Investigation Summary
The flight departed from a private heliport in Puebla at approximately 14:40 local time. While en route to Mexico City, the helicopter experienced a catastrophic loss of control. Evidence suggests that both linear roll actuators of the Stability Augmentation System (SAS) extended simultaneously without pilot command, inducing a rapid left roll. The pilot in command was unable to recover from the upset, leading the aircraft to strike the ground in an inverted position. The post-impact fire consumed much of the wreckage, but investigators found a critical component in the SAS 2 system with two loose screws, a defect that had been documented as an intermittent malfunction in the days leading up to the crash. Despite these known issues, the operator continued to fly the aircraft, violating the Minimum Equipment List (MEL) requirements.
Final Conclusions
The final report, released on March 27, 2020, concluded that the helicopter should not have been in operation. The probable cause was a loss of control due to a sudden left roll caused by the uncommanded extension of linear roll actuators. Contributing factors included ineffective maintenance practices by Rotor Flight Services, an inadequate safety culture at SAASA, and pressure from the operator to continue flights despite known malfunctions in the SAS 2 system. The investigation also cited insufficient supervision by the Mexican Civil Aviation Authority.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Stability Augmentation System (SAS)
A system designed to improve helicopter handling by providing automated stabilization. A malfunction in the SAS 2 linear roll actuator caused the uncommanded roll.
Minimum Equipment List (MEL)
A document specifying which instruments and equipment may be inoperative for a flight to still be considered airworthy; the operator ignored MEL restrictions regarding the SAS.
Interesting Facts
- 01The helicopter was manufactured in 2011.
- 02The crash occurred just ten days after Governor Martha Erika Alonso took office.
- 03Investigators found no evidence of a mid-air collision or external objects striking the helicopter.
- 04The Stability Augmentation System (SAS) had a documented intermittent failure that was ignored by the operator.
- 05The aircraft impacted the ground in an inverted (upside down) position.
Safety Actions & Advisories
Operator Suspension
The Mexican government suspended the operations of Servicios Aéreos del Altiplano (SAASA) and the maintenance provider Rotor Flight Services following the investigation.
Criminal Prosecution
The case was turned over to federal prosecutors, leading to the arrest of maintenance personnel for their role in allowing the unairworthy aircraft to fly.
Known Controversies & Unanswered Questions
Political Foul Play Allegations
Reference ↗Due to a bitterly contested election and the death of two high-profile opposition figures, some politicians and members of the public initially alleged the crash was not an accident, leading to calls for international oversight of the probe.