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13 Cards in this Set
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- Back
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44.2.2
Define Mach# and associated computational formulae |
Mach# = TAS ÷ LSS
LSS = 38.94 × √ T
Where T = Temp in °Kelvin |
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44.2.4 Explain the principal of operation of a Machmeter |
Works by blending dynamic pressure (Airspeed) and static pressure (Altitude) inputs. Essentially an ASI + Altimeter combined. |
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44.2.6
Explain the errors affecting a Machmeter |
a. Instrument Error Friction, lost motion in linkages and gearings. Usually 0.01M between 0.5 and 1.0M. Increase with a/s and alt
b. Position (pressure) Error More prevalent as static pressure is subtracted twice. Inspect port
c. Lag Due to time required for pressure changes to reflect within the instrument, Climbing/Descending and/or accelerating/decelerating quickly will result in a slight lag before change in Mach number is reflected correctly. |
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44.2.8
Explain the symptoms, effects and possible remedies for blockages and leaks on the Machmeter |
Pitot Pressure blocked, Machmeter will not sense nor display changes in Airspeed/Mach. Over read in climb, under read in descent. Static pressure blocked, changes in altitude will not be sensed and Machmeter will under read in climb and over read in descent.
"COPS DUO"
In the event of a blocked pressure sensor, the alternate pitot or static source should be selected. |
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44.4.2 State the purpose of the air data computer |
To provide digital air data output to aircraft instruments and systems |
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44.4.4 Explain the operating principle of the ADC |
Converts various analogue inputs to electrical signals and transmits them via data buses to the various aircraft instruments and flight instruments. |
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44.4.6
Describe the inputs, outputs and the supplied units of a digital ADC |
Inputs: Pitot, static, temp & AOA. Outputs: Altitude, Vertical speed, IAS/TAS/CAS, Mach #, Vmo/Mmo, AOA, TAT & SAT. Supplied units: EFIS, FD, AFCS, FMC, TAWS, Data Acquisition unit of FDR, Captain and FO's standby instruments. |
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44.4.8 Explain backup function of ADC in the case of a pressure source blockage |
There will be at least 2 ADC's with their own supply of input data. In the event of a blockage or other failure, provision is made to switch to there other ADC or to switch static sources from normal to alternate |
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44.6.2 Explain the principle of operation of an air temperature probe |
Air passes into the opening of the probe and an amount of air is directed into a cavity around the sensing element and virtually brought to rest inside the probe |
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44.6.4
Define TAT, SAT and OAT |
TAT - SAT corrected for the maximum possible ram rise in the temp probe in the prevailing conditions.
SAT - true temperature of the ambient air through which an aircraft is flying, which is not affected (usually by kinetic heating) by the passage of the aircraft.
OAT - the temperature of air indicated on the outside air temp gauge. |
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44.6.8 Formula for SAT from IOAT + Recovery Factor + Mach#? |
Ts = Tm ÷ (1 + ( 0.2 × k × M^2)) |
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44.6.10 Calculate SAT given TAT + Mach Number |
Ts = TAT ÷ ( 1 + (0.2 × M^2) ) Also Ts = TAT - (V ÷ 100)^2 Where V = TAS in kts |
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44.8.2 Describe the function of: a. A Flight Director (FD) system b. An Automatic Flight Control System (AFCS) |
Dhhssha |
