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Flight crew of an medium large transport air carrier aircraft returned to land after not being able to prevent aircraft yaw during climb.
| Attributes | |
| ACN | 253828 |
| Time | |
| Date | 199310 |
| Day | Mon |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : bos |
| State Reference | MA |
| Altitude | msl bound lower : 1000 msl bound upper : 10000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : bos |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | climbout : intermediate altitude |
| Route In Use | enroute airway : bos |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : instrument pilot : commercial pilot : atp pilot : cfi |
| Experience | flight time last 90 days : 180 flight time total : 12300 flight time type : 2500 |
| ASRS Report | 253828 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| Events | |
| Anomaly | aircraft equipment problem : critical other anomaly other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
Aircraft began uncommanded yaw left and right at about 1000 ft AGL. First suspected engine failure/surge but all indications normal. Flight was normal for a few mins, but then began again and art (automatic reserve thrust), in the event of engine failure, fired but there still was no engine failure. Yaw continued intermittently and crew declared emergency to ATC and was cleared direct back to bos. Manual rudder and yaw damper off were selected, but oscillation continued. Yaw damper to 'override' also did not help. Landing was normal and also the return to the gate at bos was normal. Maintenance found the dual, 3 axis accelerometer was defective and changed it out. Aircraft was redispatched to ewr and subsequent flight was normal.
Original NASA ASRS Text
Title: FLC OF AN MLG ACR ACFT RETURNED TO LAND AFTER NOT BEING ABLE TO PREVENT ACFT YAW DURING CLB.
Narrative: ACFT BEGAN UNCOMMANDED YAW L AND R AT ABOUT 1000 FT AGL. FIRST SUSPECTED ENG FAILURE/SURGE BUT ALL INDICATIONS NORMAL. FLT WAS NORMAL FOR A FEW MINS, BUT THEN BEGAN AGAIN AND ART (AUTOMATIC RESERVE THRUST), IN THE EVENT OF ENG FAILURE, FIRED BUT THERE STILL WAS NO ENG FAILURE. YAW CONTINUED INTERMITTENTLY AND CREW DECLARED EMER TO ATC AND WAS CLRED DIRECT BACK TO BOS. MANUAL RUDDER AND YAW DAMPER OFF WERE SELECTED, BUT OSCILLATION CONTINUED. YAW DAMPER TO 'OVERRIDE' ALSO DID NOT HELP. LNDG WAS NORMAL AND ALSO THE RETURN TO THE GATE AT BOS WAS NORMAL. MAINT FOUND THE DUAL, 3 AXIS ACCELEROMETER WAS DEFECTIVE AND CHANGED IT OUT. ACFT WAS REDISPATCHED TO EWR AND SUBSEQUENT FLT WAS NORMAL.
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.