1

Impact  of  Regulations  on  Cabin  Systems  Installations  

John  Courtright,  Structural  Integrity  Engineering  

1 APEX TC Meeting•22-23 February 2011•Huntington Beach, CA USA

APEX TC Meeting•22-23 February 2011•Huntington Beach, CA USA 2

Agenda  Points    The STC process "briefly" stated - application to installation

  "Heightened" FAA attention to technical issues related to IFE & Wi-Fi Systems Installations

  The Aging Aircraft Safety Rule – EWIS & Damage Tolerance Analysis

  The Challenge: Maximize Flight Safety While Minimizing Costs

  Issue Papers & Testing, Testing, Testing

  The role of Airworthiness Directives (ADs) on the design of many IFE systems and all antenna systems. Goal is safety AND cost-effective maintenance intervals and inspection techniques.

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The STC Process Briefly Stated  Type Certifications (TC)  Supplemental Type Certifications (STC)  The STC Process  Project Specific Certification Plan (PSCP)

  Managed by FAA Aircraft Certification Office (ACO)   Type of Project (Electrical/Mechanical Systems or

Structural)   Specific Type of Aircraft Being Modified   Schedule   Design & Installation Location

What Does the STC Plan (PSCP) Cover?   System Description – What Does the System Do?   System Qualification – Are the Components Qualified?   Certification Requirements – What FARs Are Applicable?   Installation Detail – What Is Being Modified?   Prototype Installation – What Is New?   Functional Hazard Assessment (FHA) – Is It Safe?   EZAP-EWIS Requirements – Any Aging Aircraft Issues?   Certification Data – How Is Compliance Achieved?   Delegation and FAA Involvement – Who Is Doing the Work?   Proposed Certification Schedule – When Is the Installation?

  Certification Documentation – What the FAA Expects To See

Cabin Systems Certification Concerns   In addition to Meeting the Requirements for DO-160, Cabin System

Certification Needs to Address Issues Related To:

  Power Management: Generally, IFE and Wi-Fi Systems are Classified as “Non-Essential Equipment” From a Certification Viewpoint

  Connected to “Non-Essential” Power Buses

  Must Be Able to Shed IFE & Wi-Fi Systems in a Smoke/Fire Event or Other Electrical Emergency (FAA Policy 00-111-160)

  Aging Aircraft Concerns – Electrical & Structural

  Issue Papers Addressing Technical Concerns Involving:

  “Structural Certification Criteria for Large Antenna Installations”

  Antenna “Vibration/Buffeting Compliance Criteria”

DO-160 – Environmental Test Procedures   DO 160 – “Environmental Conditions and Test Procedures for Airborne

Equipment, Issued By RTCA   Provides Guidance to Equipment Manufacturers as to Testing Requirements

  Temperature - -40ºC to +55º C   Vibration & Shock   Contaminant Susceptibility – Fluids, Dust   Electro-Magnetic Interference (EMI)

  Radio Emissions – Testing Across Multiple Frequencies   Radio Susceptibility   Power Input, Surges & Power Interruptions (200msec)   Bus Noise

  Lightning   HIRF

Installation Design Considerations: Wiring Practices

  Cabin Systems Are Generally Classified as “Non-Essential”

  “Non-Essential” Systems Are Connected to “Non-Essential” Power Buses

  Must Be Able to Shed Cabin System in a Smoke/Fire Event.

Wiring Practices & Safety   The U.S. Transportation Safety Board (TSB) Determined, in Part, That the

Swissair 111 Tragedy Was Caused By Non-Standard Wiring Practices.   TSB Report Causal Factors (Partial List)

  TSB Factor #6: “A segment of the [system] power supply unit cable a region of resolidified copper on one wire that was caused by an arcing event. This resolidified copper was determined to be located…..in the area where the fire most likely originated.”

  TSB Finding re Risk #8: “Examination revealed various wiring discrepancies that have the potential to result in wire arcing.”

  Changes Recommended Resulted in New Regulations   FAR 25 and CS 25- Subpart H   Develop Electrical Wiring Interconnection System Definition (EWIS)   Develop New Instructions for Continued Airworthiness (ICA) for Wiring

BAD WIRING – AN EXAMPLE   Susceptible to Chafing & Arcing

EWIS-WHAT IS IT?   Electrical Wiring Interconnect System

  “Any wire, wiring device, or combination of these,…installed in any area of the aeroplane for the purpose of transmitting electrical energy, including data and signals between two or more intended termination points.” CS-25 Subpart H

  “Electrical wires and cables must be designed and installed so they are compatible with the circuit protection devices required by 25.1357, so that a fire or smoke hazard cannot be created under temporary or continuous fault conditions.” FAR 25.1717

EWIS Design Implications   Installation Design Must Take EWIS Requirements Into Account   This Generally Means:

  Aircraft Surveys Are Needed to Identify Proper Wire Routing   Ensure Existing Wiring Diagrams Are Correct   Identify Primary/Secondary/Tertiary Bus Locations   Verify Proper Separation of Wire Bundles Exist   Required Separation from Fuel Quantity Indicator System (FQIS) to

Prevent Fuel Tank Ignition   Enhanced Zonal Analysis Procedure (EZAP) Performed

  EZAP was developed by the Aging Transport Systems Rulemaking Advisory Committee (ATSRAC)

  EZAP is the method for analyzing airplane zones with an emphasis on evaluating wiring systems and the existence of combustibles in the cabin.

  Maintenance & Inspection Criteria Are Developed Based on EZAP

Certification Considerations For Wi-Fi Systems   Electrical – All Existing DO 160 Testing Required   Issue Papers Required

  Onboard EMI Testing – Any interference with Aircraft Systems When Multiple Wi-Fi Users Are Logged On?

  Vibration/Buffeting Compliance Criteria – What Is the Effect of the Antenna on Aircraft Flight Characteristics?

  Structural Certification Criteria – What Are the Stress Loads on the Aircraft at the Antenna Location and What Is the Impact on Maintenance Inspection Criteria for the Airline?   Damage Tolerance Analysis Required   Goal – Minimize Maintenance Inspection Intervals

Modified Structure & Antenna Systems

Structural Considerations: Damage Tolerance Analysis   All Wi-Fi (and All Satcom) Involve Penetration of the Fuselage (Pressure

Vessel) to One Degree or Another.   When a Hole Is Drilled In an Aircraft, A Damage Tolerance Analysis (DTA) Is

Required To Determine How To Minimize Damage To the Aircraft   Solutions Include Adding Doublers/Triplers to the Affected Area   Determination of the potential crack growth & the maintenance and

inspection procedures needed to prevent catastrophic damage.   Maintenance Procedures Considered Include:

  Type of Inspections – Visual, NDT (HFEC/LFEC), etc.   Inspection Intervals – Cycles, Flight Hours or Time.

  DTA is Vital Input Into the Operators Instructions for Continued Airworthiness and the Aircraft Maintenance Manual (Supplements).

Start Evaluation

STC/Non-STC Modification

Does installation affect an

existing SSI listed in the

SSID? Has installation

substantially altered the

affected structure or increased/

redistributed the loads acting on it?

Damage Tolerance Assessment required to comply with the AD. Note: The Repair Assessment Guidelines (RAG) CANNOT be used as AMOC.

Damage Tolerance Assessment and supplemental inspections not required.

Repair

Has installation physically altered the pressure boundary

(fuselage and cargo door

skins)? Does

installation affect an existing

SSI listed in the SSID?

Does installation affect an existing

SSI listed in the SSID?

Damage Tolerance Assessment required to comply with AD 98-11-03/04 R1.

Damage Tolerance

Assessment and

supplemental inspections not

required.

Damage Tolerance Assessment required to comply with AD 12-34-56-78 R1. The Repair Assessment Guidelines can be used as AMOC, as applicable.

Refer to Repair Assessment Guidelines for supplemental inspection requirements, no AMOC approval required.

NO

NO

NO

NO

YES

YES YES

YES

YES NO

Sample DTA Flow Chart

Aging Aircraft Safety Rule (AASR)

  As of December 20, 2010, airlines that operate airplanes under Title 14 of the Code of Federal Regulations (CFR) 121 or 129 must revise their U.S. Federal Aviation Administration (FAA)-approved structural maintenance program to comply with the FAA’s Aging Airplane Safety Rule (AASR).

  This revised maintenance program must include damage-tolerance-based inspections; a means to address the effects that repairs, alterations, and modifications may have on fatigue-critical structure and these inspections; and a means by which all changes to the maintenance program receives FAA approval. Airbus & Boeing has developed materials to help operators comply with this new rule

Why Damage Tolerance Analysis Is Important  Aloha Airline Flight 243 - 1988

OTHER CONSIDERATIONS: AIRWORTHINESS DIRECTIVES (ADs)   An AD is a Compulsory Modification or Maintenance Ordered by the FAA or

EASA Usually In Reaction To a Problem With ANY Element of the Aircraft.   Operator Must Comply By a Given Date   May Involve Multiple Aircraft Types or a Subset of Aircraft Types   ADs Are An Important Regulatory Tool to Ensure Air Safety

  In An STC Program Situation – The Operator and the Engineering Firm MUST Take Into Account All ADs That Apply to That Aircraft.   If there Is a Pending AD on the Aircraft, the Installation Design Must Not

Adversely Affect the AD   This Requires Research & Investigation of the Affected Areas of the Install

and Any Pre-Existing ADs.

THANK YOU John Courtright

Structural Integrity Engineering jcourtright@SIEinc.com

(425) 493-2828 (206) 618-3128