A319 flight crew is unable to pressurize the aircraft after departing mmun.

Attributes
ACN	580100
Time
Date	200304
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : mmun.airport
State Reference	FO
Altitude	msl single value : 8000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : mmun.tower tower : ixd.tower
Operator	common carrier : air carrier
Make Model Name	A319
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 190 flight time total : 9000 flight time type : 2400
ASRS Report	580100
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : ecam warning other flight crewa other flight crewb
Resolutory Action	flight crew : declared emergency flight crew : diverted to another airport flight crew : landed as precaution
Consequence	other other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

It was a hot and humid cancun day when the aircraft had several MEL's due to an avionics smoke ECAM warning due to the hot and humid WX and not due to an avionics fire or smoke. Shortly before rotation, we received a 'vent skin valve' fault ECAM warning. The captain continued the takeoff, talked to ATC, while I handled the ECAM and communication. Unable to pressurize was the underlying problem, so we followed the ECAM and leveled off at 8000 ft, requested to divert back to cun and requested to hold in order to burn fuel and avoid an overweight landing. I was trying to no avail to pressurize manually. After notifying operations that we will be returning to cun in 5 mins, we decided to declare an emergency. After holding at amita intersection and a point 50 NM from cun, we were given vectors to intercept the ILS DME runway 12. We landed and informed tower that we did not need further emergency vehicle assistance.

Original NASA ASRS Text

Title: A319 FLT CREW IS UNABLE TO PRESSURIZE THE ACFT AFTER DEPARTING MMUN.

Narrative: IT WAS A HOT AND HUMID CANCUN DAY WHEN THE ACFT HAD SEVERAL MEL'S DUE TO AN AVIONICS SMOKE ECAM WARNING DUE TO THE HOT AND HUMID WX AND NOT DUE TO AN AVIONICS FIRE OR SMOKE. SHORTLY BEFORE ROTATION, WE RECEIVED A 'VENT SKIN VALVE' FAULT ECAM WARNING. THE CAPT CONTINUED THE TKOF, TALKED TO ATC, WHILE I HANDLED THE ECAM AND COM. UNABLE TO PRESSURIZE WAS THE UNDERLYING PROB, SO WE FOLLOWED THE ECAM AND LEVELED OFF AT 8000 FT, REQUESTED TO DIVERT BACK TO CUN AND REQUESTED TO HOLD IN ORDER TO BURN FUEL AND AVOID AN OVERWT LNDG. I WAS TRYING TO NO AVAIL TO PRESSURIZE MANUALLY. AFTER NOTIFYING OPS THAT WE WILL BE RETURNING TO CUN IN 5 MINS, WE DECIDED TO DECLARE AN EMER. AFTER HOLDING AT AMITA INTXN AND A POINT 50 NM FROM CUN, WE WERE GIVEN VECTORS TO INTERCEPT THE ILS DME RWY 12. WE LANDED AND INFORMED TWR THAT WE DID NOT NEED FURTHER EMER VEHICLE ASSISTANCE.

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.