1、_ 6$(7HFKQLFDO6WDQGDUGV%RDUG5XOHVSURYLGHWKDW7KLVUHSRUWLVSX EOLVKHGE6$(WRDGYDQFHWKHVWDWHRI technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, LVWKHVROHUHVS
2、RQVLELOLWRIWKHXVHU SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2016 SAE International All rights reserved. No part of this publication may be reproduced
3、, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-4970 (outside USA) Fax: 724-776
4、-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AIR5416 AEROSPACE INFORMATION REPORT AIR5416 Issued 2010-03 Reaffirmed 2016-10 Maintenance Life Cycle Cost Mo
5、del RATIONALE AIR5416 has been reaffirmed to comply with the SAE five-year review policy. TABLE OF CONTENTS 1.SCOPE 21.1Purpose . 21.2Background . 22.REFERENCES 32.1Applicable Documents 32.2Abbreviations and Acronyms 32.3Mathematical Symbols 43.AIRCRAFT MAINTENANCE LIFECYCLE COST MODEL . 43.1General
6、 . 43.2Definition of Equations 73.3Definition of Variables . 133.4NOTES 204.MODEL OUTPUTS . 215.METHODOLOGY FOR MODEL USE . 256.SENSIVITITY ANALYSIS 257.DAMAGE MODE ANALYSIS 268.CASE STUDIES 278.1Boeing 777 Slat Wedge Disbond and Retrofit Analysis 278.2V2500A Fan Cowl Disbond and Retrofit Analysis 3
7、68.3Sensitivity Analysis for Boeing 737 Series Nose Radome - 3 ply vs. 4 ply Sandwich Structure Change. . 409.RECOMMENDATIONS FOR FUTURE EFFORTS 419.1Additional Reporting 419.2OEM/Airline Partnerships 4110.SUPPORT . 4111.NOTES 41APPENDIX A GENERIC ECONOMIC FACTORS AND AIRPLANE LEVEL INPUTS 42SAE INT
8、ERNATIONAL AIR5416 Page 2 of 45 1. SCOPE This document describes a life cycle cost model for commercial aircraft composite structure. The term life cycle cost used herein, refers to the airline costs for maintenance, spares support, fuel, repair material and labor associated with composites after in
9、troduction into service and throughout its useful life. This document contains the equations that can be programmed into software which is used to estimate the total cost of ownership aircraft, including structure. Modification costs and operating costs are estimated over a specified life (any perio
10、d up to 30 years). Modification costs include spares holding, training, support equipment, and other system related costs. Annual operating costs include: Schedule interruption, fuel, spares, insurance, and maintenance. Maintenance costs are separated by scheduled maintenance or unscheduled damage,
11、or can by grouped into the typical organizations of line, shop, and hangar maintenance. This Lifecycle Cost allows users to evaluate the impact of Service Bulletins, potential design changes, changes in maintenance programs, or effectiveness of maintenance operations. 1.1 Purpose This document descr
12、ibes a way to estimate Maintenance Life Cycle Cost (MLCC) using a model that is a consensus among airframe manufacturers, airlines maintenance organizations, and repair stations. The CACRC is co-sponsored by the Air Transport Association (ATA), the International Air Transport Association (IATA), and
13、 the Society of Automotive Engineers (SAE), which acts as secretary and publishes documents. Since this document is in the public domain, it can be used by Original Equipment Manufacturers (OEM), suppliers, and airlines who desire to estimate these costs for internal use or to communicate externally
14、. Some of the potential changes that can be justified with the MLCC model include: Service Bulletin implementation, design changes during original production, optimization of airline maintenance programs, overhaul turn-times reduction by additional investing in tooling or facilities, reliability imp
15、rovements, overhaul program justification, additional training justification, or nearly any other component or operational change. The CACRC goal for this document is to provide: a. an educational tool for designers describing life cycle costs, b. a tool for use by airlines and OEM with which to car
16、ry out trade studies that are representative of the cost of airline maintenance, and c. A standard model that is a consensus of the CACRC members that will hopefully lead to a common language spoken by various airlines amongst themselves and to the various OEMs or suppliers. Since the actual cost mu
17、st be calculated with many equations, this document is intended to act only as a blueprint or plan for software that can be developed to meet the specific needs of the using companies. The features of such software can vary considerably, so we have tried to suggest desirable options. Sometimes the o
18、ptional features are enhancements to increase functionality, and sometimes they are desired to accommodate the different methods airlines use to account for cost and/or gather reliability information. In support of this goal, Boeing has created an MS Excel-based file which implements the equations i
19、n this document, available from the SAE. 1.2 Background This task grew out of a concern by the CACRC that the changes identified by the Design Task Group (see Guide for the Design of Repairable, Maintainable and Reliable Composite Structures - SAE Document AE-27) that could reduce airline burdens we
20、re economically unjustifiable and were therefore not implemented. Often this was due to a lack of cost data available to the aircraft designer for anything other than original production cost and weight (and associated fuel burn). The Design Task Group then examined the existing LCC models used in d
21、esign trade studies and discovered that they universally focus on Line Replaceable Units (LRUs). LRUs account for a large portion of airline cost, and are the most unreliable as defined by the commonly used measures of MTBUR or delays and cancellations. However, existing LCC models do not adequately
22、 deal with structure, which sometimes is not removable but repaired on the aircraft, and therefore not captured in the usual measures. SAE INTERNATIONAL AIR5416 Page 3 of 45 This MLCC model focuses on the system life cycle from the airline perspective, especially the operational and support costs. U
23、nlike systems engineering or at aircraft manufacturers, this MLCC excludes costs of research and development, production, retirement and disposal - except as these costs are reflected in the acquisition costs from the airframe manufacturer or in airline overhead. Since this model is intended to refl
24、ect the cost to the airline, all costs are from the airline perspective which often differs from the OEM costs. For example, the price of a spare part for the airline may be much different than the manufacturers cost to produce it or to procure it. 2. REFERENCES The following publications for a part
25、 of this document to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of the other publications shall be the issue in effect on the date of the purchase order. In the event of conflict between the text of this document and references cited herein, t
26、he text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 2.1 Applicable Documents Benjamin Blanchard and Wolter Fabrycky, Systems Engineering and Analysis, pub. 1981, Prentice-Hall, Englewo
27、od Cliffs, NJ Boeing, Dependability Cost, pamphlet, pub. by Boeing 1995. “Spare Parts = Cost Benefit Management”, FAST Number 21, pp. 25-24, Airbus magazine MIL-HDBK-470A, Designing and Developing Maintainable Products and Systems, 4 Aug. 1997. “Aircraft Maintenance Cost Reduction”, Aerospace Engine
28、ering, Jan/Feb. 1996, p. 15-17 SAE Committee on Reliability ATA Common Spec Dictionary, 1992 2.2 Abbreviations and Acronyms ATA Airline Transport Association OEM Original Equipment Manufacturer SAE Society of Automotive Engineers CACRC Commercial Aircraft Composite Repair Committee MLCC or LCC Maint
29、enance Life Cycle Cost Model IATA International Airline Transport Association LRU Line Replaceable Unit MTBMAS Mean Time Between Maintenance Action Scheduled MTBMAU Mean Time Between Maintenance Action Unscheduled MTBO Mean Time Between Overhaul MTBR Mean Time Between Removal MTBUR Mean Time Between
30、 Unscheduled Removal SAE INTERNATIONAL AIR5416 Page 4 of 45 MTBURS Mean Time Between Unscheduled Removal Scheduled MTBURU Mean Time Between Unscheduled Removal Unscheduled MTTF Mean Time To Failure MTTR Mean Time To Repair QPA Quantity per Aircraft 2.3 Mathematical Symbols + Addition - Subtraction *
31、 Multiplication / Division 3. AIRCRAFT MAINTENANCE LIFECYCLE COST MODEL 3.1 General The airline maintenance process is modeled pictorially in Figure 1. The arrows represent the flow of the aircraft parts or resources through the maintenance system. Locations where repairs or overhauls are performed
32、are either on the line, in the hangar, or in the shop. Composites and other aircraft structural elements are often not easily replaced. This can be due to the lack of spares, the lack of interchangeability between aircraft, or the inability to disassemble. All of these may result in the aircraft bei
33、ng taken out of service and possibly ferried to a maintenance base. The MLCC Model attempts to simulate the elements of the whole system, with inputs that airlines already typically use either for business reasons, or for reporting reliability of aircraft or components. SAE INTERNATIONAL AIR5416 Pag
34、e 5 of 45 Shop Repair and Return to Line Aircraft Repair MaterialS c h e d u l e d M a i n t e n a n c e Sp ar es D i s t r i b u t i o n Ct r Sh o p Main t en an ceR e p a i r O n P l a n e - L i n e Removed partService Ready partRepaired partS e r v i c e r e a d y p a r t R e m o v e d p a r t S
35、h o p R e p a i r a n d R e t u r n - S c h ed u l e d Repair On Plane-ScheduledH A N G E R 1 Line Maintenance a spare will be available or conversely 5% of the time an out of stock condition will exist when a replacement is required. For those items which are flight critical and are not on the Mini
36、mum Equipment List (MEL) a fill rate of 0.95 may be used. For flight critical items which are MEL items a fill rate of 0.90 may be used and for all other non essential items 0.85 may be used. In the event that the analyst elects not to use the default spares calculation and the number of spares is o
37、btained from another source this input will not be used and a zero can be input. 3.3.5.6 Shop Turnaround Time in Days (number of days) Input 44 If the component under consideration is rotable and initial spares requirement is to be calculated, the shop turnaround time must be specified. This is the
38、expected number of days that a component will be unavailable for use. It includes shipping and queue time, in addition to the actual time to repair the item. If the actual turnaround time is known it should be used, otherwise use the suggested default of 30 days. For an expendable item, the default
39、time is 90 days, if the actual time is unknown. 3.3.6 Baseline & Alternate Part Maintenance Event Variables 3.3.6.1 Unscheduled Damage Evaluation Events per Year (events/year) Input 45 This is the number of unscheduled damage evaluation and troubleshooting events for a particular part per year. This
40、 is equal to or greater than the sum of the unscheduled maintenance actions per year and unscheduled removals per year. 3.3.6.2 Unscheduled Maintenance Actions per Year (events/Year) Input 46 This is the number of unscheduled “on-wing” repairs for a particular part per year. 3.3.6.3 Unscheduled Remo
41、vals per Year (events/Year) Input 47 This is the number of unscheduled removals, from a line operation, for shop repairs for a particular part per year. 3.3.6.4 Unscheduled Removals per year (after scheduled inspection) (events/year) Input 48 This is the number of unscheduled removals for shop repai
42、r, per year after scheduled inspection. 3.3.6.5 Mean Time Between Overhaul (Flight Hours) Input 49 Mean Time Between Overhaul represents the time in flight hours between scheduled removals for overhaul of a part. 3.3.6.6 Scheduled Inspection Events per Year (Events/Year) Input 50 The number of sched
43、uled events for a particular part per year. Optional to the Scheduled Inspection Events per Year is the Scheduled Maintenance Interval. This is mainly used for long-term inspections having greater then a one-year interval, such as corrosion visits, engine overhauls, landing gear overhauls, etc. (Air
44、craft Life Inspection Threshold)/Inspection Interval - 1/ Length of System Life Aircraft Life Expected total life in years of aircraft model. Inspection Threshold The year that inspections start. Inspection Interval Number of years between inspections after threshold. Length of System Life This vari
45、able represents the number of years (from 1 to 30) representing a systems life over which an evaluation is being conducted. In general, new airplanes represent the total lifetime whereas a modification to existing airplanes refers to the remaining lifetime. System life plus aircraft age at modificat
46、ion equals aircraft life. SAE INTERNATIONAL AIR5416 Page 19 of 45 The minus one factor is for rounding down, since an aircraft near the end of its life is often retired before the next scheduled heavy maintenance visit. This interval is most likely to be used when major work is required, such as ove
47、rhaul of a component every 25,000 hours, or for an Aging Aircraft Inspection for airframe. This calculation also accounts for cases where the first inspection occurs after an interval different than the recurring inspection. (For example, a flap assembly may be overhauled at every other D-check, sta
48、rting with the third D-check.) 3.3.6.7 Maintenance Actions Scheduled per year (after scheduled inspection) (events/year) Input 51 This number of events is the occurrence of unscheduled repairs on plane after scheduled inspection. 3.3.7 Baseline & Alternate Part Maintenance Material & Labor Variables 3.3.7.1 Damage Evaluation/Troubleshooting Labor Hours per Unscheduled Event (hours/event) Input 52 A
