Altitude deviation autoplt inadvertently knocked off.

Attributes
ACN	154496
Time
Date	199008
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : dtw
State Reference	MI
Altitude	msl bound lower : 5000 msl bound upper : 5600
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dtw
Operator	general aviation : personal
Make Model Name	Small Transport
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 50 flight time total : 1300 flight time type : 150
ASRS Report	154496
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : private
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

During a stop climb to 10000', I was instructed to dlb to 5000'. The autoplt was engaged in altitude hold mode. For some reason the autoplt 'kicked off' unknown to me until I noticed we had climbed to 5600'. The controller called and alerted me to this. I immediately told him of the autoplt failure and descended back to 5000'. This autoplt is easily 'kicked off' by a slight touch to the elevator trim on the control wheel, with no alert that it is 'off line'. This is a dangerous fault in a high performance twin like this. Is this responsible for some structural failures die to 'high G' pull outs?

Original NASA ASRS Text

Title: ALT DEVIATION AUTOPLT INADVERTENTLY KNOCKED OFF.

Narrative: DURING A STOP CLB TO 10000', I WAS INSTRUCTED TO DLB TO 5000'. THE AUTOPLT WAS ENGAGED IN ALT HOLD MODE. FOR SOME REASON THE AUTOPLT 'KICKED OFF' UNKNOWN TO ME UNTIL I NOTICED WE HAD CLBED TO 5600'. THE CTLR CALLED AND ALERTED ME TO THIS. I IMMEDIATELY TOLD HIM OF THE AUTOPLT FAILURE AND DSNDED BACK TO 5000'. THIS AUTOPLT IS EASILY 'KICKED OFF' BY A SLIGHT TOUCH TO THE ELEVATOR TRIM ON THE CTL WHEEL, WITH NO ALERT THAT IT IS 'OFF LINE'. THIS IS A DANGEROUS FAULT IN A HIGH PERFORMANCE TWIN LIKE THIS. IS THIS RESPONSIBLE FOR SOME STRUCTURAL FAILURES DIE TO 'HIGH G' PULL OUTS?

Data retrieved from NASA's ASRS site as of July 2007 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.