FAA Process for Federal Aviation Policy and Guidance

Federal Aviation Administration

Presented to: MARPA

By: FAA, Standards Staff, Engine and Propeller Directorate

Date: October 28, 2015

FAA Process for

Policy and Guidance

Public Comments


Presented to: MARPA



FAA Guidance

Advisory Circulars Turbine Engine and APU Parts

2 Federal Aviation Administration

FAA Advisory Circulars

October 28, 2015

New Guidance

• Materials [See previous presentation.]

• Statistics

• Geometry

• Rub Rig

• Influencing Parts Guide

Advisory Circulars



October 28, 2015

Status: Ready for Second Comment Review

• Provides clarification for determining the appropriate sample

sizes for certification purposes

• Explains the proper use of statistical methods to show

equivalency between two populations of parts

• History

- Issued August, 2014, then withdrawn January, 2015

- Industry concerned about interpretation and applicability

- AC was revised and reviewed by MARPA (New Step)

Guidance Update (continued)

Statistics AC



October 28, 2015

Status: Public Comment Complete

• Purpose

- Provides information about how dimensional characteristics are

affected by reverse engineering techniques

- Enhances awareness about where differences can originate in the

reverse engineering process

- Intended to supplement applicant’s ability to identify suitable

compliance methods for comparative approaches to certification

New Step - Coordinating finalized version with MARPA prior

to issuance and posting comments in the Federal Register

Geometry AC




October 28, 2015

Status: In Development

• This AC will provide information to help applicants

develop their own methods for establishing equivalence

for wear related degradation

• Unlike the burner rig, there are no standardized

approaches for assessing relative wear capability for

replacement parts

Rub Rig AC




October 28, 2015

Status: AIA Accepted FAA Tasking Letter

• The anticipated document is intended to be a

Familiarization Guide that helps applicants recognize

when their replacement part could have an effect on the

integrity of Life Limited engine parts

• How can you help?

Influencing Parts Guide



PMA Material Compliance Using

the Comparative Test and Analysis

Method

Presented to: MARPA




MARP

Draft AC 33.15-3

Objective

Provide a Methodology and Standards for assurance that the

proposed material used in PMA hardware has capability at

least equivalent to Original Type Design (OEM) material.

Verification Process

Utilizes a series of tests to define and evaluate the PMA and

OEM material and compare material capabilities.

Tests are performed according to accepted Aerospace

Standards.


MARP

Verification Process Rationale

Based on the fundamental metallurgical principle that a material’s

capabilities (mechanical and physical properties) are controlled by

its “metallurgical properties”.

These Metallurgical properties include:

Chemical Composition

Material Form (i.e. casting or wrought material type)

Microstructure

Hardness

Surface Coating or Treatment

Draft AC 33.15-3


MARP

Draft AC 33.15-3 Verification Process Methodology

PMA Applicant can perform comparison tests on finished PMA

parts and similar Design Type parts. This is suitable when sufficient

test material can be extracted from these.

PMA Applicant can perform comparison tests on specially prepared

test material which duplicates the metallurgical properties in the

corresponding finished parts.

If Metallurgical Property equivalence is proven, the PMA

Applicants component is equivalent to the Type Design one.

This comparative test program must be reviewed and agreed upon

by the FAA prior to execution


MARP

Draft AC 33.15-3

If Metallurgical Equivalence is Not met

The PMA Applicant is guided through a series of mechanical

and physical properties which could affect part function. Evaluating

these properties with approved techniques would validate the PMA

Part suitability for qualification.


MARP

Draft AC 33.15-3

This AC provides

A disciplined methodology for evaluating the capability of PMA

material relative to Type Design material

Provides standards for testing and demonstrating “equivalency”

of materials

Handles situations where material substitution occurs

Provides alternate means of compliance other that comparative

testing.


MARP

Additive Manufacturing

• The Design, Manufacturing, & Airworthiness Division (AIR-100)

recognizes that Additive Manufacturing (AM) is a potential game

changer in the fabrication and repairs of aircraft, engine and

propellers.

• AIR-100 Issued a Memorandum requiring ACOs / MIDOs to notify

FAA of AM projects.

• AMNT is developing a checklist to provide a list of the key questions

that need to be asked when certifying a part using AM technology.


FAA Protocol for Public Documents

October 28, 2015

Advisory Circular Review Process

• Early Notification of Guidance to Industry

• Reasons for the AC (description, applicability)

• Solicit input during document development

• FAA Internal Review and Comments

• Public Review and Comments

• Review AC Updates with Industry

• Issue Document



October 28, 2015

Comment Log

Agency Disposition



October 28, 2015

Potential Comment Disposition

Adopted

• FAA concurs with the comment and the suggested

changes are incorporated into the document

Partially Adopted

• Some suggested changes are incorporated into the

document or clarification is added

Non-Concur

• No changes are made to the document



October 28, 2015

Potential Comment Disposition

Concur but Outside of Scope

• Comment is valid, but it affects a broader range of

Products, Regulations or Processes than intended

Answer to a Question or Statement rather than

a Comment

• Generally, questions and statements are considered as

comments and often prompt changes that clarify the

document intent and applicability



October 28, 2015

Effective Comments

Examples

• Comment proposes additional considerations

that take into account specific concerns

• Comment highlights potential for unintended

consequences

• Comment explains the impact to their company,

and provides details to support the statement



October 28, 2015

Ineffective Comments

• Non-specific critiques with no or little rationale

without suggestions for alternative words

– “We don’t need this AC.”

– “No testing is required for PMA.”

– “If this is true, FAA needs to issue ADs for all PMA.”

– “The engine manufacturer must provide critical design

information so it can be copied.”

• Sometimes ineffective comments support the

need for the advisory circular