The Air Accident Investigation Authority (AAIA) of Hong Kong found a hydraulic system failure led to the emergency landing of an Atlas Air freighter at Hong Kong International (HKIA) in June.
The preliminary report suggests that the incident on June 17 – classed as serious – was related to a “multiple hydraulic system failure” on the Atlas Air Boeing 747-400 freighter (5y4304).
The report states that during take-off the crew experienced a slight yawing and shimmy sensation.
However, in the absence of cockpit indications and other cues that would suggest the aircraft’s flyability was compromised, the take-off continued normally with normal gear retraction.
Then 26 minutes into the flight an alert message appeared as the aircraft levelled off from its climb to an initial cruise level.
“After following the appropriate checklist and consulting the Atlas Air’s ground office, the pilot in command (PIC) made the operational decision to return to Hong Kong,” the report stated.
“Once the aircraft came to a stop on runway 25R, Air Traffic Control (ATC) relayed from the Airport Authority Hong Kong (AAHK) staff on site that there was smoke coming from the wheels.
“Confirming the brake temperatures were within the normal range and no other hazards were observed, the crew shut down the engines and waited for further assistance from the ground support personnel.
“Evacuation was not considered necessary. Post-flight inspection indicated that number nine and number 10 tyres were shredded. Parts of number nine and number 10 wheels were missing and significant damage was observed on number nine wheel.
“Several hydraulic lines located in the right-hand wing landing gear wheel well were found fractured and punctured, and the fluid in hydraulic systems one, two and four was completely lost.
“In addition, some damage was sustained by the lower forward fuselage, lower right wing sections and components/systems inside the wheel well.”
The AAIA will now: Analyse the factors that led to the failure of the tyres and multiple hydraulic systems; analyse all relevant operational safety risks subsequent to the tyre failure and the loss of multiple hydraulic systems; conduct an in-depth examination of the retained aircraft components, with some components to be dispatched to overseas testing facility for detailed examination and testing; and review the operator’s procedures and crew actions.
The incident resulted in the closure of one of HKIA’s two runways for more than eight hours and delayed around 180 flights.
The freighter, which is owned by Nippon Cargo Airlines and operated by Atlas, landed on the airport’s North runway at 7.12am.
Cargo was offloaded from the aircraft and the tyre was replaced. As the hydraulic system of the freighter had broken down, the emergency handling took longer than expected.
The north runway reopened at 15.45pm.
Atlas Air co-operating with Hong Kong authorities following emergency landing
