Return land mandated when widebody transport aircraft unable to pressurize. Fuel dumped.

Attributes
ACN	350641
Time
Date	199610
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : las
State Reference	NV
Altitude	msl bound lower : 2200 msl bound upper : 2200
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : las tower : yul
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude climbout : initial other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 150 flight time total : 6500 flight time type : 150
ASRS Report	350641
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : unable other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

On initial climb from las, a popping sound was heard, dust was swirling in cockpit, and aircraft would not pressurize. Accomplished the 'unable to pressurize cabin' checklist, still unable to pressurize. Adjusted gross weight of aircraft by dumping fuel per checklist and returned to las. As landing gear was extended the cockpit filled up with dust, and door below and behind captain's seat opened up. After arriving at the gate, maintenance found the avionics compartment wheel well door open and a malfunctioning door microswitch not showing door open on flight engineer annunciator panel.

Original NASA ASRS Text

Title: RETURN LAND MANDATED WHEN WDB ACFT UNABLE TO PRESSURIZE. FUEL DUMPED.

Narrative: ON INITIAL CLB FROM LAS, A POPPING SOUND WAS HEARD, DUST WAS SWIRLING IN COCKPIT, AND ACFT WOULD NOT PRESSURIZE. ACCOMPLISHED THE 'UNABLE TO PRESSURIZE CABIN' CHKLIST, STILL UNABLE TO PRESSURIZE. ADJUSTED GROSS WT OF ACFT BY DUMPING FUEL PER CHKLIST AND RETURNED TO LAS. AS LNDG GEAR WAS EXTENDED THE COCKPIT FILLED UP WITH DUST, AND DOOR BELOW AND BEHIND CAPT'S SEAT OPENED UP. AFTER ARRIVING AT THE GATE, MAINT FOUND THE AVIONICS COMPARTMENT WHEEL WELL DOOR OPEN AND A MALFUNCTIONING DOOR MICROSWITCH NOT SHOWING DOOR OPEN ON FE ANNUNCIATOR PANEL.

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.