What happened
On September 17, 2015, a Boeing 737-400 was undergoing engine start-up procedures at EPBY following a pushback from its parking stand. During this process, ground personnel observed thick white smoke emanating from the area near the right main landing gear. In response to the visible smoke, the flight crew elected to shut down the engines and initiate an emergency evacuation of all passengers, supported by the airport fire services.
The investigation
Technical personnel conducted a detailed inspection of the landing gear bay to identify the source of the smoke. The investigation established that the smoke was caused by hydraulic fluid leaking onto the hot brake assembly. Specifically, the inspection revealed a rupture in the brake line of the right main landing gear unit. The leak occurred while the crew was utilizing the parking brake, which allowed the fluid to contact the heated components.
Following the discovery, maintenance crews replaced the damaged brake line and also replaced the number 3 and number 4 wheel assemblies along with the brake units. After replenishing the hydraulic fluid and successfully performing system leak tests, the aircraft was cleared for return to service without operational restrictions.