What happened
On November 3, 2014, an Agusta AW139 helicopter, registration PR-SES, operated by Omni Táxi Aéreo S.A., was performing an offshore passenger transport flight. The aircraft departed from the Sapura Diamante offshore unit (9PIN) in the Santos Basin, Rio de Janeiro, bound for Jacarepecuá Airport (SBJR).
During the initial climb, approximately five minutes after departure, the crew noticed that the pilot's side storm window was open. Upon closing it, the pilot in command observed a 4 cm crack extending from the storm window frame to the front of the main window. Because the Quick Reference Handbook (QRH) provided no specific instructions for this discrepancy, the crew decided to continue the flight to the destination, intending to log the issue upon landing.
Approximately 18 minutes into the flight, while cruising at 7,500 ft over the ocean, the entire right-side window detached from the aircraft. The crew immediately reduced speed to 80 kt and followed emergency procedures. The aircraft landed safely at SBJR with no injuries to the two crew members or eight passengers, though the aircraft sustained light damage.
The investigation
CENIPA's investigation confirmed that the pilots were fully qualified, with valid medical certificates and instrument ratings. The aircraft was airworthy, within weight and balance limits, and maintained according to regulations. The weather conditions were favorable for the flight.
The investigation focused on the cause of the window separation. Because the window fell into the ocean, it could not be recovered for physical analysis. However, the investigation reviewed manufacturer data and similar incidents. Agusta Westland informed investigators that three previous cases of cockpit window detachment had occurred in the global fleet, all linked to improper installation procedures during maintenance or window replacement.
Further investigation into similar incidents involving the same aircraft model (specifically registrations PR-EFX and PR-SE0) revealed that maintenance errors, such as leaving paint or primer on the window frame edges or using uncured sealant, were contributing factors in those cases.
Findings
- The right-side window detached in flight while the aircraft was over the ocean.
- A crack had been identified by the crew prior to the detachment.
- The specific cause of the detachment for PR-SES remained undetermined due to the loss of the component.
- Maintenance records for the aircraft were up to date, and the pre-flight inspection had not detected the crack.