Sweep Patterns

The antenna sweep is the same for takeoff and approach PWS modes. The PWS changes the sweep when PWS is active. Both WXR and PWS sweeps decrease to -60 to +60 degrees.

PWS and WXR Sweep Pattern

Position	Dir	Radar Sweep	Paint Sweep	Angle (Degrees)	Time
Sweep 1	L-R	Capt WXR data updated	Capt WXR +icon painted	-60 to +60
Sweep 2	R-L	Both PWS data updated	None	+60 to -60

PWS and WXR Sweep Pattern

Sweep 3	L-R	F/O WXR data updated	F/O WXR +icon painted	-60 to +60
Sweep 4	R-L	Both PWS data updated	None	+60 to -60

The sweep pattern may go to a PWS only mode during takeoff and approach when WXR is not selected and PWS is automatically activated. The scan is -60 to +60 degrees.

PWS Sweep Pattern

Position	Dir	Radar Sweep	Paint Sweep	Angle (Degrees)	Time
Sweep 1	L-R	None	None	N/A
Sweep 2	R-L	Both PWS data updated	None	+60 to -60
Sweep 3	L-R	None	None	N/A
Sweep 4	R-L	Both PWS data updated	None	+60 to -60

WXR SYSTEM - OPERATION - FAILURE DISPLAYS

WXR System Alert Messages and Display

Alert messages show on the ND when the R/T processes data that is not satisfactory. The WXR display will continue to show with an alert message.

Only one alert message shows on the ND. When the R/T processes unsatisfactory data from more than one source only the highest priority message shows. These are the alert messages and priority from highest to lowest:

· WXR WEAK shows for an R/T gain calibration failure

· WXR ATT shows when the selected attitude input fails

· WXR STAB shows when stabilization is off.

The alert messages show on these alert lines:

· Line 1 shows WXR in amber

· Line 2 shows WEAK, ATT, or STAB in amber.

WXR System Fail Messages and Display

A failure of these components causes a WXR failure:

· R/T

· WXR control panel

· WXR antenna.

A WXR failure causes these conditions:

· WXR FAIL message shows on ND

· Mode, tilt, and gain messages go out of view

· WXR display goes out of view.

The fail message shows on these alert lines:

· Line 1 shows WXR in amber

· Line 2 shows FAIL in amber.

A failure of these components will cause a PWS failure:

· Loss of any RA

· Loss of ADR data

· Loss of IR data

· Scan and tilt antenna faults

· Internal WXR system faults

· Loss of CAS and TAS.

A failure of the predictive windshear causes an amber PWS FAIL message on the ND.

WXR SYSTEM - ND RANGE DISAGREEMENT

General

The DEUs compare the ND ranges from these components:

· EFIS CP

· WXR R/T

· Flight management computer (FMC).

A difference between any of these ranges causes an amber range disagreement message on alert line 3.

These WXR range disagreement messages are possible:

· WXR RANGE DISAGREE; shows when there is a difference between the EFIS CP range and the WXR R/T range

· MAP/WXR RANGE DISAGREE; shows when there is a difference between the EFIS CP range, the WXR R/T range, and the FMC range.

WXR RANGE DISAGREE will show in these modes:

· Expanded approach

· Expanded VOR

· Expanded map

· Centered map.

MAP/WXR RANGE DISAGREE will show in these modes:

· Expanded map

· Centered map.

This happens during a range disagreement:

· WXR display goes out of view

· mode, tilt, and gain messages show

· FMC range shows.

WXR SYSTEM - WXR R/T FUNCTIONAL DESCRIPTION

General

The WXR R/T makes RF pulses and sends them to the antenna. The antenna transmits pulses and receives the return signals and sends them to the WXR R/T. The R/T processes the return signals to make display data that shows on the NDs. The WXR data on the ND shows the weather patterns in front of the airplane.

The WXR R/T also comes on automatically during take off and approach to detect windshear events in front of the airplane. If a windshear event is detected, the WXR sends cautions or warnings to the flight compartment.

Дата добавления: 2015-10-26