Operation of the M-18A in accordance with Civil Aviation Safety Authority exemptions EX56/07 and EX09/07 at weights in excess of the basic Aircraft Flight Manual maximum take-off weight (MTOW), up to the MTOW listed on the Type Certificate Data Sheet, may not provide the same level of safety intended by the manufacturer when including that weight on the Type Certificate.
CASA has issued a revised exemption that explicitly requires pilots to observe limitation associated with the higher weights. They will also be sending a letter to operators to point out the requirements. This will result in overweight operations that are ALARP.
On 2 December 2011, CASA advised that it would inform all M18A operators other than those that have a supplemental type certificate permitting operation to 6,600 kg, that the exemptions do not permit agricultural operations in the restricted category above 4,700 kg MTOW. CASA also advised that they will be revising the exemptions to ensure that the intended interpretation is clear to operators.
The ATSB is satisfied that, when completed, the action taken by CASA will adequately addresses the safety issue.
