What happened
On October 30, 1998, a Robinson RH-22, registration PT-YVA, operated by Hellipoint Clube de Helicópques, was conducting a basic flight instruction mission at Campo de Marte, São Paulo. The flight, which included an instructor and a student, proceeded to the Heliponto Uno sector to perform maneuvers within ground effect.
During the training, the aircraft was subjected to strong winds and rain. While performing a hover, a sudden tailwind gust caused the aircraft to enter an abnormal attitude. In an attempt to regain altitude, the student pilot applied aft cyclic input. However, this action caused the tail to dip, resulting in the tail rotor striking the ground. The impact severed the tail boom, and the aircraft subsequently spun several times before crashing violently into the terrain. The instructor escaped without injury, but the student sustained serious injuries to an arm caused by broken plexiglass during the evacuation.
The investigation
CENIPA investigators examined the meteorological conditions, which included visibility of 700 meters and wind gusts of up to 20 knots—exceeding the manufacturer's specified control limit of 17 knots. The investigation focused on the flight crew's decision-making and the student's control inputs. The analysis revealed that the student, who was an experienced fixed-wing pilot but had only 27 hours of helicopter experience, applied cyclic inputs based on fixed-wing muscle memory rather than helicopter aerodynamics. Furthermore, the investigation looked into the instructor's failure to intervene timely to prevent the loss of control.
Findings
- Adverse weather conditions: The presence of rain, restricted visibility, and wind gusts exceeding the aircraft's certified limits created a high-risk environment.
- Improper control inputs: The student pilot applied aft cyclic in an attempt to climb, which actually caused the tail to descend into the ground.
- Deficient judgment: The instructor elected to continue training maneuvers in ground effect despite the deteriorating weather conditions.
- Inadequate supervision: The instructor failed to maintain a sufficient state of alert to intervene before the tail rotor strike occurred.
- Lack of experience: The student's reliance on fixed-wing flight characteristics contributed to the incorrect response to the wind gust.
Safety action
CENIPA issued several recommendations to the operator, including the development of educational activities to ensure crew members respect manufacturer operating limits and the necessity of instructor intervention. The operator was also directed to establish standardized instruction programs, define stricter wind limits for basic training, and implement procedures to cancel flights when meteorological conditions are unsuitable.