A B767-300ER was reported by the first officer as not passing a stabilizer trim preflight test that ...

Attributes
ACN	727826
Time
Date	200702
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B767-300 and 300 ER
Operating Under FAR Part	Part 121
Flight Phase	ground : parked ground : preflight
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	727826
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	aircraft equipment other aircraft equipment : stabilizer brake speeds other flight crewa
Consequence	other
Supplementary
Problem Areas	Flight Crew Human Performance Maintenance Human Performance Chart Or Publication
Primary Problem	Chart Or Publication

Narrative:

At one time our preflight checklist provided for checking the stabilizer trim brake. This check involved turning on the hydraulic pumps; running the stabilizer trim; and then moving the yoke in opposite direction of trim input; which operated the stabilizer trim brake; thereby stopping the trim movement. This item was removed from our preflight checklists; and is not described in our operations manual. I still do these checks anyway; and believe that 1 stabilizer trim brake is inoperative on ship. When the trim is run up; and yoke pushed forward; the trim stops. However; when running nose down trim; and then pulling back on the yoke; the trim does not stop. Since this check is no longer part of our checklists; and no information about it is provided in our operations manual; and since the trim did slow noticeably; although not stopping completely; the captain did not write it up; believing no discrepancy existed. A mechanic was questioned about it; but he was not knowledgeable about this system; and left it up to the discretion of the captain as to whether it needed maintenance action. I just learned about another pilot's experience with an aircraft that involved some erratic flight control inputs due to a pressure switch problem and the stabilizer trim brake; and believe this preflight check should be placed back in the checklist.

Original NASA ASRS Text

Title: A B767-300ER WAS RPTED BY THE FO AS NOT PASSING A STABILIZER TRIM PREFLT TEST THAT IS NOW DELETED FROM THE PREFLT COCKPIT CHK PROCS.

Narrative: AT ONE TIME OUR PREFLT CHKLIST PROVIDED FOR CHKING THE STABILIZER TRIM BRAKE. THIS CHK INVOLVED TURNING ON THE HYD PUMPS; RUNNING THE STABILIZER TRIM; AND THEN MOVING THE YOKE IN OPPOSITE DIRECTION OF TRIM INPUT; WHICH OPERATED THE STABILIZER TRIM BRAKE; THEREBY STOPPING THE TRIM MOVEMENT. THIS ITEM WAS REMOVED FROM OUR PREFLT CHKLISTS; AND IS NOT DESCRIBED IN OUR OPS MANUAL. I STILL DO THESE CHKS ANYWAY; AND BELIEVE THAT 1 STABILIZER TRIM BRAKE IS INOP ON SHIP. WHEN THE TRIM IS RUN UP; AND YOKE PUSHED FORWARD; THE TRIM STOPS. HOWEVER; WHEN RUNNING NOSE DOWN TRIM; AND THEN PULLING BACK ON THE YOKE; THE TRIM DOES NOT STOP. SINCE THIS CHK IS NO LONGER PART OF OUR CHKLISTS; AND NO INFO ABOUT IT IS PROVIDED IN OUR OPS MANUAL; AND SINCE THE TRIM DID SLOW NOTICEABLY; ALTHOUGH NOT STOPPING COMPLETELY; THE CAPT DID NOT WRITE IT UP; BELIEVING NO DISCREPANCY EXISTED. A MECH WAS QUESTIONED ABOUT IT; BUT HE WAS NOT KNOWLEDGEABLE ABOUT THIS SYS; AND LEFT IT UP TO THE DISCRETION OF THE CAPT AS TO WHETHER IT NEEDED MAINT ACTION. I JUST LEARNED ABOUT ANOTHER PLT'S EXPERIENCE WITH AN ACFT THAT INVOLVED SOME ERRATIC FLT CTL INPUTS DUE TO A PRESSURE SWITCH PROB AND THE STABILIZER TRIM BRAKE; AND BELIEVE THIS PREFLT CHK SHOULD BE PLACED BACK IN THE CHKLIST.

Data retrieved from NASA's ASRS site as of January 2009 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.

A B767-300ER was reported by the first officer as not passing a stabilizer trim preflight test that is now deleted from the preflight cockpit check procedures.