The National Transportation Safety Board (NTSB) has found that pushing the rudder of a public transport-category aircraft fully one way and then almost immediately fully the other way - rudder reversals - "can produce loads [on the vertical fin] higher than those required for certification". Certification tests, says the NTSB, require that the rudder should be able to be pushed fully to its limit in one direction, and held there until full sideslip is established, then suddenly released and returned to neutral. There is no requirement to test by pushing fully one way and then fully the other, as appears to have occurred on 12 November. On 8 February, the Board re-issued advice to pilots about rudder handling in transport aircraft. The NTSB says it is going to review the certification requirements for vertical fin structural limitations.

Source: Flight International