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Development of Certification Maintenance Requirements and Instructions for Continuing Airworthiness

Melbourne – May 2013

Design and Manufacturing Seminar

Development of Instructions for Continuing Airworthiness

A process for ICA creation performed by the OEMs as a part of Type

Certification (FAR / CS 23/25/27/29 – 1529, MSG – 1/2/3).

Regulatory and engineering principles used for creation of Certification Maintenance Requirements.

A process used for unique MEL items and Permissible Unserviceability assessment and approval.

MSG 3 approach.

A process used for in house versus OEM maintenance data creation and approval.

Processes involved in TBO and maintenance task / schedule frequency escalations and one-off escalations / overruns.


Instructions for Continuing Airworthiness (ICA) are developed during the Type Certification process of an aircraft in accordance with relevant certification standards. ICA are usually provided through MM, SRM, SBs, SLs, MPD, AFM, MEL, etc.

Instructions for Continuing Airworthiness (ICA) are also developed during the Supplemental Type Certification process in accordance with relevant certification standards. In this case ICA are usually provided through Supplements to MM, SRM, MPD, AFM, MEL, etc. STC Holders could also publish SBs, SLs related to their STCs.


ICA are developed in accordance with relevant certification standards. CASA accepts EASA CSs and FAA FARs as acceptable relevant standards for Normal and Transport Category Aircraft / Rotorcraft (ref. CASR Part 23/25/27/29)

ICA are developed in accordance with relevant regulations provided in the FAR / CS 23/25/27/29 section 1529 and applicable appendices. Section 1529 and applicable appendices set the basic requirements for ICA.


FAR PART 25—AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Subpart G—Operating Limitations and Information § 25.1529 Instructions for Continued Airworthiness. The applicant must prepare Instructions for Continued Airworthiness in accordance with appendix H to this part that are acceptable to the Administrator. The instructions may be incomplete at type certification if a program exists to ensure their completion prior to delivery of the first airplane or issuance of a standard certificate of airworthiness, whichever occurs later. [Amdt. 25-54, 45 FR 60173, Sept. 11, 1980]


EASA approach is almost identical to FAA

Certification Specifications (CS) section 1529 deals with ICA.

For example: EASA CS 29 Certification Specifications For Large Rotorcraft - OPERATING LIMITATIONS Section 29.1529 states:

Instructions for continued airworthiness in accordance with Appendix A to CS–29 must be prepared.


NAA Policy Statements must be considered when ICA are developed. Regulation of the Configuration, Maintenance, and Procedures (CMP) Process for Developing SFAR 88-related Instructions for Maintenance and Inspection of

Fuel Tank Systems

Some of other NAA documents may need to be considered:

AC 25.1529-1A - INSTRUCTIONS FOR CONTINUED AIRWORTHINESS OF STRUCTURAL REPAIRS ON TRANSPORT AIRPLANES

AC 120-93 DAMAGE TOLERANCE INSPECTIONS FOR REPAIRS AND ALTERATIONS AC25.1581-1 - Airplane Flight Manual AC120-16F - Air Carrier Maintenance Programs AC120-42B - Extended Operations (ETOPS and Polar Operations) AC121-16 - Maintenance Certification Procedures AC121-16 - Maintenance Certification Procedures AC120-76B - Guidelines for the Certification, Airworthiness, and Operational Use of

Electronic Flight Bags AC 120-98A - Operator Information for Incorporating Fuel Tank Flammability Reduction

Requirements into a Maintenance or Inspection Program AC121-22C - Maintenance Review Boards, Maintenance Type Boards, and OEM/TCH

Recommended Maintenance Procedures


Some of applicable CASA regulations may need to be considered when ICA are developed.

Civil Aviation Order 20.4 (PROVISION AND USE OF OXYGEN AND PROTECTIVE BREATHING EQUIPMENT)

Civil Aviation Order 20.18 (Aircraft equipment — basic operational requirements)

Civil Aviation Order 20.11 (Emergency and life saving equipment and passenger control in emergencies)

CASR 1998 Part 90 (Additional Airworthiness Requirements )

CASR 1998 Part 90 Manual of Standards (MOS)

CASA AC 90-1(0) (EXCLUSIONS AGAINST PROVISIONS IN CASR PART 90)

AAC 1-116 Approved Single Engine Turbine Powered Aeroplane (ASETPA)

Questions?

Lesson 7 Development of Instructions for Continuing Airworthiness

Certification Maintenance Requirements (CMR) Principles A CMR is a required scheduled maintenance task established during the design certification of the airplane systems as an operating limitation of the type certificate (TC) or supplemental type certificate (STC).

A CMR usually results from a formal, numerical analysis conducted to show compliance with the requirements applicable to catastrophic and hazardous failure conditions. Compliance may also result from a qualitative, engineering judgment-based analysis.


CMR Principles

1 • The CMRs are required tasks, and associated intervals, developed to

achieve compliance with § 25.1309.

2 • A CMR is intended to detect safety-significant latent failures that would, in

combination with one or more other specific failures or events, result in a hazardous or catastrophic failure condition.

3 • A CMR can also be used to establish a required task to detect an

impending wear-out of an item whose failure is associated with a hazardous or catastrophic failure condition.

4 • Further reading FAA AC 25-19A - Certification Maintenance Requirements


CMR Principles The CMRs verify that a certain failure has or has not occurred, indicate that repairs are necessary if the item has failed, or identify the need to inspect for impending failures (e.g., heavy wear or leakage).

In other words, there are two main drivers for CMRs

System Safety Analysis (1309 Analysis).

Impending wear-out of an item that could lead to a hazardous or

catastrophic failure condition.

In both cases latent failures must be considered in the analysis.


CMR Principles The CMRs analysis is different from the MSG-3 analysis and although both types of analysis may produce equivalent maintenance tasks and intervals, it is not always appropriate to substitute a CMR with an MSG-3 task.

The CMRs are to be developed and managed separately from any structural inspections programs that are developed to meet the inspection requirements for damage tolerance, as required by§ 25.571, 25.1529, and Appendix H25.4 (Airworthiness Limitations section). Scheduled Maintenance Tasks Developments


CMR Principles System Safety Analysis or System Safety Assessment (SSA) (1309 Analysis). Part 23/25/27/29.1309 Equipment, systems, and installations - General and main requirements

The requirements of this section, are applicable, in addition to specific design requirements of part 23/25/27/29, to any equipment or system as installed in the airplane. This section is a regulation of general requirements and does not supersede any requirements contained in another section of part 23/25/27/29.


CMR Principles System Safety Analysis or System Safety Assessment (SSA) (1309 Analysis). Part 23/25/27/29.1309 Equipment, systems, and installations - General and main requirements

The airplane equipment and systems must be designed and installed so that any equipment and system does not adversely affect the safety of the airplane or its occupants, or the proper functioning.

The airplane systems and associated components considered separately and in relation to other systems, must be designed and installed so that each catastrophic failure condition is extremely improbable and does not result from a single failure, each hazardous failure condition is extremely remote and each major failure condition is remote.


CMR Principles SSA (1309 Analysis) The applicant is responsible for identifying and classifying each failure condition and choosing the methods for safety assessment. The applicant should then obtain early concurrence from NAA on the identification of failure conditions, their classifications, and the choice of an acceptable means of compliance.


CMR Principles Documentation and Handling of CMRs.

The CMR data location should be referenced in the type certificate data sheet (TCDS).

The latest version of the CMR document should be controlled by a log of pages approved by the NAA of the TC / STC holder or CASA.

CMRs are functionally equal to airworthiness limitations. An acceptable means is to include CMRs in the Airworthiness Limitations section of the airplane maintenance manual.

Any post-certification changes to CMRs should be reviewed by the same entities that participated in the initial CMR selection and approval and must be approved by the NAA of the TC / STC holder or CASA.

Questions?


MEL / PU Items assessment / approval MEL Assessment

An operator’s MEL must take into account

The aircraft configuration Type of operation and operating environment

An MEL condition or item is normally not less restrictive than the corresponding MMEL

Except where regulatory requirements permit. FAA AD 74-08-09R3

MEL is derived from the Master Minimum Equipment List (MMEL)

MMEL is developed by the TC Holder and its NAA

MMEL is approved by the NAA of the TC Holder


MEL / PU Items assessment / approval

Items not covered in an MMEL - assessment / approval process

The following methods of justification can be used for those items not covered in an MMEL.

Optional Equipment - When optional equipment is fitted (over and above the aircraft type certification equipment).

Redundant Items - If the purpose or function of a component or system can be carried out by some other item(s) of equipment.

Passenger Convenience Items - Item(s) such as galley equipment, in flight entertainment, overhead reading lamps etc which are not addressed in the MMEL.

Any Other Items will require Qualitative and / or Quantitative Safety Analysis.



Items not covered in an MMEL - assessment / approval process

Other • Any Other Items

And/Or • Qualitative Safety Analysis.

And/Or • Quantitative Safety Analysis.

• The unserviceability may be accepted.


MEL / PU Items assessment / approval Qualitative Safety Analysis

These analytical processes assess system and aircraft safety in a subjective, non-numerical manner, based on experienced engineering judgement.

Consider the impact that the proposed inoperative item has on all other aspects of the aircraft’s operation.

The impact on crew workload and operating environment.

The impact of invoking multiple PU or MEL items.

The impact of any other existing defects.

The complexity of maintenance and/or operational procedures.



Quantitative Safety Analysis If the operation of aircraft with an item inoperative cannot be justified by the previous means or criteria, then a safety analysis must be carried out. This involves a quantitative analysis of the likely risk of the worst effects that could result from additional failures, events and/or environmental conditions occurring during a flight, with the particular inoperative item in question. Assessment techniques / analysis that should be employed in this case are

the same or similar to those used for SSA (1309 Analysis).

Questions?


MAINTENANCE STEERING GROUP (MSG)

The development of maintenance programs dates to FAA Aeronautical Bulletin 7E of May

15, 1930. In the past, each air carrier proposed its own unique program.

Today, the process is a collaborative effort in which the associated regulatory authorities, and industry work

together to develop the minimum scheduled maintenance/inspection requirements for new and derivative aircraft, aircraft engines, and propellers.

In 1968, the Maintenance Steering Group - 1st Task Force (MSG-1) developed maintenance requirements decision

and analysis logic. MSG-1 introduced three broad processes to classify the scheduled maintenance

requirements.

Hard Time (HT) On-Condition (OC) Condition Monitoring (CM)


MAINTENANCE STEERING GROUP (MSG) The MRB process should be used for:

(1) Transport category airplanes designed to carry 10 or more people or having a

maximum weight of 33,000 lb or more,

(2) Transport category “A” helicopters, or (3) Powered-lift aircraft.

MRB may also be used for any aircraft by choice of the OEM/TCH. An MRBR contains the minimum scheduled tasking/interval requirements for a

particular aircraft and on-wing engine maintenance programs.

MRBR should undergo an annual review by the OEM/TCH, Industry Steering Committee (ISC), and the Maintenance Review Board (MRB) chairperson.



Scheduled maintenance, as such, cannot correct deficiencies in the inherent safety and reliability levels of the aircraft. The scheduled maintenance can only prevent deterioration of such inherent levels. If the inherent levels are found to be unsatisfactory, design modification is necessary to obtain improvement.

The objectives of efficient aircraft scheduled maintenance

To ensure realization of the

inherent safety and reliability levels of

the aircraft.

To restore safety and reliability to

their inherent levels when

deterioration has occurred.

To obtain the information

necessary for design

improvement of those items whose inherent reliability

proves inadequate.

To accomplish these goals at a minimum total cost, including

maintenance costs and the costs of resulting failures.

Questions?


Maintenance data creation and approval

Maintenance data can also be developed outside the TC / STC process of an

aircraft. This is usually done by an operator or an AMO or a CASR Part 21M Authorised Person in order: to facilitate more efficient work practices, or to address the unavailability of materials, parts or tools required by already

approved maintenance data and facilitate their substitution, or there is no existing maintenance data covering the particular maintenance, or to address a repair or modification of the aircraft / aeronautical product made

under CASR Part 21M approval.

A development of alternative maintenance data and practices in order to cut maintenance costs is usually not an acceptable reason to redevelop maintenance data. A process used by the operators or AMOs or a CASR Part 21M Authorised Persons to develop maintenance data is essentially identical to the process used by the TC / STC holders.



Civil Aviation Regulations 1988

CAR 2A Approved maintenance data (2) For the purposes of paragraph (1) (a), the maintenance data are: (e) any other instructions, approved by CASA under subregulation (4) for the purposes of this paragraph, relating to how maintenance on aircraft, aircraft components or aircraft materials is to be carried out. (4) CASA may, for the purposes of paragraph (2) (e), approve instructions relating to how maintenance on aircraft, aircraft components or aircraft material is to be carried out.

Only CASA can approve newly created maintenance data that are not listed in or not created by persons identified in CAR 2A (2).




Division 7 Exemptions from, and variations of, requirements CAR 42ZS Granting of exemptions and approval of variations (1) CASA or an authorised person must grant the exemption or approve the variation if CASA or the authorised person is satisfied that granting the exemption or approving the variation would not adversely affect the safety of air navigation. (2) If CASA or the authorised person grants the exemption, or approves the variation, the grant or approval may be made or given subject to such conditions as CASA or the authorised person thinks necessary in the interests of the safety of air navigation.



The process used for justifying exemptions from or amending (making variation) to maintenance data is the same as the process used for creating maintenance

data (as a part of ICA) during the TC process.

The justification must demonstrate a sound

understanding of certification requirements

for the aircraft, their relation to and impact on the

affected maintenance data.

An assessment of the impact of the exemption or variation on the certification requirements of the aircraft

should be performed.

The outcome of the assessment should identify necessary conditions for the

approval.

Approval can be granted by CASA or a CAR 42ZS

authorised person.


CAR 42ZS provides an opportunity to approve variation to or exemptions from approved maintenance data.

Questions?

Lesson 14 System of Maintenance

TBO and maintenance schedule frequency escalations and one-off overruns Basic principles: Source: CAAP 42M-1(0) Approved System of Maintenance for Class A Aircraft Airworthiness limitations are mandatory replacement times, structural inspection

intervals, and related structural inspection tasks. Airworthiness limitations are excluded from any escalation process by the operator.

Critical Design Configuration Control Limitations (CDCCL) - An Airworthiness

Limitation that preserves a critical feature of the aircraft needed for the Flammability Reduction Means (FRM) or Ignition Mitigation Means (IMM) to perform their intended function and prevent the occurrence of an unsafe condition.


TBO and maintenance schedule frequency escalations and one-off overruns Basic principles: Source: CAAP 42M-1(0) Approved System of Maintenance for Class A Aircraft The maintenance task frequencies included in the initial SOM generally

reflect the recommendations (MRB Report, MPD, Chapter 5 of the Maintenance Manual, etc.) issued by the aircraft certification authority or the aircraft TC holder. Frequencies may be adjusted later in accordance with the operator’s reliability program or as a result of the operator’s monitoring of the effectiveness of the SOM and IAW previously approved procedures for adjustment.


TBO and maintenance schedule frequency escalations and one-off overruns Basic principles: Source: CAAP 42M-1(0) Approved System of Maintenance for Class A Aircraft Task intervals of CMRs, CDCCL, ALIs and any regulatory requirements are

not permitted to be varied without prior approval of CASA or an authorised person.

TC holders' recommendations or inspection program revisions do not, by

themselves, permit change to an SoM. Any change to an SoM must be justified by the registered operator and approved by CASA or an authorised person.

TBO and maintenance schedule frequency escalations and one-off overruns Some of the engineering, maintenance and reliability considerations that must be taken into account when preparing a justification for maintenance schedule frequency escalations and one-off overruns are provided in FAA AC 121-22C Chapter 12 and Appendix 2. A summary of these considerations is provided below.

Evaluation of in-service data, both scheduled and unscheduled maintenance findings

related to the intent of the Maintenance Steering Group (MSG) task. Weighing of the relevance and significance of findings.

Ensuring of data quality, integrity, completeness, and clarity.

Consideration of each task individually.

A review of original design and engineering specifications, as required.



TBO and maintenance schedule frequency escalations and one-off overruns Some of the engineering, maintenance and reliability considerations

review of all information related to continuing airworthiness (e.g., Airworthiness Directives, Service Bulletins (SB), in-service reports/letters, and modifications/repairs).

Basing MRBR task evolution/optimization or deletion/addition on worldwide

representative samples that span the operating environment and age groupings of the aircraft.

Application of statistical models to support the evolution/optimization or

deletion/addition exercise. Measurement of task effectiveness.


TBO and maintenance schedule frequency escalations and one-off overruns The same FAA AC 121-22C in Chapter 12 also provides the following statement:

If this chapter is not followed, the OEM/TCH will be limited to no more than 10 percent escalation with approved data. Further escalation is not allowed until a task is repeated and sufficient data are available.

Many OEM/TCH use this provision to incorporate one-off 10% extension option in their ICA in order to allow for maintenance and operational scheduling flexibility.


TBO and maintenance schedule frequency escalations and one-off overruns The engineering, maintenance and reliability considerations and

principles that must be taken into account when preparing a justification for maintenance schedule frequency escalations and one-off overruns for Class B aircraft are essentially the same as those previously presented for Class A aircraft.

EASA policy on escalations is provided in IP 44 Evolution-Optimization Guidelines and Work Instruction “Maintenance Review Board team WI.MRB.00002-001” and it is essentially the same as FAA approach.

Questions?

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