Narrative:

The aircraft had a history of the #2 engine EPR gauge as being inaccurate. Also, the #2 engine egt had a history of being higher than normal, but still operated within normal limits. All logbook discrepancies had been cleared by maintenance (they replaced gauges and transmitters). When we applied power for takeoff, engine #2 EPR appeared to still be inaccurate. We set #2 engine power using N-1. All engine instruments were in the normal range (except #2 EPR, which appeared to be inaccurate). The flight thru aircraft clean-up was normal. When we set climb power, engine #2 N-1 was lower and N2 was higher than engines 1 and 3 when egt and fuel flow were evened up. At 10,000' the second officer noted engine #2 CSD 'in' temperature was in the caution range (about halfway). I had the second officer go thru the abnormal. When I retarded the throttle the CSD temperature decreased below the caution range. At this time everything was in the normal range. But, I decided it would be best to return to cvg and did so with no further abnormals. The mechanics found a hole in the 13TH stage anti-ice duct between the engine and the anti-ice shutoff valve. Evidently this hole had been increasing in size over several flts. Possibly a sensor could be placed near these unprotected and uncontrollable anti-ice ducts to sense a leak before it can cause a major problem.

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Original NASA ASRS Text

Title: IRREGULAR READINGS ON #2 ENGINE OF LGT CAUSED FLT CREW TO RETURN LAND AT DEP ARPT.

Narrative: THE ACFT HAD A HISTORY OF THE #2 ENGINE EPR GAUGE AS BEING INACCURATE. ALSO, THE #2 ENGINE EGT HAD A HISTORY OF BEING HIGHER THAN NORMAL, BUT STILL OPERATED WITHIN NORMAL LIMITS. ALL LOGBOOK DISCREPANCIES HAD BEEN CLRED BY MAINT (THEY REPLACED GAUGES AND XMITTERS). WHEN WE APPLIED POWER FOR TKOF, ENGINE #2 EPR APPEARED TO STILL BE INACCURATE. WE SET #2 ENGINE POWER USING N-1. ALL ENGINE INSTRUMENTS WERE IN THE NORMAL RANGE (EXCEPT #2 EPR, WHICH APPEARED TO BE INACCURATE). THE FLT THRU ACFT CLEAN-UP WAS NORMAL. WHEN WE SET CLIMB POWER, ENGINE #2 N-1 WAS LOWER AND N2 WAS HIGHER THAN ENGINES 1 AND 3 WHEN EGT AND FUEL FLOW WERE EVENED UP. AT 10,000' THE S/O NOTED ENGINE #2 CSD 'IN' TEMPERATURE WAS IN THE CAUTION RANGE (ABOUT HALFWAY). I HAD THE S/O GO THRU THE ABNORMAL. WHEN I RETARDED THE THROTTLE THE CSD TEMPERATURE DECREASED BELOW THE CAUTION RANGE. AT THIS TIME EVERYTHING WAS IN THE NORMAL RANGE. BUT, I DECIDED IT WOULD BE BEST TO RETURN TO CVG AND DID SO WITH NO FURTHER ABNORMALS. THE MECHANICS FOUND A HOLE IN THE 13TH STAGE ANTI-ICE DUCT BETWEEN THE ENGINE AND THE ANTI-ICE SHUTOFF VALVE. EVIDENTLY THIS HOLE HAD BEEN INCREASING IN SIZE OVER SEVERAL FLTS. POSSIBLY A SENSOR COULD BE PLACED NEAR THESE UNPROTECTED AND UNCONTROLLABLE ANTI-ICE DUCTS TO SENSE A LEAK BEFORE IT CAN CAUSE A MAJOR PROBLEM.

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.