| Occurrence Briefs are concise reports that detail the facts surrounding a transport safety occurrence, as received in the initial notification and any follow-up enquiries. They provide an opportunity to share safety messages in the absence of an investigation. Because occurrence briefs are not investigations under the Transport Safety Investigation Act 2003, the information in them is de-identified. |
What happened
On 10 December 2024 an Airbus AS350 B2 (Squirrel) was being operated on a multi-day ferry flight from Caloundra Airport, Queensland to Papua New Guinea (PNG). At about 1000 local time, the helicopter was landed at Gladstone Airport for fuel and then continued north for Cairns Airport. Abeam Rockhampton Airport and about 4 km from the airport control zone boundary, the left front door upper window became detached from the aircraft and was briefly observed by the crew member seated in the left side as falling down and away from the aircraft.
Following the incident the crew aerially searched the area for the window, however, were unable to find it in the dense bushland. Shortly after this the crew landed the aircraft to check for damage to the helicopter. No damage was found and the crew elected to continue to Cairns Airport where a spare window was fitted.
Figure 1: Airbus AS350 B2 left front door upper window before the incident
Source: Operator, annotated by the ATSB
After a repair in Cairns, the helicopter had a post-maintenance flight check before the planned departure.
The remainder of the flight to PNG continued without incident. The crew were reported to be startled by the loud noise that was created as the window detached from the helicopter, however, no injuries were sustained by the crew and no other damage to the helicopter was observed.
The operator advised that, in line with scheduled maintenance of the aircraft, some of the windows had recently been refitted after a period in storage. The operator’s internal review of the incident concluded that the seal on the left-hand door window was installed without sealant and in the incorrect orientation. Further, as depicted in Figure 1, the left front door upper window also displayed a bulge due to the incorrect orientation after refit. This improper fit reduced the security of the window to stay in place permanently during flight. The review identified that an apprentice aircraft mechanical engineer fitted the window, however, the subsequent inspection and sign‑off process did not identify any problem with the installation.
Safety message
Attention to detail is critical for all aspects of aviation safety, as even small omissions can have serious safety implications. Maintenance manuals for manufacturer and operator procedures should be followed closely. Quality assurance checks to verify compliance following maintenance, and fostering a culture of vigilance in maintenance practices, is essential for preventing inadvertent errors.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.