Md-82 captain rejected takeoff at 120 KTS due to 10% less N1 and 25 degrees lower egt on right engin...

Narrative:

I was the pilot flying. We performed a max power takeoff due to a slight tail wind component. After a power check at 1.4 EPR that was normal; autothrottle was selected and power increased to 2.04 EPR. At the 80 KT airspeed check; I glanced at the engine instruments and saw the left EPR was a bit low and the right a bit high; I modulated the throttles very slightly to match; N1's and N2's were normal and matched left/right. At about 110 KTS; with my fingers on the reversers; I glanced at the EPR's again because I felt a throttle split under my arm. They were still at about 2.04 EPR; but the split was about 1 knob. The throttle split caused me to re-check the N1's; N2's and egt's. The right N1 had decreased to about 4-5% less than the left. With the speed at about 115 KTS I scanned EPR's again; then the N1's again. The N1 on the right engine had now dropped to about 9-10% less than the left: estimated at 88% left and 78% right; left egt was about 575 and the right about 550. Both EPR's remained at 2.04. I initiated a rejected take off at 120 KTS and the first officer advised tower. I taxied clear of the runway and briefed the flight attendants and passengers.

Original NASA ASRS Text

Title: MD-82 Captain rejected takeoff at 120 KTS due to 10% less N1 and 25 degrees lower EGT on right engine than left engine. EPR's were matched at 2.04. Successful reject with no issues other than required brake cooling.

Narrative: I was the pilot flying. We performed a max power takeoff due to a slight tail wind component. After a power check at 1.4 EPR that was normal; autothrottle was selected and power increased to 2.04 EPR. At the 80 KT airspeed check; I glanced at the engine instruments and saw the left EPR was a bit low and the right a bit high; I modulated the throttles very slightly to match; N1's and N2's were normal and matched left/right. At about 110 KTS; with my fingers on the reversers; I glanced at the EPR's again because I felt a throttle split under my arm. They were still at about 2.04 EPR; but the split was about 1 knob. The throttle split caused me to re-check the N1's; N2's and EGT's. The right N1 had decreased to about 4-5% less than the left. With the speed at about 115 KTS I scanned EPR's again; then the N1's again. The N1 on the right engine had now dropped to about 9-10% less than the left: estimated at 88% left and 78% right; left EGT was about 575 and the right about 550. Both EPR's remained at 2.04. I initiated a rejected take off at 120 KTS and the First Officer advised Tower. I taxied clear of the runway and briefed the flight attendants and passengers.

Data retrieved from NASA's ASRS site 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.

Attributes
ACN	1178924
Time
Date	201406
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	MD-82
Operating Under FAR Part	Part 121
Flight Phase	Takeoff
Flight Plan	IFR
Component
Aircraft Component	Turbine Engine
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Not Flying First Officer
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy

Md-82 captain rejected takeoff at 120 KTS due to 10% less N1 and 25 degrees lower egt on right engine than left engine. EPR's were matched at 2.04. Successful reject with no issues other than required brake cooling.