(b)  
The Go-Around mode may be terminated from a minimum of one second to a maximum of eight seconds depending on engine spool-up by operating the pushbutton EPR or SPD switch on the AFCS MCP or by an automatic compatible mode change initiated by the AFCS. This operation automatically provides a climb thrust rating. The FMA will continue to show the EPR display.

5C5 
22-31-01 Page 18  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Oct 20/85 

AUTOTHROTTLE SYSTEM - TROUBLE SHOOTING
EFFECTIVITY
SA ZS-SIA and on SD ST-AIB and on WA N235WA thru N241WA GJ B-2509 and B-2510
1.  General
A.  Malfunctions or failures of the Autothrottle system can be identified by using the BITE (self-test) procedure. Most system problems (other than autothrottle engagement problems) will normally appear as a BITE FAIL condition. The BITE test sequence consists of twelve parts that test:
A/T Computer
Thrust Lever Position Verification
Throttle Servos Response
PDC Interface
Flap Position
Longitudinal Accelerometers
Alpha Vane
Radio Altimeter Output Voltage
EPR Transducer Output Voltage
DADC Interface
Autopilot Interface
FMA and ADI Fast/Slow

B.  If the autothrottle fails BITE test A, the computer is faulty. Replacement of the computer will correct the majority of any autothrottle problems which may occur. The twelve BITE tests, the significance of any BITE fail indication, and the component that should be replaced are all identified in the following trouble shooting procedure. In addition, the trouble shooting table also identifies typical autothrottle problems and fault isolation procedures.
2.  Prepare for Trouble Shooting
A.  The airplane must be parked in a normal configuration.
B.  Verify that all circuit breakers are closed for following systems:
(1)  
Autothrottle (A/T) system

(2)  
Automatic Flight Control System (AFCS)

(3)  
Attitude reference system (VG and ADI)

Jun 20/83 22-31-01 Page 101
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

(4)  
Performance Data Computer (PDC) system

(5)  
Engine Pressure Ratio (EPR) indication

(6)  
Digital Air Data Computer (DADC) system

(7) 
 Mach-Airspeed Indicators

(8)  
Flap Position Indicator

C.  Verify that following systems are on and that no flags are in view:
(1) 
 Attitude Reference

(2)  
DADC No. 1

(3)  
PDC

NOTE:  PDC is required for PDC SPD mode but is not required to engage A/T in SPEED mode or EPR mode.

(4) 
 Autopilot/Flight Director

NOTE: If autopilot is not engaged, verify that at least one F/D switch is on.
D.  Initialize PDC by inserting:
NOTE:  Initialization steps are not required if BITE only is to be performed. Use Metric or English units as required.
(1)  
Outside air temperature (OAT)

(2)  
Destination elevation (100 ft)

(3)  
Zero fuel weight (30.0 thousand Kg. or 66.0 thousand pounds)

(4)  
Reserve fuel (5.5 thousand Kg. or 12.0 thousand pounds)

3.  Self-Test (A/T BITE Test from PDC)
A.  General
(1)  
The standard message set up for A/T BITE is displayed on the CRT throughout the test in the following format: A/T TEST 4-(X) TEST _____*[1] AT ENG FLAP  TH IDLE STOP *[1] PASS or FAIL is indicated here at the conclusion of each test except at the end of

test 6, CMPL will appear instead of PASS.

(2)  
There are twelve (12) A/T BITE tests identified as A, B, C, D, E, 0, 1, 2, 3, 4, 5 and 6.

(3)  
The BITE test sequence occurs in the order given in step (2). It is not possible to skip or override any of the twelve tests.

(4)  
There will be a blank on PASS or FAIL location on CRT during each test indicating that test is in process.

(5)  
If A/T will not enter BITE, verify squat switch is down (LANDING GEAR - LIGHTS circuit breaker on P6-2 panel is closed), thrust lever LVDT's are at idle (thrust levers full aft), and gear switch is down (landing gear position lever is in the DOWN position).

(6)  
Once the A/T BITE test is initiated, continue through the entire A/T BITE test sequence even if FAILS are indicated. When a test fail is indicated, make a note of the test that failed. If there is a FAIL of test A, B, C or 3, make a note of the test fail code that appears in the hexadecimal display window on the front of the Auto Throttle Computer, and then proceed with the test.
　
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