On September 30, 2017, Air France’s Airbus A380 (registered F-HPJE) started out its day as per usual, operating Flight AF66 from Paris-Charles De Gaulle International Airport (CDG) to Los Angeles International Airport (LAX) with 497 passengers and 24 crew members onboard. What commenced after the aircraft took off, however, was far off normal.

While cruising over Greenland, the number four engine suffered a failure. Its fan, the first rotating assembly at the front of the engine, together with the air inlet and fan case, separated during the flight. The Airbus A380 landed safely at Goose Bay, Canada (YYR) with no injuries to the people on board.

The investigation is still under progress and no final report is yet published. The Bureau d'Enquêtes et d'Analyses pour la sécurité de l'aviation civile (BEA), the designated investigator of the incident, published an update on the challenges and difficulties of locating the engine parts, which was finally achieved in June 2019 after a 21-month long search campaign.

ARTICLE: Engine part of Air France A380 found under Greenland ice

Three-phase operation

The search for the engine parts was split into three phases: 

Phase I, a 12-day visual scan of parts laying on the ice sheet;

Phase II, where an aerial campaign using synthetic aperture radars (SAR) tried to detect parts under the ice sheet was combined with a ground campaign, which utilized ground-penetrating radars (GPR) after SAR identified potential locations of the parts, however, Phase II ended without any conclusive results;

Finally, after the completion of Phase II at the end of 2018, with new targets identified by ONERA, a French aerospace research center, and the availability of a new electromagnetic sensor, BEA made the decision to conduct Phase III in May 2019. However, difficult weather conditions postponed the search to June 2019, which finally resulted in the recovery of engine fan hub fragments that still had its fan blades attached to it on June 30, 2019.

Narrowing the territory down

The first challenge was to narrow down the potential area where fragments of the Engine Alliance GP7000 could have fallen. BEA notes that a simulation was used to “estimate the size, mass, velocity and angle of ejection of each hub fragment, to help refine the ballistic computation and the search area on the Greenlandic ice sheet.” Engine Alliance used the LS-Dyna fan hub failure simulation.

The area was further narrowed down by defining the position of the Air France A380 during the failure. French investigators, coupled with Airbus, decided to use the position indicated by the Flight Management System (FMS), a combination of GPS and Inertial Reference System (IRS) data. The next step was to determine the altitude and pursue ballistic calculations. Calculations were done by the BEA, the National Transportation Safety Board (NTSB) and Airbus. Further analysis of radar data imagery was done “in order to reliably detect the fragments being searched,” noted BEA’s report.

Ground-penetrating radars (GPR) were concluded as a “sub-optimal instrument choice for a wide area search,” thus the investigators decided to explore several newly available options if a new search operation was to be launched.

“[...] more effective detection sensors with a bigger swath and giving a more robust response were needed to launch Phase III.”

RECCO systems, an “off-the-shelf, mature device which is used for avalanche search and rescue procedures,” sniffer dogs and electromagnetic (EM) sensors were considered for Phase III. In the end, electro-magnetic sensors prevailed. However, they had to be adapted to a system called the SnowTEM, as the “depth at which the missing part was located and its characteristics could not be worked on,” with traditional and available EM sensors.