subtract the static pressure around this diagram you get your airspeed.

9. Airspeed Indicator
Pitot tube is blocked you will have no ram air if relief holes clear airspeed will read 0.
Pitot heat helps to eliminate ice blockage on the pitot tube, controlled by pilot.

10. BLOCKED PITOT & DRAIN CLEAR STATIC

12. BLOCKED STATIC

13. Different types of Airspeed
ICET
Indicated Airspeed (IAS)-direct reading from the face of the instrument
Calibrated Airspeed (CAS)- IAS corrected for position and installation error. 5-8 B19
Equivalent Airspeed (EAS)-CAS corrected for compressability.
True Airspeed (TAS)- EAS corrected for altitude, temperature

14. Airspeed Indicator (P98)
White arc, full flap operating range
Green arc normal operating range
Yellow arc operate with caution, only in smooth air
Redline, maximum speed for all operations

15. MARKINGS

16. Airspeed Indicator
Most airspeed indicators will have MPH inner scale, Knots outer scale
Some airspeed indicators will also have a true airspeed indicator built in.

17. Vertical Speed Indicator
Registers the rate of change of static pressure and converts this to an indication in feet per minute.
Is hooked directly to static ports
Has a calibrated leak
Is accurate as a trend instrument immediately
Is accurate as a rate instrument after 6 to 9 seconds

18. Vertical Speed Indicator

19. Altimeter
Altimeter translates the barometric pressure into a display of elevation in feet
Works on the principle that atmospheric pressure decreases with altitude.
It has a sealed case except for static source inlet. Inside the case are aneroid wafers which sense changes in static pressure by expanding or contracting (are sealed with a reference pressure)

20. Mechanism of the altimeter

21. Altimeter (P101)
How to read it
Number Drum Altimeter

22. Altimeter Why do we set the altimeter in the Kollsman window?
To have the current sea level barometric pressure which will give an accurate indication of field elevation.

23. Altimeter
Approximately 1" of pressure measured in inches of mercury is equivalent to 1000' of altitude
The altimeter must be calibrated before takeoff and about once an hour sometimes more and every 100 miles

24. Change in pressure/temp on altitude (P104)
When flying from High to low look out below (altimeter reads high). When flying from Low to High your high in the sky
When temp lowers in transit, you are lower than your altimeter reads.

26. Altimeter
Current barometric pressure is set in the Kollsman window, the scale goes from 28.00" to 31.00"
Sometimes millibars are set in an alternate window (usually everywhere outside North America)
Altitude should read + or - 75 feet

27. ALTERNATE STATIC SOURCE POH 3-8, 5-8, 5-10

28. Different types of Altitudes

29. Different types of Altitudes
Indicated altitude-Read off altimeter
Pressure altitude- Altimeter reading when set to 29.92
Absolute altitude-Height above terrain
True altitude-Height above sea level.
Density Altitude-pressure altitude corrected for nonstandard temperature

30. Different types of Altitudes
Pressure altitude calculations
29.92-station pressure=X
X times 1000 added to field elevation equals pressure altitude at airport
Density altitude need formula, E6B/or chart to figure out

31. Gyro Instruments Attitude Indicator
Directional Gyro (or Heading Indicator)
Turn Coordinator

32. Gyroscopic Instruments
A gyroscope is a mass spinning rapidly about an axis. The rotor is typically suspended within a set of interconected frames or gimbals.
Two fundamental properties of a gyro are
Rigidity in Space and Precession

33. Rigidity in Space and Precession
Rigidity in Space = gyroscope will tend to maintain its orientation in space and resist any forces that tend to displace it.

34. Rigidity in Space and Precession
Precession = When a gyro is displaced by a force that force acts 90 degrees from the applied force in the direction of rotation.

35. PRECESSION

36. PRECESSION

37. Typical Vacuum System

38. Attitude Indicator
Provides pilot with attitude indication in respect to horizon.
Gives Pitch and bank info; vacuum driven gyro; some are electric or pressure driven
Gyro is gimbled on 3 axis
Gyro is mounted with a vertical spin axis

39. Attitude Indicator (P112)

40. Attitude Indicator

42. Attitude Indicator Limitations
Bank limits 100 to 110 degrees
Pitch limits 60 to 70 degrees
If limits are exceeded gyro may tumble and become unreliable.

43. Attitude Indicator (P114)
Markings are at 10, 20, 30, 60 and 90 degrees bank pitch is usually on the 5s

44. Heading Indicator
Directional gyro instrument that is vacuum driven; some are electric; some are pressure driven
10,000 to 18,000 rpm
Pitch and bank limits of about 55 degrees (older ones)

45. Heading Indicator
Precession error of no more than 3 degrees in 15 minutes
Gyro aligned horizontally and remains rigid in space as the azimuth card rotates around it

46. Heading Indicator (P119)
Mechansim of the heading indicator

48. Vacuum Instruments (P120)
Attitude indicator, heading indicator, and suction guage.

49. Turn Coordination (P115)

50. Turn Coordinator/Turn and Slip Indicator
Electric gyro instrument some are vacuum
All indicate rate of turn in seconds
A standard rate turn is 3 degrees per second
A 360 degree turn takes 2 minutes
Red flag to tell if you have electrical power or not.

51. Turn Coordinator Actually a combination of two instruments
Inclinometer curved glass tube filled with kerosene and a steel ball bearing powered by gravity
Centrifugal force or lack of it accounts for the ball's movement

52. Turn Coordinator Turn coordinator gyro is mounted on a 30 deg angle
The turn coordinator can sense both rate of roll, rate of turn and yaw
Displays only rate of roll and rate of turn doesn't directly display bank angle

53. Turn and Slip Indicator (P117)
Turn and slip gyro is horizontal
The turn needle indicates the rate of turn about the vertical axis in degrees per second
Older models required 1 needle with deflection for standard rate turn

56. Magnetic Compass
Two magnetic needles attached to a floating card inside a sealed case filled with acid free white Kerosene or alcohol (whiskey compass)
The kerosene supports the card, dampens oscillations, and lubricates the pivot assembly that the card rotates around

57. Magnetic Compass (p108)

58. Magnetic Compass Lubber line inside the glass face Errors
Variation angular difference between true north and magnetic north
Deviation the pull of the aircraft's magnetic fields generated by radio and such on the compass card
Reads opposite heading indicator

60. UNOS or NOSS

61. ANDS

63. Magnetic Compass
Magnetic dip points downward closer to the poles causes errors
Closer to the poles magnetic compass becomes unreliable.

64. Magnetic Compass Errors
Acceleration-deceleration error - (ANDS) Most appartent on easterly or westerly headings. If you accelerate in the northern hemisphere causes a dip and indication of a turn to the north. Deceleration turn to south
Northerly turning error (NOSS) Most pernounced when the aircraft is headed north or south. Turned from a heading of north will initially indicate a turn in the opposite direction. Turn from the South compass will jump ahead and lead

65. Engine Instruments Ammeter Oil Temp Guage Oil Pressure Guage
Fuel Pressure
Fuel Flow
EGT (exhaust gas temperature)
Cylinder Head Temperature
Tachometer

66. Ammeter
Ammeter-talked about first lesson. Messures electrical discharge from battery or electrical power being used from alternator. (as a pilot in flight looking for ammeter to read 0 or +.

67. Oil Temp Guage
The most common type of oil temperature gage is operated electrically and may utilize either a Wheatstone brige circuit or a ratiometer circuit. (604) (Higher heat greater resistance differential in voltage.) Connected to battery.

68. Fuel Pressure/Oil Pressure
Typically measure in units of PSI (pounds per square inch)
Use a Bourdon Tube design, diaphragm type, or bellows type design (600)

69. EGT/CHT Referred to as thermoscouple instruments.
A thermocouple is the junction of two dissimilar metals which generate a small electrical current that varies according to the temperature of the junction.
Does not require an external power source.

70. Tachometer
Primary engine instrument designed to provide an accurate indication of engine RPM.
Can be mechanical, magnetic, electronic
Upper limit of Tach in B-19
2700 RPM, red light will come on if you overspeed the prop.

71. Misc Instruments Outside Air Temperature Guage Altitude Alerter Clock
Hobbs meter

72. Basic T arrangement
Airspeed, Attitude Indicator, Altimeter, Heading Indicator

73. Inspections and Tests
Pitot Static Instruments Must be inspected and tested every 24 calendar months for IFR
Elt every 12 months
Transponder and encoder every 24 months

74. Homework Required VFR instrument FAR Part 91.205C TOMATO FLAMES
Tach, Oil Temp, Magnetic D.I., Airspeed, Temp guage for liquid cooled engine, Oil Pressure guage, Fuel Guage, Landing Gear lights, Altimeter, Manifold Pressure, ELT, Seatbelts
Night FLAPS-Fuses, Landing light, Anti collision lights, Position lights, Source of Power