By Pat Flynn
Passengers were forced to cover their mouths with handkerchiefs and clothing while the flight crew had to don their oxygen masks after fumes were detected on board an early morning flight from Dublin to Germany.
The Air Accident Investigation Unit (AAIU) of the Department of Transport has issued a report into the 2015 "serious incident" involving Aer Lingus flight EI-352 that returned to Dublin soon after take-off.
Immediately after departure on the morning of October 3, 2015, the flight crew detected a "strange smell" in the cockpit. The Senior Cabin Crew Member (SCCM) called the flight deck to advise that there was an "extremely bad fumy smell in the cabin straight after take-off".
There were however no cockpit warnings or indications of any malfunction. The flight commander switched the air conditioning system to high but the smell was still apparent in the cockpit.
The captain asked if the SCCM was feeling okay and asked her to check if the other cabin crew members at the rear of the aircraft had noticed anything. Staff at the rear of the aircraft reported seeing a "smoke-like effect" in the cabin after take-off, which had since cleared.
The commander advised the SCCM that because the smell was still present he would "go back into Dublin" and air traffic control was advised of the situation.
After informing the cabin crew and passengers of the decision, the captain noticed that the smell was becoming worse and instructed the co-pilot to declare a ‘PAN’ (state of urgency) to air traffic control. The flight crew donned their oxygen masks and carried out the necessary checklist in the Quick Reference Handbook (QRH).
The flight returned to Dublin for a normal landing and was accompanied to the terminal by the airport fire service.
As the aircraft taxied towards the parking stand, the flight crew contacted the airline's station controller, to request ground staff to assist on arrival. However, when the aircraft reached the parking stand, there was no one at the air bridge.
At the same time, the SCCM called the flight crew and advised of the need to "get the [cabin] doors open straight away, to get some fresh air". The captain informed her that they were waiting for the air bridge.
The flight crew made several further requests to the station controller for the air bridge while the SCCM again asked the captain if the door could be opened a little, advising that it was "very fumy".
Positioning of the air bridge commenced approximately three minutes after arrival on stand and once completed, the forward passenger door was opened and the passengers disembarked the aircraft.
The airline reported that the smell/fumes in the cabin were such "that by disembarkation, many passengers had [their] mouths covered with items of clothing and handkerchiefs".
The investigation determined the "probable cause" of the incident was the presence of corrosion inhibitor in the Intermediate Pressure (IP) bleed ducts and IP engine bleed ducts following an engine wash procedure, leading to contamination of the air conditioning system.
The investigation team also established that corrosion inhibitor had been erroneously added to the water tanks of the engine wash rig and that the airline did not have an engine wash training program in place prior to the occurrence. As a result, neither engineer had received training in engine wash procedures.
Subsequent to the occurrence however, the airline developed an engine wash training programme.
As a result of the remedial actions taken by the airline and the further actions proposed, this report does not sustain any Safety Recommendations.
Medical tests on the flight crew and cabin crew resulted in no adverse findings while there were no reports of associated illness from any of the crew members involved or from the passengers.