On 1 January 2021, the Skippers Aviation contracted aeronautical engineer submitted an engineering order (MEO-0400-003 Rev 0: Emergency exit door - bondline modification) with supporting documentation to the Civil Aviation Safety Authority. The purpose was to seek regulatory authority to approve changes to the emergency exit door as a major modification for Skippers Aviation Cessna 441 aircraft.
The engineering order modified the bonded skin assembly of the emergency exit door with the installation of backup rivets through the bondline. After return-to-service, the modified emergency exit door was subject to additional inspection requirements, which included a detailed visual inspection and ultrasonic inspection.
On 6 January 2021, the Civil Aviation Safety Authority provided their design advice response, which approved the modification, but also indicated that a full review of the analysis used for the structural inspection procedures was required. On 2 June 2021, the Civil Aviation Safety Authority reported the proposed structural inspection procedure was still under review and they had provided feedback to an authorised person (CASR Part 21M) regarding the procedure.