What happened
On September 10, 2022, at 17:00 UTC, a McDonnell Douglas DC-9-82, registration YV3475, operated by RAVSA, departed from General José Santiago Mariño International Airport in El Yaqué, Nueva Esparta, bound for Barquisimeto. The flight was operating as a scheduled commercial service.
During the climb phase at approximately 15,000 feet, the right-side air conditioning pack ceased operation. This failure caused the cabin climb rate indicator to rise abnormally fast, as the flow control valve remained completely closed, preventing the regulation of the pressure differential between the cabin and the outside atmosphere.
The pilot requested authorization from the Maiquetía Area Control Center (ACC) to limit the ascent to 20,000 feet to perform the Quick Reference Handbook (QRH) procedures. However, because the cabin pressure continued to fluctuate irregularly, the crew determined it was necessary to descend to 10,000 feet and divert the flight. The aircraft returned to Maiquetía International Airport, landing at 17:45 UTC. There were no injuries reported, and the aircraft sustained no significant damage.
The investigation
The JIAAC investigation included interviews with the pilot and first officer, as well as a physical inspection of the aircraft. Investigators performed troubleshooting according to the Aircraft Maintenance Manual (AMM) regarding the flow control valve and addressed a pneumatic duct leak. Documentation reviewed included maintenance records from OMAC-N°441B, flight logs, and airworthiness certificates.
Findings
The investigation established that the incident was caused by the malfunctioning of the flow control valve and a pneumatic leak in a duct.