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A B737-700's engines accumulated fan blade ice during taxi and extended hold for RVR improvement in dense fog and freezing temperatures.
| Attributes | |
| ACN | 636478 |
| Time | |
| Date | 200411 |
| Day | Fri |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : geg.airport |
| State Reference | WA |
| Altitude | agl single value : 0 |
| Environment | |
| Flight Conditions | IMC |
| Weather Elements | Ice Fog |
| Aircraft 1 | |
| Controlling Facilities | tower : vps.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | ground : holding |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| ASRS Report | 636478 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| ASRS Report | 636486 |
| Events | |
| Anomaly | aircraft equipment problem : critical inflight encounter : weather other anomaly other |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | other |
| Consequence | Other |
| Supplementary | |
| Problem Areas | Weather |
| Primary Problem | Weather |
Narrative:
Prior to pushback preflight indicated need for deciding due frost. Temperature was -1 degree C dew point -1 degree C. Visibility was initially reported as 1/4 mi. After deicing and during taxi to runway 3, visibility dropped to 600-800 ft RVR. Tower cleared us into position and hold on runway 3 and said 'RVR 600 ft.' further inquiry revealed mid RVR to be 500 ft. Now cleared into position and hold while waiting for RVR to improve. Holdover time of approximately 17 mins was now exceeded. I (first officer) went back to perform contamination check. No contamination. Shortly after I was again seated, we both noticed a slight vibration. All engine parameters appeared normal. Captain started to run up engines for clearing procedure and thought better of it at approximately 40% N1. Captain and I discussed it further and decided to return to gate suspecting fan blade icing. After returning to gate inspection showed 1/4 to 3/8 inch of ice on both fan and stator as well as considerable build up of ice on the back of fan blades. Contacted maintenance control and dispatch. Mechanics heated the engines with conditioned air units and after another deicing of the airframe we departed with no further problems.
Original NASA ASRS Text
Title: A B737-700'S ENGS ACCUMULATED FAN BLADE ICE DURING TAXI AND EXTENDED HOLD FOR RVR IMPROVEMENT IN DENSE FOG AND FREEZING TEMPS.
Narrative: PRIOR TO PUSHBACK PREFLT INDICATED NEED FOR DECIDING DUE FROST. TEMP WAS -1 DEG C DEW POINT -1 DEG C. VISIBILITY WAS INITIALLY RPTED AS 1/4 MI. AFTER DEICING AND DURING TAXI TO RWY 3, VISIBILITY DROPPED TO 600-800 FT RVR. TWR CLRED US INTO POS AND HOLD ON RWY 3 AND SAID 'RVR 600 FT.' FURTHER INQUIRY REVEALED MID RVR TO BE 500 FT. NOW CLRED INTO POS AND HOLD WHILE WAITING FOR RVR TO IMPROVE. HOLDOVER TIME OF APPROX 17 MINS WAS NOW EXCEEDED. I (FO) WENT BACK TO PERFORM CONTAMINATION CHK. NO CONTAMINATION. SHORTLY AFTER I WAS AGAIN SEATED, WE BOTH NOTICED A SLIGHT VIBRATION. ALL ENG PARAMETERS APPEARED NORMAL. CAPT STARTED TO RUN UP ENGS FOR CLRING PROC AND THOUGHT BETTER OF IT AT APPROX 40% N1. CAPT AND I DISCUSSED IT FURTHER AND DECIDED TO RETURN TO GATE SUSPECTING FAN BLADE ICING. AFTER RETURNING TO GATE INSPECTION SHOWED 1/4 TO 3/8 INCH OF ICE ON BOTH FAN AND STATOR AS WELL AS CONSIDERABLE BUILD UP OF ICE ON THE BACK OF FAN BLADES. CONTACTED MAINT CTL AND DISPATCH. MECHS HEATED THE ENGS WITH CONDITIONED AIR UNITS AND AFTER ANOTHER DEICING OF THE AIRFRAME WE DEPARTED WITH NO FURTHER PROBS.
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.