How important is a shift/task turnover in aircraft maintenance? Let's take a look at an historical accident investigation that helped change the safety culture in aircraft maintenance. The accident aircraft was an Britt Airways Embraer 120RT, N33701, operating as Continental Express flight 2574 which crashed in Eagle Lake, Texas on September 11,1991 as a result of an in-flight structural breakup, killing all 14 people on board.
According the National Transportation Safety Board (NTSB) aircraft accident report:
The evidence is clear that the events during the maintenance and inspection of N33701 the night before the accident were directly causal to the accident. Several errors were made by the individuals responsible for the airworthiness of the airplane. The Safety Board believes that the reasons for the errors and the overall failure of the maintenance program are complex and are not simply related to a single failure by any single individual. Consequently, the Safety Board's analysis of the maintenance and inspection program concentrated on the systemic reasons for the accident, as well as the specific errors made by the individuals concerned.
The Safety Board concludes that the upper row of screws that had been removed from the leading edge of the left horizontal stabilizer was undetected because the approved procedures in the General Maintenance Manual were not followed by the maintenance, supervisory and quality control personnel directly charged with evaluating the airworthiness of N33701 before it was returned to service.
The following are examples of substandard practices and procedures and oversights by individuals, who had an opportunity to prevent the accident:
The second shift supervisor responsible for N33701 failed to solicit an end-of-shift verbal report (shift turnover) from the two mechanics he assigned to remove both horizontal stabilizer deice boots. Moreover, he failed to give a turnover to the oncoming third shift supervisor and to complete the
maintenance/inspection shift turnover form. He also failed to give the work cards to the mechanics so that they could record the work that had been started, but not completed, by the end of their shift.
The Safety Board believes that the accident would most likely not have occurred if this supervisor had solicited a verbal shift turnover from the two mechanics he had assigned to remove the deice boots, had passed that information to the third shift supervisor, had completed the maintenance shift turnover form, and had ensured that the mechanics who had worked on the deice boots had filled out the M-602 work cards so that the third shift supervisor could have reviewed them.
Chapter 4, Shift\Task Turnover, of The Operator’s Manual for Human Factors in Aviation Maintenance states:
Shift and task turnover are critical periods in aircraft maintenance activities because workers relay crucial information for ending a shift and starting another. This can also apply to an exchange of task information within a shift. Efficient and effective turnovers require adherence to policies, procedures, planning guidelines, teamwork, and effective communication practices. The classic challenges associated with fatigue, distraction, false assumptions, personnel conflicts, cultural prejudices, and failure to properly document can negatively affect the quality of shift turnover as well as task turnovers within shifts. Events have shown us that inadequate information exchange during shift and task turnovers can have serious consequences.
If you cannot complete a maintenance task before you leave work, it is your legal responsibility to document what has been accomplished and/or what has been left undone. This vital information should then be passed down to the next mechanic taking over the job or as a reminder to yourself if you will be the one resuming the task at a later time. This is also important to do prior to taking an extended period away from the job site such as a lunch break.
A shift/task turnover may be a mundane task, but this accident is a sobering reminder to take an extra few minutes before you walk away from a maintenance task to record this critical information. It could mean the difference between life and death.