Honeywell BENDIX/KING KAP 140

BENDIX/KING

KAP 140

Page 4 -- 1

Revision 2, Dec/ 2002

CS: 15574F02. I DU

SECTION IV

TROUBLESHOOTING

4.1 GENERAL

The Rem ot e Ter m inal I nt er f ace is an im por t ant r esour ce f or t r oubleshoot ing pr oblem s involving

t he KAP 140 syst em. A descript ion of t he problem as viewed f r om t he c ockpit t oget her wit h t he

logged er r or s accessible v ia t he RTI will help t o nar r ow t he f ocus of t r oubleshoot ing. The t im e t hat

t he problem occurred s hould be c orrelat ed wit h t he power cycle t ime in t he error log. A m ore

det ailed descript ion of t he error codes is cont ained in sect ion V. Some syst em f ault s can lead t o

m ult iple er r or c odes being logged. I n t hese inst ances, t he f ir s t er r or logged is usually t he m ost

signif icant . I t s hould also be k ept in m ind t hat only t he f ir s t occur r ence of an er r or code is logged

within a power cycle.

The f ollowing s ect ion describes how t o t r oubleshoot a syst em wit h problems t hat do not generat e

an error code; these are primarily related to system performance. The subsequent sections aid

in the troubleshooting of systems with logged errors by describing the various interfaces to the

KAP 140 syst em as seen t hrough t he RTI in diagnost ic m ode (see sect ion 3. 3. 2, Diagnost ic M ode

Screens, and its sub--sections for more information on accessing diagnostic mode). Use of this

information with the wiring harness diagrams and a multimeter should allow diagnosis of most

system problems.

4.2 PERFORMANCE PROBLEMS

The following table assumes there are no logged error codes to assist in troubleshooting the

system. If an error code has been stored, attempt to resolve the associated problem before using

the following table.

Symptom

Possible Cause(s)

Checks to Perform



Autopilot indicates engage-

ment on FCC, but does not

drive servos.



CWS switch stuck active.



Check CWS switch in diagnostics.



Autopilot won’t engage

pitch modes.



If “P” LED on, pitch servo may

be invalid or FCC acceleration

monitor may be active.



Check servo validity and acceleration

monitor outputs in diagnostics.



Autopilot won’t engage any

modes.



AP DISC switch pressed or

stuck active (Both “P” and “R”

LEDs on).



Check diagnostics for proper switch

operation.



Roll servo invalid (“R” LED

on).



Check roll servo and interconnecting

harness.



Turn Coordinator invalid

(dashes in mode annunci-

ations).



Check Turn Coordinator for flag in

view. Replace T.C.



Install strap mismatch (Mode

annunciations dashed with “P”

and “R” LEDs.)



Check harness strap code in diagnos-

tics and compare with STC data.



All pitch modes “porpoise”

or have poor tracking be-

havior.



Pitch servo bridle cable below

minimum allowed tension.



Check and adjust bridle cable tension

to certified value.

Honeywell BENDIX/KING KAP 140 - Page 75

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