Ice and Rain Control Systems practice questions

Answer: D) Isopropyl alcohol

• AIncorrect. Oil would smear the windshield.
• BIncorrect. Water would freeze.
• CIncorrect. That would block visibility.
• DCorrect. Alcohol prevents ice from forming.

Answer: B) Senses ice accretion and either alerts the crew or turns on the ice protection system

A primary ice detection system senses ice accretion and automatically activates the airframe ice protection or alerts the crew to activate it (14 CFR 25.1419(e)(1)). Temperature cues, malfunction cautions and probe heat are different functions.

• AIncorrect. Using static or total air temperature plus visible moisture is a separate method (14 CFR 25.1419(e)(3)). The crew identifies icing conditions themselves; no detector senses ice.
• BCorrect. Under 14 CFR 25.1419(e)(1), a primary ice detection system automatically activates the airframe ice protection system or alerts the flightcrew to activate it.
• CIncorrect. That is the caution information required by 14 CFR 25.1419(c) for a malfunctioning ice protection system. It does not detect ice.
• DIncorrect. That is pitot-static probe heat, which is an anti-icing function. It does not detect ice building up on the airframe.

Answer: A) Brush and slip ring wear, contamination, and correct brush alignment and contact

Slip rings and brushes carry electrical power to the propeller heaters. They are inspected for wear, contamination, and proper alignment and contact, because poor contact causes intermittent or uneven heating.

• ACorrect. The brushes and slip rings carry current to the heaters on the spinning propeller. Wear, dirt or oil contamination, and poor alignment or contact can cause intermittent or uneven heating, so these are the inspection items.
• BIncorrect. Inflation pressure and pneumatic sequencing apply to pneumatic boot systems. An electrothermal propeller system uses electric heaters, not inflatable boots.
• CIncorrect. Slinger rings and fluid tanks belong to fluid (alcohol) propeller anti-icing systems, not to the electrical slip ring and brush assembly.
• DIncorrect. The brushes have to ride in firm contact with the slip rings to carry current. An air gap would break the circuit to the propeller heaters.

Answer: B) Overheating the glass

• AIncorrect. Wipers handle rain.
• BCorrect. It regulates temperature to prevent damage or delamination.
• CIncorrect. This is unrelated.
• DIncorrect. This is unrelated.

Answer: B) It can stall the tailplane and cause a sudden nose-down pitch, often after the flaps are extended

Ice on the horizontal stabilizer can cause a tailplane stall. The tail loses its download and the nose pitches down suddenly, often when the flaps are extended.

• AIncorrect. The weight of tail ice has only a minor effect. The main danger is aerodynamic: the tail stalls and loses its download, which pitches the nose down, not up.
• BCorrect. Even a small amount of ice lowers the angle of attack at which the tail stalls. Extending the flaps increases the tail's negative angle of attack, so the tail can stall, lose its download and pitch the nose down sharply.
• CIncorrect. Tail ice disrupts airflow over the stabilizer. Its effects are aerodynamic, not hinge friction, and they can come on suddenly, so pitch response is not predictable.
• DIncorrect. The tail-stall risk is greatest when the flaps are extended, as on approach. Flap extension increases the tail's negative angle of attack.

Answer: A) Electrothermal heater blankets mounted on the inside of the wing leading edges

The Boeing 787 replaces the usual bleed air wing anti-ice system with electrothermal heater blankets in the wing leading edges. This removes the bleed air ducting and the wing exhaust holes.

• ACorrect. The 787 uses an electro-thermal wing ice protection system. Electric heater blankets warm the leading edges, so no bleed air ducts are needed and there are no bleed air exhaust holes in the wing.
• BIncorrect. Pneumatic boots are mostly used on smaller turboprops and piston airplanes, where they are usually inflated with engine bleed air or engine-driven pump air. The 787 does not use boots on its wings.
• CIncorrect. Weeping wing (fluid) systems are found on some general aviation and business aircraft. The 787 heats its wing leading edges electrically.
• DIncorrect. The 787's cabin air compressors supply air for cabin pressurization, not wing anti-icing. Its wing ice protection uses electric heating, not hot air ducted through piccolo tubes.

Answer: B) The estimated time the applied fluid prevents frost, ice, and snow buildup

Holdover time is the estimated time applied deicing/anti-icing fluid keeps frost, ice, and snow from building up on protected surfaces. It runs from the start of the final application until the fluid loses its effectiveness.

• AIncorrect. Fluid heating time is a matter of equipment preparation. Holdover time is about how long the fluid already applied keeps protecting the aircraft.
• BCorrect. Per 14 CFR 121.629, holdover time is the estimated time deicing/anti-icing fluid will prevent frost or ice from forming and snow from accumulating on protected surfaces. It starts when the final fluid application begins and ends when the fluid loses its effectiveness.
• CIncorrect. Ground deicing/anti-icing fluids do not provide in-flight icing protection. Holdover time applies only while the aircraft is on the ground before takeoff.
• DIncorrect. The five-minute figure in 14 CFR 121.629 is for the pretakeoff contamination check that may be needed when holdover time is exceeded. It is not the definition of holdover time.

Answer: A) Electrically or hydraulically driven windshield wipers; B) A high-velocity engine bleed air blast across the glass

Windshield rain removal uses wipers, chemical rain repellent, or a pneumatic bleed-air blast across the glass. Deicer boots, static wicks and pitot heat do other jobs.

• ACorrect. Wiper systems are a standard rain removal method and help meet the requirement for a means to keep part of the windshield clear in precipitation (14 CFR 25.773(b)(1)).
• BCorrect. Pneumatic rain removal systems blow high-velocity bleed air across the windshield. This breaks up raindrops and keeps them from striking and sticking to the glass.
• CIncorrect. Deicer boots break up ice on wing and tail leading edges. They are not used to remove rain from windshields.
• DIncorrect. Static wicks discharge static electricity from trailing edges to cut radio interference. They have no effect on rain on the windshield.
• EIncorrect. Pitot heat keeps the pitot tube free of ice so airspeed readings stay accurate. It does nothing to clear rain from the windshield.

Answer: A) Fluid weeps out

• ACorrect. Glycol-based fluid weeps from porous leading edges to prevent ice.
• BIncorrect. That is a pneumatic boot system.
• CIncorrect. That is thermal anti-ice.
• DIncorrect. This is not a wing system.

Answer: A) Washing with a mild soap and water solution, then rinsing

Clean deicer boots with mild soap and water. Strong solvents such as MEK or gasoline, and abrasive pads, damage the neoprene and its conductive surface.

• ACorrect. Mild soap and water removes dirt without attacking the neoprene or its conductive surface.
• BIncorrect. MEK is a strong solvent that softens and degrades the rubber of the boot.
• CIncorrect. Gasoline attacks rubber compounds and is also a fire hazard. It should not be used to clean boots.
• DIncorrect. Abrasives wear away the boot's surface ply and conductive coating, which shortens boot life.