CE560 captain reports aircraft climbing when flaps are extended with the autopilot engaged in altitu...

Narrative:

Flying in VMC conditions on the ILS 19 teb at 2;000 ft 1-2 miles outside glide slope intercept. Approach armed; localizer captured; glide slope full scale deflection above with glide slope capture armed and altitude hold the current vertical mode at 2;000 ft. Flaps were moved to approach and at some point there after the airplane began to quickly climb. I instinctively pressed the formerly called 'tcs (touch control steering)' button and pushed the control yolk forward to stop the climb. This leveled the airplane; so I released the tcs button to vertical speed back down to 2;000. As soon as I released the tcs button the airplane began to climb again. I then pressed the autopilot disconnect button and the airplane reduced the climb rate confirming to me the autopilot was definitely engaged throughout the event. I hand flew from 2;300 ft back to 2;000 ft and then the rest of the approach. This happened as we left approach control to go to teb tower control. No mention was made from ATC about any altitude deviation. I called rockwell/collins in wichita; ks to report the event. They made a report and are looking into any other reported similar events.

Original NASA ASRS Text

Title: CE560 Captain reports aircraft climbing when flaps are extended with the autopilot engaged in altitude hold mode and the approach armed. The autopilot is disengaged and the approach resumed manually.

Narrative: Flying in VMC conditions on the ILS 19 TEB at 2;000 FT 1-2 miles outside glide slope intercept. Approach armed; localizer captured; glide slope full scale deflection above with glide slope capture armed and ALT hold the current vertical mode at 2;000 FT. Flaps were moved to approach and at some point there after the airplane began to quickly climb. I instinctively pressed the formerly called 'TCS (touch control steering)' button and pushed the control yolk forward to stop the climb. This leveled the airplane; so I released the TCS button to vertical speed back down to 2;000. As soon as I released the TCS button the airplane began to climb again. I then pressed the autopilot disconnect button and the airplane reduced the climb rate confirming to me the autopilot was definitely engaged throughout the event. I hand flew from 2;300 FT back to 2;000 FT and then the rest of the approach. This happened as we left approach control to go to TEB Tower Control. No mention was made from ATC about any altitude deviation. I called Rockwell/Collins in Wichita; KS to report the event. They made a report and are looking into any other reported similar events.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	931688
Time
Date	201102
Local Time Of Day	0601-1200
Place
Locale Reference	TEB.Airport
State Reference	NJ
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Citation V/Ultra/Encore (C560)
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Flight Plan	IFR
Component
Aircraft Component	Autopilot
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 90 Flight Crew Total 3500 Flight Crew Type 250
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

CE560 captain reports aircraft climbing when flaps are extended with the autopilot engaged in altitude hold mode and the approach armed. The autopilot is disengaged and the approach resumed manually.