Executive summary
The aircraft suffered an in-flight structural failure due to flutter of the tail surfaces originating at the elevator trim tab.
No conclusive reason could be established for the aircraft's speed increasing to the extent that flutter would ensue but defects in the trim control system and a rudder modification rendered ZK-DAG susceptible to flutter at a lower airspeed than other aircraft of the same type. Safety recommendations were made to the Amateur Aircraft Constructors' Association in respect of construction techniques; and to the Meteorological Office and the Minister of Transport, in regard to the standard of weather forecasts available to general aviation pilots.
Related Recommendations
Direct the Meteorological Service to sponsor a study of the best way to present weather information to general aviation pilots and to implement the system which shows the best results.
Direct the Meteorological Service to provide Aerodrome Forecasts, using the best available information.
Provide a library of collated technical information for builders and prospective builders.
Adopt a programme to improve the prospects of continuing airworthiness: • By requiring a mandatory strip inspection at an appropriate time interval in the life of wooden aircraft; • Requiring inspection ports, both in fabric coverings and in closed structures.
Ensure competent inspection of aircraft under construction is available by: • Selecting inspectors/designated persons who are not only sufficiently knowledgeable, but who have sufficient strength of personality to ensure proper standards of construction are met; • Stipulating the test pieces continue to be preserved for inspection when the Regulations are changed; • Ensuring an inspector/designated person is present when structures are enclosed.
Promulgate a requirement for independent, qualified inspection: for renewal of permit-to-fly, and on sale of an aircraft.
Direct that a study be made of the cost of obtaining sufficient information to enable the Meteorological Service to forecast medium-scale phenomena and that these costs be related to the potential costs of aircraft accidents.
Prepare a programme to educate builders and prospective builders on: • The need for craftsmanship, access to precision machinery and recognition of jobs which are beyond the builder's skills; • The need to evaluate any proposed changes to drawings to ensure there are no adverse consequences from incorporation of such modifications; • The need for sufficient manpower at critical stages of construction.