Scholarly article on topic 'Airworthiness Management of CFM56 Products in FAA and EASA'

Airworthiness Management of CFM56 Products in FAA and EASA Academic research paper on "Mechanical engineering"

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Procedia Engineering
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{"FAA (Federal Aviation Administration)" / "EASA (European Aviation Safety Agency) ;TC (Type Certificate)" / "VTC (Validation of Type Certificate)" / "TCDS (Type Certificate Data Sheets)" / CFM56}

Abstract of research paper on Mechanical engineering, author of scientific article — Gao Yanlei, Zhou Yanpei

Abstract Discussion on airworthiness management of CFM56 products in FAA and EASA is presented in this paper. The successful experience of the CFM56 series is summarized about engine model design, type certification and continuous aviation safety management, which would provide some guidance for international cooperation at engine design, manufacture and airworthiness management in civil aviation.

Academic research paper on topic "Airworthiness Management of CFM56 Products in FAA and EASA"

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Procedía Engineering 17 (2011) 588 - 594

Procedia Engineering

The 2ed International Symposium or Aircraft Airworthiness (ISAA 2711)

Airworthiness Management of CFM56 Products in FAA and

GAO Yanleia, ZHOU Yanpeib, a*

aAeroengine Airworthiness Certification Center Preparatory Office, China Academy of Civil Aviation Science and Technology

CAAC, ChaoYangDistrictXIBAHEBEILINo.24A, Beijing, 100028, China bAeroengine Airworthiness Certification Center Preparatory Office, China Academy of Civil Aviation Science and Technology CAAC, ChaoYang District XIBAHE BEILI No.24A, Beijing, 100028, China


Discussion on airworthiness management of CFM56 products in FAA and EASA is presented in this paper. The successful experience of the CFM56 series is summarized about engine model design, type certification and continuous aviation safety management, which would provide some guidance for international cooperation at engine design, manufacture and airworthiness management in civil aviation.

© 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of Airworthiness Technologies Research Center NLAA, and Beijing Key Laboratory on Safety of Integrated Aircraft and Propulsion Systems, China

Keywords: FAA (Federal Aviation Administration); EASA (European Aviation Safety Agency );TC (Type Certificate); VTC (Validation of Type Certificate); TCDS (Type Certificate Data Sheets); CFM56

1. Introduction

CFM56 series is a family of high-bypass turbofan aircraft engines made by CFM International (CFMI), with a thrust range of 18,000 to 34,000 pounds-force (80 to 150 kilonewtons). The first completed CFM56 engine ran in June 1974[1]. There were totally 11 engines for CFM56 model certification test including 5 engines for flight test. It was up to 130 flight hours from the first flight on Boeing 707-320 assembled in United States in November 1979. And during that time there were also several flight tests finished on

* Gao Yae Lei. Tel.: 86-17-64481277; fax: 86-17-64481221. E-mail address: oaoyl@mail.castc.oao.ce.

1877-7058 © 2011 Published by Elsevier Ltd. doi:10.1016/j.proeng.2011.10.074

Caravelle in France. On 9th November 1979, the type certificates were issued by FAA and DGAC (EASA now). It takes almost 7 years and 1 billion dollars in developing the CFM56 engine model. Despite initial political problems, the CFM56 is now one of the most common turbofan aircraft engines in the world, widely used on the Boeing 737 airliner and fitted to Airbus A320 series aircraft, with more than 21,000 having been built in four major variants and more than 5 billion flight hours accumulated[2]. CFM56 is one of the most successful international cooperation projects also.

2. CFM International and CFM56 Project

CFM International is a 50-50 joint-owned company of Snecma, France and GE Aviation (GE), USA.[3] Snecma and GE are licensees of CFMI to design engines and components, manufacture parts, certify engines, assemble production engines and provide product support and continued airworthiness functions. Snecma manufactures the fan, low-pressure turbine, gearbox, and exhaust. GE produces the high-pressure compressor, combustor, and high-pressure turbine.[4] The engines are assembled by GE in Evendale, Ohio, and by Snecma in Villaroche, France. The completed engines are marketed by CFMI.

CFMI has a unique method to implement the administrative, financial and business management[5]. The central administrative authority in each parent company, Snecma and GE, is set up to manage and supervise the CFM56 project, and also CFMI provides single point of contact to its customers. A Single Organizational Interface for Customers is showed in figure 1. The CFMI board of directors is currently split evenly between Snecma and GE. There are two vice presidents, one from each company, who support the President of CFMI. The president tends to be drawn from Snecma and sits at CFMI's headquarters near GE in Cincinnati, Ohio. CFMI consists of many experienced people from two parent companies, the resources and abilities of which are shared there. Every important decision is made by the advisory committee of CFMI, which is composed of the parent company's main leaders or its representatives. In two companies there are the vice presidents and general managers of CFMI, who will directly report to CFMI's president and CEO. The target of development and technology of the CFM56 and all the engine parts is made by CFMI, and every parent company is responsible to meet the requirements.[6]

President and CEO GE Aviation

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Chairman and CEO Snecma

Executive Vice President Commercial Engine Snecma

Fig. 1. Organizational Interface for Customers

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CFM56 engine market sales and technical support are divided into two areas by region, in order to ensure the efficiency of the sales and support, and also avoid competition with each other. [7]Snecma is responsible for Europe, Africa and Middle East, meanwhile GE is responsible for the America, Asia and pacific region, as showed in CFM Operational Structure ( see figure 2).

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Fig.2. CFM Operational Structure

Since the days of the CFM56 series it has been committed to improving the key technology.[8] Figure 3 shows technical updating process of CFM56 series, which is divided into three stages.

Fig.3 Technical updating process of CFM56 series

First stage is the FADEC

FADEC (Full Authority Digital Engine Control or Full Authority Digital Electronics Control) is a system consisting of a digital computer, called an electronic engine controller (EEC) or engine control unit (ECU), and its related accessories that not only control all aspects of aircraft engine performance, but also monitor the working conditions of all the engine system[9]. If the failure is detected, its classification and the information will be finished and stored. The goal of any engine control system is to allow the engine to perform at maximum efficiency for a given condition. The complexity of this task is proportional to the complexity of the engine.

In CFM56 series FADEC came into using in CFM56-2/-3 and now in the CFM56-5/-7 model, which includes three important parts, engine electronic control (EEC), hydraulic mechanical unit (HMU), actuators and external sensors. EEC is a type of electronic control unit, which can control the engine operation, make inspection function, classify the failure and store its information. HMU is another very important part, which can transfer the electrical signal to hydraulic signal and enlarge it. Through the external sensors the engine parameters are provided to EEC and engine accessories control is carried out by actuators.

Better fuel efficiency can be obtained using FADEC to control the engine performance. The automatic engine protection system will be started if the out-of-tolerance operation is detected. Multiple channels FADEC computer can offer redundancy protection when some failure occurs. One type of engine model can apply on different users by reprogramming the FADEC to adjust the thrust of demand, which can integrate the engine and the aircraft system efficiently and also contributes to continuous management of engine healthy monitor and failure diagnosis.

Second stage is the 3D aerodynamic design

With the development of CFD (Computational Fluid Dynamics), most of the engine parts including rotors and stators of the fan, the compressor and the turbine are designed in all three dimensions with viscous fluid characteristics of the aerodynamic, in order to improve the component efficiency and expand the stability operation scope of engine. Using this method of aerodynamic design, CFMI increase the 9th stage of compressor efficiency and improve its aero-performance. Meanwhile the high pressure turbine is designed with 3D aerodynamic and also with the active clearance control. Low pressure turbine is also designed with 3D aerodynamic in order to improve the efficiency and fuel consumption. So far the improvement of the engine performance can be achieved by optimizing of thermodynamics analysis, 3D aerodynamic design, application of the composite material, such as organic materials, ceramic composite, titanium and aluminum, and innovating industrial processes.

Third stage is the TECH56 [10]

To maintain the civil engine market competitive advantage, CFMI launched the "Tech56" development program. This 5-year program focused on developing a large number of new technologies for the theoretical future engine. CFMI applied some of those Tech56 technologies to the CFM56 in the form of the "Tech Insertion" program which focused on three areas: fuel efficiency, maintenance costs and emissions. All the technical improvements will be verified on the engine simulation the real work conditions and those techniques attested will be used to the new engine design and the variant development of the CFM56 series.

Launched in 2004, the package included redesigned high-pressure compressor blades, an improved combustor, and improved high- and low-pressure turbine components which resulted in better fuel efficiency and lower nitrogen oxides (NOx) emissions. The new components also reduced engine wear, lowering maintenance costs by about 5%. The engines entered service in 2007, and all new CFM56-5B and CFM56-7B engines are being built with the Tech Insertion components. CFMI also offers the components as an upgrade kit for existing engines.

GAO YanleiandZHOU Yaroci/Procedia Engmelrmg17 )0511)588 - 594

Since its creation, CFMI has been no stop making the technical updated on CFM56 series. In 2005 CFMI began to implement the LEAP56, which is the frontier research on jet propulsion, making a technical preparation for civil engines in next 30 years. The goal of the next generation is to reduce fuel consumption rate by 10%, maintenance costs by 25%, extend life to over 20,000 hours on wings and also make environmental improvement. The cost reduction of ownership will be focus on the following parts in future CFM56 engines, the first one is to reduce fuel consumption, using light weight and composite structure, the second one is to enhance the reliability using the new technology and new engine structure, the third one is to adopt remote improved diagnostic techniques and the advanced electric control system, the fourth one is to introduce advanced material technologies. Aiming at the next generation of single-aisle Airbus and Boeing aircraft, LEAP56 will be used on CFMI engine products in 2013.

3. Airworthiness management of CFM56 in FAA and EASA

There is the particular, dual FAA/EASA engine certification process for CFM engines. [11][12]Several Type Certificates are issued to CFMI for CFM56 engines in order to comply with the FAA and EASA administrative and procedure requirements, but they correspond to only one type design certification and airworthiness activity conducted jointly and simultaneously by CFMI/FAA/EASA for the same engine models. There is no difference between an FAA and an EASA certification for a CFM product. No separate CFM type certificates are awarded to GE or Snecma.

3.1. Joint FAA/EASA Certification

CFM products are "jointly" certified by both FAA and EASA under the terms of a unique agreement between the two Authorities. CFM demonstrates compliance to both FAA and EASA engine certification requirements. Each authority then issues its own TC and TCDS. It is most important that each authority does not validate the others certification. It's a "joint" and simultaneous certification by both authorities. Copies of both FAA TC/TCDS and the EASA TC/TCDS for the CFM engines were included in the original validation package. Applicant and Type Certificate Holder of CFM56 in TC/TCDS is CFM International S.A Paris, France which is one Joint Company of GE and Snecma, formed in France. CFM International, Inc. is the other Joint Company of GE and Snecma, U.S. Corporation. The approved compliance checklist (CCL) is "joint" in that it lists both FAA and EASA requirements (14CFR Part 33 (FAA) and JAR-E / CS-E (EASA) respectively) by subject. Once approved by both authorities, the CCL becomes the certification basis for the product. Accordingly, all FAA and EASA certifications are "joint" because they share an identical, common certification basis. Only one common CFM report for each CCL item covers both FAA and EASA requirements. These certification documents are "joint" as well. They address both sets of regulations and are jointly and simultaneously approved by both Agencies. There is no separate set of certification documents for the FAA (USA), no separate set of certification documents for the EASA (France) and all engines are produced to an approved parts list that is common to both GE and Snecma. Consequently there is no difference between an FAA and an EASA certification for a CFM product.

This certification arrangement provides the validating Authority a significant degree of flexibility in its validation process and the structuring of their validation certificates and data sheets. Some Authorities validate to the FAA requirements while others may use the JAR-E/EASA CS-E requirements. The Authority may simply choose the FAA or EASA certificate to validate without having to reconcile FAA and JAR-E/CS-E differences with their own requirements.

3.2. Dual FAA/EASA Engine Certification Process

All of CFM56 engine certification process is based on Regulatory Management Plan (RMP), which is an agreement between the Civil Airworthiness Authorities of France (DGAC) and the United States of America (FAA) issued on June 16, 1980 and modified in 1999. The RMP is accepted by EASA until it is replaced by specific US/EU document.

CFMI and the Agencies (EASA and FAA) work together to define the appropriate certification program for new CFM56 engine models and design changes, to define certification expectation and deliverables summarized in detailed Compliance Check List (CCL), to define Certification Basis. CFMI/EASA/FAA Certification Team conduct a Preliminary Type Board Meeting (PTBM) for a new engine model, define and approve a detailed Compliance Check List (CCL), and also define certification subjects and method of compliance (test or analysis or both). According to CCL agreement testing and reporting of each subject is assigned to GE or SNECMA depending on hardware responsibility and consistent with test facility capability. The test plan and report jointly approved by GE / SNECMA / CFMI should be submitted from either GE or SNECMA to both the FAA/EASA, and joint reviewed by both EASA and FAA. Then joint agency approval letter will be provided by the Authority on side of submittal. If it is needed, some tests can be witnessed by Authority on side of test.

3.3. CFM Typo Caetifirdtipa(TC) daC Typo Caetifirdta Ddtd Shaat(TCDS)

New full centerline engine programs result in three regulatory Type Certificates: One is for EASA and the other two for FAA including domestic and import certificates. As the FAA and EASA are separate Authorities, they cannot issue a "joint" TC and must issue their own. From the administrative or procedure aspect, the TCs are issued according to the 14 CFR Part 21 (FAA) and IR Part 21 (EASA).

On the FAA side, the 14 CFR Part 21 require identification of the place of manufacture of the engine, and this is why FAA issues both domestic and export TCs for the CFM56 engines, E00055EN and E00056EN. E00055EN is for the models assembled in the United States, E00056EN is the one in France. As for the engines in E00055EN, GE is responsible for the assembling and production. FAA takes GE as authorizer by CFMI, after reviewing its manufactory system, issued Production Certificate NO. 108 to it, and takes Snecma as GE's supplier. As for the engines in E00056EN, Snecma is responsible for the assembling and production. EASA takes Snecma as authorizer by CFMI, after reviewing its manufactory system, issued Production Certificate FR.21G.0007 to it, and takes GE as Snecma's supplier.

On the EASA side, the EASA issues only one TC, because the IR Part 21 does not require identification of the place of manufacture of the engine. However, comparison of the FAA/EASA TCs shows that all ratings, limitations and all other pertinent airworthiness and certification data listed are identical. Older CFM models, for example the CFM56-2 and-3 series, still retain the dual French DGAC TCs, one is for the models assembled in the United States, and the other one is in France. But these two TCs are accepted by EASA. These TCs are revised to a single EASA TC as the need to revise the original TC arises.

4. Summary

Airworthiness certification is a comprehensive and integrated process, through which civil aircrafts, including engines and propellers installed, can get the certificates issued by the authorities, and also which is a prerequisite for aircraft's entering into civil aviation market. The basic purpose of airworthiness certification is to ensure aircraft in accordance with requirements, passengers' lives and property security. From the successful experience of CFM56 products, it can be seen that the international cooperation in model design, manufacture and getting certificates of aero engine is possible. In order to capture the global civil market, it may be a good choice for aero engine manufactories in China to

GAO ^cmleia^d^HOU Yaroce/Procedia rmg17 )0511)588 - 594

enhance the international cooperation in aero engine project, which can not only share the risk of engine development but also make full use of both sides' resources.

Aviation industry is a high technology industry integrating with new material, new techniques and new technology. Being a national mainstay industry, the aviation industry in China grows out of nothing, from small to large, from repairing to manufacturing and from replicating to developing itself. By now a comprehensive industrial system, including research, experimentation, manufacture, management and marketing, has already been established and perfected in China, with which China is able to make an engine design independently, and also get a lot chances to take the international cooperation. Further study on engine development and airworthiness management of CFM56 series will conduce to improve the research and development system of civil aircraft and promote the ability to obtain the airworthiness certificate in China.


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[2] "CFM Delivers 21,000th CFM56 Engine While Retaining Solid Delivery Backlog'. CFM International Website Retrieved: 8 August 2011.

[3] Ni Jin Gang. CFM56 EQUATION [M], Aviation Industry Press, 2007

[4] "WorkSplit". CFM International website Retrieved: 8 August 2011.

[5] Chen Chen. CFM56-What Next?[J], AVIATION MAINTENANCE & ENGINEERING, No.3, 2008: P27-29

[6] Fang Chang De. CFM56: A Successful International Cooperation[J], INTERNATIONAL AVIATION, No.1, 2006: P45-47

[7] Liu Sheng Jun. Engines for Next Generation Narrow body Commercial Aircraft [J], INTERNATIONAL AVIATION, No.8, 2006: P80-82

[8] Su Gui Ying, Chen Jin Guo. Technical Approach of Thrust Growth in CFM56 Engine Family [J], AEROENGINE, Vol.33, No.3, 2007: P55-58

[9] "Chapter 6: Aircraft Systems" (PDF). Pilot's Handbook of Aeronautical Knowledge. Federal Aviation Administration. Retrieved: 8 August 2011 .

[10] "Preparing for the future of aircraft engines - TECH56". Aerospace Engineering and Manufacturing Online. Retrieved: 8 August 2011.