11.4 Pressurisation Systems Control & Indication Flashcards
how is an aircraft pressurised?
by supplying a constant flow of air conditioned air into the fuselage, and controlling the amount by using outflow valves
when an outflow valve is opened, what hapens to the pressure ?
pressure inside the pressurised bulkhead decreases
what is used to tell the outflow valve what to do?
flight deck pressuristation panel
what form of power is used to operate the outflow valves?
choices:
- electricity
- mechanical
- pnuematic
pneumatic operation or electrical operation
what safety devices must be fitted to any cabin pressurisation system ?
excessive differential pressure relief valves
inward opening relief valves
dump valves
pressurisation gauges/ indications
what is the purpose of an excessive differential pressure relief valve?
to release a build up of excessive pressure over the desired pressure
how could overpressurisation be identified after a flight?
some excessive differential pressure relief valves may display a colour when the valve has been triggered during flight
what is the purpose of an inward opening relief valve ?
if the outside pressure exceeds that of the inside of the aircraft, it will open to prevent a negative pressure
what is the danger associated with negative pressure and why is it important to regulate this with inward opening relief valves?
negative pressure at low volumes can make it hard to open doors or if high enough, it could cause structural damage, as it is not designed for cabin pressure to be lower than outside pressure
what are dump valves used for ?
used to quickly remove air from the cabin incase of emergency, abnormal events or maintenance
what gauges are used to provide the cabin crew information about any pressurisation defect?
- cabin altimeter
- cabin rate of climb or VSI
- cabin differential pressure indicator
if you are on a modern aircraft where will infrmation about pressure be displayed?
on the EFIS system
how many modes of operation are there on a pressurisation panel ?
auto and manual
what switch should be seleced when the aircraft begins to taxi ?
GROUND/FLIGHT switch should be set to FLIGHT, ensuring gradual pressurisation and no surges of pressure to occur
when the aircraft’s logic system senses the aircraft is in climb, what will this cause the pressurisation system to do ?
increases the cabin pressure in proportion to the rate of climb
