# Policy Statement

Subject: Risk Assessment Methodology for Transport Category Airplanes Date: 11/4/2011
Initiated By: ANM-117 Policy No: PS-ANM-25-05

Summary

To support implementation of a Safety Management System (SMS) within the Aircraft Certification Service (AIR), AIR released Order 8110.107, Monitor Safety/Analyze Data (MSAD), on March 12, 2010. That order provides re quirements and guidance for a standardized, SMS-based, continued-operati onal-safety process to be used across the service.

The MSAD order requires each aircraft directorate to—

Develop product-specific continue d-operational-safety risk-analysis methodology and guidelines by which risk can be reported in terms of the statistical probability of a fatal accident. This methodology must be quantitative, or it must be structured in such a way that it can evolve into a quantitative methodology.

An intra-directorate team was formed and char tered by the Transport Airplane Directorate in 2002 to develop a transport-airplane-specific risk-a nalysis process. The result of that multi-year team development is the Transport Airplane Risk Assessment Methodology (TARAM). The TARAM has evolved significantly from lessons learned, and from comments and suggestions from many sources. The TARAM has also been redu ced in scope to be compatible with, and to support, the MSAD process, which is de scribed in the at tached TARAM Handbook.

The TARAM is to be used within the MSAD pro cess for risk analysis and risk management. Aircraft-certification offices will use it to resolve issues of continued operational safety for transport-category airplanes. 1 This methodology may also be used by design-approval holders, in whole or in part, by agreem ent with the applicable aircraft-certification office.

1 Continued-operational-safety risk analyses for engine and propeller, small airplane, and rotorcraft issues will be accomplished using the applicable directorate-defined methodology.2 Current Regulatory and Advisory Material

In general, the regulatory basis and roles and requirements for transport-airplane continued operational safety can be found throughout 14 CFR parts 21, 39, 91, 121, and 135. Mandatory corrective actions to address uns afe conditions are addressed by airworthiness directives as prescribed by 14 CFR part 39. Existing guidance for risk assessments for powerplant continued operational safety is contained in Advisory Circular (AC) 39-8, “Continued Airworthiness Assessments of Powerplant and Auxiliary Powe r Unit Installations of Transport Category Airplanes.” 2 Order 8110.107 outlines a standardized proce ss that aircraft-certi fication offices will use for safety decision-making and resu lting airworthiness-directive action.

Relevant Past Practice

Previously, no formal process, guidance, or polic y was in place for transp ort-airplane continuedoperational-safety risk analyses/management be yond that contained in AC 39-8 for powerplant continued operational safety. Tran sport-airplane continued-operati onal-safety risk determinations are currently based on en gineering judgment and, to a lesser extent, derived very loosely from the certification guidanc e given in AC 25.1309-1A.

To fill the need for such guidance, as part of AIR SMS development, the AIR SMS MSAD team has now created a standardized and documented continued-operational-safety process for each aircraft-certification office/direct orate to use identifying and resolv ing safety issues. That process is contained in Order 8110.107. Integr al to that process is the anal ysis of risk and the comparison of that risk to the product-specific risk guideline s that the directorates ha ve developed. The riskassessment methodology and risk guidelines for tr ansport category airplanes are found in the TARAM Handbook, attached.

Policy

The methodology in the attached TARAM Hand book is meant to be used by FAA aerospacesafety engineers within the MSAD process. It is important that the pub lic and affected design approval holders also know how the risk associated with transport-airplane continuedoperational-safety issues will be analyzed and cons idered within that overall process. In addition, affected design-approval holders s hould know, in general, the data and information that could be requested from them when aircraft -certification offices are analyz ing the risk associated with continued-operational-safety issu es (failure rates, failure mode /physics of failure, root cause, potential accident sequence [causal chain], fault- trees, conditional probabilities, affected fleet size, etc.). Design-approval holders may request to perform, or be asked to perform, all or part of the TARAM process pursuant to an organizati on delegation approval ornegotiated continuedoperational-safety-management agreement. In t hose cases, the design-approval holder will need to understand the details of the TA RAM contained in the TARAM Handbook.

2 The certification-guidance material for § 25.1309 (e.g., AC 25.1309-1A) contains no continued-operational-safety guidance3
Accordingly, for the purposes of public and design-approval-holder awareness, review, and comment, the TARAM Handbook is attached to this policy statement. The TARAM Handbook is intended as a job aid for FAA aerospace-safety e ngineers. It provides deta iled instructions and guidance. Members of the public who want to understand the risk-analysis methodology and risk-level guidelines that support the MSAD process, without reviewing the entire handbook, will find an explanation of those concepts in these sections of the TARAM Handbook:

 Section 5.0, Risk Analysis, incl uding Appendix B, C, and D

 Sections 6.1 and 6.2, Fail-Safe Design and Risk Level Guidance

Effect of Policy

This policy does not change or contravene th e guidance in AC 39-8. Fo r issues related to powerplant or auxiliary power unit (APU) continued operational safety, see AC 39-8. That AC describes the recommended methodology for iden tifying, analyzing, priori tizing, and resolving unsafe conditions on transport-category airplane power plants and APUs.

FAA safety determinations, as described thr oughout 14 CFR parts 21 and 39, are an important function of the Administrator, yet the Administra tor has a great deal of flexibility and latitude when making safety determinations. The TA RAM Handbook provides guidance for considering risk as a factor when determining whether a cond ition found in the transport- airplane fleet is safe or unsafe. This guidance is only one thing to consider in the sa fety decision-making process and does not constitute the sole basis for unsafe-condition determination nor limit, in any way, the FAA prerogative to make such determinations.

The TARAM Handbook, in conjunction with Orde r 8110.107, guides and sta ndardizes transportairplane-related safety decision-maki ng. Neither the TARAM Handbook nor Order 8110.107 requires or obligates the FAA to perform any pa rt of the TARAM process before issuing an airworthiness directive.

The general policy stated in this document does not const itute a new regulation. The FAA individual who implements policy should follow th is policy when it is applicable to a specific action. Whenever safety decision-making is outsid e this established polic y, that individual must coordinate the decision-making with the policy-i ssuing office. Similarly, if an implementing office becomes aware of reasons that an applicant’ s proposal that is based on the guidance in this policy should not be approved, that implementing office must coordinate its response with the policy-issuing office.

Design-approval holders should expect that regula ting officials will consider this policy when making safety findings and issuing airworthiness directives. In addition, as with all advisory material, this statement of policy identifies one means, but not the only means, of accomplishing safety decision-making.4
Implementation

This policy discusses methods that should be applied during continue d-operational-safety decision-making for transport-categ ory airplanes certificated in th e United States, except where the guidance of Advisory Circular 39-8 is applicable.

Direct your questions or comment s to Forrest Keller, Transport Directorate Standards Staff, Safety Management Branch, ANM-117, phone 425-227-2790.

/s/ Ali Bahrami

Ali Bahrami Manager, Transport Airplane Directorate Aircraft Certification Service

Attachments5

Attachment 1

Terms

Table A-1 defines the use of key terms in this po licy statement. The table describes the intended functional impact.

Table A-1 Definition of Key Terms

Regulatory Requirements Acceptable Methods of Compliance (MOC) Recommendations

Term Must Should Recommend Meaning Refers to a regulatory requirement that is mandatory for design approval Refers to instructions for a particular MOC Refers to a recommended practice that is optional

Functional Impact No Design Approval if not met Alternative MOC has to be approved by issue paper. None, because it is optional