LOCAL CHANNEL
CCDL
CTC-231-026-00 SIGNAL PROCESSING
EFFECTIVITY
ALL CFM56-5B ENGINES FOR A319-A320-A321
CFMI PROPRIETARY INFORMATION FAULT DETECTION
FAULT DETECTION
& ANNUNCIATION Page 19
Nov 02
CFM56-5B TRAINING MANUAL
PARAMETER SELECTION
When both channels are operational and cross-channel data is available, the validity of channel A and B dual sensor measured values and the absolute difference between the two inputs are checked. The outcome
of these tests determines the selected value and the corresponding selection status.
If one channel’s input is invalid, then the other channel’s value is selected. If both channels’ inputs are invalid, and the sensor has an ECU calculated model, then the model value is selected. If the sensor does not have a calculated model, then failsafe value 2 is selected.
If channel A and B measured values are considered valid, the ECU checks that the absolute difference between the two inputs is within a predetermined range.
If the delta between the two inputs is outside the predetermined range and the inputs have a model, then the value that is closest to that model is selected. If
the sensor does not have a model, failsafe value 1 is selected.
T495, TC, TEO, TECU, HPTC, TBV, LPTC are parameters without ECU-calculated models.
Input. F/S 1. F/S 2.
T495 Max 15°C
TC Min -60°C
TEO Max 178°C
TECU Max 65°C
HPTC Max 101.0%
TBV Max 101.0%
LPTC Max 105.0%
Sensor inputs PS3, N1, N2, T3, T25, FMV, VSV and VBV have ECU-calculated models.
For persistent, or intermittent failures, the ECU sets latch flags after a specific number of fault counts are exceeded to prevent repeated switching between sensor values and modeled values. The dual sensor fault is latched until the next ECU reset.
EFFECTIVITY
ALL CFM56-5B ENGINES FOR A319-A320-A321
CFMI PROPRIETARY INFORMATION FAULT DETECTION
FAULT DETECTION
& ANNUNCIATION Page 20
Nov 02
CFM56-5B TRAINING MANUAL
CTC-231-027-00 INPUT DATA SELECTION
EFFECTIVITY
ALL CFM56-5B ENGINES FOR A319-A320-A321
CFMI PROPRIETARY INFORMATION FAULT DETECTION
FAULT DETECTION
& ANNUNCIATION Page 21 Nov 02
CFM56-5B TRAINING MANUAL
SIGNALS DISAGREE TRA signals disagree.
The ECU interfaces with two TRA resolvers, one dedicated to channel A and the other to channel B. Each ECU channel provides excitation for and accepts inputs from its resolver.
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