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A B737's number two engine N1 gauge and egt gauge alternately indicated full scale high with red lights; but the engine operation remained normal.
| Attributes | |
| ACN | 957981 |
| Time | |
| Date | 201107 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | RPM/N1/N2/Etc Indication |
| Person 1 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
After leveling at our cruise altitude of 32;000 ft we observed the #2 engine N1 gauge go to full scale high RPM and the red light illuminate. All other engine parameters were normal. The N1 indication did not respond to throttle movement. After approximately 20 seconds the N1 gauge returned to normal. After about 5 minutes the #2 engine egt gauge did the same thing. Tapping the gauge had the most effect on the indication. After this second occurrence; which we determined was most likely an indication error; we had no further problems with the indications until on final approach. On final approach; once again the egt gauge went to full scale high and the digital display went blank. I pulled the #2 engine throttle to idle and treated it as a single engine approach and landing. Prior to landing; the #2 egt returned to normal. Apparently there was a defective system in the #2 engine that reported certain parameters. The aircraft was repaired and returned to service approximately 24 hours later.
Original NASA ASRS Text
Title: A B737's number two engine N1 gauge and EGT gauge alternately indicated full scale high with red lights; but the engine operation remained normal.
Narrative: After leveling at our cruise altitude of 32;000 FT we observed the #2 engine N1 gauge go to full scale high RPM and the red light illuminate. All other engine parameters were normal. The N1 indication did not respond to throttle movement. After approximately 20 seconds the N1 gauge returned to normal. After about 5 minutes the #2 engine EGT gauge did the same thing. Tapping the gauge had the most effect on the indication. After this second occurrence; which we determined was most likely an indication error; we had no further problems with the indications until on final approach. On final approach; once again the EGT gauge went to full scale high and the digital display went blank. I pulled the #2 engine throttle to idle and treated it as a single engine approach and landing. Prior to landing; the #2 EGT returned to normal. Apparently there was a defective system in the #2 engine that reported certain parameters. The aircraft was repaired and returned to service approximately 24 hours later.
Data retrieved from NASA's ASRS site as of April 2012 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.