Airliners Engine Maintenance Management under Overall Care Model *

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1 Journal of Aeronautics, Astronautics and Aviation, Series A, Vol.42, No.3 pp (2010) 191 Airliners Engine Maintenance Management under Overall Care Model * Chin E. Lin ** and Wu-Chang Huang Department of Aeronautics and Astronautics, National Cheng Kung University No.1, Ta-Hsueh Road, Tainan 701, Taiwan, R.O.C. ABSTRACT With the advent of high fuel costs, it has become increasingly important for airlines to concentrate on their core business on maximizing operational capacity with minimizing costs and financial risk. While different operation models of maintenance strategy have been presented, the Overall Care Model operated by the Original Equipment Manufacturer (OEM) is closely developed for airline customers. This paper investigates the feasibility of applying Overall Care on domestic airline new fleet. TotalCare provides a single source solution which ensuring the lifetime support for the engine, from the time the engine is delivered to the customer until the engine goes out of service. The goal is achieved through sharing of knowledge, expertise and experience between airlines and OEM providers. The feasibility of TotalCare to newly formed fleet is surveyed to summarize some possible actions to new organization and management to meet the performance requirements. Keywords: Engine maintenance, Overall Care, TotalCare, Power-by-the-Hour, Original Equipment Manufacturer I. INTRODUCTION Maintenance management can best be defined as the integration of technical, commercial and logistics to a seamless fleet management program. Strategies adopted for maintenance management will vary depending upon numbers of factors [1]. The most significant key factors are the nature of the airlines business and operational strategies (low cost carrier or flag carriers). On the most recent contract from China Airlines, engine maintenance contract is signed up with Rolls-Royce for Trent XWB engine to power a fleet of 14 firm and 6 option Airbus A350 XWB twinjets on January 22, New issue on key operations for the total care concept in airlines is arisen. The new generation medium-capacity, such as seat, and long-haul aircraft is being acquired by China Airlines as part of their future fleet modernization program. The potential value of the business, which includes a long-term engine maintenance management of Total Care Agreement by Rolls-Royce [3], has been chosen as an engine supplier by China Airlines and implemented into the engine maintenance management under the TotalCare, marks the debut of the Trent engine series in Taiwan. Total Care Agreement is designed and customized-fit for individual airlines operators, to offer a range of services from Rolls-Royce covering all aspects of asset management in support of its civil aerospace products. These services include elements such as predictive maintenance, logistics management and global repair and overhaul offerings [3]. Based on the newly development, the engine maintenance management model will be introducing to China Airlines in This paper is mainly derived from TotalCare program [3, 4] by Rolls-Royce including three major parts: (1) Information and Management on engine health monitor, engine management and technical publications; (2) Repair and Overhaul for planned shop visit, un-planned off-wing maintenance and accuracy repair and overhaul; (3) Operation Support for technical support, asset management and line support [5]. The feasibility study on TotalCare program in China * Manuscript received, Nov. 16, 2009, final revision, May 25, 2010 ** To whom correspondence should be addressed, chinelin@mail.ncku.edu.tw

2 192 Chin E. Lin Wu-Chang Huang Airlines new fleet will be surveyed. How to contribute such a new concept and new model system into airline operation would need some preparation to accommodate the fleet management. II. MAINTENANCE STRATEGY CONCEPT Considering the major factors in engine maintenance, airline may assess and drive the choice of a maintenance management strategy [4] as shown in Figure 1. By drawing upon examples that engine maintenance overall care has seen within the industry, how to identify the strategies which are most likely to different types of operation becomes the most fundamental and principle consideration. The concept of PBTH (Power by the Hour) was developed and initiated by Rolls-Royce over the past two decades to describe their performance-based contracts for engines to commercial airlines. Today, engine manufacturers such as General Electric, Pratt & Whitney, and Rolls-Royce all have established their owned long-term and performance-based contracts with commercial airlines. A large number of airlines have been outsourcing their engine maintenance for operators with two different models as T&M (Time and Material) contracts or PBTH contracts. Figure 1 Engine maintenance management considerations [4] 2.1 T&M Model Time & Material (T&M) model is a traditional business model when both sides could not ensure the total cost before the agreement [4, 6]. T&M contract includes a basic quotation on work-man-hours, materials and facilities. Therefore both sides will compromise or negotiate the terms for the calculation cost basis. Major terms include [7]: Labor rate including mechanic and engineer charge rate; Material handling charge concerns new material handling charge, material outsourcing handling charge, material exchange handling charge; Customer provided material handling charge; and Engine test charge. The principle of time and material contracts is that engine shops are required to perform shop visits by an airline s request. Time and material keep the control of maintenance in-house when the airline determines engine removal and shop visit work scopes. This requires airlines to maintain an expertise for engine management and the monitoring of shop visits, and they carry all the risk of engine maintenance. 2.2 PBTH Model The Power-by-the-Hour (PBTH) concept was introduced in the early 1990s for the European regional airlines, whose capital base may be limited, the major airlines prefer to an intensive maintenance package. Most recently the airlines concentrate on the reliability and utilization of the existing equipment parts If the spare parts are not being used frequently, airlines sell the equipment to the open market, recouping a benefit from those spare parts as their initial investment. The early PBTH agreement involved mostly on the power plants, hence the name PBTH is common and well prevailing to an aviation industry. Actually fixed-price maintenance programs have many different terminologies presently [9]. These programs have evolved considerably over years as a tool for predicting future maintenance needs. The scope of parts varies from an engine, avionics to landing gear and so on. PBTH was a hot issue on an aviation industry in recent year, while some of airline operators have doubted a win-win situation of the model of PBTH, further complaints to the contained - PBTH contracts are: which parts should or should not be covered under the PBTH model. On the opposite side, the Original Equipment Manufacturer (OEM) complains that some operators take advantage of their PBTH arrangements by insisting that the manufacturer pick up the tab for maintenance problems that were blamed to the operator s fault. Most manufacturers PBTH programs covers scheduled and unscheduled shop visits based on a cost-per-flight-hour (CPFH) fixed rate. For engines, optional items included a spare engine availability, foreign object damage (FOD) coverage, Service Bulletins (SB) and LRU (Line Replaceable Unit). Typically the PBTH program coverage items should be excluded under a circumstance of the engine operating beyond a normal operation guideline. Fee charged for engine-related PBTH program typically are based on three variables: utilization per year, flight time and how much the particular engine has been de-rated. An operator that flies in a more severely environment will pay more PBTH fee monthly. Criteria for PBTH program offered by other equipment manufacturers are similar. Many benefits in PBTH program is tied directly to airlines weight in outsourcing for all or most of their heavy maintenance needs. Like they did with catering, airlines are considered to outsourcing more maintenance task as part of long-term plans to return in core activities. This trend, if it continues, will keep the door of opportunity open wider for across-the-board PBTH programs.

3 Airliners Engine Maintenance Management under Overall Care Model 193 III. ENGINE FLEET MANAGEMENT (EFM) In the aviation industry, not only aircraft maintenance cost but also engine maintenance cost has inclined to an unlimited black hole which a large amount of money has returns little profits. Most airlines endeavor to reduce cost and increase productivity, top management begins to realize that well-maintenance management can offers real opportunities in both ends. The maintenance workload is greatly influenced by the maintenance philosophy [8], There are two maintenance tasks being introduced, where (1) the Preventive maintenance carries scheduled repairs and rebuilds based on the Mean Time Between Failures (MTBF), in order to prevent sudden failure of equipment and assure an operation in a satisfactory manner; and (2) the Predictive maintenance monitors the mechanical conditions and the system efficiency, aims to predict the precise failure time under close accuracy [10]. 3.1 Engine Performance Exhaust gas temperature (EGT) is an important parameter for engine operation, since an engine is not allowed to operate if EGT value exceeds the engine s EGT Red Line. At maximum rated takeoff power, the engine endures the highest pressures, temperatures and rotor speeds. The highest EGT value of an engine cycle (engine startup to shutdown) occurs widely during takeoff phase. Engine ratings are the manufacture s guarantee for the performance of specific type engine, i.e. takeoff rating, maximum continuous rating, and etc. At or below the flat rated temperature (around 30 C for most engine types), the engine produces the maximum amount of thrust with lower EGT levels due to cooler air being ingested [11]. A flat rated engine gives a constant thrust for all ambient conditions below flat rate temperature. It makes sure that the necessary thrust for take-off and climb. This increases the engine service life. EGT Margin is the distance from an engine s actual EGT to the EGT Red Line while at full rated power, at a specified outside air temperature, usually the flat rated temperature, as shown in Figure 2 [4, 13]. Thrust production is reduced to hold EGT close to constant [12]. 3.2 Airlines Fleet Management Basically, there are three key elements of the total operating cost for airlines. Each of these elements has a direct impact on engine reliability as (1) Engine Maintenance Cost (EMC), (2) Aircraft Indirect Operating Cost (A/C IOC), (3) Fleet Fuel Consumption (FC) [12]. The engine maintenance cost should be monitored on a continuous basis and the variables affecting the cost should be clearly defined. The variables affecting maintenance cost can be grouped into four categories: (1) Operational environment: (a) sea level cold versus high altitude hot, (b) short haul flight Legs versus long haul flight Legs. (2) Engine age: first run engines versus mature engines Figure 2 EGT Margin Concept [4], for 1 New Engine, 2Deteriorated Engine, 3Limited Engine (3) Accounting practices: assets, depreciation rates (4) Airline maintenance practices and policies: In-house refurbishment versus vendor, on-condition versus hard time. The engine work scope plan should be meet the expected engine time on-wing. The expected time on-wing could set the desired fleet mean time between shop visit rates (SVR). Once a desired fleet SVR threshold level is set, the engine workscope plan should be designed to meet this target. IV. OVERALL CARE PROPOSAL (OCP) STUDY Overall Care is a comprehensive solution that provides customers with a superior method of managing engines maintenance management for economically and efficiently [13]. This long-term service package delivers technical predictability and financial stability, allowing the airline management team to focus on core business. An Overall Care service package benefits airline operator by: (1) Providing predictable engine operating costs; (2) Reducing administrative burden of engine management; (3) Transferring product risk to engine OEM; (4) Allowing more accurate budgeting; and (5) Improved business planning. An Overall Care Agreement incorporates the first aircraft and continue whilst ever the aircraft remain in service for the airlines, commence from the date of entry into service in airlines operation, typically, the Period of Cover subject to a minimum term of ten to fifteen (10 ~15) years. 4.1 OCP Covered Services Engine OEM should take responsibility for the following services of Qualified Events. They are (1) Engine Shop Maintenance on Overhaul Basis, (2) Emergency Lease Engines: Provide an emergency lease engine under pool parts agreement, (3) Engine Management Program (EMP), (4) Engine Health Monitoring (EHM) services, (5) Overall Care Program (OCP) Management: Shop visit planning support and workscope Management, (6) Line Replaceable Unit

4 194 Chin E. Lin Wu-Chang Huang (LRU), (7) Engine Transportation, (8) Line Maintenance Technical support. 4.2 Airline Operator Responsibility Under the Overall Care Agreement (OCA) outlined in this proposal, airlines should take a responsible for the costs associated with Non-Qualified events and the provision of services [13, 14, 15]. The Overall Care services is under continual monitor and review by both OEM and Airlines, to ensure a well services, in order to create a win-win situation and benefits for both ends meet. By charging for Overall Care on a dollar per engine flying hour ($/EFH) basis, engine OEM acts as an operational and financial partnership with the airlines operator, where the incentives and rewards are complementary. Engine OEM is rewarded for its engine staying on the wing, and therefore, OEM encouraged and makes efforts to keep that engine s component in the best condition as possible. 4.3 Engine Health Monitoring (EHM) EHM is an essential part of modern aircraft engine management, helping to prevent aircraft in-service disruption and optimize operating costs. Utilize OEM s (Original Equipment Manufacturer) EHM software system to monitor and analyze on-wing engines operating condition in order to find abnormal trends at an early time, then take corrective actions aim to prolonging the engine life. This quality procedure not only assist in monitoring the on-wing engines performance, but also assist with maintenance shop load planning and spares scheduling [14]. The necessary parameters include Flight Level (FL), Total Air Temperature (TAT), Mach Number (Mn), and N1, N2, EGT, F/F, AVM etc. OEM s EHM software can process the above data and produce trend reports which are analyzed by Powerplant System Engineer in order to figure out the engines performance deterioration for long term or the corresponding system / components failures for short term [15]. Operating Requirements, CFR (Code of Federal Regulations) , Responsibility for Airworthiness. (1) Each certificate holder is primarily responsible for: the airworthiness of aircraft, including airframes, aircraft engines, and the performance of the maintenance, preventative maintenance, and alteration of its aircraft, including airframes, aircraft engines, in accordance with its manual and the regulations. (2) A certificate holder may make arrangements with another person for the performance of any maintenance, preventative maintenance, or alterations. 4.4 Engine Health Monitoring Tools AIRMAN System AIRMAN (AIRcraft Maintenance ANalysis) [16] system was developed by Airbus. It is a tool for aircraft maintenance system data analysis, as shown in Figure 3. Its objective is to help airlines maintenance department to monitor aircraft non-routine events and linked the fault message to other relevant maintenance manual, such as AMM (Aircraft Maintenance Manual), IPC (Illustrated Parts Catalog), ASM (Aircraft Schematic Manual) and WDM (Wiring Diagram Manual), to participate troubleshooting for the upcoming or existing non-routine event. Figure 3 AIRMAN A/C status menu AIRMAN receives real time information of ACARS OOOI (Out, Off, On, In) times; PFR (Post Flight Report) for faults and warnings, and to acquire and display all ACMS (Aircraft Condition Monitoring System) reports. AIRMAN features to simplify the analysis of the PFR, and display fault cases by correlating fault messages and warnings that are linked together, as shown in Figure 4. Figure 4 AIRMAN Link to TSM for troubleshooting ACMS System In the face of state-of-the-art technology like the fly-by-wire, or the Full Authorized Digital Engine Control (FADEC), the complexity of the aircraft systems leads to the development of the Central Maintenance System (CMS), and the Aircraft Condition Monitoring System (ACMS) [17]. ACMS is designed to collect data from onboard aircraft ARINC 429 DITS (Digital Information Transfer System) data busses and dedicated discrete inputs. The ACMS analyzes and sorts this information according to the users' needs, and then distributes the resulting information accordingly in the form of printout on the Multiple Cockpit Printer, down linked via the Aircraft Communication Addressing Reporting System (ACARS),

5 Airliners Engine Maintenance Management under Overall Care Model 195 displayed on the Multi-purpose Control Display Unit (MCDU), for maintenance troubleshooting-aids requirement. The ACMS mainly consists of the Data Management Unit (DMU), and an optional DAR. The DMU is the central part of the ACMS, The DMU is a high-performance avionic computer specialized for the acquisition of ARINC 429 DITS data and associated processing. The applied ACMS format is shown in Table 1. Table 1 ACMS Format (Sample) typical ACARS reports of Crew identification, OOOI times, Engine performance, Flight status, and Maintenance items. V. RELIABILITY CONTROL PROGRAM China Airlines (CAL) is authorized to operate its airplanes under a Reliability Program. This program will ensure the Continuous Airworthiness of all airplanes operated by CAL. This program combines the function of inspection, and maintenance to fulfill CAL's total maintenance needs. This Reliability Program is made of two elements, a Maintenance Program (MP) and a Reliability Control Program (RCP). The Reliability Control Program is based on the principles set forth in the FAA Advisory Circular A, entitled Maintenance Control by Reliability Methods. 5.1 Maintenance Program The Maintenance Program is documented in five parts of (1) The Aircraft Maintenance Program (AMP), (2) The Engine Off-wing Maintenance Program (EMP), (3) The Component Maintenance Program (CMP), (4) The Engine Condition Monitoring System (ECM), (5) The Oil Consumption Monitoring Program ACARS System The aircraft ACARS is a voice and data communication system to manage flight plan data, and maintenance data between the airplane and the airline. It reports between an airplane and ground base. A message or report from the airplane to the airline ground base is called a downlink. A message or report from the airline ground base to the airplane is called an uplink. ACARS automatically sends reports when necessary and at scheduled times of the flight to reduce crew workload. The ACMS provides an interface for communicating with an ACARS function per the requirements of ARINC 724 and ARINC 724B. The ACARS interface provides the capability of Automatic Downlink of ACMS Reports via the MCDU. ACARS Communication Protocol is established by a dedicated low speed ARINC-429 bus to transmit data to the ACARS, and a separate low speed ARINC-429 bus to provide receiving data from the ACARS. These are 5.2 Reliability Control Program The Maintenance Program is continuously optimized and updated to reflect recent experience, and to correct shortcomings identified by the Reliability Control Program [18]. Therefore, this process should be carried out mainly by means of a Reliability Control Program. It contains data collection from aircraft, performance analysis, problem investigation and then system correction until reliability reaches certain optimized level. According to this Reliability Control Program, all maintenance activities are accomplished in a closed loop function, ensure a safe, reliable and economical fleet operation. The Reliability Control Program is managed, and governed by the Reliability Control Board (RCB). The Reliability Control Program is an event-reporting system. It provides a means of measuring the performance of aircraft systems and components, and comparing the performance to predetermined acceptable levels of performance. The event-reporting system and analysis of the data from the reporting system permit the rapid identification of adverse trends. If systems and components do not able to meet acceptable levels of performance, an alert is issued and an investigation is initiated to assess the problems and initiate corrective actions. The China Airlines (CAL) Reliability Control Program [18] monitors the performance of each fleet of aircraft operated by the airlines. Events monitored by the program, including scheduled maintenance, unscheduled maintenance, engine/component removals and failures, significant findings, delays and cancellations event, to ensure the continuous optimization of the Maintenance Programs.

6 196 Chin E. Lin Wu-Chang Huang VI. DISCUSSION This paper explores airline s engine maintenance management under Total Care model, operated by Rolls Royce Trent series engine, especially designed to help airliner to develop Total Care management skill, the new concept of engine maintenance management which operated by Rolls Royce will debut in Taiwan aviation sector in In terms of technical point of view, thus successful strategy to meet in Taiwan aviation environment relies on the following considerations: (1) A Total Care Contract can be regarded as an insurance policy, where cover range from basic protection against the more unforeseen events. Operators might ask themselves, whether they want simply to cover the material, labor and testing associated with unscheduled events, and so avoid bad surprises, or if they wish to include aspects such as mandatory repairs, service bulletin (SB) actions, replacement of life limited parts (LLPs), refurbishment of line replaceable units (LRUs) and foreign object damage (FOD) repairs. (2) An absolutely comprehensive overall care package might include all of these along with technical assistance, logistics management, emergency inventory cover (including spare engines) and technical documents update. (3) Engine OEM has to involved engaging more actively and continuously interactive with customers, A imperative strategic was to build up global repair service and overhaul capability to cope with any unscheduled events. In case of AOG (Aircraft On Ground) event occurred, a strong technical supports will be offers timely from worldwide technical service, via seamless technical supports to ensure continuous revenue flight. (4) An on-board engine health monitoring (EHM) system features on-board monitoring function, once abnormal status is detected, EHM system will automatic downlink real time engine parameters and fault message to maintenance home base facility. Concurrently, EHM system monitors engine performance adverse trends so that home-based engineer can analyze it and determines if the subject engine should need to remove immediately or can be cleared to safe to fly condition under closely monitor before have to conduct a shop level check. Total Care management offers customers with risk mitigation and budgetary predictability, a successful maintenance management should be included an accurate planning, forecasting and costing of maintenance activities. Once those activities have been established, it becomes significantly easier to control the process. What is more, a well- planning help reducing the risk of costly unplanned events which clearly define each engine shop visit cost, allows those unplanned events scheduling to be optimized. Effective maintenance management requires a thorough understanding of the technical aspects of the product and of the commercial implications behind the technical issues. Technical expertise is the key to tailoring the maintenance strategy to meet the operational needs. In terms of an engine, LLP (Life Limit Parts) status, operational thrust, EGT (Engine Exhaust Temperature), SB (Service Bulletin) and the workscopes that have been performed at previous shop visits that all need to be considered. In addition, maintenance management also needs to include contract management. A perfect engine maintenance management contracts should be satisfied to the airline s strategic approach, those contracts shall be subsequently become a validated documents, The main contracts are mostly considered aircraft technical support agreements, such as those for spare engines and engine maintenance management contracts. The main disadvantage of this approach is that total control management over the maintenance resource has be limited and followed by the situation has become reliant upon outsourcing partners to respond swiftly as airlines need. When looking at maintenance strategies, it is essential that a careful analysis of the exact nature of the required maintenance resources. Based upon this analysis, it is possible to assess whether a business model requires either internal resourcing or a complete outsourcing solution, or a mixture of the two. Choosing for the suitable strategy will lead to an optimized maintenance cost, which will enable a long-term competitive and ensure the most-favored-engine maintenance management to be maintained. VII. CONCLUSIONS This paper aims a contribution to national airliner in Taiwan s aviation industry, not only to manage the Rolls-Royce Trent series engine maintenance management under long-term contract, but also to realize the on-wing engine health monitor (EHM) system functionality. Both benefits developed on-wing engine with a high performance and reliability, as result to create profitability for both airlines and engine OEM throughout the Overall Care model. It may become a promising way to manage properly engine maintenance and reduce much more engine overhaul cost, especially for airlines that strive for survival due to high fuel prices and increasing price as be expected in future. To cope with globalize aviation downturns, profits severity impacts and financial as results in the red, there are a few benefits to China Airlines for new A-350 aircraft fleet which will be delivery in 2015, amid in the currently high fuel price today. First at all, it is the first time ever operates Rolls Royce Trent engine under Total Care model in Taiwan, Based on the new engine management model, China Airlines may operate a brand-new and high performance XWB (Extra Wide Body) engine with less investment for the engine overhaul facility, and less cost for the spare engines inventory, less workload and less manpower in limited work force policy in China Airlines. Second, due to no engine overhaul capacity and limited spare engines, for the Rolls Royce Trent XWB

7 Airliners Engine Maintenance Management under Overall Care Model 197 engine, management workload is less, in others word, no necessity to make any management organization reshuffled. Third, once the newly engine delivery, for the line maintenance capacity, it will build up and accumulate maintenance experience for the Rolls Royce Trent engine the customer s service section under Line Maintenance Department may seek to expand operation for third party capacity in Tao-Yuan International Airport. With certified by Rolls Royce Trent engine for line maintenance operation those mechanics can serve as maintenance agency to handle line maintenance task to other airlines, which aircraft has equipped with the Rolls Royce Trent engine, as result it is not only make more profits to China Airlines, but also to established the high-end & full-scale engine maintenance service, including worldwide three well-known engine OEM (GE, RR and PW), lead the China Airlines to be a pioneer and a prominent leader in Taiwan aviation sector, especially in Asia Pacific region. REFERENCES [1] Tiwari, M., An Exploration of Supply Chain Management Practices in the Aerospace Industry and in Rolls-Royce, Massachusetts Institute of Technology, June 2005, pp [2] Lawley, J., Aircraft Maintenance Costs: A Review of the Third-Party Maintenance Market, Air Transport Group, College of Aeronautics, Cranfield University, 2004, pp [3] Rolls Royce Engine TotalCare Product, from website: http//: totalcare, July 12, [4] Introduction to Pratt & Whitney Engine Fleet Management Training Guide, January 2006, pp [5] Wouters, J., Aero Engine Manufacturing, Aero Engine Cost Management Conference, February 1-2, [6] GE Aircraft Guidelines for Parameter Trend Monitoring, Engine CF6-80C2 Rep Tip No.373, Revision 2, September 8, [7] Boeing, AERO Quarterly Magazine Qtr, 03, 2007, available from website: commercial/aeromagazine, July 12, [8] Thompson, M., Maintenance Planning and Control Tools, Air Transport Group, College of Aeronautics, Cranfield University, [9] Benoff, D., Maintenance Cost Control Programs, Business and Commercial Aviation, August 2001, pp [10] Jet Aircraft Maintenance Fundamentals Gas Turbine Fundamentals, Lufthansa Technical Training GmbH Base, Hamburg, Germany, January 1999, pp [11] Pattison, L., Developments in Engine Diagnostics and Prognostics, Presentation from Data Systems and Solutions company, February 1, 2005, USA. [12] Beck, A., Managing Long Term Maintenance Costs Through Flight Hour Agreement, Aero-Engine Cost Management Conference, February 2005, Scottsdale, Arizona, USA. [13] Wiggins, A., Trent XWB maintainability, Presentation from A350 XWB/Trent XWB Powerplant Customer Focus Group, March 18-19, 2008, Derby, UK. [14] Young, M., Externals layout and engine mounts, Presentation from A350 XWB/Trent XWB Powerplant Customer Focus Group, March 18-19, 2008, Derby, UK. [15] Hernandez, B., A350 XWB Powerplant Program Overview, Presentation from A350 XWB/Trent XWB Powerplant Customer Focus Group March 2008, Derby, UK. [16] AIRMAN mini user guide, Airbus, September 2007, pp [17] Product Specification for the B Data Management Unit (DMU)-Common Functions, Honeywell International Inc., April 18, 2001, Sheet 10. [18] China Airlines Reliability Control Program Manual, Revision: 09, September 28, 2006.