Created Friday, Mar 31st 2023 13:13Z, last updated Thursday, Aug 10th 2023 15:05Z
A Link Airways Saab 340B on behalf of Virgin Australia, registration VH-VEZ performing flight
VA-625 from Canberra,AC to Sydney,NS (Australia), was climbing out of Canberra when the crew stopped the climb at about 12,000 feet due to the failure of the pressurization. The aircraft continued to Sydney at 10,000 feet for a safe landing about 40 minutes after departure.
Australia's TSB reported on Mar 31st 2023: "During the pre-flight inspection, the crew identified missing trim from the cabin door. During climb, the aircraft did not pressurise as expected and the crew conducted a precautionary descent. The engineering inspection identified a door seal failure. The investigation is continuing."
On Aug 10th 2023 the ATSB released their final report concluding the probable causes of the incident were:
Contributing factors
- The misidentification of the cabin door seal seat as door trim resulted in the company deferral process being incorrectly applied.
- An additional piece of broken door seal seat was misidentified as the section deferred the previous night. In combination with the previously deferred item, this resulted in degradation of cabin pressurisation during the following flight.
The ATSB analysed:
Application of non-safety of flight defect deferral
Part 42 of Civil Aviation Safety Regulations6 allows continued operation of aircraft with minor defects that are not immediately repairable. The operator’s non-safety of flight defect (NSOFD) deferral process was written and approved in accordance with these regulations.
The application of the NSOFD deferral process was applied by the terminating flight crew and the approving licenced aircraft maintenance engineer based on an incorrect assessment that the defect was to a piece of internal trim with no consequence to aircraft serviceability. While a piece of door cosmetic trim would be considered a deferrable defect, the door seal seat defect adversely affects aircraft airworthiness and is therefore not eligible to be deferred under the NSOFD process.
It is important that the licenced aircraft maintenance engineer accurately identifies a defect and its potential effect on aircraft systems prior to applying a maintenance deferral. In this case the use of photo or video to supplement the phone call between the involved pilot and licenced aircraft maintenance engineer would probably have enabled the engineer to identify the detached components as not eligible for repair deferral. This in turn would have resulted in the aircraft being repaired prior to further flight.
Misidentification of additional defect
The ability to defer defects on aircraft is reliant on the ability to accurately communicate the defect between aircrew and maintenance engineering as well as off going and on coming shifts.
The existence of a second defect was not understood by the on-coming flight crew and was not identified until sometime after the incident flight. The specific level of contribution of each section of broken door seal seat could not be determined, however it is likely that the combined effect of both pieces of broken door seal seat was greater than either individual piece, and resulted in degradation of the aircraft’s pressurisation system.
Maintenance and Inspection notes:
Effective shift turnover depends on three basic elements:
1. The outgoing worker’s ability to understand and communicate important elements of the job or task being turned over to the incoming worker.
2. The incoming worker’s ability to understand and assimilate the information being provided by the outgoing worker.
3. A formalized process for exchanging information between outgoing and incoming workers and a place for such an exchange to take place.
Where the possibility of ambiguity exists, it is important that aircrew and maintenance staff take the necessary steps to clarify the message being communicated. This will assist defect identification generally and, in this instance, would have prevented continued operation of an unserviceable aircraft.
Related Flight:
VA625, Twitter:
#VA625,
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