DOC AIRBUS | AMM A320FANALYZERS - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The engine vibration measurement channel comprises :
The engine vibration system provides the following functions :
** ON A/C NOT FOR ALL The engine vibration measurement channel comprises :
- two transducers (piezoelectric accelerometers)
- an Engine Vibration Monitoring Unit
- two vibration indications N1 and N2.
The engine vibration system provides the following functions :
- vibration indication due to rotor unbalance via N1 and N2 slaved tracking filters
- excess vibration (above advisory levels)
- fan trim balancing
- shaft speed (N1 and N2)
- storage of balancing data
- BITE and MCDU communication
- accelerometer selection
- frequency analysis when the printer is available (option).
2. Engine Vibration Sensor
A. No. 1 Bearing Vibration Sensor
(1) General
The No. 1 bearing vibration sensor permanently monitors the vibrations from No. 1 bearing. It also senses vibrations from LPT and HPT shafts, though it is less sensitive to LPT and HPT shaft vibrations. It is also used for trim balance operations.
The No. 1 bearing vibration sensor permanently monitors the vibrations from No. 1 bearing. It also senses vibrations from LPT and HPT shafts, though it is less sensitive to LPT and HPT shaft vibrations. It is also used for trim balance operations.
(2) Description
The accelometer part of the vibration sensor is located at the 9:00 o'clock position on No. 1 and No. 2 bearing support (near No. 1 bearing).
The sensor cable is routed through the fan frame. It comes out at the 3:00 o'clock position on fan frame mid-box structure aft face. The No.1 bearing vibration sensor consists of the following items :
The accelometer part of the vibration sensor is located at the 9:00 o'clock position on No. 1 and No. 2 bearing support (near No. 1 bearing).
No. 1 Bearing Vibration Sensor and Cable AssemblyThe sensor cable is routed through the fan frame. It comes out at the 3:00 o'clock position on fan frame mid-box structure aft face. The No.1 bearing vibration sensor consists of the following items :
(a) A housing including :
- a 100 pc/g sensing element (accelerometer)
- a bracket with 2 holes ensuring housing attachment to the engine with 2 bolts.
(b) A semi-rigid cable including :
- 2 conductors inserted in an inner sheath and an outer sheath
- 2 metal tubes providing for cable rigidity
- a metal plate for cable attachment to the forward flange of fan frame mid-box structure
- 5 shock absorbers to guide and dampen the cable in a tube through fan frame
- a 3-pin connector with a nut at one end. The nut ensures connector attachment to the fan frame aft face. The connector body has 2 flats which ensure its positioning with a lockplate secured by 2 bolts
- 4 clamps for attachment of the tube to fan frame.
(3) Operation
The sensor is of the piezo-electric type. It includes a stack of piezo-electric discs placed between a mass and a base. When the accelerometer is subjected to a vibration, the mass exerts a variable force on the discs : this generates a potential difference directly proportional to the acceleration in a certain frequency range.
This potential difference delivers a signals. The analysis of the signal enables identification of vibration characteristics of the monitored part.
The sensor is of the piezo-electric type. It includes a stack of piezo-electric discs placed between a mass and a base. When the accelerometer is subjected to a vibration, the mass exerts a variable force on the discs : this generates a potential difference directly proportional to the acceleration in a certain frequency range.
This potential difference delivers a signals. The analysis of the signal enables identification of vibration characteristics of the monitored part.
B. Turbine Rear Frame Vibration Sensor
(1) General
The Turbine Rear Frame (TRF) vibration sensor is used in conjunction with the No. 1 bearing vibration sensor to monitor and, if necessary, reduce the engine vibration level using the trim balance procedure.
The vibration signal is used by the aircraft Engine Vibration Monitoring Unit (EVMU).
The Turbine Rear Frame (TRF) vibration sensor is used in conjunction with the No. 1 bearing vibration sensor to monitor and, if necessary, reduce the engine vibration level using the trim balance procedure.
The vibration signal is used by the aircraft Engine Vibration Monitoring Unit (EVMU).
(2) Description
The TRF vibration sensor is installed at 12 o'clock on the front flange of the turbine rear frame.
It consists in a hermetically sealed housing that encloses the sensing element. A flange with two holes is used to attach the housing to the engine. One electrical connector at the end of semi-rigid cable provides the interface with an aircraft harness.
The accelerometer sensitivity is 50 pC/g.
The TRF vibration sensor is installed at 12 o'clock on the front flange of the turbine rear frame.
It consists in a hermetically sealed housing that encloses the sensing element. A flange with two holes is used to attach the housing to the engine. One electrical connector at the end of semi-rigid cable provides the interface with an aircraft harness.
The accelerometer sensitivity is 50 pC/g.
(3) Operation
The sensor is of the piezo-electric type.
A piezo-electric material generates electrical charges when it is submitted to a mechanical stress.
An inert mass is attached to a piece of piezo-electric material. When the assembly is submitted to vibrations, the inertia of the mass generates mechanical stresses in the piezo-electric material. It is therefore possible to collect an electrical signal the frequency and intensity of which are representative of the vibration level to be measured.
The sensor is of the piezo-electric type.
A piezo-electric material generates electrical charges when it is submitted to a mechanical stress.
An inert mass is attached to a piece of piezo-electric material. When the assembly is submitted to vibrations, the inertia of the mass generates mechanical stresses in the piezo-electric material. It is therefore possible to collect an electrical signal the frequency and intensity of which are representative of the vibration level to be measured.
3. Engine Vibration Monitoring Unit (EVMU)
A. General
The Engine Vibration Monitoring Unit (EVMU) is located in the avionics compartment shelf 86VU.
The EVMU receives analog signals from :
The EVMU sends signals through the digital ARINC 429 data bus to :
The Engine Vibration Monitoring Unit (EVMU) is located in the avionics compartment shelf 86VU.
The EVMU receives analog signals from :
- the 4 engine accelerometers (2 per engine)
- and the N1 and N2 speed sensors of each engine.
The EVMU sends signals through the digital ARINC 429 data bus to :
- SDAC1 and 2 for cockpit indication
- the CFDIU
- the DMU
- and printer (if installed) for maintenance purposes.
B. Description
The signal conditioner is composed of :
The signal conditioner is composed of :
- 1 power supply module
- 2 channel modules
- 1 balancing module
- 1 data processing module
(1) Channel module
Each channel module processes the signals from the two engine accelerometers and from the two speed signals N1 and N2 : this enables extraction from the overall vibration signal, of a component due to rotor first order unbalance.
Only one accelerometer is used at any particular time. The second accelerometer is selected manually via MCDU 'ACC. RECONFIGURATION menu' or automatically at the next power up due to a failure of the N1 BEARING ACCEL.
The N1 and N2 signals are used :
Each channel module processes the signals from the two engine accelerometers and from the two speed signals N1 and N2 : this enables extraction from the overall vibration signal, of a component due to rotor first order unbalance.
Only one accelerometer is used at any particular time. The second accelerometer is selected manually via MCDU 'ACC. RECONFIGURATION menu' or automatically at the next power up due to a failure of the N1 BEARING ACCEL.
The N1 and N2 signals are used :
- to drive the tracking filters, and
- slave their center frequencies at the shaft rotational speed.
(2) Balancing module
The balancing module receives :
The balancing module receives :
- the accelerometer signal
- the N1 signal including the 1/REV synchronisation pulse.
(3) Data processing module
This module manages under program control, the whole signal conditioner operation.
The data processing module :
This module manages under program control, the whole signal conditioner operation.
The data processing module :
- receives the necessary inputs from the CFDS
- provides outputs to the aircraft corresponding to the selected mode (the outputs depend on the aircraft status).
- the normal mode
- the MENU mode, used on the ground for maintenance purposes (Ref. paragraph Operation).
(4) Power supply module
The power supply module receives the 115VAC/400Hz power. It provides the other modules with the necessary voltages.
The power supply module receives the 115VAC/400Hz power. It provides the other modules with the necessary voltages.
C. Power Supply
The EVMU is supplied with 115V/400Hz by busbar 101XPA, through circuit breaker 1EV.
The maximum power consumption is less than 30VA.
The EVMU is not affected by power loss up to 5 ms. For power interrupt time between 5 ms and 20ms, the equipment does not supply any inadvertent indication. It returns to normal operation 200 ms after power return.
The EVMU is supplied with 115V/400Hz by busbar 101XPA, through circuit breaker 1EV.
The maximum power consumption is less than 30VA.
The EVMU is not affected by power loss up to 5 ms. For power interrupt time between 5 ms and 20ms, the equipment does not supply any inadvertent indication. It returns to normal operation 200 ms after power return.
D. Operation
The EVMU provides the following functions :
The EVMU provides the following functions :
(1) Actual vibration level
Measurement of the actual vibration velocity corresponding to acceleration signals filtered with narrow band filter slaved to rotor speeds.
As normal vibration is depending on rotor speed an absolute actual level cannot give a correct vibration indication : so for each speed, the EVMU processes the ratio actual value/maxi value. This ratio is multiplied by 10 and is available on the EVMU output for display.
- N1 vibrations are measured as a displacement in mils (1/1000 of an inch), while N2 vibrations are measured as a speed in ips (inch per second). N1 phase angle is also measured in degrees for balancing purposes.
- MAX N1 narrow band vib selection and normalization for display: the display between 0 and 10 units depicts a vibration between 0 and 10 mils (linear).
- MAX N2 narrow band vib selection and normalization for display: the display between 0 and 10 units depicts a vibration between 0 and 4 ips (linear).
Measurement of the actual vibration velocity corresponding to acceleration signals filtered with narrow band filter slaved to rotor speeds.
As normal vibration is depending on rotor speed an absolute actual level cannot give a correct vibration indication : so for each speed, the EVMU processes the ratio actual value/maxi value. This ratio is multiplied by 10 and is available on the EVMU output for display.
- N1 vibrations are measured as a displacement in mils (1/1000 of an inch), while N2 vibrations are measured as a speed in ips (inch per second). N1 phase angle is also measured in degrees for balancing purposes.
- MAX N1 narrow band vib selection and normalization for display: the display between 0 and 10 units depicts a vibration between 0 and 10 mils (linear).
- MAX N2 narrow band vib selection and normalization for display: the display between 0 and 10 units depicts a vibration between 0 and 4 ips (linear).
(2) Measurement of the unbalance data
The EVMU measures the position and the amplitude of the rotor unbalance of each engine. It provides these information to the output bus when available.
The EVMU measures the position and the amplitude of the rotor unbalance of each engine. It provides these information to the output bus when available.
(3) Computation of the advisory level
The advisory level is equal to the following limit:
Limit = 6U for N1 and 4.2U for N2
The advisory level is permanently compared with the actual level. If the advisory level is reached, a digital information is sent to the ECAM.
The advisory level is equal to the following limit:
Limit = 6U for N1 and 4.2U for N2
The advisory level is permanently compared with the actual level. If the advisory level is reached, a digital information is sent to the ECAM.
(4) Frequency analysis
The EVMU can do a frequency analysis if requested from the MCDU on the ground. The EVMU does the analysis at a selected N1 or N2 speed and uses any valid accelerometer. The maximum frequency analysis is 500 Hz and the frequency increment between adjacent spectral lines is 4 Hz.
The EVMU can do a frequency analysis if requested from the MCDU on the ground. The EVMU does the analysis at a selected N1 or N2 speed and uses any valid accelerometer. The maximum frequency analysis is 500 Hz and the frequency increment between adjacent spectral lines is 4 Hz.
(5) Storage of unbalance data
If requested, the system can store the balancing data during the cruise phase at five predetermined different engine speeds.
If requested, the system can store the balancing data during the cruise phase at five predetermined different engine speeds.
(6) BITE maintenance and fault information
The equipment contains a BITE to detect internal and external failure.
Complete description of the BITE system is given in 31-30-00.
During the execution of the cyclic BITE sequence, the following parts of the EVMU are checked :
The equipment contains a BITE to detect internal and external failure.
Complete description of the BITE system is given in 31-30-00.
During the execution of the cyclic BITE sequence, the following parts of the EVMU are checked :
- the non-volatile memory
- the timers
- the analog-to-digital converter
- the ARINC 429 transmitter and receivers
- the real tacho generators.
- N1 and N2 NB velocity
- unbalance data
- N1 and N2 tacho frequencies
- accelerometer signals.
E. Interfaces
(1) Inputs
The receives analog signals from :
The receives analog signals from :
- the 4 engine accelerometers (2 per engine)
- the N1 and N2 speed sensors from each engine.
(2) Outputs
The EVMU transmits output signals through an ARINC 429 data bus.
The data transmitted on the single low speed line is in conformity with ARINC 429.
The SDI definition is as follows :
The status matrix definition is as follows :
The data transmitted on the ARINC 429 line is defined in the following tables
EVMU ARINC Output Data Bus
The EVMU transmits output signals through an ARINC 429 data bus.
The data transmitted on the single low speed line is in conformity with ARINC 429.
The SDI definition is as follows :
| ------------------------------------------ |
| ! BITS ! 10 9 ! |
| !-------------------!--------------------! |
| ! Engine 1 ! 0 1 ! |
| ! Engine 2 ! 1 0 ! |
| ------------------------------------------ |
The status matrix definition is as follows :
| ------------------------------------------ |
| ! BITS ! 31 30 ! |
| !-------------------!--------------------! |
| ! Failure warning ! 0 0 ! |
| ! Not computed data ! 0 1 ! |
| ! Test ! 1 0 ! |
| ! Normal operation ! 1 1 ! |
| ------------------------------------------ |
The data transmitted on the ARINC 429 line is defined in the following tables
| ------------------------------------------------------------------------------- |
| ! PARAMETER ! LABEL! UPDATE! BINARY! SIGNIFICANT! OPERATING! UNITS! |
| ! ! ! TIME ! RANGE ! BITS ! RANGE ! ! |
| ! ! ! (ms) ! ! ! MIN ! MAX! ! |
| !-----------------------!------!-------!-------!------------!-----!----!------! |
| ! N1 vibration ! 135 ! 200 ! 12.8 ! 7 ! 0 ! 10! ! |
| ! N2 vibration ! 136 ! 200 ! 12.8 ! 7 ! 0 ! 10! ! |
| ! Unbalance phase ! 226 ! 200 ! 512 ! 9 !-180 !+179!Degree! |
| ! Unbalance displacement! 227 ! 200 ! 25.6 ! 8 ! 0 ! 25!mils ! |
| ! N1 speed ! 346 ! 200 ! 256 ! 14 ! 15 ! 120!Degree! |
| ! ! ! ! ! ! ! ! Rpm ! |
| ! N2 speed ! 344 ! 200 ! 256 ! 14 ! 15 ! 120!Degree! |
| ! ! ! ! ! ! ! ! Rpm ! |
| ! Discrete word ! 035 ! 200 ! ! ! ! ! ! |
| ! Maintenance word (a) ! 356 ! 200(b)! ! ! ! ! ! |
| ------------------------------------------------------------------------------- |
(a) Label 356 is used for communication with the CFDS. Its definition is in accordance with the CFDS communication (Ref. AMM D/O 31-30-00-00).
(b) 200 ms in normal mode. 30 ms in menu mode.
EVMU Status Word-Label 035
| ----------------------------------------------------------------- |
| ! ! ! BIT STATUS ! |
| ! BIT No. ! FUNCTION !--------------- ! |
| ! ! ! 1 ! 0 ! |
| !-----------!----------------------------------!-------!--------! |
| ! 1 ! ! ! X ! |
| ! 2 ! ! ! X ! |
| ! 3 ! ! ! X ! |
| ! 4 ! ! X ! ! |
| ! 5 ! Label ! X ! ! |
| ! 6 ! ! X ! ! |
| ! 7 ! ! ! X ! |
| ! 8 ! ! X ! ! |
| ! 9 ! SDI ! ! ! |
| ! 10 ! SDI ! ! ! |
| ! 11 ! N1 vib above advisory ! Yes ! No ! |
| ! 12 ! N2 vib above advisory ! Yes ! No ! |
| ! 13 ! Accelerometer reconfiguration ! Yes ! No ! |
| ! 14 ! Spare always at 1 ! ! ! |
| ! 15 ! Frequency analysis performed ! Yes ! No ! |
| ! 16 ! N1 bearing accel channel Fault ! Yes ! No ! |
| ! 17 ! TRF accel channel Fault ! Yes ! No ! |
| ! 18 ! N1 speed channel Fault ! Yes ! No ! |
| ! 19 ! N2 speed channel Fault ! Yes ! No ! |
| ! 20 ! Unbalance Fault ! Yes ! No ! |
| ! 21 ! Frequency Fault ! Yes ! No ! |
| ! 22 ! NVM Fault ! Yes ! No ! |
| ! 23 ! BB above threshold ! Yes ! No ! |
| ! 24 ! Spare ! ! ! |
| ! 25 ! Spare ! ! ! |
| ! 26 ! Spare ! ! ! |
| ! 27 ! Adv on sel. acc. in flight or ! Yes ! No ! |
| ! ! other acc. in FP6 ! ! ! |
| ! 28 ! EVM SYST CLASS II FAULT ! Yes ! No ! |
| ! 29 ! EVMU CLASS I FAULT ! Yes ! No ! |
| ! 30 ! SSM ! ! ! |
| ! 31 ! SSM ! ! ! |
| ! 32 ! Parity ! ! ! |
| ----------------------------------------------------------------- |
(3) Indicating
The engine vibration indications are displayed (in green) on the lower display unit of the ECAM, in the engine and cruise pages. The ECAM display unit receives the information through the ARINC 429 data bus via the SDAC 1 and SDAC 2. If the advisory level is reached the indication flashes (0.6 sec bright, 0.3 sec normal). If the indication is not available the corresponding indication is replaced by 2 amber crosses.
The engine vibration indications are displayed (in green) on the lower display unit of the ECAM, in the engine and cruise pages. The ECAM display unit receives the information through the ARINC 429 data bus via the SDAC 1 and SDAC 2. If the advisory level is reached the indication flashes (0.6 sec bright, 0.3 sec normal). If the indication is not available the corresponding indication is replaced by 2 amber crosses.
(4) CFDS interface
The Centralized Fault Data System (CFDS) enables access to the systems.
The CFDS gives, maintenance information and initiates tests through the system BITE (Refer to 31-30-00).
When the maintenance personnel needs information on the condition of the EVMU, the CFDS operates in menu mode. The first menu sent to the MCDU is the main menu. The various functions are detailed here after.
The Centralized Fault Data System (CFDS) enables access to the systems.
The CFDS gives, maintenance information and initiates tests through the system BITE (Refer to 31-30-00).
When the maintenance personnel needs information on the condition of the EVMU, the CFDS operates in menu mode. The first menu sent to the MCDU is the main menu. The various functions are detailed here after.
(a) Last leg report
The EVMU sends the list of the LRUs which have been detected faulty during the last leg. During the flight the following faults can be detected :
The EVMU sends the list of the LRUs which have been detected faulty during the last leg. During the flight the following faults can be detected :
- EVMU
- N1 SPEED SENSOR, L
- N1 SPEED SENSOR, R
- N2 SPEED SENSOR, L
- N2 SPEED SENSOR, R
(b) Previous leg report
The EVMU sends the list of the LRUs which have been detected faulty during the legs (maximum 62) previous to the last leg. The faults detected are the same as for the last leg report.
The EVMU sends the list of the LRUs which have been detected faulty during the legs (maximum 62) previous to the last leg. The faults detected are the same as for the last leg report.
(c) LRU identification
The EVMU sends the EVM unit part number and manufacturer
The EVMU sends the EVM unit part number and manufacturer
(d) Class 3 failures
The EVMU sends the list of the LRUs which have been detected faulty during a ground test. Only the three last detected failures are displayed. The following LRUs are tested :
The EVMU sends the list of the LRUs which have been detected faulty during a ground test. Only the three last detected failures are displayed. The following LRUs are tested :
- EVMU
- N1 BEAR VIB SENSOR, L
- N1 BEAR VIB SENSOR, R
- TRF VIB SENSOR, L
- TRF VIB SENSOR, R
(e) Test
The test item allows initiation of a complete check of the EVM system.
If no failure has been detected, the message TEST OK is displayed.
If any failure has been detected the failed LRU is displayed. Checked LRUs are the ones listed in "GROUND FAILURES" item.
The test item allows initiation of a complete check of the EVM system.
If no failure has been detected, the message TEST OK is displayed.
If any failure has been detected the failed LRU is displayed. Checked LRUs are the ones listed in "GROUND FAILURES" item.
(f) Initial values
In that menu, ten sub-menus may be selected by the operator, which allows :
In that menu, ten sub-menus may be selected by the operator, which allows :
- command of the initial values acquisition during the next flight
- cancelling of the initial values acquisition demand
- reading of the initial values taken
- direct loading modification of the existing values.
(g) Accelerometer reconfiguration
This menu allows selection of the accelerometer (Fan No. 1 bearing or TRF) to be used for the next flights. The EVMU also indicates which accelerometer is in operation.
This menu allows selection of the accelerometer (Fan No. 1 bearing or TRF) to be used for the next flights. The EVMU also indicates which accelerometer is in operation.
(h) Engine unbalance
This menu allows selection, per engine, of five different engine speed, (from 50 percent to 100 percent N1 RPM) at which unbalance data will be stored. It also permits reading of the unbalance data which were acquired during the previous command and to perform balancing for both engines with both accelerometers.
This menu allows selection, per engine, of five different engine speed, (from 50 percent to 100 percent N1 RPM) at which unbalance data will be stored. It also permits reading of the unbalance data which were acquired during the previous command and to perform balancing for both engines with both accelerometers.
(i) Frequency analysis
This menu offers the possibility to request a frequency analysis of the acceleration signal to be performed. Results of frequency analysis is sent to the printer.
This menu offers the possibility to request a frequency analysis of the acceleration signal to be performed. Results of frequency analysis is sent to the printer.
(j) Shop maintenance
This menu is operational only when the EVMU is in the shop for maintenance. It allows trouble shooting of the LRU itself and corresponds to failures at SRU level.
This menu is operational only when the EVMU is in the shop for maintenance. It allows trouble shooting of the LRU itself and corresponds to failures at SRU level.