建構民用航空器發動機維修業作業基礎成本制資訊系統

Abstract

民航發動機維修業具有資本與技術密集、維修範圍多樣化、流程複雜及作業時間變異性大等特性。為協助維修廠做好管理決策，俾增進其獲利性，須擁有以下資訊：（1）維修作業耗用之各項資源，（2）維修作業與流程成本，（3）不同維修範圍所關連到之作業量、成本與獲利，（4）不同顧客對維修作業之需求差異。然而目前所採行的傳統成本制度卻無法依照不同的維修範圍、不同的顧客需求提供準確的成本資訊，亦無法指出維修廠各項資源耗用與執行作業之因果關係。因此，本研究嘗試以作業基礎成本制建構民航發動機維修業之作業基礎成本資訊系統，並且利用此系統所產生的各種資訊，進行作業基礎管理應用之示範。 有關作業基礎成本資訊系統發展方面，包括（1）界定成本標的、（2）決定作業、（3）確認作業中心、（4）從分類帳找出各部門成本、（5）重整財務資料、（6）選擇資源動因、（7）選擇作業動因、（8）定義屬性以及（9）計算產品成本。本研究選擇一個案公司進行研究，界定成本標的為每具待維修之發動機，其次決定發動機各項維修作業與作業中心，瞭解作業內容與其執行之組織單位，之後找出有關發動機維修之部門成本，並將個案公司財務資料加以重整。完成財務資料重整後，選擇適當的資源動因與作業動因，將資源成本歸屬至作業，並將作業成本歸屬至其相關之成本標的。此外，此一系統可依維修廠各種管理決策需求，增加屬性欄位，以提供特定資訊。最後則是計算產品的成本。另本研究在系統發展過程中應用Oros ABC/M商業模型軟體加以輔助，以進行相關資料構建與計算工作。 在作業基礎管理應用方面，本研究以（1）作業成本分析、（2）流程成本分析、（3）作業價值分析、（4）產品成本分析、（5）成本動因分析為例。作業成本分析指出個案公司之發動機試車作業成本最高，另作業動因費率的資訊可作為預期支出功能。流程成本分析顯示模組組裝流程成本最高，另亦可提供管理者作為選擇改善作業流程優先順序之參考。作業價值分析指出料件籌補作業屬於無附加價值作業。產品成本分析可瞭解不同維修範圍之發動機維修成本差異，亦可瞭解發動機機型、結構之成本分佈情形。成本動因分析指出作業如何消耗資源、資源項目為固定或變動成本、預算與實際發生成本比較、成本標的對作業的需求情形以及作業績效衡量。

The civil aircraft engine maintenance business includes the following characteristics: capital and technology intensive, diversification of work scope, complexity of processes, variation of maintenance time of activities, etc. For helping make managerial decisions and make profit, maintenance plants require following information:（1）related resources used by different activities,（2）the costs of different activities and processes,（3）related activities, cost and profit by different work scope,（4）the frequency and intensity of use of activities by different customers. However, the traditional cost systems can not provide accurate cost information according to different work scope or different demamds of customers. Besides, we can not understand the relationships between used resources and related activities of the maintenance plant. Hence, this study attempts to construct an activity-based costing（ABC） information system for civil aircraft engine maintenance business, and to demonstrate the applications of activity-based management（ABM）. The ABC system is developed through the following steps:（1）identifying cost objects,（2）identifying activities,（3）creating activity centers,（4）developing department cost from the general ledger,（5）reconstructing the general ledger,（6）selecting resource drivers,（7）selecting activity drivers,（8）defining attributes, and（9）calculating the cost of products. This study adopted a case study. The author identified cost objects as each engine. Then the activities of engine maintenance and activity centers were identified for understanding the content of activities and the unit of organization of activities accomplished. Next, developed department cost and reconstructed the general ledger. Then selected appropriate resource drivers and activity drivers to assign cost to activities, and assigned cost to cost objects based on related activities. Besides, the ABC system increased some columns of attributes on the basis of managerial decisions to provide the relevant information. The last step of the ABC system developed is to calculate the cost of products. This study applied Oros ABC/M software to constructing and calculating related data. For ABM, this study demonstrated the following example:（1）activity cost analysis,（2）process cost analysis,（3）activity value analysis,（4）products analysis, and（5）cost driver analysis. Activity cost analysis showed that the cost of engine test is the most expensive, and that activity unit cost can be used to expect the future expenditure. Process cost analysis indicated the cost of module assembly process is the most expensive. Besides, it can provide managers with priorities of processes improvement. Activity value analysis showed that the non-value-added activity is marshalling. Products analysis can understand the cost difference of engine maintenance according to different work scope. Moreover, it can provide the cost of different engine models and structure. Cost driver analysis can reveal how activities consuming resources, fixed/variable costs of different resource items, the comparison of actual cost and budget cost, the related activities used by cost objects, and performance measurement by activities.