British Aerospace Plc BAe 146-100, VH-NJA

Shortly after takeoff, and in accordance with standard
procedure, the flight crew selected engine bleed air as the source
of air for the aircraft's two airconditioning packs. Subsequently,
the cabin staff reported a strong smell of fumes in the cabin. As
there was also a smell of fumes entering the flight deck, the
flight crew donned their oxygen masks in accordance with the
non-normal procedure for suspected cabin air contamination.

The flight crew then proceeded to identify the source of the
fumes using a contamination source location schedule. That
procedure involved selecting different combinations of engine air
and airconditioning packs. During normal operation, bleed air from
engines one and two was fed to pack one, which in turn supplied
conditioned air to the flight deck and cabin. Bleed air from
engines three and four was fed to pack two, which normally only
supplied air to the cabin. Additionally, bleed air from the
Auxiliary Power Unit (APU) was used by either pack during the
takeoff and landing phases or when airconditioning was required
during ground operations. It was determined that with pack two
selected off, the fumes dissipated. The flight was continued with
only pack one supplying conditioned air to the cabin and flight
deck. The two cabin staff and several passengers were affected by
the fumes with symptoms of sore eyes, sore throat and headache.

On arrival of the aircraft in Brisbane, a Licensed Aircraft
Maintenance Engineer (LAME) addressed the reported defect in
accordance with the Civil Aviation Safety Authority airworthiness
directive AD/BAe146/086 and the British Aerospace Systems
Information Service Bulletin (ISB) 21-150. The ISB required certain
actions to be performed whenever a cabin air quality problem was
identified which was suspected of being associated with oil
contamination of the air supply from the airconditioning packs. The
engineer's inspection of the airconditioning system, engines and
APU revealed no signs of oil contamination or oil leaks. The defect
was therefore cleared and the aircraft resumed service.

The following day, the same aircraft but with a different crew
was involved in a similar occurrence. A strong smell of fumes was
noticed, mainly in the cabin, during the cruise. The flight crew
donned oxygen masks as a precautionary measure. Symptoms of sore
eyes, sore throat and headache were reported by both the crew and
passengers. The pilot in command, who had been affected by fumes on
previous occasions, received medical attention after landing.

Engineering inspection revealed oil contamination in the
number-3 engine bleed band. The defect was deferred in accordance
with the aircraft's approved Minimum Equipment List that allowed
the aircraft to be flown with only the number one airconditioning
pack in use. No further fumes were evident during following
flights. Subsequent engineering investigation of the number-3
engine revealed that the oil leak was a result of a worn number one
bearing seal. The number-3 engine was replaced and the defect was
cleared.

Evidence from previous incidents of air system contamination on
this type of aircraft had indicated that the fumes were associated
with engine or APU oil contamination of the airconditioning system.
As a result, operators have incorporated various modifications to
the cabin air system, APU, and engines. They have also introduced
improved maintenance practices to further address the issue.
However, that action has not completely solved the problem. The air
supplied to the airconditioning packs was protected from
contamination by oil seals in the engines and APU. A technical
defect arising in one of the seals can result in oil entering the
cabin airconditioning system, with the first signal of the defect
being an awareness of fumes by the members of the crew. The
difficulty of identifying the origin of the contamination is
exacerbated by the often-intermittent nature of the fumes
events.