Name the 3 types of Ice warning detection units
Serrrated rotor (as ice builds up on rotor it is harder to scrap off so torque on turning shape increases)
Pressure operated( little aero-foil has holes on leading and trailing edge, blocked leading edge decreases internal pressure)
Vibrating rod (probe vibrates at 40KHz, ice forming reduces the vibration freq)
Electrical heating of propeller leading edges. How many props are de-iced at once, and how long is the heating cycle?
Only on prop de-iced at a time,
30 secs typically.
On turboprops it is part of the engine de-icing system.
Describe windscreen heating system
Each window operated separately,
Conductive braid and film sandwiched between acrylic ply window.
Sensors regulate temp to keep it in optimum range.
Aids during a birdstrike to have it on, so it's usually put on during pre-takeoff
Does rain repellent affect view through dry screen
Yes; it will obscure the view,
also using wipers in the dry may scratch window
What are the rubber boots condition susceptible to?
Oils and Greases
Knocks and abrasions
Exposure to strong sunshine.
what is a Jet Pump in the fuel system?
A form of a fluid pump that produces a low pressure by moving fuel at a high velocity through a venturi. A jet pump helps remove vapors from fuel before it enters a fuel control unit. Some of the fuel from the main pump is returned to the tank through a venturi or a jet pump. The low pressure at the throat of the venturi pulls the vapor out of the chamber where vapor gets collected before returning fuel to the tank
Whats the benefit of a submersible electric fuel pump in the tank
Prevents cavitation due to no elevation difference between pump and fuel
What is the normal order of tank usage in large A/C?
Center and auxiliary tanks are generally used first to keep weight in wings to reduce lifting stress and bending
What happens to C/G during fuel burn
It will move forward due to the swept wing config if fuel is burnt from wing tanks!
What is a fuel tank expansion space?
Each fuel tank must have an expansion space of not less than 2% of the tank capacity, unless the tank vent discharges clear of the airplane (in which case no expansion space is required). It must be impossible to fill the expansion space inadvertently with the airplane in the normal ground attitude.
Fuel Jettison considerations
- One boost pumps draws from a Standpipe (so only a certain amount can be jettisoned)
- Or only fuel from one tank - usually the centre- can be jettisoned
- Exits at wing tip through Jettison valve with flame arrestor
- Flaps down prevents chance of vapour entering jet exhaust and causing fire.
Describe actuation of Pax Oxygen system (Chemical)
- 3 masks per generator typically
- Aneriod controlled release mechanism drops it to "half hang" at 14,000ft
- When pulled to face, a lanyard trips the firing mechanism
- Give oxygen for 15 mins
When are chemical oxygen generators used and why?
What are the chemicals?
For Pax oxygen, as there is no need for storage bottles, and they can be put at all pax station.
Sodium chlorate and iron powder (generate a lot of heat 250 degrees)
What type of Oxygen system is usually for Crew
- Diluter demand.
- Bottle max 2000psi (filled to 1600-1800) dumps overboard excess and shows green disk outside A/C
- Oxygen is diluted with cabin Air (up to 28,000 then 100%)
- Mixture only flows when inhaling
- The demand regulator can be set to emergency for continuous flow to purge mask of smoke
How does crew oxygen mask go on
harness inflates when pulled from the stowage and after put on face deflates to fit.
What is a class A fire and what Extinguisher is best
Class A ordinary combustible stuff like wood and paper
Water is good, also dry powder
What is a class B fire and what Extinguisher is best
Petroleum products or liquids like solvents or paint
- BCF Halon are best
- dry powder (sodium Bicarbonate)
What is a class C fire and what Extinguisher is best
- CO2 are the best
- Dry Powder