Date: 201401
Local time of day: 0001-0600
Location: TEB.Airport, NJ
Flight conditions: IMC
Weather elements / visibility: Snow; 2
Light: Daylight
Aircraft: Learjet 60
Operator: Air Taxi
Operating under: Part 135
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Climb
Airspace: Class C TEB
ATC / advisory: TRACON N90
Aircraft component: Elevator Trim System
Component problem: Design; Malfunctioning
Reporter organization: Air Taxi
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Confusion; Human-Machine Interface; Troubleshooting; Communication Breakdown
Anomaly: Aircraft Equipment Problem Critical; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Detector: Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance; Flight Crew Overcame Equipment Problem
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: Upon departure from Runway 24 at TEB via the RUUDY FOUR departure; I began trimming nose down which is required after gear and flaps are retracted. I noticed as I commanded nose down trim that the control forces were not decreasing but instead increasing in a nose up direction. As we approached 1;500 FT; which is the initial level off altitude; I was having difficulty arresting the climb; but using brute force managed to level the aircraft. I announced to the First Officer I was having trim problems but he was reading the after Takeoff Checklist and made no comment. In my peripheral vision I could tell there was an amber light flashing on the annunciator panel. I took my eyes off the flight instruments to notice it was the 'pitch trim' warning light. When I looked back at the altimeter it was at 1;600 FT. At this time the First Officer had switched to New York Departure and checked in announcing our altitude as 1;600 FT. While he was doing this; I looked down at the pitch trim switch on the center console and saw it was positioned in the secondary position instead of the primary where it should be for normal operation. I quickly repositioned the switch; the trim began working and control forces were returned to normal. During the time I looked down and repositioned the switch; taking my eyes off the flight instruments; the aircraft climbed to 1;800 FT. As I looked back at the flight instruments to see we were 300 FT high; New York Departure responded to our call of level at 1;600 FT with 'maintain 1;500 FT;' and I was already correcting to quickly descend back to 1;500 FT. From the time I realized the trim commands were not working; to the fix and level back at 1;500 FT was approximately 10-15 seconds; so this all happened very quickly. I know I was remarking to the First Officer that the trim was not working and he could see me pushing on the controls; but he didn't seem to realize the problem until I had it corrected. He said he returned the switch to the primary position after completing the pre-flight trim check and thought we may have bumped the switch into that position when entering/exiting the cockpit. The switch has to be lifted out of a detent to move out of primary; so I don't think that happened. Also; during the Pre-Taxi Checklist; the trim switch is an item that is checked; so this was obviously overlooked by both of us during that check. I believe the trim switch was simply left in the secondary position after the trim check and the error was not caught; as it should have been; during the Pre-Taxi Checklist. After takeoff; the trim forces were great enough that just a momentary glance away from the flight instruments was enough to cause drift upward. There was no traffic advisory from the TCAS during this problem; so we were not in danger of an incursion; but nevertheless; deviated from our assigned altitude.




Synopsis: When they took off from TEB with the pitch trim switch in the secondary vice primary position the pilot flying was unable to maintain the required 1;500 MSL level off on the RUUDY SID. After repositioning the switch operation returned to normal.