What happened
On September 2, 2003, at approximately 18:45 UTC, a Robinson R22 helicopter with registration PT-YPJ was involved in an accident during a training flight at Jacarepaguá Airport (SBJR) in Rio de Janeiro, Brazil. The aircraft, operated by NEP Nacional Escola de Pilotagem, was conducting a pre-solo training phase for a student pilot.
The incident occurred while the student pilot was practicing lateral hovering maneuvers on a grass strip in the southwest sector of the airfield. As part of the training sequence, the student allowed the right ski to touch the ground. This contact shifted the helicopter's center of gravity away from its pivot point, initiating an uncommanded roll to the right.
The flight instructor, who was occupying the left seat, attempted to regain control by applying cyclic input opposite to the direction of the tilt and increasing collective pitch. However, these inputs were incorrect for the specific dynamic rollover scenario. The main rotor struck the ground, causing the helicopter to capsize onto its right side. Both the instructor and the student exited the aircraft without injury.
The investigation
CENIPA (Centro de Investigação e Prevenção de Acidentes Aeronáuticos) conducted a final investigation into the occurrence, classified as a loss of control in flight. The report noted that the aircraft was within weight and balance limits and held a valid airworthiness certificate. The last 25-hour inspection had been performed just days prior.
The investigation focused on the operational procedures and human factors involved. The R22 Flight Manual specifies a minimum safe altitude of five feet above ground level (AGL) for lateral and rearward hover exercises to prevent ski contact. The manual also outlines specific recovery procedures for dynamic rollover, which require lowering the collective pitch to settle the aircraft onto its skids, rather than raising it.
The instructor had 532 total flight hours and held a Commercial Pilot License with helicopter type ratings and flight instructor qualifications. The student pilot had only 3 hours and 40 minutes of total flight time, with just three hours on the R22 type. The incident was the student's fourth mission in this specific aircraft.
Findings
The investigation identified several contributing factors to the accident:
- Improper Control Inputs: The most critical factor was the instructor's reaction upon assuming control. Instead of lowering the collective as recommended by the manufacturer to arrest a dynamic rollover, the instructor raised the collective and applied opposite cyclic. This action failed to stop the roll and resulted in the main rotor striking the ground.
- Failure to Maintain Safe Altitude: The student pilot allowed the ski to touch the ground during a lateral hover, likely due to limited experience in judging height variations. The manual requires maintaining at least five feet AGL for such maneuvers.
- Inadequate Supervision and Judgment: The instructor failed to monitor the student's altitude closely enough to prevent the ski contact. Furthermore, the instructor did not correctly identify the dynamic rollover phenomenon, leading to the inappropriate control corrections.
- Training Environment: The training was conducted on a grass surface, which can obscure height perception compared to paved surfaces.
The investigation concluded that while the aircraft and pilot certifications were valid, the accident resulted from a combination of student error in maintaining altitude and instructor error in both supervision and emergency recovery technique. No safety recommendations were recorded as having been adopted by the operator at the time of the report's issuance, though CENIPA had issued broader safety recommendations to helicopter operators regarding situational awareness and adherence to flight manuals.
Safety action
CENIPA issued several Safety Recommendations (RSV) in 2004 and 2011 related to this investigation. These included advising aviation schools and operators to:
- Disseminate the report's findings to all pilots, emphasizing standardization and knowledge of aircraft limitations.
- Conduct training sessions to improve technical knowledge and situational awareness regarding operational characteristics.
- Address the risks of overconfidence in pilots and ensure constant supervision of pilot performance, particularly during initial training phases near the ground.
- Ensure instructors maintain heightened attention and strictly adhere to manufacturer-recommended minimum altitudes for hover exercises.