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B737-200 aircraft when starting engine the 'a' system hydraulic pump was inadvertently left on resulting in the system pressurizing as aircraft was being pushed. The pressurized system resulted in breaking the tow bar.
| Attributes | |
| ACN | 388870 |
| Time | |
| Date | 199712 |
| Day | Thu |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : hnl |
| State Reference | HI |
| Altitude | agl bound lower : 0 agl bound upper : 0 |
| Environment | |
| Flight Conditions | VMC |
| Light | Dusk |
| Aircraft 1 | |
| Controlling Facilities | tower : sea |
| Operator | common carrier : air carrier |
| Make Model Name | B737-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | ground : preflight |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 10500 flight time type : 8000 |
| ASRS Report | 388870 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| Events | |
| Anomaly | aircraft equipment problem : critical non adherence : published procedure other anomaly other |
| Independent Detector | other flight crewa other other : unspecified |
| Resolutory Action | none taken : detected after the fact |
| Consequence | other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
The before start through flight checklist was completed through the pushback line. During pushback, and starting engine #2, the 'a' hydraulic system pressurized the nose gear breaking the tow bar connection. There was a series of 3 or 4 loud bang noises and lurching at which time I applied the brakes and the aircraft stopped. 1 flight attendant was thrown to the floor but was not injured and continued later on a new aircraft. Although we did the checklist we failed to turn off the 'a' system hydraulic pumps to depressurize the nose gear for pushback. The company does not have nose gear lockout valves installed like most carriers do. The tug pushed the tow bar under the nose gear strut after it broke off and slightly damaged the nose gear hydraulic servicing valve causing a hydraulic leak. Corrective action: scan panel during checklist to ensure switch position. Company install nose gear lockout devices to guard against this situation happening again.
Original NASA ASRS Text
Title: B737-200 ACFT WHEN STARTING ENG THE 'A' SYS HYD PUMP WAS INADVERTENTLY LEFT ON RESULTING IN THE SYS PRESSURIZING AS ACFT WAS BEING PUSHED. THE PRESSURIZED SYS RESULTED IN BREAKING THE TOW BAR.
Narrative: THE BEFORE START THROUGH FLT CHKLIST WAS COMPLETED THROUGH THE PUSHBACK LINE. DURING PUSHBACK, AND STARTING ENG #2, THE 'A' HYD SYS PRESSURIZED THE NOSE GEAR BREAKING THE TOW BAR CONNECTION. THERE WAS A SERIES OF 3 OR 4 LOUD BANG NOISES AND LURCHING AT WHICH TIME I APPLIED THE BRAKES AND THE ACFT STOPPED. 1 FLT ATTENDANT WAS THROWN TO THE FLOOR BUT WAS NOT INJURED AND CONTINUED LATER ON A NEW ACFT. ALTHOUGH WE DID THE CHKLIST WE FAILED TO TURN OFF THE 'A' SYS HYD PUMPS TO DEPRESSURIZE THE NOSE GEAR FOR PUSHBACK. THE COMPANY DOES NOT HAVE NOSE GEAR LOCKOUT VALVES INSTALLED LIKE MOST CARRIERS DO. THE TUG PUSHED THE TOW BAR UNDER THE NOSE GEAR STRUT AFTER IT BROKE OFF AND SLIGHTLY DAMAGED THE NOSE GEAR HYD SVCING VALVE CAUSING A HYD LEAK. CORRECTIVE ACTION: SCAN PANEL DURING CHKLIST TO ENSURE SWITCH POS. COMPANY INSTALL NOSE GEAR LOCKOUT DEVICES TO GUARD AGAINST THIS SIT HAPPENING AGAIN.
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.