B747-400 had a 4 ft by 6 ft non structural panel depart the aircraft fuselage on departure.

Attributes
ACN	631847
Time
Date	200409
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zzzz.artcc
Operator	common carrier : air carrier
Make Model Name	B747-400
Operating Under FAR Part	Part 121
Flight Phase	climbout : initial
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 17000 flight time type : 1400
ASRS Report	631847
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other other : departure airport company dispatch
Resolutory Action	flight crew : diverted to another airport flight crew : landed as precaution
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

While en route, company advised us that a panel of about 4 ft by 6 ft from bottom of fuselage had fallen off just after takeoff. Per company request we dumped fuel and returned to ZZZ1. Upon arrival we did see that a panel (non standard) had fallen off. Total flight was otherwise normal. Callback conversation with reporter revealed the following information: reporter stated that he was not told and did not know why the panel departed the aircraft.

Original NASA ASRS Text

Title: B747-400 HAD A 4 FT BY 6 FT NON STRUCTURAL PANEL DEPART THE ACFT FUSELAGE ON DEP.

Narrative: WHILE ENRTE, COMPANY ADVISED US THAT A PANEL OF ABOUT 4 FT BY 6 FT FROM BOTTOM OF FUSELAGE HAD FALLEN OFF JUST AFTER TKOF. PER COMPANY REQUEST WE DUMPED FUEL AND RETURNED TO ZZZ1. UPON ARR WE DID SEE THAT A PANEL (NON STANDARD) HAD FALLEN OFF. TOTAL FLT WAS OTHERWISE NORMAL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT HE WAS NOT TOLD AND DID NOT KNOW WHY THE PANEL DEPARTED THE ACFT.

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.