Narrative:

The automatic reserve thrust system activated during the application to takeoff power. The takeoff was discontinued. After clearing the runway, the engines were run up and they check out ok. The takeoff was made and everything was normal. In cruise, while adjusting power, it was noticed that the EPR gauges responded to the opposite engines. The EPR gauges were wired backwards. The EPR gauge reversal was not noticed during the engine run up check because both engines were run up simultaneously. Looking for a spread in engine gauge reading. Callback conversation with reporter revealed the following information: first officer was making the takeoff. When he applied the power the left engine was a little high so captain adjusted the left throttle back only to have the left engine increase thrust. Not realizing what the problem was the takeoff was aborted returned to runup pad and ran up both engines. This time they performed normal so trip departed. En route captain wondered if maybe a fuel controller problem so to get information for maintenance he pulled throttles back individually and discovered the engine pressure gauges reversed. This was when the crew realized that on the original takeoff run the engines performed properly. This model has a system that senses engine failure and when N1 RPM of one engine is 30% below the other engine it shifts the fuel control to give the good engine an extra 850 pound of thrust. So when throttle adjusted on first takeoff run with reversed EPR gauges, captain actually reduced low engine to cause 30% spread and kick in the automatic reserve thrust. Later it was ascertained the aircraft had had maintenance 2 nights before and had flown all the previous day with the EPR gauges reversed by three different crews and since engines had always been even the error by maintenance was not discovered. Reporter had not followed up after the incident but is fairly certain that the cannon plugs had been reversed at the gauges behind the instrument panel since this is the one place where the engine wiring is close together.

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Original NASA ASRS Text

Title: ACR MLG ABORTED TKOF DUE TO UNEVEN POWER ON POWER APPLICATION AND UNWANTED ARTS, AUTOMATIC RESERVE THRUST, ACTIVATION WHEN POWER ADJUSTED.

Narrative: THE AUTO RESERVE THRUST SYS ACTIVATED DURING THE APPLICATION TO TKOF PWR. THE TKOF WAS DISCONTINUED. AFTER CLRING THE RWY, THE ENGS WERE RUN UP AND THEY CHK OUT OK. THE TKOF WAS MADE AND EVERYTHING WAS NORMAL. IN CRUISE, WHILE ADJUSTING PWR, IT WAS NOTICED THAT THE EPR GAUGES RESPONDED TO THE OPPOSITE ENGS. THE EPR GAUGES WERE WIRED BACKWARDS. THE EPR GAUGE REVERSAL WAS NOT NOTICED DURING THE ENG RUN UP CHK BECAUSE BOTH ENGS WERE RUN UP SIMULTANEOUSLY. LOOKING FOR A SPREAD IN ENG GAUGE READING. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: F/O WAS MAKING THE TKOF. WHEN HE APPLIED THE PWR THE L ENG WAS A LITTLE HIGH SO CAPT ADJUSTED THE L THROTTLE BACK ONLY TO HAVE THE L ENG INCREASE THRUST. NOT REALIZING WHAT THE PROB WAS THE TKOF WAS ABORTED RETURNED TO RUNUP PAD AND RAN UP BOTH ENGS. THIS TIME THEY PERFORMED NORMAL SO TRIP DEPARTED. ENRTE CAPT WONDERED IF MAYBE A FUEL CTLR PROB SO TO GET INFO FOR MAINT HE PULLED THROTTLES BACK INDIVIDUALLY AND DISCOVERED THE ENG PRESSURE GAUGES REVERSED. THIS WAS WHEN THE CREW REALIZED THAT ON THE ORIGINAL TKOF RUN THE ENGS PERFORMED PROPERLY. THIS MODEL HAS A SYS THAT SENSES ENG FAILURE AND WHEN N1 RPM OF ONE ENG IS 30% BELOW THE OTHER ENG IT SHIFTS THE FUEL CTL TO GIVE THE GOOD ENG AN EXTRA 850 LB OF THRUST. SO WHEN THROTTLE ADJUSTED ON FIRST TKOF RUN WITH REVERSED EPR GAUGES, CAPT ACTUALLY REDUCED LOW ENG TO CAUSE 30% SPREAD AND KICK IN THE AUTO RESERVE THRUST. LATER IT WAS ASCERTAINED THE ACFT HAD HAD MAINT 2 NIGHTS BEFORE AND HAD FLOWN ALL THE PREVIOUS DAY WITH THE EPR GAUGES REVERSED BY THREE DIFFERENT CREWS AND SINCE ENGS HAD ALWAYS BEEN EVEN THE ERROR BY MAINT WAS NOT DISCOVERED. RPTR HAD NOT FOLLOWED UP AFTER THE INCIDENT BUT IS FAIRLY CERTAIN THAT THE CANNON PLUGS HAD BEEN REVERSED AT THE GAUGES BEHIND THE INSTRUMENT PANEL SINCE THIS IS THE ONE PLACE WHERE THE ENG WIRING IS CLOSE TOGETHER.

Data retrieved from NASA's ASRS site as of August 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.