What happened
On 1 November 2023, a Beechcraft B1900D, registration ZS-OKN, was operating a cargo flight from Bram Fischer International Airport to Port Elizabeth Airport. The aircraft was transporting a toxic, corrosive chemical (UN2922) used in platinum purification, stored in 20-litre plastic containers.
While taxiing at Port Elizabeth, the crew noticed the cockpit and cabin filling with white smoke and pungent fumes. To obtain fresh air, the pilot and first officer opened the direct-vision windows and leaned outward. The aircraft was stopped on the apron, and the engines were shut down. Upon inspecting the cargo, the crew discovered that the chemical had leaked and seep and underneath the cabin floorboards.
The investigation
An investigation by the SACAA AIID revealed that the leak originated from a container that had been punctured by a loose DZUS fastener used to secure the cabin floorboards. The chemical had seeped into the aircraft's internal structure. Because the cargo was secured only with a net and lacked protective measures like pallets or drip trays, the liquid was able to spread across the floor.
Following the incident, the aircraft underwent a thorough inspection. The corrosive nature of the substance caused substantial damage to the main wing spars, the floor rails, and the underbelly skin. Due to the extent of the structural degradation, the aircraft was declared a constructive total loss.
Findings
- A loose DZUS fastener pierced the bottom of a chemical container, initiating the leak.
- The cargo was secured using a net attached to floor rails, but no drip trays or pallets were utilized to contain potential spills.
- The chemical seeped beneath the floorboards, leading to significant corrosion of the wing spars and underbelly.
- The aircraft was transporting dangerous goods while a passenger was seated behind the cockpit, which was in violation of ICAO and local regulations.