What happened
On April 15, 2021, an EC 225 LP helicopter, registration PR-OMW, operated by Omni Air Taxi, was performing a specialized external load operation near Carauari, Amazonas. While the crew was framing the final approach to the Fortaleza Base, approximately 1 km from the landing site, the aircraft experienced an uncommanded jettisoning of its external load, which weighed approximately 1,800 kg.
The aircraft was flying over a region of dense vegetation. Following the release, the crew attempted to locate the fallen cargo, but the thick forest canopy prevented them from identifying the exact coordinates. Despite the loss of the load, the helicopter proceeded to its destination and completed a normal landing. There were no injuries to the two pilots, and the aircraft sustained no damage.
The investigation
CENIPA's investigation focused on the mechanical and procedural circumstances surrounding the load release. Investigators examined the aircraft's maintenance records, which were found to be up to date, and reviewed the flight data recorders, which showed no evidence of the crew manually activating the load jettisoning system.
Technical inspections of the cargo hook system revealed several discrepancies. While the aircraft's maintenance logs were current, investigators found that the primary ring used to connect the cargo to the hook was non-compliant with manufacturer specifications. Specifically, the ring measured 160 mm, exceeding the 120 mm limit established by Alert Service Bulletin EC225, nº 04A004. Additionally, the investigation identified that the electrical and mechanical components for the cargo hook installation were configured for a 'PRE-MOD' specification, even though the installation followed a 'POST-MOD' configuration, contradicting established Service Bulletins.
Findings
- The uncommanded jettisoning of the external load was the primary event.
- The primary ring used for the cargo attachment was out of specification, which the manufacturer warns can lead to the loss of external loads.
- There was evidence of managerial oversight regarding the supervision of maintenance services, specifically allowing the use of non-compliant rings.
- Discrepancies were found in the installation of the cargo hook's electrical and mechanical control cables relative to the aircraft's modification status.
- The exact cause of the detachment remains undetermined because the lost cargo and lifting equipment could not be recovered for examination.