1 The Route to Continuing Airworthiness Brian L Perry BSc (Eng), C.Eng, FRAeS, MIET Vice President (Technical), International Federation of Airworthiness.

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The Route to Continuing Airworthiness

Brian L Perry BSc (Eng), C.Eng, FRAeS, MIET Vice President (Technical), International Federation of Airworthiness

Airworthiness Consultant

Processes and Programmes Leading from Certification to Operation

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Content

• A bit of History

• An overview of where we are Now

• A brief look into the Future

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Where It All Began

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1930’s Airliner

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Douglas DC3 G-AMRA - Norwich UK - May 2008

Andrew McClymont

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AIRWORTHINESS

• “Airworthiness” organisations had been set up, before the war, both in the UK (1934) and the USA (1938).

• Aircraft development during the war was driven by military needs.

• By 1944 the rapid growth of Civil Aviation led to the establishment of an International organisation.

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Airworthiness

• What is meant by the term

Airworthiness

My Definition:

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Airworthiness and Continuing Airworthiness

FITNESS TO FLY SAFELY

THROUGH OUT THE LIFE OF THE AIRCRAFT

Dependent upon:

• Design and Manufacture

• Operations

• Maintenance and Repair

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International Civil Aviation Organisation

• Under The 1944 Chicago Convention the various National Governments agreed to set up an International Organisation, ICAO, in order that:

• “----International civil aviation may be developed in a safe and orderly manner---”

• “---and to secure the highest practicable degree of uniformity in regulations, standards and procedures---”

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ICAO Annexes

• 18 Annexes including:• Personnel Licensing and Approval of

Organisations• Rules of the air• Meteorological Services• Aeronautical Charts• Units of Measurement• Operation of aircraft• Aircraft registration Marks• Airworthiness and Continuing Airworthiness

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Annexes continued

• Facilitation• Aeronautical Telecommunication• Air Traffic Services• Search and Rescue• Aircraft Accident Investigation• Aerodromes• Aeronautical Information Services• Environmental Protection• Security• Transport of Dangerous Goods by Air

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ICAO SARPS

Standards And Recommended Practices for the interpretation of the Annex material

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Implementation of Annexes and SARPS

• In practice these are implemented by National Codes such as:

• In the Europe by JARs now EASA CS’s.

• In the USA by FAR’s.

• In most other counties by National Codes often based upon or related to FAR’s and/or the EASA Codes.

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FAA---------------------------------------------EASA FAR’s - Requirements - CS’s

Acceptable Means of Compliance - AMC’sAppendices

AC’s - Advisory Circulars________________________________________________________

_

SAE/RTCA ------------------------------- EUROCAE ARINC ARINC

Detailed Specifications and Guidance material

eg. DO 160/ED 14, DO 178/ED12 etc. ________________________________________Prime Manufactures in-house standards which are

applicable to all sub contractors and suppliers

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High Accident Rates particularly related to piston engine failures

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A Major Step for SafetyIntroduction of Jet Engines

• Cabin Air Conditioning and Pressurisation• Increased cruise altitude speed and range• Increase in engine reliability BUT in

some early jet-engined aeroplanes:• Accidents caused by Structural Fatigue• Results of the investigations and tests and

the resultant changes to the airworthiness requirements were shared across the world.

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De Havilland Comet

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Another Major Step

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Concorde - Advanced Systems • High Speed and High Altitude• Limited Fly- by Wire• Extreme Temperatures on Aircraft skin• Reheat and Full Authority Electronic Engine

Controls• Full Authority, Safety Critical, Digital Air Intake

controls• Centre of Gravity Control using Aircraft Fuel • Equipment Cooling using Aircraft Fuel• Exposure to Radiation and Lightning Strikes

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Lightning Strike

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Current Requirements

• The Concorde and other experience led to major changes in the requirements, in particular for the certification of Systems and Equipment which are applicable throughout the in-service life of the aeroplane

• These will be discussed in more detail later in this presentation.

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Airworthiness

• We shall today be concentrating upon Part 25 Requirements covering the TC (Type Certification) of Large Aeroplanes.

• These requirements also take account of all the ICAO annexes and their related national standards.

• Plus Systems and Equipment fitted to obtain a C of A (Certificate of Airworthiness)

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Certification Specifications for Airworthiness of Large

Aeroplanes CS 25• Subpart A - Applicability

• This airworthiness Code is applicable to Turbine Powered Large Aeroplanes over 5670kg weight

• Operated under Part 121(or similar rules)

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CS 25 SubpartsAlso containing Appendices and AMC’s

• B – Flight

• C – Structure

• D – Design and Construction

• E – Powerplant

• F – Equipment

• G – Operating Limits and Information

• J – Gas turbine APU Installations

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Some Sections of CS 25 which are particularly related to Continuing

Airworthiness• Weight and Centre of Gravity limits.• Guidance for in-service flight tests, where

required following maintenance actions.• AMC 25.561 – Load conditions for seats and

other items of ‘commercial’ equipment.• AMC 25.581-- Lightning protection and bonding

of structural elements.• Provision of CDL (Configuration Deviation List)

information for Flight Manual.

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Some Sections of CS 25 which are

particularly related to Continuing Airworthiness (ctd.)

• Much of the content of Subpart D – Design and Construction including, for example:

• AMC’s No. 1 and 2 to CS.603. Suitability of materials including Appendix F - Fire Test Criteria and Procedures.

• Emergency Exits arrangements and Emergency Demonstration - Appendix J.

• Appendix H – Instructions for Continuing Airworthiness which details, in particular, the required content of the Maintenance Manuals.

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Some Sections of CS 25 which are particularly related to Continuing

Airworthiness (ctd.)• Requirement for Engine Type Certification.• Design Considerations for Minimizing

Hazards caused by Uncontained Turbine Engine and APU Rotor Failure, AMC 20-128A.

• Detailed information on the contents of the Flight Manual including CDL and MMEL, AMC 25.1581.

• Requirement for APU approval.

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SEE ALSO

IFA WHITE PAPERDated April 2003

CONTINUING AIRWORTHINESSThe basic story

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CS 25 Subpart F - Equipment

• The Concorde and other experience led to major changes in the requirements, in particular for the certification of Systems and Equipment which are applicable throughout the in-service life of the aeroplane

• For example the concept of the inverse relationship between the probability of occurrence of an event and the severity of its effect.

• These and the related certification procedures are as detailed in 25.1309 and the associated AMC’s or AC’s.

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FAA---------------------------------------------EASA FAR’s - Requirements - CS’s

Acceptable Means of Compliance - AMC’sAppendices

AC’s - Advisory Circulars________________________________________________________

_

SAE/RTCA ------------------------------- EUROCAE ARINC ARINC

Detailed Specifications and Guidance material

eg. DO 160/ED 14, DO 178/ED12 etc. ________________________________________Prime Manufactures in-house standards which are

applicable to all sub contractors and suppliers

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Extract from CS 25.1309 (a)(1)

• Systems and equipment must be designed and installed so that those required for Type Certification or by operating rules, or whose improper functioning would reduce safety, must perform as intended under the aeroplane operating and environmental conditions

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Extract from CS 1309 (a)(2)

• The aeroplanes systems and equipment must be designed so that other equipment and systems are not a source of danger in themselves and do not adversely affect the proper functioning of those covered by CS 25,1309 (a)(1)

• SEE ALSO AMC 25.1309

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Systems and Equipment Certification Requirements

• While subpart F of the requirements and, in particular, 25.1309, covers the certification of Systems and Equipment, their specific requirements may be detailed in other sub parts.

• For example the subparts and associated Appendices and AMC’s, covering:

• Flight, Structures, Design and Construction, Power Plant, Operating Limits, Auxiliary Power Units (APU’s).

• Including any new equipment and systems required or fitted after entry into service.

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The Type Certification Process

• A review of this process will now be made.

• The steps shown contain information which may need to be taken into account when any in-service modifications, repairs or replacements are made to the aircraft, its systems and its equipment.

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Preliminary Hazard Analysis –PHAFailure Conditions and Criticalities

• Determines system hazards and effects –Catastrophic, Hazardous, Major, Minor, No Safety Effects and the associated level of analysis required .

• Hence Safety Objectives• Quantitative or Qualitative analysis• Involves system designers and pilots• Agreed between Design Organisation and

Certification Authorities

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Software Verification and Validation

• Document used Internationally for V & V RTCA - DO 178B (Eurocae – ED 12B)

• Amount of work depends upon Software Levels

• Watch out for the need for ‘Partitioning’ which separates those portions which can be modified after Type Certification and those which cannot.

• Summarised in Accomplishment Summary

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Software Levels

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Equipment Approval

• All equipment fitted to the aircraft must be tested to ensure that it meets all the relevant environmental and safety standards, as specified in DO 16O, or the airframe manufacturers equivalent specification.

• Evidence must be provided to confirm this, for example: TSO (Technical Standing Order) or DDP (Declaration of Design and Performance.

• Information on failure modes and reliability rates will, where relevant, be required for use in the FMEA.

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FMEA - Failure Modes and Effects Analysis

• This will be required for those systems where a quantitative analysis of the particular event is required by the PHA.

• Normally carried out by the airframe constructor using a computer programme.

• All sub systems and equipment failure and reliability information used in the analyses to be to the same standard.

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Rig and Aircraft Tests

• These are particularly relevant in the evaluation of complex system inter-reactions and related system indications, warnings and procedures, under normal, standby and emergency conditions. For example: power supply failures and bus-bar failures.

• Establish Flight Manual procedures.• Involvement of the flight test crew is essential.• In-service changes and additions must not affect

these, otherwise a formal amendment is needed.

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Zonal Analysis

• Initial confirmation that the design standards cover the requisite Zonal Configurations.

• Including: fire and explosion; corrosion; segregation and separation of power supplies and back-up systems and associated earthing/grounding; disc burst zones; other electrical and mechanical segregation requirements; physical fastening and protection of cables and equipment; safe and easy access for required maintenance activities.

• These standards remain critical throughout the service life of the aircraft and must not be invalidated

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Zonal Analysis (continued)

• Detailed inspection of the completed aircraft to ensure that these standards are met and to ensure that no other potential safety hazards have been introduced during manufacture.

• This can be a difficult and potentially time consuming task, but it is essential to ensure that these standards are maintained throughout the in-service life of the aeroplane.

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System Safety Assessment - SSA

• This process confirms that:• The assumptions of the PHA are correct, or have to be

modified, and that the derived System Safety Objectives have been met.

• That the installation of the equipment on the aircraft meets the design standards and no further potential hazards have been introduced.

• Provides Flight Manual Procedures covering the relevant system and equipment failure conditions.

• Provides MMEL (Master Minimum Equipment List) information and any related operational or time restraints, based upon the data used in the assessments.

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SSA (continued)

• Details any CMR (Certification Maintenance Requirements) which have shown to be essential to retaining the required levels of reliability and availability, during the SSA and FMEA process, and which cannot be changed using normal in-service procedures, AMC 25-19

• Provides other information as required by the pre-operations maintenance review panel (MSG-3).

• Provides the basis for the Compliance Check List for 25.1309.

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In Service Experience

• The Airbus range of Fly By Wire aircraft

• (A319, A320, A330, A340) were the first civil aircraft designed and certificated to these standards using these or equivalent certification processes.

• Also the FBW Boeing 777, with this aircraft also utilising a ‘Digital Data Bus’ System.

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Airbus original viaAndrew McClymont

Airbus A320 msn 002 F-WWDA in 1987 - One side painted in BCAL colours

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In the Near Future

• The Boeing 787 and the Airbus A350 will be entering service in the near future to basically the same certification standards but with such Special Conditions as are required by the use of the new materials and system design features, such as much increased dependence upon electrical power.

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Boeing 787

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Airbus A350

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Potential Continuing Airworthiness Issues in the use of Carbon Fibre

Materials• Detection and repair of damage caused

mainly by collisions on the ground.• Repair of damage to the external surfaces

metallic protection caused by lightning strikes.

• Deterioration and corrosion due to spillage of contaminating fluids such as fuel, hydraulic and de-icing fluid, toilet fluids and galley spillage.

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ETOPS – Extended Range Twin-Engine Operations

• An example of how airworthiness is achieved and maintained for a particular type of operation.

• Original standards did not allow commercial operation of twin engine aircraft for more than 60 minutes, single engine flying time, away from a ‘suitable’ airport.

• Very high engine reliability gave the opportunity to review this rule

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ETOPS - Design and Manufacture

• Proven engine reliability and low shut-down rate from any cause

• System augmentation:Back–up Power supplies needed.

APU with in flight start and run capability.Enhanced De-icing capability.Increased cargo bay fire suppressant.Review of other potential system effects

andprocedures relevant to single engine operation.

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ETOPS - Operations

• Procedures and training for extended periods of single engine operations at lower cruise altitudes and speeds.

• Provision of additional fuel to allow an emergency diversion at any time to an alternate airport.

• Availability of ‘suitable’ diversion airports and knowledge of their meteorological conditions during the flight.

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ETOPS - Maintenance

• Required ETOPS maintenance and reliability programme to include:

• Maintenance of engines, systems and equipment.

• Engine and System routine maintenance limited to one engine or one critical system at a given time. For example top-up of oil or other fluids.

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Successful ETOPSNow extended to 180 minutes and, on certain routes, 207 minutes

Design of Aeroplane approved for ETOPS

Operator approved for ETOPS operation

Maintenance approved for ETOPS

See EASA AMC 20-6and FAA AC 120-42A

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Some Other Safety Related Equipment and Initiatives

Examples of equipment already mandated under ICAO and

other rulesTAWS (GPWS) Terrain Avoidance and Warning System.TCAS (Traffic Collision and Avoidance System).Accident Data and Cockpit Voice Recorders.Fuel Inerting Systems.Ageing Aircraft checks on structures and systemsPlus others.

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Some Other Safety Related Future Equipment and Initiatives (ctd.)

EquipmentHUMS (Health and Usage Monitoring Systems) linked with ACARS

(Aircraft Communications, Addressing and Reporting System).Equipment providing warning of runway traffic, and potential

incursions and excursions.Improved and extended CVR’s (Cockpit Voice Recorders) and

ADR’s (Accident Data Recorders).ADS-B (Automatic Dependence Surveillance-Broadband).The extended use of the failure and maintenance monitoring

systems which are an integral part of the aeroplane. “Believe what the aeroplane is telling you”

The extension of the use of EFB’s (Electronic Flight Bags) to include maintenance and spares information and to replace the hard copy of the Tech. Log.

.

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Some Other Safety Related Future Equipment and Initiatives (ctd.)

InitiativesExtension of non-punitive data recording to cover

incidents as well as accidents both in flight and during maintenance.

International co-ordination of this data with detailed analysis to ensure that ‘lessons learned’ are understood and shared by all.

SMS (Safety Management Systems) introduced in all the organisations involved. This provides the opportunity to establish sound communication links between all parts of the organisation and with external bodies, where appropriate.

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Longer Term AirworthinessDriven by customer requirements, environmental pressures,

costs, including fuel and maintenance, with always the need to maintain and improve safety standards.

• Probable changes include:• New ATM systems, for example, NextGen in the USA and

Single Europeans Skies in Europe, plus similar systems in many parts of the world.

• More safety critical, operational and maintenance systems.• Many more cabin services such as entertainment systems and

internet and telephone access, which have the potential to interfere with the airworthiness critical aircraft systems.

• All leading to increased complexity and inter-system communication, with dependence upon ground based services and equipment for flight critical operations.

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Longer Term Airworthiness (ctd.)

• The outputs from CAST (Civil Aviation Safety Team) extended to all areas of the world, such as ECAST in Europe. Many of these Safety Enhancements relate to industry guidance material rather than needing to change the basic airworthiness standards

• The output from FAST (Future Aviation Safety Team) taken in account in future design, operation and maintenance.

• Possible need to rethink, perhaps automate, the whole of the system certification process to ensure that such complex and inter-related systems are subjected to a thorough and independent airworthiness review. This will affect both the initial Type Certification and in-service modifications including those covered by STC’s (Supplemental Type Certification)

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Unmanned Airborne Systems?UAS’s

• Small vehicles for limited surveillance and maintenance roles, but penetrating controlled airspace.

Already in operation

• Freighter Aircraft (for long range operations?)Probable

• Passenger Transport AircraftUnlikely, but the pilot may have more of a surveillance

rather than an operational role.

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Major Accidents Worldwide Commercial Jets

1998 – 1 November 2009

Majo

r Accid

en

ts 10

20

40

30

Majo

r Accid

en

t R

ate

*

0.20

0.40

0.60

0.80

1.00

1.20

2008 2009

2008 2005 2006 2007200420032002

2001

2000

17

13

19

13 13

16

11

1719

13

Hull Losses Western Major Accident Rate *

* Reliable worldwide departure/rate data not available for Eastern-Built Aircraft

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Back to the FutureMaintaining Continuing Airworthiness in the future will be:

COMPLEX and

CHALLENGING

.YOU CAN BE SURE HOWEVER THAT THE FOLLOWINGAIRWORTHINESS COMMUNICATIONS CHART WILL STILL BEAPPLICABLE, PERHAPS WITH SOME ADDITIONAL TOPIC AREAS.

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THANK YOU