Narrative:

This is a clear case of a mechanical malfunction. Conditions at time of departure: very cool temperature; near sea level and a very light aircraft. On departure; our initial rate of climb was 4000 FPM. As I lowered the pitch and reduced power to level at our assigned altitude of 3000 ft; I noticed that my attempt to trim the pitch nose down had no effect. I soon had the control yoke at the full forward mechanical limit with the power reduced as much as practical and was still climbing. I instructed the copilot to trim nose down from his side and that; too; was unsuccessful. I then had the copilot go to emergency trim. By the time we were able to regain trim control and thus level the aircraft; we had climbed 800 ft above our assigned altitude. As a professional pilot; it is truly disappointing not to comply with a clearance -- no matter the reason. I can assure you that I made every reasonable effort to level the aircraft at 3000 ft. As stated; this was a mechanical issue. I'm not sure there is anything that can be done to prevent a recurrence. The aircraft trim system continues to test normal. Callback conversation with reporter revealed the following information: the reporter stated the control horn trim switch serves 2 purposes: 1) functions as a pitch trim switch; and 2) functions as an aileron trim control. The reporter stated the switch can be moved up; down; left; and right to perform the trim functions. To date; maintenance has not been able to duplicate the report; but suspect the switches. The reporter indicated this trim system has no manual backup -- only electric functions.

Google
 

Original NASA ASRS Text

Title: A B400A IN TKOF CLB WAS UNABLE TO TRIM NOSE DOWN TO 3000 FT ASSIGNED ALT. TRIM FAILED FROM BOTH CTL COLUMN TRIM SWITCHES.

Narrative: THIS IS A CLR CASE OF A MECHANICAL MALFUNCTION. CONDITIONS AT TIME OF DEP: VERY COOL TEMP; NEAR SEA LEVEL AND A VERY LIGHT ACFT. ON DEP; OUR INITIAL RATE OF CLB WAS 4000 FPM. AS I LOWERED THE PITCH AND REDUCED PWR TO LEVEL AT OUR ASSIGNED ALT OF 3000 FT; I NOTICED THAT MY ATTEMPT TO TRIM THE PITCH NOSE DOWN HAD NO EFFECT. I SOON HAD THE CTL YOKE AT THE FULL FORWARD MECHANICAL LIMIT WITH THE PWR REDUCED AS MUCH AS PRACTICAL AND WAS STILL CLBING. I INSTRUCTED THE COPLT TO TRIM NOSE DOWN FROM HIS SIDE AND THAT; TOO; WAS UNSUCCESSFUL. I THEN HAD THE COPLT GO TO EMER TRIM. BY THE TIME WE WERE ABLE TO REGAIN TRIM CTL AND THUS LEVEL THE ACFT; WE HAD CLBED 800 FT ABOVE OUR ASSIGNED ALT. AS A PROFESSIONAL PLT; IT IS TRULY DISAPPOINTING NOT TO COMPLY WITH A CLRNC -- NO MATTER THE REASON. I CAN ASSURE YOU THAT I MADE EVERY REASONABLE EFFORT TO LEVEL THE ACFT AT 3000 FT. AS STATED; THIS WAS A MECHANICAL ISSUE. I'M NOT SURE THERE IS ANYTHING THAT CAN BE DONE TO PREVENT A RECURRENCE. THE ACFT TRIM SYS CONTINUES TO TEST NORMAL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE CTL HORN TRIM SWITCH SERVES 2 PURPOSES: 1) FUNCTIONS AS A PITCH TRIM SWITCH; AND 2) FUNCTIONS AS AN AILERON TRIM CTL. THE RPTR STATED THE SWITCH CAN BE MOVED UP; DOWN; L; AND R TO PERFORM THE TRIM FUNCTIONS. TO DATE; MAINT HAS NOT BEEN ABLE TO DUPLICATE THE RPT; BUT SUSPECT THE SWITCHES. THE RPTR INDICATED THIS TRIM SYS HAS NO MANUAL BACKUP -- ONLY ELECTRIC FUNCTIONS.

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.