What happened
On 27 January 2009, an Airbus A330-322, registration CS-TMT, operated by HiFly, was performing a non-scheduled flight from Darwin International Airport, Australia, to Malé International Airport, Maldives. The aircraft was carrying 64 passengers and 11 crew members.
Prior to takeoff, the crew noted a strong, unpleasant odor in the cabin resembling decaying organic matter. Although maintenance inspections found no immediate issues, the flight proceeded. Approximately one hour and ten minutes into the flight, while cruising at FL3/70, the crew received a "SMOKE LAV" warning. While no visible smoke was detected, a strong odor persisted throughout the cabin.
Shortly thereafter, the crew encountered a "PACK #2 OVERHEAT" caution and a "CPC1 FAULT" indication on the ECAM. Following the established checklists, the crew deactivated Pack #2. Despite an extensive search of the cabin and cargo areas by the crew and an onboard engineer, no smoke or toxic fumes were found, though the odor intensified. To mitigate risks, the crew decided to return to Darwin, performing a holding pattern at FL100 to reduce the aircraft's weight. The aircraft landed safely at Darwin at 16:39 UTC.
Following the landing, several passengers and three crew members required medical attention due to feeling unwell from the cabin atmosphere; they were treated with oxygen and later released from the hospital.
The investigation
The GPIAA investigation, initiated following notification from the ATSB, focused on the aircraft's recent maintenance history. The aircraft had recently completed a scheduled C check at a maintenance facility in Jordan.
Investigators discovered oil at the APU intake and within the pneumatic ducts leading from the APU to both air conditioning packs. The investigation identified that a seal connecting two duct sections downstream of Pack #2 had been incorrectly installed, causing an air leak. Additionally, a portion of the plenum at Pack #1 was found to be broken and missing. Maintenance engineers also suspected that an overfilling of the APU reservoir may have contributed to the oil leak.
Findings
- The cabin odor and the lavatory smoke warning were caused by APU oil particles being vaporized and distributed through the bleed air ducts into the passenger cabin.
- The "PACK #2 OVERHEAT" warning was the result of an air leak caused by an incorrectly installed seal between two duct sections.
- The "CPC1 FAULT" was triggered by instability in Pack #1 due to a broken and missing plenum component.
- The observed issues likely originated from improper maintenance servicing during the recent C check, specifically regarding the APU oil system and duct sealing.