Chapter 2 - Pitot/static systems Flashcards
Why is a static system where there are static vents on either side of the fuselage not suitable for higher speeds?
Effect of shock waves can give false values
When is an electrically heated combined or pitot head required?
Mandatory on all aircraft which has a Certificate of Airworthiness to fly in icing conditions
How can pressure error caused by turbulent air be reduced?
Situating static pressure points on the aircraft structure less affected by turbulence
Why are drain holes accurately calibrated on combined pitot static heads?
So that pressure leakage from pitot to static, and then static to atmosphere will not affect instrument readings
What can cause incorrect pressures to be fed to the instruments giving false readings with regards to the pressure heads?
If they are bent or moved out of alignment with the airflow
Why are non-standard dimensions used for pitot static pipelines?
Carry only low pressure
So prevents them being used in high-pressure systems
Why are hose clips, if fitted, usually made from brass or stainless steel when fitted to pitot static pipelines at instruments?
Prevent them affecting direct reading magnetic compass systems which may be nearby
What are used with special union nuts and at what value of pressure are these used for?
Rubber bushes
Up to a pressure of 1.7 bars (25 psi)
How are pitot static pipelines identified?
Marked at each end and at intervals with adhesive tape marked INSTRUMENT AIR
- Colour coded orange/grey
- Standard symbol code black zigzag on white
What must maintainers be aware of with regards to the rubber bushes used with union nuts in pitot static systems?
Can only be used once
Where are moisture drain traps fitted?
At the lowest part of the system
What problems can be caused with moisture in pitot static pipelines which don’t become frozen?
Acts as a piston, causing a fluctuation in pressure at the instruments
What instruments are affected by water in the pitot pipeline?
ASI and machmeter
What instruments are affected by water in the static pipeline?
All the instruments readings to fluctuate
What precautions have to be taken with regards to blowing air through the pipelines to remove moisture?
- Use clean, dry warm air in the reverse direction
- Pressure must not exceed 1.7 bars
