 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
A B737-400 flight crew diverted after the cause of multiple large fuel imbalances could not be determined and destination weather would prevent continuous crew monitoring of the fuel system.
| Attributes | |
| ACN | 986796 |
| Time | |
| Date | 201112 |
| Local Time Of Day | 0001-0600 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Aircraft 1 | |
| Make Model Name | B737-400 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Initial Climb |
| Flight Plan | IFR |
| Person 1 | |
| Function | First Officer |
| Person 2 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Inflight Event / Encounter Fuel Issue |
Narrative:
During climbout; at about 15;000 ft; the captain noticed that there was an 800 pounds imbalance between the left and right main tanks (left heavy). He called it out; and announced that he would wait to balance until the aircraft was in cruise; straight and level (aircraft was in a right turn; climbing). Within a few minutes; he announced that the imbalance had increased to 1;100 pounds; and that he was going to crossfeed to correct. Cross feeding was used to return the two tanks to within about 100 pounds of each other. This series of events was repeated twice more (once as we neared cruise altitude; and once in cruise). As the third event was occurring; we began attempting to contact maintenance control; but were in a dead zone and couldn't reach them for several minutes. At that time; the main tanks had been balanced and seemed to be holding even; however; we were concerned by the rapidity with which the imbalances were occurring (500 plus pounds within 10 minutes) and by the weather at destination (less than 1/8 SM with fog). Specifically; what if a significant imbalance occurred with lesser amounts of fuel in the mains; during a go-around or a divert if the weather went below minimums? After contact was made with maintenance control; the captain informed maintenance control and dispatch of his intent to divert to sort the problem out on the ground; with which they concurred. We received an amended release to the divert airport; informed ATC; received a clearance and proceeded to the airport where we conducted an overweight landing; with a sink rate of 250 FPM. Aircraft main tank fuel was not being consumed in an appropriate manner. Right wing tank appeared to be being consumed faster than left tank; although total consumption was normal. Cause unknown; but suspected to be a fuel system check valve.
Original NASA ASRS Text
Title: A B737-400 flight crew diverted after the cause of multiple large fuel imbalances could not be determined and destination weather would prevent continuous crew monitoring of the fuel system.
Narrative: During climbout; at about 15;000 FT; the Captain noticed that there was an 800 LBS imbalance between the left and right main tanks (left heavy). He called it out; and announced that he would wait to balance until the aircraft was in cruise; straight and level (aircraft was in a right turn; climbing). Within a few minutes; he announced that the imbalance had increased to 1;100 LBS; and that he was going to crossfeed to correct. Cross feeding was used to return the two tanks to within about 100 LBS of each other. This series of events was repeated twice more (once as we neared cruise altitude; and once in cruise). As the third event was occurring; we began attempting to contact Maintenance Control; but were in a dead zone and couldn't reach them for several minutes. At that time; the main tanks had been balanced and seemed to be holding even; however; we were concerned by the rapidity with which the imbalances were occurring (500 plus LBS within 10 minutes) and by the weather at destination (less than 1/8 SM with fog). Specifically; what if a significant imbalance occurred with lesser amounts of fuel in the mains; during a go-around or a divert if the weather went below minimums? After contact was made with Maintenance Control; the Captain informed Maintenance Control and Dispatch of his intent to divert to sort the problem out on the ground; with which they concurred. We received an amended release to the divert airport; informed ATC; received a clearance and proceeded to the airport where we conducted an overweight landing; with a sink rate of 250 FPM. Aircraft main tank fuel was not being consumed in an appropriate manner. Right wing tank appeared to be being consumed faster than left tank; although total consumption was normal. Cause unknown; but suspected to be a fuel system check valve.
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.