Pratt & Whitney PW2000 Engine
Fault message troubleshooting
By Joe Escobar
April 2001
Pratt & Whitney’s PW2000 series engines, designed for the Boeing 757, are mid-range thrust gas turbine engines that cover a range of 37,000 to 43,000 pounds of thrust. This article will briefly discuss some fault message troubleshooting involved with PW2000 engines installed on Boeing 757 aircraft with EICAS (Engine Indication and Crew Alerting System) computer -511 and on.
This article has been reprinted from a troubleshooting training guide prepared by Customer Maintenance Support Line Maintenance & Troubleshooting. The information and instructions are prepared for general information purposes only, and shall not be considered in any way as replacing or superseding the information contained in the PW2000 Turbofan Engine Maintenance Manual, or the Airframe Manufacturers Maintenance Manual.
Electronic Engine Control (EEC)
The electronic engine control (EEC) is a dual channel (primary/secondary) FADEC (Full-Authority Digital Electronic Control). It manages and coordinates a wide range of engine related functions. It operates as the primary interface between the engine and the aircraft. The EEC provides thrust management and fuel flow control for all engine operations. It also provides data to the indication system and aircraft computers.
Some of the possible EEC fault messages as well as corrective action are listed in Figure 1 on page 37.
Fuel Control Unit (FCU)
The fuel control unit (FCU) on PW2000 engines
acts on commands from the EEC to schedule correct fuel flow for engine start, acceleration, steady state, and deceleration. It operates the stator vane actuator (SVA) and the air/oil heat exchanger actuator. The torque motors for these actuators are located in the FCU. It also transmits servo fuel supply pressure to the 2.5 bleed actuator, 14th stage bleed converter valve, and LCC/HCC torque motors. The FCU also detects and protects against N2 RPM overspeed. If N2 exceeds 105 percent, the FCU willtake control from the EEC and try to maintain 85.5 percent N2. (To reset after an overspeed, a shutdown and restart must be performed to regain EEC control.)
Some of the FCU fault messages as well as troubleshooting suggestions are included in Figure 2 on pages 40-41.
This article has covered only a small percentage of possible fault messages for these engines. Refer to manufacturers maintenance manual for troubleshooting guidance on these and other fault codes.
Message Meaning Corrective Action P (S) 273-14 PT5 Interface Failed Replace EEC P (S) 273-15 PB Interface Failed Replace EEC P (S) 273-16 PT2 / PAMB Interface Failed Replace EEC P (S) 273-17 Thermocouple Interface Failed Replace EEC P (S) 273-18 Interface Failed Replace EEC P (S) 273-19 T5 Interface Failed Replace EEC P (S) 273-20 TF Interface Failed Replace EEC P (S) 273-21 A / D Interface Failed Replace EEC P (S) 273-22 AC Excitation Interface Failed Replace EEC P (S) 273-23 SVA Interface Failed Replace EEC P (S) 273-24 N1 Interface Failed Replace EEC P (S) 273-25 N2 Interface Failed Replace EEC P (S) 273-26 P5 Sensor Prom Failed Replace EEC P (S) 273-27 P2 Sensor Prom Failed Replace EEC P (S) 273-28 PB Sensor Prom Failed Replace EEC P (S) 273-29 Background is not executing Replace EEC
P (S) 274-14
thru
274-15
FCU FAULT MESSAGE TROUBLESHOOTING
P(S) FCU/EEC (276-19)
(FCU Function Failed)
This fault is set to indicate a fault exists either within the FCU or in one of the EEC to FCU circuits. The following faults will cause this to be set fault:
* 350-20 WF F/B Signal Failed
* 351-16 WF T/M Wraparound
* 351-17 SVA T/M Wraparound
* 351-21 AOX T/M Wraparound
* 351-23 WF Track Check Failed
*** Corrective Action: Check for above fault messages perform corrective action.
P(S) FCU F/B INT (276-27)
(FCU F/B Intermittent)
This fault is set when the EEC determines that the F/B signal from the FCU LVDT is intermittent.
*** Corrective Action: Check harness feedback circuit per the intermittent fault troubleshooting procedure. Use FCU wiring schematics for circuit information.
P(S) 350-20
(WF F/B Signal Failed)
This fault is set if the channel’s fuel valve feedback signal fails.
*** Corrective Action: Troubleshoot per the fault message troubleshooting procedure. Use FCU wiring schematics for circuit information.
CORRECTIVE ACTION VERIFICATION: Apply alternate power to EEC.
P(S) 351-16
(WF T/M Wraparound)
This fault indicates that this channel’s fuel flow torque motor coil or its wiring harness has a circuit fault.
*** Corrective Action: Troubleshoot per the fault message troubleshooting procedure. Use FCU wiring schematics for circuit information.
CORRECTIVE ACTION VERIFICATION: Apply alternate power to EEC.
P(S) 351-17
(SVA T/M Wraparound)
This fault indicates that this channel’s stator vane torque motor coil or its wiring harness has a circuit fault.
*** Corrective Action: Troubleshoot per the fault message troubleshooting procedure. Use FCU wiring schematics for circuit information.
CORRECTIVE ACTION VERIFICATION: Apply alternate power to EEC.
P(S) 351-21
(AOX T/M Wraparound)
This fault indicates that this channel’s air/oil heat exchanger valve torque motor coil or its wiring harness has a circuit fault.
*** Corrective Action: Troubleshoot per the fault message troubleshooting procedure. Use FCU wiring schematics for circuit information.
CORRECTIVE ACTION VERIFICATION: Apply alternate power to EEC.
P(S) 351-23
(WF Track Check Failed)
This fault indicates the fuel metering valve is not in its commanded position.
*** Corrective Action:
1) Replace FCU.
2) Troubleshoot per the wiring harness troubleshooting procedure. Use FCU wiring schematics for circuit information.
CORRECTIVE ACTION VERIFICATION: Engine run at take-off.
P(S) SVA or FCU/EEC (351-24)
(SVA Track Check Failed)
This fault indicates the stator vane actuator is not in its commanded position.
*** Corrective Action:
1) Replace FCU.
2) If fault persists troubleshoot per the wiring harness inspection/check procedure. Use FCU wiring schematics for circuit formation.
3) If fault persists replace SVA.
4) If fault persists troubleshoot per the wiring harness inspection/check procedure. Use SVA wiring schematics for circuit formation.
CORRECTIVE ACTION VERIFICATION: Engine run at idle or engine run at take-off when possible.
P(S) AOX or FCU/EEC (351-28)
(AOX Track Check Failed)
This fault indicates the air/oil heat exchanger actuator is not in its commanded position.
*** Corrective Action:
1) Replace AOX.
2) If fault persists troubleshoot per the wiring harness inspection/check procedure. Use AOX wiring schematics for circuit formation.
3) If fault persists replace FCU.
4) If fault persists troubleshoot per the wiring harness inspection/check procedure. Use SVA wiring schematics for circuit formation.
CORRECTIVE ACTION VERIFICATION: Engine run at idle or engine run at take-off when possible.
FCU/EEC (353-22)
(WF F/B Crosscheck Failed)
This fault indicates the primary and secondary WF feedback disagree by more than the normal accuracy tolerance. Fault will appear on primary channel only.
*** Corrective Action: Troubleshoot per the fault message troubleshooting procedure. Use FCU wiring schematics for circuit information.
CORRECTIVE ACTION VERIFICATION: Apply alternate power to EEC.
