Maintenance incidents contribute to a significant proportion of
worldwide commercial jet accidents, yet until recently, little was
known of the nature of maintenance incidents and the factors which
promote them.
In face-to-face interviews, maintenance technicians were asked
to report examples of maintenance incidents which they had
experienced first-hand. Eighty-six incident reports were
recorded.
Human factors were involved in most of the reported incidents,
with workers on duty between the hours of 0200 and 0400 having a
greater chance of having an incident than workers on duty at other
times of the 24-hour clock. The frequency of incidents increased as
the shift progressed up to the second-last hour, after which the
frequency of incidents diminished.
For those incidents which had the potential to affect the
airworthiness of an aircraft, difficulties with procedures emerged
as the most significant factor. This included misunderstandings and
ignorance of procedures.
For those incidents which had the potential to affect the health
and safety of workers, difficulties with tools and equipment
emerged as the most frequent factor.
The majority of the human errors involved in incidents were
rule-based mistakes, many relat-ed to mistaken assumptions.
Absent-minded slips and lapses were involved in approximately
one-third of the incidents.
The final section of the report contains suggested safety
actions, intended firstly to reduce the frequency of human error
and maintenance incidents and secondly, to reduce the conse-quences
of any such errors which do occur.