British Aerospace Plc BAe 146-200, VH-JJU

On 6 September 1999, the Australian Transport Safety
Bureau issued recommendation R19990052 to the Civil Aviation Safety
Authority. That recommendation stated that:

"The Civil Aviation Safety Authority, in conjunction with the
aircraft manufacturer, British Aerospace Plc, address deficiencies
that permit the entry of fumes into the cockpit and cabin areas of
BAe 146 aircraft. These deficiencies should be examined by the
regulatory authority as part of its responsibilities for initial
certification and continued airworthiness of the BAe 146
aircraft."

The Civil Aviation Safety Authority responded on 14
March 2000 stating:

"In the lengthy period between the incident and the release of
your report, CASA has investigated this issue in considerable
detail, in conjunction with the aircraft manufacturer and the major
Australian operators. As a result of this work, and discussions
with the certifying authority (the UK Civil Aviation Authority),
CASA is satisfied that the BAel46 aircraft in service in Australia
are safe for public transport. CASA technical specialists are
available to brief your investigators on the scope and findings of
this work.

"As your recommendation does not specify the nature of any
additional deficiencies that the Bureau believes need to be
addressed by CASA and the aircraft manufacturers, I am seeking
details of any deficiencies that you believe have not been
appropriately dealt with. It would also assist us in providing a
meaningful and constructive response to your recommendations if you
were to provide us with details of any incidents that have occurred
since the original incident in 1997.

"In the meantime, we will continue to monitor the situation and
review any information that comes to hand."

The Bureau classified the response as "Open" and has initiated
further correspondence with CASA. On 12 October 2000, the Senate
Rural and Regional Affairs and Transport References Committee
tabled its report into Safety and Cabin Air Quality in the BAe 146
Aircraft. The Government tabled its response to the References
Committee's report on 28 June 2002.

The cabin manager's observations, during the takeoff roll, of a
smoky burning smell, and her subsequent symptoms, suggested
contamination of the cabin air supply with the by-products of
engine combustion. Her blood test results, appearing consistent
with CO exposure, seemed to confirm that hypothesis. Although
maintenance engineers traced the source of oil contamination to the
number-3 engine, the investigation was unable to positively
determine the exact origin of the fumes that affected the cabin
manager. At the stage of flight when fumes affected the cabin
manager, the air conditioning packs were being supplied with air
from the APU, not from the engines.

It was considered possible that, at some stage prior to the
flight, airconditioning pack number two was contaminated with the
by-products of the thermal degradation of oil from the number-3
engine. That would have resulted in the tainting of the APU air as
it passed through airconditioning pack two before entering the
cabin. It is also possible that the cabin air became contaminated
from an external source. While taxiing, the aircraft's engine
exhaust or a preceding aircraft's engine exhaust may have been
ingested into the APU air intake, resulting in the cabin air
contamination.

The fumes had a detrimental effect on the well being of the
cabin manager. The potential effect on her ability to effectively
carry out her duties in the event of an emergency could not be
determined.

During the takeoff roll, the cabin manager of the BAe 146
aircraft became aware of a smoky, burning smell coming from an air
vent in the region of her crew seat at the forward (L1) exit door.
Initially there was a mild odour. That was followed by the rapid
onset of strong fumes for a short period after which the fumes
dissipated quickly. The event was of 2-3 minutes duration.

The cabin manager felt overwhelmed by the fumes and was on the
verge of passing out when her colleagues became aware of the
situation and provided her with portable oxygen. After
approximately 10 minutes of using oxygen, the cabin manager felt
well enough to attempt a resumption of her duties but was unable to
continue due to the effect of the fumes exposure.

The cabin manager, who had ten years of operational experience
on the BAe 146, spent the duration of the flight seated at the rear
of the aircraft; breathing portable oxygen for most of that time.
The cabin manager reported that when she was not using oxygen she
felt unwell, she had difficulty in thinking clearly and she found
it difficult to coordinate her thoughts with her actions. No other
members of the crew or any of the passengers reported being
affected by the fumes.

Upon arrival in Kununurra, engineering inspections were
performed on the aircraft and further action was deferred in
accordance with the Civil Aviation Safety Authority airworthiness
directive AD/BAe146/086. That airworthiness directive 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. Subsequent engineering inspections revealed that the cause
of the oil contamination was a worn number one bearing seal in the
number-3 engine. The engine was replaced and no further fumes were
evident during following flights.

The cabin manager sought medical treatment and tests in
Kununurra on the day of the incident and in Perth on the following
day. Although she was eventually cleared to return to work,
symptoms of anxiety, impaired judgement, and light-headedness
remained with her for in excess of one week. Of note was the result
of a blood test that revealed she had been exposed to a higher than
normal level of carbon monoxide (CO). When inhaled, CO combines
with the haemoglobin, the blood's oxygen-carrying molecule, to form
carboxyhaemoglobin (COHb). Once in that state, the haemoglobin is
unable to carry oxygen. Thus, the blood's ability to carry oxygen
to body tissues, including vital organs such as the heart and
brain, is inhibited.

CO is the product of incomplete combustion of carbonaceous
material. It is found in varying amounts in the smoke and fumes
from burning aircraft engine fuels and lubricants. The gas itself
is colourless, odourless, and tasteless but is usually mixed with
other gases and fumes that can be detected by sight or smell.
Individuals that have been exposed to CO should be removed from the
exposure and administered 100 percent oxygen through a tight
fitting mask until all symptoms have been resolved. If blood
testing for measurement of COHb level is required, the samples
should be drawn as soon as possible after the exposure, as COHb has
a short half-life in the body of 4-5 hours. If an individual is
administered 100 percent oxygen, the half-life is reduced to 40 to
80 minutes.

The same aircraft was the subject of a pilot report three days
prior to the cabin manager's experience, in which an oil-like smell
was evident in the cockpit but not in the cabin. The event was of
short duration and occurred just after takeoff, when the source of
air supply was changed from the Auxiliary Power Unit (APU) to the
engines. Inspection by maintenance engineers of the engines, APU,
and air-conditioning system revealed no signs of contamination and
the defect was cleared.

Evidence from previous incidents of air system contamination on
this type of aircraft has indicated that fumes were associated with
engine or APU oil contamination of the airconditioning system. The
BAe146 is similar to many aircraft in that the supply of cabin air
originates in the aircraft's engines. Air is bled from the final
stage of the engine's high-pressure compressor just prior to the
combustion chamber. The air destined for the cabin then passes
through a catalytic converter in order to clean the air of any oil
contaminants. Catalytic converters operate at maximum efficiency
under highly specific conditions of temperature and contaminant to
air ratio. The air is then passed through a heat exchanger and then
through one of two airconditioning packs before entering the cabin.
During normal operation bleed air from engines one and two is fed
to pack one, which in turn supplies conditioned air to the flight
deck and cabin. Bleed air from engines three and four is fed to
pack two, which normally only supplies air to the cabin.
Additionally, bleed air from the APU is used by either pack during
the takeoff and landing phases or when airconditioning is required
on the ground.