What happened
On 22 October 2018, a Federal Airlines flight operating a Beechcraft B1900D, registration ZS-PHX, departed from Londolozi Aerodrome in Mpumalanga. The aircraft was carrying 11 passengers and 2 crew members on a scheduled flight toward OR Tambo International Airport.
While cruising at flight level 200, approximately 40 nautical miles east of the WIV VOR, the aircraft suffered an explosive decompression. Following the event, a "CABIN ALT HI" alert was triggered on the flight deck. The crew immediately initiated an emergency descent to flight level 120 and declared a mayday. All onboard oxygen masks deployed and functioned correctly. The aircraft was rerouted directly to Johannesburg, landing safely on runway 03R. There were no injuries to the 13 people on board.
The investigation
SACAA AIID investigators examined the aircraft and the circumstances surrounding the failure. The investigation confirmed that the decompression was caused by the structural failure of the third cabin window on the right-hand side of the fuselage.
Maintenance records were reviewed, noting that while the aircraft's recent 50-hour routine check did not require window inspections, the last detailed inspection of the cabin windows had occurred in early 2014. The window in question was a single-pane design that had been in service for approximately 6,025 hours since its installation in 2007. The investigation also noted that the aircraft's engines, when in a feathered position, can direct exhaust gases toward the cabin windows, a factor relevant to window temperature and integrity.
Findings
- The primary cause of the decompression was the failure of the third cabin window on the right side of the fuselage.
- The aircraft sustained minor damage to the window, a side wall panel, and an insulation blanket.
- The crew's emergency procedures, including the descent and use of oxygen systems, were effective.