Plane descended 5,000ft a minute

AN AER LINGUS airbus on the Dublin/London route was forced to descend at 5,000-feet a minute following warnings that cabin pressure was dangerously low.

The incident happened shortly after take-off, at 10.36am, from Heathrow Airport on January 26, 2004.

As the aircraft was climbing, the crew received an ECAM (Electronic Centralised Aircraft Monitoring) warning that the cabin altitude was excessive and a subsequent warning of low cabin pressure. The captain donned his oxygen mask and asked for descent. Rapid depressurisation continued and the First Officer (FO) donned his oxygen mask. The FO put out an emergency call and got permission from air traffic control to descend into Cardiff Airport.

An emergency descent was carried out without further incident.

The aircraft landed safely without injury to the 155 passengers and eight crew.

An inspection of the airbus 321-200 revealed a metal clamp holding bellows to the air conditioning condenser unit was broken.

The bellows had detached from the condenser and was ruptured. A value - the Pack Outlet Check Valve (POCV) flap downstream from the condenser - was also found broken. This would have affected the air in the cabin.

In addition, a small 1.5cm piece had broken away from the centre of the flap and was not found. The blow-out panel had opened.

Earlier that day, on landing at Heathrow, a noise from the forward hold area was reported by the flight crew. An inspection by ground crew found a blow out panel open.

Finding nothing amiss, the panel was reset and the aircraft released for the return flight to Dublin.

The clamp, which was found to be broken on the condenser end of the bellows, had been removed and reinstalled during an inspection on January 19.

The aircraft had carried out 36 flights since that inspection.

A report was sent to the aircraft manufacturer. The manufacturer stated that in the past 10 years they had received about 15 reports from operators who had experienced damaged POCV flaps.

In the opinion of the aircraft manufacturer, the clamp had originally been installed incorrectly.