INPUT VALIDATION
Parametric and discrete inputs. ARINC429 inputs.
The ECU provides fault accommodation for all engine The ECU monitors all ARINC429 inputs from the ADC’s
control signals. This includes engine sensors, actuator/ and the EIU for presence (activity).
solenoid position feedbacks and ARINC429 databus
inputs. ARINC429 words pass through an ARINC processor and
the converted word is then checked for basic validity. The
The ECU converts parametric analog inputs into a digital converted words are considered valid if they are received
format and then checks if the conversion has been within the correct ARINC transmit interval and the parity
successful. If the conversion test fails, the ECU sets a is odd.
fault flag and the parameter status to invalid.
At the same time, the ECU checks the Status Matrix
If the signal passes the conversion test, it is considered (SM). The SM depends on the label of the received word.
valid and passes onto a range test stage, which checks For most labels, the word is considered valid if the SM
for minimum and maximum limits. is ‘11’, but for some labels (e.g. EIU discrete words), the
SM is a different value. If the word fails the basic validity
As most discrete inputs are treated as digital signals, they check, the ECU flags the word as invalid.
pass directly to the range test logic.
If the word passes the validity test, the data contained in the word is then passed to the next check logic, which tests it for range.
EFFECTIVITY
ALL CFM56-5B ENGINES FOR A319-A320-A321
CFMI PROPRIETARY INFORMATION FAULT DETECTION
FAULT DETECTION
& ANNUNCIATION Page 4
Nov 02
CFM56-5B TRAINING MANUAL
RANGE TESTING
The ECU carries out range tests on the inputs after they have passed the validation tests.
The tests are managed by the ECU internal software and vary depending on the engine status.
The simplest range test on a parameter is a check of maximum and minimum limits against predefined values.
Pressure sensors : P0, PS12, PS13, P25, PS3. RTD temp sensors : T12, T25, TECU.
Thermocouple temp sensors : T3, EGT, T5, TC, TEO. Speed sensors : N1, N2.
The ECU checks the sensor output signal and generates a fault message for that channel if the sensed pressure/ temperature is not within the specified maximum and minimum ranges.
If a parameter fails the tests, the ECU sets the validation status to ‘Invalid’ and holds the parameter at its last valid value.
When a parameter passes the range tests, the ECU sets the validation status to ‘Valid’ and the value is passed on for further processing.
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