GLF5 REJECTS TKOF DUE TO CONFIGURATION WARNING CAUSED BY STAB TRIM OUT OF LIMITS.

Narrative

THE GV HAS A KNOWN HISTORY OF HORIZ TRIM 'CREEP.' THE TRIM MAY DRIFT DUE TO ELECTRICAL NOISE. THE TRIM SETTING WILL ALSO CHANGE SLIGHTLY WHEN THE ELEVATOR IS MOVED. MY TRIM SETTING WAS 8.0 WHICH IS ON THE VERY LIMIT OF ALLOWABLE SETTINGS FOR TKOF. DURING THE INITIAL TKOF ROLL; THE TRIM CHANGED FROM 8.0 TO 7.5 WHICH CAUSED THE 'ACFT CONFIGN' RED CAS MESSAGE. THIS CAUSED US TO ABORT THE TKOF AT 75-80 KTS. GULFSTREAM NEEDS TO FIX THIS. THIS HAS BEEN A KNOWN PROB FOR SOME TIME. PLTS SHOULD BE CAUTIONED NEVER TO SET THE ELEVATOR TRIM WITHIN 1/2 (OR 1) UNIT OF THE TKOF LIMITS DUE TO THIS TRI 'CREEP' TO AVOID UNNECESSARY ABORTS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER ADVISED THE TRIM CREEP PHENOMENON IS KNOWN TO THE MANUFACTURER AND IS THE SUBJECT OF PLT ADVISORIES THROUGH THEIR WEBSITE. HE FURTHER NOTED THE READOUT BY WHICH THE TRIM IS SET IS DIGITAL IN NATURE AND ONLY DISPLAYS TRIM SETTINGS IN HALF UNIT INCREMENTS; SUGGESTING THAT A READOUT OF 8.0 MIGHT BE ONLY FRACTIONALLY REMOVED FROM THE 8.5 READOUT THAT WOULD TRIGGER THE WARNING. HE SUGGESTED THAT; POTENTIALLY; MANUFACTURING TOLERANCES IN THE SYSTEM COULD COMBINE TO PUSH THE SETTING TO THE WARNING LEVEL AS FORCES ON THE AIRFRAME ARE ALTERED BY THE ARPT SURFACE AND/OR THE ENVIRONMENT -- A FORM OF HYSTERESIS.