Chinese investigators have found that the fire which destroyed a Tupolev Tu-204C freighter at Hangzhou originated from a crew oxygen system malfunction in the right-hand side of the cockpit, with leaking oxygen and hot components igniting combustible material.
The Aviastar-Tu twinjet (RA-64032), with eight occupants, had been departing for a flight to Novosibirsk on 8 January 2022.
Russian investigators had indicated in early 2023 that the fire had originated in the cockpit, and recommended that Tu-204s and Tu-214s undergo checks on crew oxygen systems to ensure absence of leaks.
As the aircraft started pushing back from stand 204, the first officer pressed the test button for the right-hand oxygen mask as part of the pre-departure procedure.
The cockpit-voice recorder captured “distinct” audio of a gas leak some 4s later, says the Civil Aviation Administration of China, which led the inquiry. It adds that the captain, first officer and flight engineer all heard the same leak.
While the leak continued for 2min 25s, three surveillance cameras at the parking stand recorded a flash in the right of the cockpit just moments after it began.
Analysis of the video footage shows the flame was “bright and white”, says the inquiry.
Crew testimony indicates it appeared to the right rear side of the first officer’s seat, and the inquiry believes it originated behind an audio control panel in front of the oxygen shut-off and above regulator units.
While the ignition source has not been specified, several electrical components in the right-hand side of the cockpit – including the nose-wheel tiller control, emergency power switch, and regulators – can generate heat during normal operation.
The aircraft had been pushed back about 30m from stand 204 when the blaze broke out. Fuelled by oxygen under high pressure, the intense fire spread to the whole cockpit in a short time.
Such was the rapid development of the fire that it engulfed the cockpit escape ropes, forcing the three crew inside to use the left forward exit and right forward service door. The crew had to jump from these exits – about 3.9m above ground – because the aircraft was not fitted with inflatable slides.
All those on board evacuated safely, sustaining only minor injuries.
But the aircraft’s fuselage section burned from the forward doors to the right wing, and the fuselage fractured aft of its main landing-gear.
