What happened
On October 10, 2008, a Bell 412 helicopter, registration PT-HRH, operated by the Federal Highway Police (PRF), was conducting a training flight at the Brasília model aircraft track. The flight was intended to practice continuous landings to prepare the crew for emergency scenarios, such as hydraulic failures or autorotations.
During the third contact of a continuous landing maneuver, the crew heard a loud cracking sound. A crew member identified that the front cross tube of the right skid had fractured. The instructor pilot immediately took control of the aircraft and initiated a go-around.
Following the incident, the aircraft was directed to a maintenance workshop located at Brasília International Airport (SBBR). To avoid the risk of the aircraft tipping over upon landing with the damaged component, the crew decided to maintain a steady hover. While the helicopter remained hovering, maintenance personnel performed an improvised procedure to replace the skid assembly. Once the replacement was successfully completed, the aircraft returned to its hangar.
The investigation
CENIPA investigated the structural failure and the subsequent operational decisions. Investigators were unable to determine the exact cause of the component failure, as detailed metallurgical examinations of the fractured material could not be performed. Furthermore, no evidence was found in technical literature suggesting that operating on asphalt runways contributed to the failure of this specific model's skid components.
The investigation also scrutinized the crew's credentials and the safety of the maintenance procedure. It was noted that the co-pilot's medical certificate (CCF) had expired several days prior to the flight. Additionally, the investigation highlighted the extreme danger posed by the decision to perform a component replacement while the aircraft was in a hover, noting that such improvised procedures significantly compromise flight safety.
Findings
- The primary cause of the structural failure remained undetermined due to the lack of detailed material analysis.
- The decision to perform maintenance while the aircraft was hovering created a high-risk environment for both the flight crew and the ground personnel.
- The co-pilot was operating with an expired medical certificate, indicating a failure in the organization's flight scheduling and supervisory processes.
- The aircraft sustained light damage and all four occupants were uninjured.