A CE560 flight crew lowered the flaps and temporarily lost aircraft control.

Attributes
ACN	584033
Time
Date	200306
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : hpn.airport
State Reference	NY
Altitude	msl single value : 5000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90.tracon
Operator	general aviation : corporate
Make Model Name	Citation V
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	descent : approach
Route In Use	arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : cfi pilot : atp
Experience	flight time last 90 days : 200 flight time total : 4200 flight time type : 600
ASRS Report	584033
Person 2
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude inflight encounter : weather other anomaly
Independent Detector	other flight crewa
Resolutory Action	flight crew : regained aircraft control
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance Weather
Primary Problem	Weather

Narrative:

Condition: 5000 ft MSL on vectors for runway 16 at hpn, flaps: approach. Autoplt: on, WX IMC. Shortly after lowering the flaps from 0 degrees to 15 degrees we received a master caution light and autoplt pitch mis-trim down light. Autoplt fail indication also illuminated. The aircraft pitched up and climbed 380 ft before immediately recovering to 5000 ft. Supplemental information from acn 584413: at 5000 ft approximately 1 min after flap extension, the autoplt disengaged due to excessive trim pressures.

Original NASA ASRS Text

Title: A CE560 FLT CREW LOWERED THE FLAPS AND TEMPORARILY LOST ACFT CTL.

Narrative: CONDITION: 5000 FT MSL ON VECTORS FOR RWY 16 AT HPN, FLAPS: APCH. AUTOPLT: ON, WX IMC. SHORTLY AFTER LOWERING THE FLAPS FROM 0 DEGS TO 15 DEGS WE RECEIVED A MASTER CAUTION LIGHT AND AUTOPLT PITCH MIS-TRIM DOWN LIGHT. AUTOPLT FAIL INDICATION ALSO ILLUMINATED. THE ACFT PITCHED UP AND CLBED 380 FT BEFORE IMMEDIATELY RECOVERING TO 5000 FT. SUPPLEMENTAL INFO FROM ACN 584413: AT 5000 FT APPROX 1 MIN AFTER FLAP EXTENSION, THE AUTOPLT DISENGAGED DUE TO EXCESSIVE TRIM PRESSURES.

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.