BE40 autoplt malfunctioned on ILS approach to gso. Aircraft lost 350 ft before recovery.

Attributes
ACN	582298
Time
Date	200305
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : gso.airport
State Reference	NC
Altitude	msl bound lower : 1850 msl bound upper : 2200
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : gso.tracon
Operator	general aviation : corporate
Make Model Name	Beechjet 400
Operating Under FAR Part	Part 91
Navigation In Use	ils localizer & glide slope : 23 other
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp pilot : multi engine
Experience	flight time last 90 days : 140 flight time total : 25000 flight time type : 1100
ASRS Report	582298
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly
Independent Detector	other flight crewa
Resolutory Action	controller : issued advisory flight crew : regained aircraft control flight crew : overcame equipment problem flight crew : overrode automation
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Autoplt began uncommanded abrupt pitch down. Lost 350 ft before manual recovery. Callback information from reporter revealed the following information: reporter stated that autoplt was in the altitude hold mode, properly annunciated, and the incident happened prior to GS capture. Gso approach alerted them of the deviation about the same time they took action to take manual control. Maintenance inspected and tested the system and was unable to duplicate. Aircraft is back in service.

Original NASA ASRS Text

Title: BE40 AUTOPLT MALFUNCTIONED ON ILS APCH TO GSO. ACFT LOST 350 FT BEFORE RECOVERY.

Narrative: AUTOPLT BEGAN UNCOMMANDED ABRUPT PITCH DOWN. LOST 350 FT BEFORE MANUAL RECOVERY. CALLBACK INFO FROM RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT AUTOPLT WAS IN THE ALT HOLD MODE, PROPERLY ANNUNCIATED, AND THE INCIDENT HAPPENED PRIOR TO GS CAPTURE. GSO APCH ALERTED THEM OF THE DEV ABOUT THE SAME TIME THEY TOOK ACTION TO TAKE MANUAL CTL. MAINT INSPECTED AND TESTED THE SYS AND WAS UNABLE TO DUPLICATE. ACFT IS BACK IN SVC.

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.