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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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2 engines on an air carrier widebody transport began to surge after nacelle heat was turned on. Airspeed decreased and when unable to maintain altitude the aircraft was turned off course until power stabilized. Nacelle ice was the problem.
| Attributes | |
| ACN | 187451 |
| Time | |
| Date | 199108 |
| Day | Thu |
| Local Time Of Day | 0001 To 0600 |
| Place | |
| Locale Reference | atc facility : nrt |
| State Reference | FO |
| Altitude | msl bound lower : 36500 msl bound upper : 37000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : rjtg |
| Operator | common carrier : air carrier |
| Make Model Name | Widebody, Low Wing, 4 Turbojet Eng |
| Navigation In Use | Other |
| Flight Phase | cruise other |
| Route In Use | enroute : other oceanic enroute : pacific |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : second officer |
| Qualification | pilot : flight engineer pilot : instrument pilot : atp |
| Experience | flight time last 90 days : 210 flight time total : 5000 flight time type : 800 |
| ASRS Report | 187451 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude other spatial deviation |
| Independent Detector | other flight crewa |
| Resolutory Action | aircraft : equipment problem dissipated flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | other |
Narrative:
In an area of scattered thunderstorms we entered an area of warm air and our static air temperature rose from -46 degree to -33 degree. We turned on our engine nacelle anti-ice and the power on engines #2 and #3 began to fluctuate. N1 and N2 RPM began to decrease while egt remained normal. Unable to maintain altitude and airspeed we turned off track and began a descent. Within 30 seconds engine operation returned to normal and we resumed course and altitude. We were only a few mi off course and had only lost 500 ft. The sudden increase in temperature led to ice forming on the engines which caused our power fluctuations.
Original NASA ASRS Text
Title: 2 ENGS ON AN ACR WDB BEGAN TO SURGE AFTER NACELLE HEAT WAS TURNED ON. AIRSPD DECREASED AND WHEN UNABLE TO MAINTAIN ALT THE ACFT WAS TURNED OFF COURSE UNTIL PWR STABILIZED. NACELLE ICE WAS THE PROBLEM.
Narrative: IN AN AREA OF SCATTERED TSTMS WE ENTERED AN AREA OF WARM AIR AND OUR STATIC AIR TEMP ROSE FROM -46 DEG TO -33 DEG. WE TURNED ON OUR ENG NACELLE ANTI-ICE AND THE PWR ON ENGS #2 AND #3 BEGAN TO FLUCTUATE. N1 AND N2 RPM BEGAN TO DECREASE WHILE EGT REMAINED NORMAL. UNABLE TO MAINTAIN ALT AND AIRSPD WE TURNED OFF TRACK AND BEGAN A DSCNT. WITHIN 30 SECONDS ENG OP RETURNED TO NORMAL AND WE RESUMED COURSE AND ALT. WE WERE ONLY A FEW MI OFF COURSE AND HAD ONLY LOST 500 FT. THE SUDDEN INCREASE IN TEMP LED TO ICE FORMING ON THE ENGS WHICH CAUSED OUR PWR FLUCTUATIONS.
Data retrieved from NASA's ASRS site as of July 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.