Flight crew experienced autoplt uncommanded pitch down.

Attributes
ACN	317350
Time
Date	199510
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : zny
State Reference	NY
Altitude	msl bound lower : 32500 msl bound upper : 33000
Environment
Flight Conditions	Mixed
Light	Dawn
Aircraft 1
Controlling Facilities	artcc : zny
Operator	common carrier : air carrier
Make Model Name	Learjet 35
Operating Under FAR Part	Part 135
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 7600 flight time type : 2900
ASRS Report	317350
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : nmac inflight encounter other non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : regained aircraft control flight crew : returned to intended course or assigned course flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

During cruise at FL330 we had an uncommanded pitch down by the autoplt. The captain immediately disconnected the autoplt and recovered. The altitude loss/gain during the recovery was minus 500 ft plus 300 ft of assigned altitude. The initial pitch over was approximately minus .25 (1/4) G. There were no injuries or damage. The autoplt was on FC200 with the heading, soft, and altitude modes engaged at the time. The cause of the pitch-over is unknown at this time.

Original NASA ASRS Text

Title: FLC EXPERIENCED AUTOPLT UNCOMMANDED PITCH DOWN.

Narrative: DURING CRUISE AT FL330 WE HAD AN UNCOMMANDED PITCH DOWN BY THE AUTOPLT. THE CAPT IMMEDIATELY DISCONNECTED THE AUTOPLT AND RECOVERED. THE ALT LOSS/GAIN DURING THE RECOVERY WAS MINUS 500 FT PLUS 300 FT OF ASSIGNED ALT. THE INITIAL PITCH OVER WAS APPROX MINUS .25 (1/4) G. THERE WERE NO INJURIES OR DAMAGE. THE AUTOPLT WAS ON FC200 WITH THE HDG, SOFT, AND ALT MODES ENGAGED AT THE TIME. THE CAUSE OF THE PITCH-OVER IS UNKNOWN AT THIS TIME.

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.