 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
An MD80 captain aborts his takeoff when the aircraft confign warning horn alerts him to a stabilizer that is out of tolerance for the takeoff trim setting. Bos, ma.
| Attributes | |
| ACN | 464057 |
| Time | |
| Date | 200002 |
| Day | Sat |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : bos.airport |
| State Reference | MA |
| Altitude | agl single value : 0 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | MD-80 Series (DC-9-80) Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | ground : takeoff roll |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 70 flight time total : 14200 flight time type : 150 |
| ASRS Report | 464057 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : multi engine pilot : instrument pilot : commercial |
| Events | |
| Anomaly | aircraft equipment problem : critical other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : takeoff configuration warning |
| Resolutory Action | flight crew : overcame equipment problem flight crew : rejected takeoff other |
| Factors | |
| Maintenance | performance deficiency : inspection performance deficiency : scheduled maintenance |
| Supplementary | |
| Problem Areas | Maintenance Human Performance Aircraft Company Flight Crew Human Performance |
| Primary Problem | Aircraft |
Narrative:
Aborted takeoff. Started normal takeoff on runway 22R in bos. Passing 100 KIAS the takeoff configuration warning horn sounded and the 'CAWS' (computer aural warning system) called 'stabilizer.' the takeoff was aborted and upon clearing the runway the brake cooling chart was consulted. No wait time was required so we reset the stabilizer position and taxied back for a normal takeoff. This aircraft type has a history of this type of incident. The stabilizer appears to be set correctly but is right on the edge. During acceleration the stabilizer indicating system may move due to vibration allowing an unsafe warning to be generated. The entire takeoff warning horn/CAWS system is tested prior to each takeoff, but if the setting is close to the limit if will not sound, ie: test 'ok,' in a static situation but announce an unsafe condition under acceleration and vibration. Callback conversation with reporter revealed the following information: 1) what was the stabilizer trim setting as to the proximity of the green edge? 2) any problems with the trim motors on the flight? 3) any automatic pilot disconnects or problems? 4) any master caution or excitation lights? 5) what was the maintenance sign off, if any? 6) was the problem entered into the logbook? Reporter called back and answered the preceding questions. 1) there is little room for error, about 1 inch of trim setting on the MD80 moveable C.G. Band when setting the flap gate. 11 degrees is standard. There is a certain amount of '...gear flop...' in the system. Captain stated that although he had referred to 'vibration' as a possible cause of movement within the trim range, he could not rule out a possibility that air loads on the takeoff roll could do the same thing, as a shift of the stabilizer itself. His answer to all the other questions was 'no,' not having entered the incident in the log book (known as an MD80 problem within the fleet). Maintenance did not know of this event.
Original NASA ASRS Text
Title: AN MD80 CAPT ABORTS HIS TKOF WHEN THE ACFT CONFIGN WARNING HORN ALERTS HIM TO A STABILIZER THAT IS OUT OF TOLERANCE FOR THE TKOF TRIM SETTING. BOS, MA.
Narrative: ABORTED TKOF. STARTED NORMAL TKOF ON RWY 22R IN BOS. PASSING 100 KIAS THE TKOF CONFIGURATION WARNING HORN SOUNDED AND THE 'CAWS' (COMPUTER AURAL WARNING SYS) CALLED 'STABILIZER.' THE TKOF WAS ABORTED AND UPON CLRING THE RWY THE BRAKE COOLING CHART WAS CONSULTED. NO WAIT TIME WAS REQUIRED SO WE RESET THE STABILIZER POS AND TAXIED BACK FOR A NORMAL TKOF. THIS ACFT TYPE HAS A HISTORY OF THIS TYPE OF INCIDENT. THE STABILIZER APPEARS TO BE SET CORRECTLY BUT IS RIGHT ON THE EDGE. DURING ACCELERATION THE STABILIZER INDICATING SYS MAY MOVE DUE TO VIBRATION ALLOWING AN UNSAFE WARNING TO BE GENERATED. THE ENTIRE TKOF WARNING HORN/CAWS SYS IS TESTED PRIOR TO EACH TKOF, BUT IF THE SETTING IS CLOSE TO THE LIMIT IF WILL NOT SOUND, IE: TEST 'OK,' IN A STATIC SIT BUT ANNOUNCE AN UNSAFE CONDITION UNDER ACCELERATION AND VIBRATION. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: 1) WHAT WAS THE STABILIZER TRIM SETTING AS TO THE PROX OF THE GREEN EDGE? 2) ANY PROBS WITH THE TRIM MOTORS ON THE FLT? 3) ANY AUTO PLT DISCONNECTS OR PROBS? 4) ANY MASTER CAUTION OR EXCITATION LIGHTS? 5) WHAT WAS THE MAINT SIGN OFF, IF ANY? 6) WAS THE PROB ENTERED INTO THE LOGBOOK? RPTR CALLED BACK AND ANSWERED THE PRECEDING QUESTIONS. 1) THERE IS LITTLE ROOM FOR ERROR, ABOUT 1 INCH OF TRIM SETTING ON THE MD80 MOVEABLE C.G. BAND WHEN SETTING THE FLAP GATE. 11 DEGS IS STANDARD. THERE IS A CERTAIN AMOUNT OF '...GEAR FLOP...' IN THE SYS. CAPT STATED THAT ALTHOUGH HE HAD REFERRED TO 'VIBRATION' AS A POSSIBLE CAUSE OF MOVEMENT WITHIN THE TRIM RANGE, HE COULD NOT RULE OUT A POSSIBILITY THAT AIR LOADS ON THE TKOF ROLL COULD DO THE SAME THING, AS A SHIFT OF THE STABILIZER ITSELF. HIS ANSWER TO ALL THE OTHER QUESTIONS WAS 'NO,' NOT HAVING ENTERED THE INCIDENT IN THE LOG BOOK (KNOWN AS AN MD80 PROB WITHIN THE FLEET). MAINT DID NOT KNOW OF THIS EVENT.
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.