An unsecured insulation blanket is to blame for a Q-Link Fokker 100 that fell 17,000 feet in six minutes in August last year, according to an ATSB investigation.
The QantasLink aircraft was cruising at 26,000 feet carrying passengers from Perth to Geraldton, when crew were alerted to an ‘excessive cabin altitude’ warning, according to the report.
Oxygen masks were deployed and the pilot commenced an emergency descent before the aircraft levelled off at 9,000 feet. The aircraft then continued to Geraldton and landed without incident.
An engineering inspection of the aircraft following the incident has since determined that an insulation blanket had “migrated from its location” and was “partially ingested” by one of the two outflow valves in the aircraft’s pressurisation system.
According to the Australian Transport Safety Bureau’s (ATSB) investigation, the insulation blanket had likely “not been properly secured to the aircraft’s structure” during recent heavy maintenance on the plane.
On the aircraft, insulation blankets in the same area as outflow valves were able to dislodge and move if not correctly secured, ATSB acting director transport safety Vik Chaudhri said.
“The investigation found that while the aircraft manufacturer’s instructions detailed that during maintenance installation blankets could be removed ‘as necessary’, those instructions did not reference the insulation blanket installation procedure,” Chaudhri said.
“This resulted in insulation blankets not being properly secured to the structure.”
According to Qantas subsidiary Network Aviation, which operates under the QantasLink brand, the airline has conducted a fleet-wide inspection of its Fokker 100s, and has already identified a “number” of aircraft with similarly incorrectly installed insulation blankets.
Additionally, Virgin Australia and Alliance Airlines have reportedly since carried out their own inspections for incorrectly installed insulation blankets.