giovedì 23 aprile 2015

Avionics Bending: Engine Standby Indicator

Back-up display of N1, EGT, and N2 is provided by the Standby Engine Indicator (SEI) on the P1-3 panel.
Engine operating limits are indicated on overlimit placards mounted on the SEI face. Respective sensor signals are input directly to the SEI to assure display in the event the Engine Indication and Crew Alerting System (EICAS) display units or EICAS computers fail.

NOTE: The Standby Engine Indication operation makes it necessary to have either 28VDC aircraft power or the engine operate.
When the SEI switch is "ON", you will see the digital display whenever the SEI is powered. When the switch is in the "AUTO" position, you will see the digital display only when the EICAS has failed. The SEI can be tested using a screwdriver operated switch on the left side of the SEI.

venerdì 3 aprile 2015

Avionics bending: Fuel quantity indicator

The fuel quantity indicator shows these informations:

-Left fuel quantity
-Right fuel quantity
-Center fuel quantity
-Total fuel quantity
-Fuel Temperature

The indicator's display has a high contrasr, dual-cell liquid Crystal display set out from the indicator bezer for increased visibility and viewing angle.
The indicator has 4 separate circuits, one for each tank display to make sure that a failure in one of them won't affect the others.

The 3 fuel tank quanityt displays have a resolution of 0.1 and a max value of 99.9.
The total fuel quantity display has a resolution of 0.1 and a max value of 999.9.
Fuel quantity shows to a resolution of 100lbs/kgs (lbs or kgs selectable by a program pin)

The indicator receives fuel quantity information over one of two ARINC 429 digital data buses, A or B.
Bus A is normally used and is selected at start-up or after a circuit test is complete. If bus A information becomes unavailable, the indicator keeps bus A data and after 4 seconds changes to bus B.
If it doesn't receive data on bus B after 4 seconds, the receiver continues to cycle at a 4-second rate until valid data is recognized.
If both buses are inactive, the tank indicator(s) show letters -Ab to show a dual bus failure.

Here is a video of gauge power up with no ARINC data provided yet.

And this video shows startup with no ARINC data, then the unit is feeded with fuel quantity data per tank

mercoledì 25 marzo 2015

Avionics Bending: GPWS Computer (GPWC)

For various flight conditions, the ground proximity warning system (GPWS) provides aural and visual warnings of airplane closeness to the terrain. The potentially dangerous flight modes are:
(1) Mode 1 - Large Descent Rate
(2) Mode 2 - Large Terrain Closure Rate
(3) Mode 3 - Too Much Altitude Loss During Climbout (at Takeoff or in Go-Around) When Not In Landing Configuration
(4) Mode 4 - Not Enough Terrain Clearance
(5) Mode 5 - Too Much Deviation Below The Glide Slope Centerline
(6) Mode 6 - Aural Callouts When Descending Through Selected Radio Altitudes
(7) Mode 7 - Windshear Detection

The system consists of:
(1) 1 - Ground Proximity Warning Computer (GPWC) or Enhanced GPWC
(2) 1 - GND PROX Light - G/S INHB Switch/Light
(3) 1 - WINDSHEAR Light
(4) 1 - PULL UP Light
(5) 1 - Ground Proximity Test Switch
(6) 1 - Gear Override Switch
(7) 1 - Flap Override Switch

The ground proximity warning computer (GPWC), or Enhanced GPWC, is located on the E1-5 rack in the main equipment center. The GPWC (or EGPWC) LRU is the main element of the Ground Proximity Warning System (GPWS).
The GPWC LRU front panel contains a toggle switch and an 8-character LED BITE display.
Present status or flight history data shows on the BITE display when the toggle switch is selected.
The computer receives and processes input signals to determine the alert and warning mode conditions. It also generates the aural and visual alert and warning messages.
The computer continuously monitors the validity of input signals and internal functions. System failures detected are stored in a non-volatile memory.