GLF5 rejects takeoff due to configuration warning caused by stabilizer trim out of limits.

Attributes
ACN	764624
Time
Date	200712
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air taxi
Make Model Name	Gulfstream V
Operating Under FAR Part	Part 135
Flight Phase	ground : takeoff roll
Flight Plan	IFR
Person 1
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : atp
Experience	flight time last 90 days : 92 flight time total : 15200 flight time type : 800
ASRS Report	764624
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	aircraft equipment other aircraft equipment : tkof warning horn
Resolutory Action	flight crew : rejected takeoff
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

The gv has a known history of horizontal 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 takeoff. During the initial takeoff roll; the trim changed from 8.0 to 7.5 which caused the 'aircraft confign' red cas message. This caused us to abort the takeoff at 75-80 KTS. Gulfstream needs to fix this. This has been a known problem for some time. Pilots should be cautioned never to set the elevator trim within 1/2 (or 1) unit of the takeoff limits due to this tri 'creep' to avoid unnecessary aborts. Callback conversation with reporter revealed the following information: reporter advised the trim creep phenomenon is known to the manufacturer and is the subject of pilot 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 airport surface and/or the environment -- a form of hysteresis.

Original NASA ASRS Text

Title: 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.

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.