History of Flight
On 8 August 2017, a flydubai Boeing B737-800, registration A6-FDS, operated scheduled passenger flight FZ081 from Dubai International Airport (OMDB) to Bahrain International Airport (OBBI). The aircraft had 35 persons on board: 29 passengers, two flight crewmembers, and four cabin crewmembers. After lining up on runway 12R and receiving takeoff clearance, the flight crew commenced the takeoff. Following lift-off, the landing gear was retracted. At about 250 feet radio altitude during the climb, the aircraft experienced a pressure loss of Hydraulic System A. The aircraft continued climbing to the pre-selected altitude of 4,000 feet. The flight crew contacted ATC Departure, declared a hydraulic system problem, and requested to hold for troubleshooting. They entered the hold at the GINLA waypoint as advised. After executing non-normal checklists, including the checklist for loss of Hydraulic System A, they decided to return to OMDB. They requested vectoring for the approach and landed safely on runway 12L. After vacating via taxiway N8, the aircraft taxied to parking stand E23.
Damage to Aircraft
The incident resulted in damage to components and lines of hydraulic system A due to the rotation of the damaged No. 1 tire inside the left main wheel well. The investigation examined the damaged tire and related systems.
Probable Cause
The Air Accident Investigation Sector determined that the cause of the incident was the rotation of the damaged No. 1 tire inside the left main wheel well, which consequently caused damage to some components and lines of hydraulic system A, and the subsequent hydraulic system A pressure loss.
Contributing Factors
The investigation identified contributing factors: the intermittent operation of the left alternate antiskid valve, which most probably allowed the two wheels of the left main landing gear to enter the wheel well while still spinning; and the rotating wheel peeled portion of the center tire tread rib of the number 1 wheel did not operate the frangible fitting, resulting in a continuation of the left gear retraction, allowing the number 1 tire peeled portion to damage the hydraulic system A and other parts in the vicinity.
Safety Recommendations
The Air Accident Investigation Sector issued two safety recommendations to the operator, one to the General Civil Aviation Authority, and one to the aircraft manufacturer.