What happened
During a dual training flight intended to review handling procedures, a Robinson R22 experienced a sudden, uncommanded right roll and a nose-down pitch. The flight was being conducted to prepare a student pilot for a private pilot license checkride. The instructor was in the process of demonstrating rotor flap-forward characteristics—a standard response to reducing airspeed—when the aircraft unexpectedly rolled and pitched.
While the instructor did not immediately implement the specific recovery procedures intended for such an event, they were able to regain control of the aircraft and perform a safe landing. However, the maneuver resulted in a mast bump, causing significant damage to the main rotor system that necessitated the replacement of numerous components.
The investigation
Investigators examined the circumstances surrounding the loss of control and the effectiveness of existing training protocols. The inquiry focused on why the uncommanded roll occurred and why the instructor did not follow the recommended recovery procedures during the actual event. The investigation also looked into the regulatory requirements for Robinson helicopter training and the clarity of safety communications within the manufacturer's flight manuals.
Findings
- The investigation determined that no mechanical defects or environmental factors triggered the uncommanded roll.
- The most likely cause was an inadvertent reduction in G-load occurring as the pilot transitioned between flight demonstrations while maintaining relatively high engine power.
- A contradiction was identified between the US Special Federal Aviation Regulation No. 73, which mandates dual instruction on low-G effects, and the Robinson R22 flight manual, which prohibits the actual demonstration of low-G conditions.
- The investigation found that the use of "Caution" instead of "Warning" in Robinson flight manuals for high-risk operating conditions likely diminished the perceived importance of critical safety information.
Safety action
Following the investigation, recommendations were directed toward the Federal Aviation Administration (FAA) to clarify that low-G instruction must be limited to discussion only and to prohibit deliberate in-flight low-G maneuvers. Additionally, it was recommended that the manufacturer update flight manuals to use the term "Warning" for procedures involving risks of serious injury or death.