Published on February 13th, 2017 | by Mark Dwyer


AAIU Report into Aer Lingus fumes incident

The AAIU have released a report into a serious incident involving fumes on an Aer Lingus A320 shortly after take-off from Dublin in 2015. Immediately after take-off from Dublin on an early morning scheduled passenger flight to Munich, Germany (EDDM), the Flight Crew detected an unusual odour in the cockpit. A short time later, the Cabin Crew reported that there were fumes in the aircraft cabin and that the CCMs at the rear of the aircraft had noticed a “smoke-like effect”

The Commander made a PA to the passengers, advising them of the situation. At this point, he noticed that the smell was becoming worse and instructed the Co-Pilot to declare a PAN to ATC, the Flight Crew donned their oxygen masks and carried out the initial items from the ‘SMOKE/FUMES/AVNCS SMOKE’ checklist in the Quick Reference Handbook (QRH), which includes the requirement to use the crew oxygen masks if necessary.

A normal landing was performed at Dublin and an expeditious taxi had been requested by the Flight Crew when the aircraft was on the approach and this was facilitated by ATC, with the AFS providing an escort. No injuries were reported to the Investigation

The aircraft, an Airbus A320-214, was manufactured in 2009. The aircraft had operated for a total time of 19,630 hours from the date of manufacture until the occurrence date.

A scheduled engine wash was performed on the aircraft when it was undergoing maintenance on the night before the occurrence. Prior to the engine wash being carried out, one can, containing eight US fluid ounces (236.6 millilitres) of corrosion inhibitor, was erroneously added to each of the 115 litre water tanks of the engine wash rig. This likely resulted in the inhibitor, which is insoluble in water, being deposited within the compressor sections of each engine during the engine wash procedure. The design of the aircraft’s engine bleed air and air conditioning systems is such that any contamination of this nature in the compressor sections of the engines, APU or associated bleed ducting can lead to fumes or unusual odours entering the aircraft cockpit and cabin.

Following the performance of the engine wash procedure, the reconnection of all previously disconnected pipes and the closing of the engines’ fan cowl doors, a ‘Post Engine Wash Test’, must be performed, which is described in a further maintenance subtask. The stated purpose of this test is “to ensure that the bleed system is free from contaminant”, which the subtask notes, has the potential to cause “smoke/smell in the cabin”.

The procedure instructs personnel to start the engine within two hours to “purge the lube/sump system of any water ingestion”. The procedure requires that the relevant engine should be run at idle for five minutes, before operating the ENG BLEED system and the ANTI ICE/WING system. The stated aim of this part of the procedure is to “purge water potentially trapped in High Pressure (HP) bleed ducts and HP engine chambers”. The engine should then be run at idle for a further five minutes, before increasing the engine thrust to “at least 60 percent Fan (N1) for 10 minutes”. Maintenance personnel are then instructed to press the ANTI ICE/WING switch twice, which operates the wing anti ice system again. The stated aim of this part of the procedure is to “purge water potentially trapped in IP bleed ducts and IP engine bleed chambers”.

An alternative post engine wash test, which is only applicable if the engine wash is performed with pure water, is permitted by the AMM. The Engineers who performed the engine wash task reported that following the wash, they carried out a post wash test in accordance with the AMM and that no fumes were noticed in the aircraft cockpit or cabin. The test performed was the ‘Alternative procedure – Post Engine Wash Test’, which permits the engines to be operated at idle power only.

The Operator did not have an engine wash training program in place at the time of the occurrence and therefore neither Engineer had received training in engine wash procedures.

Among the 14 findings were;

  • The AMM engine wash procedure required corrosion inhibitor to be added to the aircraft engines’ oil tanks, but this step could be omitted if the aircraft was returning to service within 24 hours.
  • In preparation for the wash procedure, one eight US fluid ounce (236.6 millilitres) can of corrosion inhibitor was erroneously added to each of two 115 litre water-filled engine wash rig tanks.
  • No fumes or smells were noticed during the alternative post engine wash test, which permitted the engines to be operated at idle power only.
  • Shortly after take-off on the aircraft’s first flight following the engine wash procedure, the Flight Crew detected an unusual smell in the cockpit. At the same time, the Cabin Crew noticed fumes and smoke in the aircraft cabin.

The probable cause of this 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.” As a result of the remedial actions taken by the Operator and the further actions proposed, the report does not sustain any Safety Recommendations. Read the full report here.

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About the Author

Mark is an airline pilot flying the Boeing 737 for a major European airline. In addition he is also a Type Rating Instructor, Type Rating Examiner and Base Training Captain on the B737. Outside of commercial flying Mark enjoys flying light aircraft from the smallest 3 Axis microlights up to heavier singles. He is also an instructor and EASA Examiner on single engines and a UK CAA Examiner. He flies the Chipmunk for the Irish Historic Flight Foundation (IHFF). Mark became the Chairman of the National Microlight Association of Ireland (NMAI) in 2013 and has overseen a massive growth in the organisation. In this role he has worked at local and national levels. In 2015, Mark won ‘Upcoming Aviation Professional Award’ at the Aviation Industry Awards sponsored by the IAA. Mark launched this website back in 2002 while always managing the website, he has also been Editor and Deputy Editor of FlyingInIreland Magazine from 2005 to 2015.

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