There was limited assurance that M18 and M18A Dromader aircraft incorporating Supplemental Type Certificate SVA521 would exhibit acceptable handling and performance characteristics if not fitted with vortex generators and M18B standard elevators, in particular that the risk of longitudinal instability had been reliably addressed.
Issue will no longer exist once safety action is completed.
The owner and developer of Supplemental Type Certificate (STC) SVA521 reported that pending Civil Aviation Safety Authority (CASA) approval, they were in the process of amending it to include the fitment of vortex generators and M18B standard elevators as prerequisites for applying the STC.
CASA advised that it will ensure that the SVA521 Engineering Order and aircraft flight manual (AFM) supplement are amended to add M18B standard elevators and vortex generators as required modifications
The ATSB is satisfied that the proposed safety action will, when implemented, adequately address the safety issue.
