This dissertation investigated aircraft maintenance teams performing inspections and repairs in the hangar environment of modern commercial aircraft maintenance organisations. Generalisations of all findings are intended to advance knowledge and research practice on work teams in complex work systems. After a review in Chapter 1 and 2 of the main team concepts, models and major team research directions in today commercial aviation environment, a number of six new hypotheses are proposed in Chapter 3: the impact of team competence versus external systems on operational performance (i.e., team externality), situational teamwork, adaptation and work practices, the concept of team risk distribution (i.e., Friedlander argument), and the relation between organisational resources and team proficiency. In Chapter 4 a composite model of work team in aircraft maintenance is proposed and the interdependent nature of team operations uncovered. Chapter 5 follows with an analysis of the team-attitude-behaviour-performance relationship. Chapter 6 provides evidence on the highly contextual and situational nature of teamwork in aircraft maintenance. Chapter 7, 8 and 9 the research focus widens to all processes and systems of the maintenance operation. The organisation of team performances highlights what it is here called the team externality concept. A team externality defines the specific performance of a system that is not controllable by the work team, which turns out to be dependent on that external performance. Apparently, a key hypothesis underlining the entire research is confirmed: for highly dependent systems like operational teams in hangar maintenance it is the environment (externalities) that accounts for performance more than internal team capabilities. Findings in Chapter 8 and 9 seem to suggest also a form of performance limitation that, apparently, work teams in the maintenance operations cannot overcome. Every team locally gets some supports from the organisation but not sufficient to express very high performances. This comes under the name of team risk distribution (Chapter 9) and appears to be an implicit organisational strategy to maintain a complex economy of pooled and limited resources. Finally, in Chapter 10, a new team model, the team multivariate frame is proposed and discussed. Such model underlines a system requirement proposed in Chapter 8 and termed minimal critical order of causality: the widest source of dependencies (largest set of time/sequence orders) within a process will contain the minimal causal chain to comply with and generate the maximal leverage on the system. This requirement simply suggests that there is a temporal-sequential and causal order between different upstream and downstream process elements (e.g., teamwork events, contained by work processes, contained by the organisation). In essence, upstream solutions, even external to teams, are to be favoured to optimise, downstream, operational team events and performances. Overall, causal models and explanations of team performances would miss a serious point if such explanations disregard the model of the overall business approach taken by the organisation to control its economy.

JRC.G.7-Traceability and vulnerability assessment