An F100 cleared to FL400 experienced 700 ft altitude deviation due to right slat deployment.

Attributes
ACN	569793
Time
Date	200302
Day	Sat
Local Time Of Day	0601 To 1200
Place
State Reference	AZ
Altitude	msl bound lower : 39300 msl bound upper : 40000
Environment
Flight Conditions	VMC
Aircraft 1
Controlling Facilities	artcc : zab.artcc
Operator	general aviation : personal
Make Model Name	Rockwell North American Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	climbout : vacating altitude
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Experience	flight time last 90 days : 25 flight time total : 3420 flight time type : 190
ASRS Report	569793
Person 2
Affiliation	government : faa
Function	controller : radar
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem flight crew : returned to assigned altitude other
Consequence	other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

While on a maintenance flight to the filed block altitude FL490-FL510, I was cleared under radar vector heading 240 degrees from FL350 to assigned block altitude. At FL380, I called center and asked when reaching FL400 if I could have a direct heading to deming. A controller cleared me right turn direct deming passing FL400. Approximately 1/2 way through the turn, I was at FL405 and encountered drag from a r-hand slat deployment. Aircraft descended to FL393 before controller's call. Thereafter, rolled out, lit the afterburner, and climbed to assigned block level. While dealing with the extended slat, the particular problem caused altitude loss, with wings level aircraft performed per the book. Slat problem has been attended to by maintenance.

Original NASA ASRS Text

Title: AN F100 CLRED TO FL400 EXPERIENCED 700 FT ALTDEV DUE TO R SLAT DEPLOYMENT.

Narrative: WHILE ON A MAINT FLT TO THE FILED BLOCK ALT FL490-FL510, I WAS CLRED UNDER RADAR VECTOR HDG 240 DEGS FROM FL350 TO ASSIGNED BLOCK ALT. AT FL380, I CALLED CTR AND ASKED WHEN REACHING FL400 IF I COULD HAVE A DIRECT HDG TO DEMING. A CTLR CLRED ME R TURN DIRECT DEMING PASSING FL400. APPROX 1/2 WAY THROUGH THE TURN, I WAS AT FL405 AND ENCOUNTERED DRAG FROM A R-HAND SLAT DEPLOYMENT. ACFT DSNDED TO FL393 BEFORE CTLR'S CALL. THEREAFTER, ROLLED OUT, LIT THE AFTERBURNER, AND CLBED TO ASSIGNED BLOCK LEVEL. WHILE DEALING WITH THE EXTENDED SLAT, THE PARTICULAR PROB CAUSED ALT LOSS, WITH WINGS LEVEL ACFT PERFORMED PER THE BOOK. SLAT PROB HAS BEEN ATTENDED TO BY MAINT.

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.