Honeywell PRIMUS 1000 - Built-In-Test (BIT); Pilot-Activated Self-Test (Past)

PRIMUSr 1000 Integrated Avionics System
A28--1146--112--00
PRIMUS
â
II Radio System
C--28
Built--In--Test (BIT)
GENERAL
The radio system BIT has three major functions:
D Performs a high confidence level pre--flight test
D Checks for latent failures that affect redundancy
D Assists in troubleshooting failures.
A power--on self--test (POST) is initiated when power is applied to the
RMU. POST causes the RMU to test itself, the primary digital bus that
connects both sides, each side secondary or back--up bus and the
interface to the remoteunits. Then it will command eachremote unit to
performitsself--test.FormoreinformationonPOST,refertoHoneywell
Pub. No. 28--1140--50.
In addition, each remote radio function has a pilot--activated self--test
(PAST) that performs a very comprehensive check of the individual
functions.
The BIT performs a thorough check of numerous system and internal
unit parameters. The entire system is designed to function properly
when all parameters are within their tolerance range.
NOTE: Theerrorsidentifiedbytheself--testindicatethatoneormore
internal parameters were measured to be outside their
self--test limitbutmay notnecessarilyindicatenon--operation
of the function. The pilot should verify operation of the
function. If any question remains, an authorized service
agency should be consulted.
The BIT also monitors important parameters and temperatures on a
continuousbasis.If a discrepancy occurs,the codefor thediscrepancy
is recorded in nonvolatile memory along with the power--up count, the
elapsed time since power--up, the module temperature, and the
measured value of the discrepant parameter.
To aid in troubleshooting, the maintenance memory can be read in the
aircraft on the RMU when the aircraft is on the ground. Or the remote
unitcanbetakenintotheshopwhereadigitalinterfaceunitcanbeused
to determine the failures.
PILOT--ACTIVATED SELF--TEST (PAST)
The pilot can initiate and conduct a self--test sequence of any radio
function. This pilot--activated self--test requires pushing and holding
down the TST button for the duration of the test, after the cursor is
positioned inside the window for the function to be tested.