An Embraer EMB-110C Bandeirante was scheduled to operate a training flight on this day, one year ago. Onboard the aircraft is a crew of two, The Pilot Flying (PF) in the left seat and the Pilot Monitoring (PM) in the right seat. The PF was under training, being trained by the PM. The flight was scheduled from Montevideo-Carrasco Airport to Maldonado-Capitan Corbeta C.A. Curbelo International Airport, both in Uruguay and only 85 kilometres (46 nm) apart.
During the start-up of the aircraft, it became apparent that the pressure in the hydraulic system was zero. A maintenance engineer is called over to look into the defect and it is deemed necessary to bleed the hydraulic system of (possible) trapped air. The engineer performs the procedure twice. As this has no effect it is decided to perform the procedure while taxiing to the maintenance ramp. The engines are started and when the aircraft starts to move the brakes are checked and found operating normally, the aircraft was not stopped but deceleration was noted on the application of the brakes.
As the aircraft taxies towards the maintenance ramp, the engineer is sitting on his knees without a headset (so not able to communicate with the crew) and operates the controls to bleed the hydraulic system. As the aircraft starts to accelerate the maintenance engineer decides to switch the hydraulic system to the emergency setting, this without informing the crew.
The PF notices nosewheel steering and brakes available handover control of the aircraft to the (more senior) PM. This had no effect on the controllability of the aircraft and a short while later the aircraft hits the corner of a building and came to a stop, wedged between the building and a lamppost. The aircraft is shut down and all occupants (2 pilots and one engineer) evacuate the aircraft without sustaining injury. Damage to the aircraft was extensive. The accident is reported to, and investigated by, the Uruguayan Air Force Investigation Committee, the FAU-DSV. In their report, they come to the following conclusions;
- The hydraulic feed pump had failed, causing a failure of the main pumps, causing the entire hydraulic system to be without pressure
- The knowledge of previously performed maintenance activities led the crew and engineer to believe the hydraulic system needed bleeding.
- The maintenance procedure performed was not in the aircraft’s manual
- Initial control of the nosewheel steering and the brakes was possible because of energy stored in the hydraulic accumulators.
- Brake pressure was available for the parking braking, which was not used.
- The decision to taxi the aircraft was the result of an incorrect risk assessment by the crew.
** Editorial note **
V2 Aviation – Training & Maintenance has not been able to obtain an investigation report in English on this accident. This blog is therefore based on several internet sources. Should there be inconsistencies in the blog don’t hesitate to get in touch with us. There are two possibilities to do that, via the comments function at the bottom of this page or via the contact page of the website.