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.
Synopsis
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.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.