11.12 Flashcards
What’s clear ice
(Glaze ice)
Supercooled droplets that hit the surface and freeze as they flow across the surface
Smooth, hard, glossy, transparent
What’s easier to remove rime or clear ice
Rime
How’s rime ice formed
Water hitting a sub zero surface and instantly freezing
What’s a characteristic of rime ice
Rough but lighter than clear ice
What are visual detection indicators for pilots
rods outside of cockpit Windows that are built exposed to airflow so if icing conditions avail they can be seen and anti ice systems can be operated
What’s the hot rod detector made from ans what angle is it installed at
Alluminium and 30
How does a pressure operated ice detector work
4 holes in leading edge and 2 in the trailing edge
So in flight there’s a pressure build up in the detector and when ice forms the holes on the front will become blocked and this can cause a negative pressure which is sensed by a relay unit
How does a pressure operated ice detector work
4 holes in leading edge and 2 in the trailing edge
So in flight there’s a pressure build up in the detector and when ice forms the holes on the front will become blocked and this can cause a negative pressure which is sensed by a relay unit
What powers the rotary ice detector s
Single face ac motor
How does a vibrating probe ice detector work
As it’s meant to vibrate at a constant frequency of 40 kHz but when ice forks this will change due to it being heavier which is the indication
What display is the ice warning messages displayed on
EICAS
What type of deicing method is used for leading edge
Hot Pneumatic air
How is joined ducting sections of the wing anti ice system sealed
Hermetically sealed
How are slats anti iced
Same systems as wing and the air is transferred to the slats via a telescopic duct
What’s the WAI valve and what’s it do
Wing anti ice valve
Controls amount of air from pneumatic system to wing anti ice ducts
How are wing anti ice valve controlled and actuated
Controlled- electrically
Actuated- pneumatically
What’s used to monitor the WAI valves
ACIPS
Aerofoil and cowl ice protection system
Do the WAI valves operated at same time or differential
Same to keep same heat on both wings
When’s the operation of the WAI valve not allow
When in take off mode
When been in air for less than 10 mins
If auto mode is on
What must windshields be able to withstand in relation to bird strike for it to be certified
Must be able to withstand a 2lb bird strike at cruising speed
What’s are the two modes for electric windscreen anti ice
Norm- heating supplies heat to broad area of windscreen
High- supplies to more concentrated areas with a high intensity of heat
What are wings and stabilisers using chemical anti icing system called
Weeping wings
What’s a disadvantage of TKSM (chemical anti icing)
Can only carry a certain amount of fluid so it runs out sometimes
What’s the most common DE-icing method for wings
Wing boots
How long are de icing boots inflated for
6-8 sec
What are deicing boots made of
Outside layer?
Rubberised fabric
Conductive neoprone (resistant to deterioration, chemical attacks, conductive)
What do reciprocating engine ac use for de icing boot operating air
Turbine engine?
Engine driven pump
Bleed air
What’s done on de icing boots on reciprocating engine to attempt to minimise disturbance to airflow
They are activated symmetrically but operated alternatively across the wing
What happens when ice forms on the prop
Ice collects assymetricly so it is unbalanced and gashes vibration
What type of fluid is used for chemical deicing
Glycol based
Isopropyl alcohol
What’s the advantages of isopropyl alcohol being used over a glycol based chemical used for de icing
More available and cheaper
What disadvantages are there of prop de ice systems
Heavy
Limited fluid
How long are cycling timers on a propellor electrical deicing system
15-30 sec with a cycle of two mins
What type of chemical rain repellent is used
when was irs PRODUCTION banned
Rain boe containing CFC113
1st jan 1996
Does the time the push button is held for the rain repellent affect how much repellent is discharged
No
Why should rain repellent only be used on a wet screen
Bc if it’s undiluted it can affect the visibility
What’s the outer layer of a windscreen coated with
Hydrophobic coating
What’s used to clean wind shield
50/50 of water and isopropanol alcohol
What does the heated air in the pneumatic rain removal system do
It breaks the raindrops into small particles to be blown away
It heats the windshield to prevent the moisture from freezing
How many wipers does the windscreen sit on
2
How cycles per min do the windscreen wipes do in low speed
High?
160 cycle per min
250 cycle per min
