Mexican authorities detained four people on Friday in connection with the December 2018 fatal crash of a 2011 Leonardo AW109S (XA-BON) that killed all aboard, including National Action Party opposition party member and Puebla state governor Martha Alonso, her husband senator Rafael Moreno Valle, an aid to Valle, and both pilots. The helicopter crashed minutes after takeoff on a flight from Puebla to Mexico City.
The Puebla attorney general said the four detained—all employed by Toluca-based Rotor Flight Services (RFS) at the time of the accident—were being investigated for homicide and making false statements. Accident investigators, led by Mexico’s DGAC with assistance from both the NTSB and Canada TSB, concluded that a known, preexisting problem with the helicopter’s stability system should have grounded it from further flight before the accident.
A final accident report from Mexico’s Agencia Federal de Aviacion Civil found the helicopter crashed due to a sudden left roll, causing loss of control that deteriorated into inverted flight and impact into terrain. It said the uncommanded roll could have been caused by loose actuator screws contacting the stability system’s electronic card.
Listed contributory factors included “ineffective maintenance practices” by RFS, inadequate safety culture at operator Altiplano Air Services, pressure on the operator to continue flight operations despite intermittent malfunction of the stability system during prior flights, and insufficient governmental maintenance and operations supervision.