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Файл:Aircraft Maintenance. Учебное пособие
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UNIT 3. FIRE PROTECTION. ICE AND RAIN PROTECTION
Solenoid valve – электромагнитный клапан
The TAT (total air temperature) probe – зонд полной температуры потока
Window and pitot heat module – модуль обогревателей иллюминаторов и
приёмников воздушного давления
Windshield wiper – ветроустойчивая система очистки стёкол
Wiper action speed – быстродействие системы очистки стёкол
PROBE HEAT SYSTEM
General
The following probes on B737 airplanes are heated to prevent the formation of
ice which could affect sensing accuracy:
x the left and right Pitot/Static Tubes (4);
x the elevator feel left and right Pitot Tubes (2);
x the left and right Alpha Vanes (2);
x the TAT (Total Air Temperature) Probe.
The heating is accomplished by electrical heaters installed as an integral part of
the units. The heaters consist of resistance elements which operate on 115 Volt
AC.
Window and Pitot Heat Module
The Window and Pitot Heat Mo dule contains the control switches A and B, indicating lights, transformers, and printed circuit cards. The module also contains
the switches and indicating lights for Cabin Window Anti-Icing System.
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AIRCRAFT MAINTENANCE
Window heat system
Windows No. 1, 2, 3, 4 and 5 on each side of the control cabin are provided with
electrical heating window anti-icing and defogging. Heating of the cockpit windows also improves the impact strength of the windows and is used for birdproofing the windows when flying at altitudes where bird strikes are possible.
The forward No. 1 windshield and the No. 2 slidi ng window on each side of the
cabin have a separate control system for each window. The control system mai ntains the respective window at the required temperature by use of automatic controls.
Operation
Each of the No. 1 and 2 window heat systems are operated by the actuation of
the respective control switch in the ON position. When control switch in ON position and control power supplied to the Window Heat Control Unit in the absence of an overheat condition, the control unit overheat circuit will direct 115
Volt AC heating power to the electronic switch for modulation to the control
heat transformer. If window is below 100F / 38C, the Window Heat Sensor will
signal the error det ector circuit for heat ing power and the electron ic switch will
gradually increase power to the heat transformer.
WINDSHIELD WIPER SYSTEM
Windshield wipers are provided to maintain a clear area on the pilot’s No. 1
window during takeoff, approach and landing in rain and snow. Each wiper is
operated by separate system to ensure that clear vision through one of the windows will be maintained in event of a system failure. The wiper blades clear a
patch approximately 13-1/2 inches wide through an arc of 84 +/-4 degrees. Both
wiper systems are operated by a switch located on the overhead panel. The
switch provides selection of the wiper action speeds. The switch also controls the
PARK position when the system is not in use.
Each windshield wiper system consists of these components:
x Drive Motor and Torque Converter Assembly;
x Control Switch Assembly;
x Windshield Wiper Assembly;
x Resistor Box.
Speed control is accomplished by changing the voltage applied to the windshield
wiper motor by means of resistors. The required resistance is connected into ci rcuit by turning the windshield wiper switch to a selected position. The rotary
motion of the drive motor is transmitted to the converter which reduces the shaft
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UNIT 3. FIRE PROTECTION. ICE AND RAIN PROTECTION
speed and chan ges rota ry motion to an oscillat ing mot ion of th e winds hield wiper arm.
RAIN REPELLENT SYSTEM
The Rain Repellent System consists of:
x a pressurized container of rain repellent fluid;
x a container receptacle;
x a visual reservoir;
x a pressure gage;
x two solenoid valves;
x two nozzles;
x associated plumbing;
x two electrical control circuits.
A Rain Repellent System is provided to be used in conjunction with the Windshieldwiper System to improve windshield visibility through the pilot’s No. 1
windshields during heavy rain. The system is controlled independently for each
window by separate control switches located on the overhead panel and, when
actuated, the system sprays a rain repellent solution on the respective window as
selected.
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AIRCRAFT MAINTENANCE
Noun(s)
Verb
Adjective(s)
repellent, repulsion
pressurize
rotary
vary
application
maintainable
prevent
clear
actuator
X
heat
The length of time that an application remains effective varies inversely with the
rain intensity and will last longer in the wiped area th an in the unwip ed area. Reapplication is repeated as required to maintain repellent effectiveness.
Exercise 1. Answer the following questions.
1. What is the probe heat system of the aircraft designed for?
2. What system is the cockpit windows provided with?
3. What is the main function of the window heating system?
4. What is the additional function of the window heating system?
5. Why is each windshield wiper operated by a separate drive?
6. Which components does each windshield wiper system consists of?
7. How is speed control of the windshield wipers accomplished?
8. What happens when the rain repellent system is actuated?
9. What factors affect how long the application of rain repellent fluid remains
effective ?
10. What is needed to maintain repellent effectiveness?
Exercise 2. Fill in the following word-building table. Look up the meanings
of the words you added in the dictionary.
Exercise 3. Use the words from the table above in the appropriate form to
complete the sentences. Translate the sentences into Russian.
1. Aircraft ____________ is the overhaul, repair, inspection or modification of
an aircraft or aircraft component.
2. No single method, however, is ever going to be universally ___________.
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UNIT 3. FIRE PROTECTION. ICE AND RAIN PROTECTION
3. She _________ the water in a large pan, and then put pasta into it.
4. He had already seen the report, and had requested ___________of one point.
5. The blades spin at 100 _________ per minute.
6. There are many ___________ measures that would reduce the number of
serious air accidents.
7. There is an electro-hydraulic control valve to __________ the extra gear set.
8. The lake has more than twenty __________ of fish.
9. The submarine is ___________ just like an airplane.
10. The army was ready to ___________ an attack.
Exercise 4. Read how to skim a text and try to do the task.
Skimming a text is a fast reading technique to look for main ideas in a text.
Skimming is used to obtain the gist (the overall sense) of a text.
Do the following tasks:
- read the title, subtitles and subheading to find out what the text is about;
- look at the illustrations to give you further information about the topic;
- read the first and last sentence of each para graph;
- don't read every word or every sentence; let your eyes skim over the text, tak-
ing in key words;
- continue to think about the meaning of the text.
FIRE PROTECTION
Two types of fires can affect an airplane and its occupants: in-flight and postcrash. An in-flight fire usually occurs as a result of a system or component failure or maintenance issue. A post-crash fire usually results from ignition of fuel
released during a crash landing. Boeing considers both types of fires when designing for airplane cabin fire protection. Fire protection is one of the highest
considerations at Boeing in airplane design, testing, and certification. In designing an airplane’s fire protection features, Boeing uses a systems-level approach
that goes beyond ensuring individual parts meet fire property requirements by
looking at the integration of all those parts on the airplane. This approach uses
the principles of material selection, separation, isolation, detection, and control.
These principles involve separating the three contributory factors to a fire (fuel,
ignition source, and oxygen), isolating potential fires from spreading to other
parts of the airplane, and controlling a fire should one occur. Boeing uses both
passive systems (such as the use of noncombustible or self-extinguishing materials) and active systems (such as fire extinguishing systems).
55
AIRCRAFT MAINTENANCE
Fire-protective materials
Most materials used in the construction of passenger compartment interiors are
required to be self-extinguishing. The standards for flammability of insulation
blankets have improved over time. The latest standard increases protection by
minimizing the contribution of the insulation blankets to the propagation of a
fire. Thermal/acoustic insulation install ed behind cabin interior panels with the
appropriate fire-resistant properties can delay the onset of fire into the cabin in
the event of a crash (see fig. 1). The insulation blank ets, along with the airplane
skin, must be capable of resisting burn-through from a fuel-fed post-crash fire
next to the bottom half of the fuselage for a minimum of four minutes to allow
passengers to evacuate the airplane before burn-through can occur.
Fire detection
Three types of smoke detectors are certified for use in the lavatories and crew
rest compartments, as well as in some galley complexes, purser work stations,
video control centers, and business centers: ionization-area type, photoelectricarea type, and photoelectric-ducted type. A dedicated smoke detection system is
not required in the occupied volumes of the main cabin due to the ability of passengers and the cabin crew to recognize smoke. Ionization-area type. These detectors are designed to detect the presence of ionized particles created by the
combustion process as they are convectively carried through the lavatories or
crew rest compartments in the event of a fire. They are typically mounted in the
ceiling or upper sidewalls of the protected space. Photoelectric-area type. These
detectors are designed to detect the presence of smoke particles in the air by reflection of scattered light. They also rely on particles in the air being convectively carried into a sensing chamber where light from a pilot lamp is transmitted
through a sensing chamber. If smoke is present, it will reflect light onto a photocell and trigger an alarm. Newer production airplanes use photoelectric detectors
based on an advanced smoke sensor utilizing two discrete wavelengths to dete rmine the presence of smoke and to distinguish between smoke and nonsmoke
aerosols. These are also mounted in the ceiling or upper sidewalls of the protected space. Photoelectric-ducted type. These detectors are similar to photoelectricarea type detectors, but they are typically mounted behind the walls of the protected space. They differ from the area detectors in that fans draw air samples
from the protected space into a series of air sampling ports in the monument
walls and ceiling, and then through an aluminum tube manifold to the detectors.
Current production airplanes use the more advanced area detectors mentioned
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UNIT 3. FIRE PROTECTION. ICE AND RAIN PROTECTION
above, rather than ducted photoelectric detectors. Each smoke detection system
has a built-in electronic test capability switch. This allows for the system’s elec-
trical and detector sensor integrity to be checked at any time.
Fire extinguisher locations
Fire extinguishers are located thro ughout the passenger cabin with locations designed for easy access in an emergency.
Figure 1: Distribution of handheld fire extinguishers
Crew rest compartment. A smoke detection system that consists of ceiling-
and/or sidewall-mounted smoke detectors and associated control hardware and
alarms is incorporated into crew rest compartments. Crew rest compartments are
also designed to prevent hazardous quantities of smoke from entering flight crew
or passenger areas. When smoke is detected by the smoke detection system, appropriate audio and visual alarms provide indication on the flight deck, in the
crew rest compartment, and in the nearby cabin areas. For larger crew rest compartments, the air distribution system’s air shutoff valve closes, preventing airconditioning flow to the crew rest compartment to better contain smoke and f acilitate crew firefighting procedures. In many instances, a minimal exhaust flow
is maintained to assist in preventing smoke penetration into occupied areas and
maintain visibility.
Firefighting procedures for crew rest compartments usually involve one or more
members of the cabin crew using appropriate protective equipment to manually
suppress the fire with a handheld fire extinguisher. In some cases, such as the
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AIRCRAFT MAINTENANCE
777 lower lobe attendant rest compartment, the fire is suppressed remotely by
using a built-in halon fire-extinguishing system plumbed to the compartment.
http://www.boeing.com/commercial/aeromagazine/articles/2011_q4/4/
ICE PROTECTION
Aircraft and engine ice protection systems are generally of two designs: either
they remove ice after it has formed, or they prevent it from forming. The former
type of system is referred to as a de-icing system and the latter as an anti-icing
system.
De-Icing Systems
A de-icing system has two very attractive attributes. First, it can utilize a variety
of means to transfer the energy used to remove the ice. This allows the consid eration of mechanical (principally pneumatic), electrical and thermal methods. The
second attribute is that it is energy efficient, requiring energy only periodically
when ice is being removed, with some mechanical designs requiring relatively
little energy overall. This is a significant consideration when designing ice protection for aircraft with limited excess power.
Anti-Icing Systems
Anti-icing systems reverse this paradigm. Properly used, they prevent the formation of ice continuously, resulting in a clean wing with no aerodynamic penalties. An anti-icing system must have a means of continuously delivering energy
or chemical flow to a surface in order to prevent the bonding of ice. The typical
thermal anti-icing system does this at significant energy expense. The concept is
not viable for aircraft that do not have the requ isite excess energy available during all flight phases. An exception to this is the use of a chemical system such as
TKS.
Thermal Systems
A thermal anti-ice system is designed to operate in one of two ways: fully evaporative or running wet. In the former case, sufficient energy is provided to cause
impinging supercooled water to completely evaporate. This has an obvious advantage of protecting the aft, unheated portion of the airfoil, since the evaporated
water cannot re-condense before the airfoil has passed. It is a very effective
means of ice protection, but the concept requires a great deal of excess energy.
Any fully evaporative system will necessarily transition through a running wet
phase as it both heats and cools. The ideal method for operating a ful ly evapor ative system is to activate it prior to entering icing conditions , thus allowing the
surface to stabilize at the required temperature. Many contemporary designs fea-
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UNIT 3. FIRE PROTECTION. ICE AND RAIN PROTECTION
ture a minimum engine rotor speed that is automatically limited when ice protection is selected on. This ensures adequate heat to the surfaces, but may also impact descent planning. A t hermal de-icing system requires much less energy. Using either engine bleed air, exhaust-heated air, or electrical heating, this system is
intended only to periodically break the bond between accreted ice and the surface. A typical example would be propel ler de-ice systems, which use electrically heated pads on the inboard leading edges of the propeller blades.
Pneumatic De-Ice Boots
A very common de-icing system utilizes pneumatically inflated rubber boots on
the leading edges of airfoil surfaces. This typically includes the wings and horizontal stabilizer, but may also include struts, cargo pods , or even antennae. The
system uses relatively low pressure air to rapidly inflate and deflate the boot.
This is usually done in a sequence of segments, for example, the outer wings followed by the inner wings followed by the horizontal stabilizer. Depending on the
manufacturer's specifications, the system may be operated either automatically,
through a timing circuit, or manually, using a cockpit control to initiate the boot
cycle sequence. Equally important is the correct maintenance of the boots, including adequate treatment with restorative substances and inspection for pinholes and other damage.
https://skybrary.aero/index.php/Ice_Protection_Systems
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UNIT 4. INSTRUMENTS
Text A. CLOCK DESCRIPTION
Vocabulary
adjacent – соседний
adjust – настраивать
bite – особенности
blank – пустой
continuously – непрерывно, постоянно
cycle – осуществлять включение
elapsed time – истекшее время
freeze – фиксировать
glare shield – противосолнечный козырёк на ветровом стекле
GMT – Greenwich Mean Time Гринвичское время
halt – останавливаться
internal – внутренний
interrupt – прерывать
rate – скорость
reincrement – возрастание
respectively –
соответственно
slew – поворот
spring loaded – подпружиненное
sweep second hand – парящая секундная стрелка
value – значение
General
The GMT output is provi ded in hours, minutes, and seconds. The time is accurate to ± 1 second per 200 hours at 25° C unless power to the clock is interrupted.
The electronic clocks are located on the captain’s and first officer’s instrument
panels, respectively. They are mi croprocessor controlled with two LCD displays,
controls, and a sweep second hand. The Flight Management Computer (FMC)
and the Flight Recorder System use clock data.
Upper Display
The upper display (GMT) provides GMT continuously from 00 hours 00 minutes
to 23 hours 59 minutes.
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