Gulfstream G-IV – N450KK

Incident Overview

Date: Friday 10 April 2015

Aircraft Type: Gulfstream G-IV

Owner/operator: La Venezolana de Seguros y Vida

Registration Number: N450KK

Location: over Caribbean Sea – ÿ Atlantic Ocean

Phase of Flight: En route

Status: Substantial, written off

Casualties: Fatalities: 0 / Occupants: 2

Component Affected: Cabin Pressure Relief/Safety Valve (CPRV) ? specifically the static port of the CTPR valve.Cabin Pressure Relief/Safety Valve (CPRV) ? specifically the static port of the CTPR valve.

Category: Accident

A Gulfstream G-IV, N450KK, experienced a significant overpressurization event during a flight to Fort Lauderdale-Executive Airport, Florida, resulting in a controlled descent and landing. The pilots were not injured, and the aircraft was operated by a private company. The flight originated from Caracas-Sim¢n Bol¡var International Airport, Venezuela, approximately 16:30, and the pilots reported a planned maintenance flight to FXE. The flight’s initial pressure readings indicated a maximum cabin differential pressure of 9.8 psi, prompting the crew to initiate a descent and manual valve opening. A loud ‘bam’ sound followed, and the crew initiated a controlled descent to 12,000 feet. Upon landing, a thorough inspection revealed structural damage to the floor beam, floor boards, and wing links, indicating a catastrophic failure of the cabin pressure relief/safety valve (CPRV). The foreign material found in the outflow valve safety port suggests a potential obstruction, pointing to a likely cause of the overpressurization. The incident highlights a critical failure of the CTPR valve, potentially due to a foreign material obstructing its static port.A Gulfstream G-IV, N450KK, experienced a significant overpressurization event during a flight to Fort Lauderdale-Executive Airport, Florida, resulting in a controlled descent and landing. The pilots were not injured, and the aircraft was operated by a private company. The flight originated from Caracas-Sim¢n Bol¡var International Airport, Venezuela, approximately 16:30, and the pilots reported a planned maintenance flight to FXE. The flight’s initial pressure readings indicated a maximum cabin differential pressure of 9.8 psi, prompting the crew to initiate a descent and manual valve opening. A loud ‘bam’ sound followed, and the crew initiated a controlled descent to 12,000 feet. Upon landing, a thorough inspection revealed structural damage to the floor beam, floor boards, and wing links, indicating a catastrophic failure of the cabin pressure relief/safety valve (CPRV). The foreign material found in the outflow valve safety port suggests a potential obstruction, pointing to a likely cause of the overpressurization. The incident highlights a critical failure of the CTPR valve, potentially due to a foreign material obstructing its static port.

Description

A Gulfstream G-IV, N450KK, was substantially damaged during a cabin over-pressurization event over the Caribbean Sea while en route to Fort Lauderdale-Executive Airport, Florida (FXE). The pilots were not injured. The airplane was operated by a private company. Day, visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed. The flight originated at Caracas-Sim¢n Bol¡var International Airport, Venezuela about 16:30. The pilot reported that the purpose of the flight was to fly the airplane to FXE for scheduled maintenance. About 2 hours and 15 minutes after departure, at flight level 430, the crew observed a red warning light indicating a maximum cabin differential pressure of 9.8 psi, followed by a red “DOOR MAIN” indication. The pilots donned oxygen masks and referenced the airplane’s quick reference handbook. A loud “bam” sound was then heard in the cabin and the crew initiated an immediate descent. The cabin pressure outflow valve was opened manually and the airplane was leveled at 12,000 feet above mean sea level. The flight continued to FXE unpressurized and landed without further incident. After landing, the crew performed a walk-around inspection and found no obvious anomalies with the airplane. A subsequent inspection of the airplane by maintenance and engineering personnel revealed structural airframe damage, including a cracked floor beam, dimpled areas in the floor boards, damaged structure between ribs, and damaged wing links. An initial examination of the fuselage revealed that the outflow valve safety port, located on the outer fuselage, was completely plugged with a foreign material resembling dried dirt from a mud dauber. PROBABLE CAUSE: “The in-flight failure of the cabin pressurization relief/safety valve (CPRV) due to an obstruction of the CPRV static port, which allowed the airplane to overpressurize. The reason for the initial overpressurization condition could not be determined.”

Source of Information

http://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20150827X41302&key=1http://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20150827X41302&key=1

Primary Cause

Probable cause: ‘The in-flight failure of the cabin pressurization relief/safety valve (CPRV) due to an obstruction of the CPRV static port, which allowed the airplane to overpressurize.’Probable cause: ‘The in-flight failure of the cabin pressurization relief/safety valve (CPRV) due to an obstruction of the CPRV static port, which allowed the airplane to overpressurize.’

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