martedì 15 maggio 2018

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mercoledì 1 febbraio 2017

Avionics bending: Symbol Generator

A. The flight instrument system provides the main displays for most of the airplane's navigation systems. It includes the electronic flight instrument system (EFIS), the radio distance magnetic indicators (RDMI), and the vertical speed indicators (VSI). It also includes the switches on the instrument source select panels.

B. The EFIS uses CRT indicators. It provides multicolor navigation displays. The system displays the following:

(1) Pitch, roll, and directional data; map displays and flight path data; weather radar data; altitude and decision height; autopilot mode data; and input system fault annunciations.

(2)Airspeed data.

(3)Traffic alert and collision avoidance data.

C. The two displays associated with the EFIS are the Electronic Horizontal Situation Indicator (EHSI) and the Electronic Attitude Director Indicator (EADI). Two units of each display are installed.
Each set operates independently under normal conditions. Each display set has a dedicated control panel, remote light sensor, and a symbol generator. A third symbol generator is installed, as a backup, for either display set.

D. The switches on the instrument source select panels provide selection for backup data sources in the event of a main data source failure.

E. Normally, the left and right symbol generators supply the corresponding display set. If a fault is detected by the operating symbol generator, either display set can be switched to the center symbol generator. The RDMIs and VSIs can be switched to the center IRU if a source fault is detected.
F. If the captain and F/O select the center EFIS system, a level B caution message - INSTR SWITCH - will appear on the EICAS Display.
G. The RDMIs are the secondary heading, bearing, and distance displays. A portion of the indicators display the airplane's present heading. They also display the directional bearing and navigational distance to selected reference points.
H. The RDMIs receive this data from the IRS, VOR, DME, and ADF systems.
I. The VSIs are the main vertical rate-of-climb and descent display. They receive this data from the inertial reference system.
In the following pics, a view inside of a Symbol generator during cleaning process
All Boars and power supply removed
Power supply installed
 Display driver card installed
 All cards installed, ready to be closed
SG front view

domenica 9 ottobre 2016

Avionics bending: P51 Warning System

1. General

A. The warning system provides the flight crew with visual and aural warnings. Warnings are provided for abnormal airplane system conditions. They are also provided for airplane out of configuration conditions for various operating modes.

B. The warning system consists of a warning electronics unit, aural warning loudspeakers, aural cancel switch, and test switches. It also includes the master WARNING switch-lights, SPEEDBRAKES light, and discrete warning light.

C. Input signals are received from airplane sensors, other airplane systems, or generated by the pilots. Signals are processed within the warning electronics unit (WEU).

D. The visual displays are level A warning messages on the display unit and red WARNING lights. The aural signals are bell, siren, owl, and ground proximity warning system voice messages.
2. Component Details

A. Warning Electronics Unit (WEU)

(1) The warning electronics unit (WEU) P51 is located in the forward electrical/electronic equipment area.

(2) The WEU contains two power supply modules with fault indicators and reset switch, and plug-in modules which generate warning signals. The WEU provides output signals to the warning loudspeakers, master warning lights, and discrete warning lights. The unit weighs 33 lbs and is cooled by externally blown air.

(3) The modules located in the WEU and their functions are as follows:

 (a) Power Supply Modules

1) The two redundant power supplies receive 115 volts ac power and develop the +5 volts and ±12 volts dc power required for all warning modules. There are two ball type fault indicators, one for each module. Each ball latches to black when the corresponding power supply is operating properly and latches to yellow when a fault occurs. The RESET switch is provided to set the fault balls back to the operational mode.

2) The two power supply fault indicators and a reset switch are located on the WEU BITE module inside P51.

 (b) EMI Filter Module
1) There are two EMI filter modules in the WEU. Each filter module is paired with a power supply module. The EMI filter module connects to the power line and filters the AC line noise.
 (c) Stall Warning Module
1) There are two stall warning modules. The left module provides the captain's warning signal and the right module, the first officer's warning signal. The modules are each microprocessor controlled.
 (d) WEU BITE Module
1) The WEU BITE module provides fault indications for the two power supplies and the two stall warning computers.
 (e) Altitude Alert Module
1) The altitude alert module is microprocessor controlled. It provides altitude acquisition advisory and deviation cautions.

 (f) Takeoff Configuration Warning Module

1) The takeoff configuration warning module provides warning signals for improper airplane configuration during takeoff.

 (g) Landing Configuration Warning Module

1) The landing configuration warning module is microprocessor controlled. It provides warning signals for improper airplane configuration during landing and speed brake caution signals.

 (h) Master Warning Module

1) The master warning module is microprocessor controlled and provides the warning signals to turn on the master warning lights.

 (i) Bell/Chime Aural Warning Module

1) The bell/chime aural warning module provides fire bell warning and crew call chime signals to the audio amplifiers in the siren/owl aural warning modules.

 (j) Siren/Owl Aural Warning Module

1) The left and right siren/owl aural warning modules supply level A warning and level B caution signals.

2) The siren warning is activated by overspeed, cabin altitude exceedance, T/O configuration warnings, and Landing configuration warnings.

3) The siren warning is also activated by autopilot disconnect.

4) The owl warning is activated by level B EICAS messages and altitude alert.

5) The siren/owl modules also supply amplification of the bell/chime warnings and ground proximity voice.

6) The siren/owl modules also amplify voice messages received from the TCAS.

 (k) Clacker/Wailer Aural Warning Module

1) The clacker/wailer aural warning modules provide autopilot warning signals to the siren/owl aural modules. The clacker is not used.

 (l) EICAS Signal Consolidation Card (SCC)

1) The EICAS SCC converts analog signals to digital signals which are then sent to the EICAS function.
B. Configuration Warning Test Switch

(1) The configuration warning test switch is located on the miscellaneous test panel on the right side panel. It is a two-position, spring loaded switch. The T/O position is for testing the takeoff configuration warning circuits. The LDG position is for testing the landing configuration warning circuits.

C. Gnd Prox/Config Gear Ovrd Switch

(1) The Gnd Prox/Conf Gear Ovrd Switch is located on the first officer's instrument panel. It is an alternate action light switch. The switch cancels the landing configuration aural warning and displays the amber OVRD message when pressed.

D. Master Warning Lights

(1) The red master WARNING lights are located on both ends of the pilots' glareshield P7. The lights come on when the master warning module in the warning electronics unit generates a warning signal. Pressing the indicator light cap will turn off the light and silence the fire bell warnings, Landing configuration warning, or the cabin altitude warning.

E. Discrete Warning Light

(1) The red CONFIG discrete warning light is located on the center instrument panel. The light comes on when the configuration warning module in the warning electronics unit generates a warning signal. The light is powered by the master dim and test circuit.

F. Loudspeakers
(1) The warning loudspeakers are located above the captain's and first officer's seats. Each loudspeaker is a permanent magnet speaker driven by an internal single stage amplifier. The two speakers provide aural tones and messages when turned on by either the left or right siren/owl aural warning module.
G. Speed Brake Handle Position Switch

(1) The speed brake handle position switch is located on the control stand. The switch is a thru-contact microswitch with a roller control arm. If the switch is set at the down detent position, a ground is applied to the takeoff configuration warning module. A warning is given when the switch is not in the down detent.  


In the following video a power up test and an aural test using a loudspeaker from cockpit.

venerdì 23 settembre 2016

Avionics bending: CVR

1. General

A. The voice recorder system preserves a continuing record of the latest 30 or 120 minutes of flight crew communications and conversations. The four channel voice recorder receives inputs from the audio selector panels for the captain, the first officer, and the first observer, and from an area microphone in the flight compartment.

B. The voice recorder system consists of a recorder located in the aft passenger cabin ceiling and a control panel with an area microphone located on overhead panel P5.

C. 115 VAC power is supplied to the system from the right AC bus. The VOICE RECORDER circuit breaker, located on overhead panel P11, controls power to the system.

2. Component Details

A. Voice Recorder


The voice recorder is installed in the E7 equipment rack in the aft passenger cabin ceiling. The recorder is a thermally insulated, impact resistant, 4 MCU unit, and international orangein color.

The voice recorder contains a tape transport which includes the tape, tape drive, two four-track recording heads, two erase heads, two monitor heads, and a bulk erase coil. The unit also contains four recording amplifiers, a monitor amplifier, 65 kHz bias generator,
600 Hz test circuits and power supply.
(a) The recording tape is 308 feet long, 1/4 inch wide in a continuous endless loop. The four track tape runs at 1 7/8 IPS providing 30 minutes of recording time.
(b) The front panel contains a headphone jack and a underwater locator beacon (ULB). A headset inserted into the headphone jack will monitor all channels slightly delayed after they are recorded.
(3) An ULB is attached to the voice recorder front panel and is a self-contained device. The ULB will emit a 37.5-KHz signal when the water activated switch is closed. The ULB contains a dated label to indicate when the battery requires periodic replacement.

B. Voice Recorder Control Panel

The voice recorder control panel is located on overhead panel P5.
It contains an area microphone with preamplifier and filter circuits, a HEADPHONE jack to monitor system recording, a TEST switch to initiate the functional self test, a light or meter to
provide an indication of self test success or failure, and an
ERASE switch for data erasure.

Push the TEST switch will activate test circuits within the voice recorder. A tone is applied to all four channels. If the test is successful, the needle on the monitor meter moves and stays in the green area and you hear a tone in the headse

Push the ERASE switch will cause the voice recorder data to be completely erased. Bulk erasure is possible only when the airplane is on the ground with the parking brake set.