**1. Introduction**

Aviation is a heavily regulated industry for the purpose of safe operations. All aircraft maintenance, including those in the General Aviation (GA) sector, falls under the scope of these safety regulations, since maintenance is an essential activity for sustaining airworthiness (denoted as continuing airworthiness). The GA aircraft operation, as defined by the International Civil Aviation Organisation (ICAO), is an aircraft operation other than commercial transport operation or aerial work operation [1]. The nature and the needs of the GA sector are invariably different to those of commercial air transport conducted with the use of a large complex aircraft. The GA sector has a lower risk profile (as measured by the impact of an accident). In particular, if one considers the systems safety view of risk, whereby risk is a combination of the likelihood of the hazard and the consequences of any ensuing accident [2], then, although the probability of having an accident in GA is higher than in commercial aviation [3], the lower severity of such accidents results in a lower risk profile. Moreover, GA is characterized by highly diverse operations, operators and (mostly ageing) aircraft fleets, in conjunction with scarce/unavailable financial, infrastructure and human resources (mainly attributed to the aircraft owner's limited financial capacity). This unique mix has an effect both on the continuing airworthiness rules for GA aircraft and also on how maintenance is actually practiced within this sector of the aviation industry. Thus, we often see that in the drafting of regulations and regulatory oversight in GA, a "one size fits all" approach is not the norm at a worldwide level.

In an attempt to regulate GA operations in a proportionate (and cost e ffective) manner, continuing airworthiness rules and oversight are typically less stringent than in commercial air transport [4]. Therefore it is interesting to examine the safety performance of the GA sector, namely the safety record in relation to maintenance-related accidents. The GA aircraft maintenance has been identified as an accident-precipitating factor [5], with 30% of accidents in Australia attributed to this [6]. For the Australian GA sector, this observation is alarming when taking into consideration the size of the fleet (nearly 90% of all aircrafts), its flight activity (40% of total flight hours are produced by GA aircraft) [7], and the maintenance burden cost (close to 20% of the total operational expenses for GA aircraft) [8]. In practical terms, retaining the same safety record would increase the absolute number of maintenance-related accidents if there is a continued growth of the activity.

The Australian civil aviation regulator, CASA (Civil Aviation Safety Authority), has recognised the need for safety improvements, via a regulatory reform and modernization/alignment against best practices at the international level. Special attention has also been placed on ageing aircraft issues (structural fatigue, corrosion, etc.), as the Australian fleet has an increasing average age [8]. It is of note that CASA approached this matter with a change managemen<sup>t</sup> mindset, attempting to achieve a consensus from the regulated parties. The managemen<sup>t</sup> of change, as a systematic approach/methodology to enable change at an individual and organisation level [9], has also been promoted by CASA for safety managemen<sup>t</sup> purposes in the wider aviation industry [10]. Past CASA attempts to impose regulations or dictate mandatory actions did not have the expected result, as compliance was found to be problematic. An extensive industry consultation process was employed for this purpose during 2018−2019 [11]. Tailoring of maintenance regulations (framework, oversight, and practice) for the GA aircraft was a topic on the industry's "wish list" from this consultation. This finding has also confirmed the feedback collected by CASA from their previous interaction with the GA sector.

Eventually, CASA decided to introduce a new set of maintenance regulations that mirrored the United States (US) Federal Aviation Administration (FAA) rules for GA aircraft, with these outlined in CASA's consultation accompanying documents [11]. The FAA rules' approach was by far the preferred industry choice, recording a 78% acceptance rate [11]. The decision to follow the FAA regulations for GA aircraft is not consistent with the CASA's overall regulatory structure and philosophy, as the Australian Civil Aviation Safety Regulations (CASRs) largely follow/mirror the European Aviation Safety Agency (EASA) rules. This triggers questions on the underlying reasons that provoke this type of change as well as what challenges may manifest as part of transitional e ffects.

Given the alarming statistics in the Australian GA sector, research by Naweed and Kingshott [12,13] undertaken in the interstices of work and safe operations in the Australian GA sector, has examined how a ffect influences decision making and action tendencies in maintenance engineering scenarios. This body of research has identified numerous contextual factors that feature in ways of working and give rise to system behaviours that can have a direct impact on safe operations. Identified contextual factors included distraction under pressure, incorrect manuals, maintenance costs, perceived customer disloyalty, managerial interference, and negative rumination. A number of the findings also echo normalisation of deviant behaviour, a theoretical stance where maladaptive practices come to be accepted as the norm [14,15], and which reflect a complex array of interacting factors at play where Rumsfeldian "unknown unknowns" can often loom large [16].

Empirically exploring the industry's perception on the role of regulations and the regulator, as well as other factors that may directly impact the practice of maintenance on GA aircraft, is necessary to obtain a better understanding of what is happening at an end-user level. The technical sta ff directly involved in conducting and certifying maintenance, as well as the aircraft owners, are both key stakeholders in the airworthiness sustainment business.
