What happened
On August 28, 2016, at approximately 20:44 UTC, a Bell 407 helicopter, registration PT-YZF, was conducting a police operation flying from Jacarepaguá Airport (SBJR) in Rio de Janeiro. During the flight, the rear right door of the aircraft became detached and fell onto a residential building. Following the incident, the crew successfully returned the aircraft to SBJR without further complications. All four occupants—comprising two pilots and two special equipment operators—remained unharmed, though the aircraft sustained light damage.
The investigation
CENIPA investigators examined the aircraft and the hardware responsible for securing the door. The door was held in place by two supports, each secured by a single bolt. During the investigation, one bolt was missing, while the second bolt remained attached to the airframe, though it had fractured.
Technical analysis performed by the Department of Aerospace Science and Technology (DCTA) revealed no signs of corrosion on the remaining bolt fragment. Instead, the analysis determined that the fracture was caused by an applied overload. Crucially, investigators found that the fragment of the bolt did not feature a Part Number (PN) engraved on its head, unlike the specific bolt recommended by the manufacturer's manual. This discrepancy suggested that the hardware installed on the aircraft may not have met the manufacturer's specifications.
Findings
- The detachment of the door was caused by the failure of the securing hardware under load.
- The installation of a non-compliant bolt that did not match the manufacturer's recommended part number contributed to the failure.
- The investigation identified inadequate aircraft maintenance as a contributing factor.