58508 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Parts 1, 25, 91, 121, 125, 129 

[Docket No. FAA–2004–18379; Notice No. 

05–08 ] 

RIN 2120–AI31 

Enhanced Airworthiness Program for 

Airplane Systems/Fuel Tank Safety 

(EAPAS/FTS) 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The intent of this proposal is 

to help ensure the continued safety of 

commercial airplanes by improving the 

design, installation, and maintenance of 

their electrical wiring systems as well as 

by aligning those requirements as 

closely as possible with the 

requirements for fuel tank system safety. 

This proposed rulemaking consists of 

regulatory changes affecting wiring 

systems and fuel tank systems in 

transport category airplanes. First, it 

proposes to organize and clarify design 

requirements for wire systems by 

moving existing regulatory references to 

wiring into a single section of the 

regulations specifically for wiring and 

adding new certification rules. It also 

proposes to require holders of type 

certificates for certain transport category 

airplanes to conduct analyses of their 

airplanes and make necessary changes 

to existing Instructions for Continued 

Airworthiness (ICA) to improve 

maintenance procedures for wire 

systems. It would require operators to 

incorporate those ICA for wiring into 

their maintenance or inspection 

programs. And finally, this proposed 

rulemaking would clarify requirements 

of certain existing rules for operators to 

incorporate ICA for fuel tank systems 

into their maintenance or inspection 

programs. 

DATES: Send your comments on or 

before February 3, 2006. 

ADDRESSES: You may send comments 

[identified by Docket Number FAA– 

2004–18379] using any of the following 

methods: 

• DOT Docket Web site: Go to http:// 

dms.dot.gov and follow the instructions 

for sending your comments 

electronically. 

• Government-wide rulemaking 

Web site: Go to http:// 

www.regulations.gov and follow the 

instructions for sending your comments 

electronically. 

• Mail: Docket Management Facility; 

U.S. Department of Transportation, 400 

Seventh Street, SW., Nassif Building, 

Room PL–401, Washington, DC 20590– 

001. 

• Fax: 1–202–493–2251. 

• Hand Delivery: Room PL–401 on 

the plaza level of the Nassif Building, 

400 Seventh Street, SW., Washington, 

DC, between 9 a.m. and 5 p.m., Monday 

through Friday, except Federal holidays. 

For more information on the 

rulemaking process, see the 

SUPPLEMENTARY INFORMATION section of 

this document. 

Privacy: We will post all comments 

we receive, without change, to http:// 

dms.dot.gov, including any personal 

information you provide. For more 

information, see the Privacy Act 

discussion in the SUPPLEMENTARY

INFORMATION section of this document. 

Docket: To read background 

documents or comments received, go to 

http://dms.dot.gov at any time or to 

Room PL–401 on the plaza level of the 

Nassif Building, 400 Seventh Street, 

SW., Washington, DC, between 9 a.m. 

and 5 p.m., Monday through Friday, 

except Federal holidays. 

FOR FURTHER INFORMATION CONTACT: 

Stephen Slotte, ANM–111, Airplane & 

Flight Crew Interface, Federal Aviation 

Administration, 1601 Lind Avenue SW., 

Renton, WA 98055–4056; telephone 

(425) 227–2315; facsimile (425) 227– 

1320, e-mail steve.slotte@faa.gov 

(certification rules) or Fred Sobeck, 

AFS–304, Aircraft Maintenance 

Division, Federal Aviation 

Administration, 800 Independence 

Avenue, SW., Washington, DC 20591; 

telephone: (202) 267–7355; facsimile 

(202) 267–7335, e-mail 

frederick.sobeck@faa.gov (operating 

rules). 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

The FAA invites interested persons to 

participate in this rulemaking by 

submitting written comments, data, or 

views. We also invite comments relating 

to the economic, environmental, energy, 

or federalism impacts that might result 

from adopting the proposals in this 

document. The most helpful comments 

reference a specific portion of the 

proposal, explain the reason for any 

recommended change, and include 

supporting data. We ask that you send 

us two copies of written comments. 

We will file in the docket all 

comments we receive, as well as a 

report summarizing each substantive 

public contact with FAA personnel 

about this proposed rulemaking. The 

docket is available for public inspection 

before and after the comment closing 

date. If you wish to review the docket 

in person, go to the address in the 

ADDRESSES section of this preamble 

between 9 a.m. and 5 p.m., Monday 

through Friday, except Federal holidays. 

You may also review the docket using 

the Internet at the Web address in the 

ADDRESSES section. 

Privacy Act: Using the search function 

of our docket Web site, anyone can find 

and read the comments received into 

any of our dockets, including the name 

of the individual sending the comment 

(or signing the comment on behalf of an 

association, business, labor union, etc.). 

You may review DOT’s complete 

Privacy Act Statement in the Federal 

Register published on April 11, 2000 

(65 FR 19477–78) or you may visit 

http://dms.dot.gov. 

Before acting on this proposal, we 

will consider all comments we receive 

on or before the closing date for 

comments. We will consider comments 

filed late if it is possible to do so 

without incurring expense or delay. We 

may change this proposal in light of the 

comments we receive. 

If you want the FAA to acknowledge 

receipt of your comments on this 

proposal, include with your comments 

a pre-addressed, stamped postcard on 

which the docket number appears. We 

will stamp the date on the postcard and 

mail it to you. 

Availability of Rulemaking Documents 

You can get an electronic copy using 

the Internet by: 

(1) Searching the Department of 

Transportation’s electronic Docket 

Management System (DMS) Web page 

(http://dms.dot.gov/search); 

(2) Visiting the FAA’s Regulations and 

Policies Web page at http:// 

www.faa.gov/regulations_policies/; or 

(3) Accessing the Government 

Printing Office’s Web page at http:// 

www.gpoaccess.gov/fr/index.html. 

You can also get a copy by submitting 

a request to the Federal Aviation 

Administration, Office of Rulemaking, 

ARM–1, 800 Independence Avenue 

SW., Washington, DC 20591, or by 

calling (202) 267–9680. Make sure to 

identify the docket number, notice 

number, or amendment number of this 

rulemaking. 

Organization of This NPRM 

Discussion of the proposal in this 

NPRM is organized under the following 

headings. Material supplementary to 

this discussion, but not included in it, 

appears in appendices at the end of the 

discussion, before ‘‘List of Subjects.’’ 

Whenever there is a reference to a 

document being included in the docket 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58509 

for this NPRM, the docket referred to is 

Docket Number FAA–2004–18379. A 

list of acronyms used is included as 

Appendix A. Unless stated otherwise, 

rule sections referenced in this NPRM 

are part of Title 14 of the Code of 

Federal Regulations. 

Table of Contents 

I. Executive Summary 

II. Background 

A. Flight 800 Accident 

B. Flight 111 Accident 

C. FAA Aging Transport Nonstructural 

Systems Plan 

D. Fuel Tank Safety Rule 

E. Existing Wiring Certification Regulations 

III. General Discussion of the Proposal 

A. Nature of the Problem 

B. Relationship of this Proposal to Other 

Aging Aircraft Initiatives 

C. Alternatives to Rulemaking 

IV. Overview of Proposal 

V. Section-by-Section Discussion of Proposed 

Rules 

A. Part 25 Subpart H-Electrical Wiring 

Interconnection Systems (EWIS) 

B. Part 25 Subpart I—Continued 

Airworthiness and Related Part 25 

Changes 

C. Other Proposed Changes to Part 25 

D. Part 25 Electrical System Harmonization 

Rules 

E. Proposed Changes to Part 91, 121, 125, 

and 129 Operating Rules for Fuel Tank 

Systems and EWIS and Other Existing 

Continued-Airworthiness-Related Rules 

F. Proposed Changes to Parts 121 (Subpart 

Y) and 129 (Subpart B)-EWIS 

Maintenance Programs 

G. Proposed Changes to Parts 91 (Subpart 

L), 121 (Subpart Y), 125 (Subpart M), and 

129 (Subpart B) ( Fuel Tank Maintenance 

Programs 

H. Advisory Circulars 

VI. Regulatory Analyses and Notices 

Appendices 

Appendix A—List of Acronyms 

Appendix B—Correlation Between 

Proposed New Part 25 Regulations and 

Existing Regulations 

Appendix C—Correlation Between Existing 

Part 25 Regulations and Proposed New 

Regulations 

Appendix D—Existing Part 25 

Requirements Requiring Revision to 

Support the New Proposed Regulations 

Appendix E—Flowchart 1: Pre- and PostType Certification Safety Analysis 

Concept—Flowchart 2: Post-TC Safety 

Analysis Concept 

I. Executive Summary 

Safety concerns about wiring systems 

in airplanes were brought to the 

forefront of public and governmental 

attention by a mid-air explosion in 1996 

involving a 747 airplane. Ignition of 

flammable vapors in the fuel tank was 

the probable cause of that fatal accident 

and the most likely source was 

determined to be a wiring failure 

causing a spark to enter the fuel tank. 

All 230 people aboard were killed. Two 

years later, an MD–11 airplane crashed 

into the Atlantic Ocean, killing all 229 

people aboard. Although an exact cause 

could not be determined, a region of 

resolidified copper on a wire of the inflight-entertainment system cable 

indicated that wire arcing had occurred 

in the area where the fire most likely 

originated. 

Investigations of those accidents and 

subsequent examinations of other 

airplanes showed that deteriorated 

wiring, corrosion, improper wire 

installation and repairs, and 

contamination of wire bundles with 

metal shavings, dust, and fluids, which 

would provide fuel for fire, were 

common conditions in representative 

examples of the ‘‘aging fleet of transport 

airplanes.’’ The FAA concluded that 

current maintenance practices do not 

adequately address wiring components, 

wiring inspection criteria are too 

general, and unacceptable conditions, 

such as improper repairs and 

installations, are not described in 

enough detail in maintenance 

instructions. Wiring failures result in 

airplane delays, unscheduled landings, 

in-flight entertainment system 

problems, nonfatal accidents, and fatal 

accidents. 

Up until this time, airplane wiring has 

never been singled out for special 

attention during maintenance 

inspections. Although close attention is 

paid to safe design within systems, we 

had assumed that for the wiring 

providing power to those systems, 

standard industry practice was 

appropriate, and modifications have 

often been performed without scrutiny 

for the effect their wiring additions may 

have on other systems in the airplane. 

Damaged wire and insulation can cause 

electrical arcing, providing the spark 

that can cause fire. Dust, dirt, lint, 

contamination, and vapors provide fuel 

for fire. Recent rules have established 

requirements for wiring connected to 

fuel tank systems. This proposal goes 

further, to address all the wiring 

contained in an airplane as systems on 

their own and provide scrutiny to the 

conditions that affect their safe 

functioning. It aligns with the 

requirements for fuel tank wiring. 

We are proposing new maintenance, 

inspection, and design criteria for 

airplane wiring to address conditions 

that put transport airplanes at risk of 

wire failures, smoke, and fire. We are 

proposing requirements for type 

certificate holders and applicants for 

type certificates and supplemental type 

certificates to analyze all the zones of 

their airplanes for the presence of wire 

and for the likelihood of contaminant 

materials. The proposal would also 

require them to develop maintenance 

and inspection tasks to identify, correct, 

and prevent wiring conditions that 

cause risk to continued safe flight. We 

are proposing that these tasks be 

included in new instructions for 

continued airworthiness for wiring and 

that they be compatible with 

instructions for continued airworthiness 

for fuel tank systems. We are further 

proposing to amend Title 14 Code of 

Federal Regulations (CFR) parts 91, 121, 

125 and 129 operating rules to require 

operators of transport airplanes to 

incorporate those tasks for wiring and 

fuel tanks into their regular 

maintenance programs. Finally, we are 

creating a new subpart of part 25 to 

contain all applicable certification 

requirements for airplane wiring, 

including new rules to improve safety in 

manufacture and modification. 

The total estimated benefits of the 

proposal are comprised of efficiency 

benefits and safety benefits. The 

efficiency benefits are $192.3 million 

($78.3 million present value). The safety 

benefits are $563 million ($262.4 

million present value). From 1995–

2002, 397 wiring failures were reported. 

We used industry estimates to 

determine that 68% of those failures 

would be detectable. The 7 most 

common—burned, loose, damaged, 

shorted, failed, chafed, and broken 

wires—account for 84% of all wiring 

failures. Wiring failures cause 22.1 flight 

delays per year, with an average time of 

3.5 hours and an estimated cost of 

approximately $35,639 each, and 

without this proposal, we believe that 

wiring delays will increase 

proportionately with the growth of the 

fleet. Wiring failures cause 27.5 

unscheduled landings per year at an 

average cost of approximately $200,461 

per unscheduled landing. We estimate 

that, based on expected fleet growth of 

3.82% per year, there will be 1,118 

unscheduled landings caused by wiring 

failures over a 25-year period, of which 

approximately 760 would be prevented 

by this proposal, resulting in a total 

benefit of averting unscheduled 

landings of $152.4 million. Delays and 

unscheduled landings contain safety 

risks for passengers and crew and 

increase the likelihood of a more serious 

event. We estimate 32.8 wiring-related 

incidents or accidents could be 

prevented by this proposal in the next 

25 years, for a total safety benefit of 

$563 million ($262.4 million present 

value). This includes 1.2 fatal accidents 

that can be prevented. 

The estimated total cost of this NPRM 

is $474.4 million ($209.2 million 

present value) over 25 years. The total 

estimated benefits are $755.3 million 

58510 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

($340.7 million present value) over the 

same period. This proposal is meant to 

proactively address wiring conditions 

existing in the transport airplane fleet 

that we now know affect safe flight and 

can be detected, corrected, or prevented. 

II. Background 

A. Flight 800 Accident 

Safety concerns about wiring systems 

in airplanes were brought to the 

forefront of public and governmental 

attention by a 1996 accident over the 

Atlantic Ocean near East Moriches, New 

York, involving a 747–131 airplane, 

operated as TWA Flight 800. That 

accident was investigated extensively by 

the National Transportation Safety 

Board (NTSB). It also prompted the FAA 

to investigate fuel tank wiring, and to 

focus on aging wiring in general. On 

May 7, 2001, the FAA published a final 

rule titled ‘‘Transport Airplane Fuel 

Tank System Design Review, 

Flammability Reduction, and 

Maintenance and Inspection 

Requirements’’ (66 FR 23086) to 

specifically address safety of the fuel 

tank, including wiring, which was 

determined to be the probable cause of 

the TWA Flight 800 accident. This 

NPRM addresses safety concerns related 

to aging wiring in general, and 

incorporates maintenance requirements 

specific to fuel tanks. 

The NTSB determined the probable 

cause of the TWA Flight 800 accident, 

in which the airplane broke up in flight, 

was an explosion of the center wing fuel 

tank (CWT) resulting from ignition of 

the flammable fuel and air mixture in 

the tank. The source of ignition energy 

for the explosion could not be 

determined with certainty. However, of 

all the sources evaluated, the most 

likely was a wiring failure outside the 

CWT. This failure allowed excessive 

electrical energy to enter the CWT 

through electrical wiring associated 

with the fuel quantity indication system 

(FQIS). 

During its investigation, the NTSB 

found several potentially unsafe 

conditions in and near the electrical 

wiring of the accident airplane. The 

findings included cracked wire 

insulation, metal shavings adhered to a 

floor beam where FQIS wires would 

have been routed (consistent with 

maintenance records describing 

compressed air being used to blow 

metal shavings off avionics units), other 

debris, and sulfide deposits. In addition, 

it found evidence of several repairs that 

did not comply with the guidelines in 

Boeing’s ‘‘Standard Wiring Practices 

Manual’’ (SWPM). Noncompliant 

repairs included: 

• Use of an oversized strain relief 

clamp on the terminal block of the 

number 1 fuel tank compensator. The 

clamp did not adequately secure the 

wires. 

• Many open-ended (rather than 

sealed) wire splices, which exposed 

conductors to possible water 

contamination. 

• Several wire bundles containing 

many wire splices on adjacent wires at 

the same location. 

• Excessive solder on the connector 

pins inside the fuel totalizer gauge. The 

solder had apparently caused 

inadvertent joining of connecting pins/ 

wires from the right main fuel tank and 

CWT FQIS. 

Some of these conditions may suggest 

the need for improved maintenance. 

However, the NTSB found that 

deterioration, damage, and 

contamination of aircraft wiring and 

related components, such as those 

found on the accident airplane, were 

common in other transport category 

airplanes inspected as part of the 

accident investigation. This was 

especially true in older airplanes. The 

NTSB concluded that ‘‘the condition of 

the wiring system in the accident 

airplane was not atypical for an airplane 

of its age and one that had been 

maintained in accordance with 

prevailing industry practices.’’

The NTSB expressed concern about 

the damage and contamination found on 

electrical wiring and components 

during their examinations of numerous 

transport category airplanes, including 

the accident airplane. The conditions 

found were especially disturbing 

because it was clear from those 

examinations that much aircraft wiring 

is difficult, if not impossible, to inspect 

and test because of its inaccessibility. 

The NTSB concluded that inadequate 

attention to the condition of aircraft 

electrical wiring had resulted in 

potential safety hazards. The 

conclusions from the accident 

investigation brought a heightened 

awareness to the FAA, other 

government agencies, and the general 

public of the importance of maintaining 

the integrity of aircraft wiring. A copy 

of the NTSB findings (NTSB Aircraft 

Accident Report Number AAR–00/03) 

can be found on the NTSB Web site 

http://www.NTSB.gov, and is contained 

in the docket. 

B. Flight 111 Accident 

Two years after the Flight 800 

accident, in September 1998, an MD–11 

airplane, operated as Swissair Flight 

111, crashed into the Atlantic Ocean off 

the coast of Nova Scotia, Canada. There 

were no survivors. Within 

approximately 53 minutes of the 

airplane’s departure from New York to 

Geneva, Switzerland, the flightcrew 

smelled an abnormal odor in the 

cockpit. The cockpit voice recorder 

indicates that they thought the smell 

was coming from the air-conditioning 

system. A short time after the flightcrew 

noticed the smell, there was smoke in 

the cockpit, and they diverted the 

airplane to the Halifax airport. 

While preparing for landing, the 

flightcrew were unaware that fire was 

spreading above the ceiling in the front 

of the aircraft. They declared an 

emergency and signaled a need to land 

immediately. About one minute later, 

radio communications and secondary 

radar contact with the aircraft were lost, 

and the flight recorders stopped 

functioning. About five and one-half 

minutes later, the aircraft crashed into 

the ocean. 

In its final report, ‘‘Aviation 

Investigation Report, In-Flight Fire 

Leading to Collision with Water,’’

Report Number A98H0003, the 

Transportation Safety Board of Canada 

(TSB) (the Canadian governmental body 

charged with aircraft accident 

investigation) could not identify the 

exact cause of the fire. As part of its 11 

findings of causes and contributing 

factors, however, the TSB stated that: 

‘‘A segment of in-flight entertainment 

network power supply unit cable 

exhibited 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. 

This arc was likely associated with fire 

initiation event; however, it could not 

be determined whether this arced wire 

was the lead event.’’ That report can be 

found in the docket. 

In the section of the report entitled 

‘‘Findings as to Risk,’’ the TSB cited 24 

separate risks that had the potential to 

degrade aviation safety but could not be 

shown to have played a direct role in 

the event, or are unrelated to this event 

but were found during the investigation. 

Among those findings of risks are the 

following statements. (The numbers 

under which each finding appears in the 

TSB report are indicated.) 

• ‘‘Regulations do not require that 

aircraft be designed to allow for the 

immediate de-powering of all but the 

minimum essential electrical systems as 

part of an isolation process for the 

purpose of eliminating potential 

ignition sources.’’ (3.2.3) 

• ‘‘Examination of several MD–11 

aircraft revealed various wiring 

discrepancies that had the potential to 

result in wire arcing. Other agencies 

have found similar discrepancies in 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58511 

1Recommendations for improved documentation 

and reporting and for incorporation of new 

technology are not addressed by this proposed rule. 

They are, however, part of the FAA’s Enhanced 

Airworthiness Program for Airplane Systems 

(EAPAS). The EAPAS report, dated October 15, 

2002, can be found in the docket for this NPRM. 

For a discussion of training, see ‘‘ATSRAC 

Recommendations for Rulemaking’’ in the same 

docket. 

other aircraft types. Such discrepancies 

reflect a shortfall within the aviation 

industry in wire installation, 

maintenance, and inspection 

procedures.’’ (3.2.7) 

• ‘‘The consequence of contamination 

of an aircraft on its continuing 

airworthiness is not fully understood by 

the aviation industry. Various types of 

contamination may damage wire 

insulation, alter the flammability 

properties of materials, or provide fuel 

to spread a fire. The aviation industry 

has yet to quantify the impact of 

contamination on the continuing 

airworthiness and safe operation of an 

aircraft.’’ (3.2.8) 

• ‘‘There is no guidance material to 

identify how to comply with the 

requirements of Federal Aviation 

Regulation (FAR) 25.1353(b) [relating to 

cable routing] in situations where 

physical/spatial wire separation is not 

practicable or workable, such as in 

confined areas.’’ (3.2.10) 

• ‘‘Inconsistencies with respect to CB 

(circuit breaker) reset practices have 

been recognized and addressed by major 

aircraft manufacturers and others in the 

aviation industry. Despite these 

initiatives, the regulatory environment, 

including regulations and advisory 

material, remains unchanged, creating 

the possibility that such ‘‘best practices’’

will erode or not be universally applied 

across the aviation industry.’’ (3.2.12) 

• ‘‘FAR 25.1309 requires that a 

system safety analysis be accomplished 

on every system installed in an aircraft; 

however, the requirements of FAR 

25.1309 are not sufficiently stringent to 

ensure that all systems, regardless of 

their intended use, are integrated into 

the aircraft in a manner compliant with 

the aircraft’s type certificate.’’ (3.2.21) 

In addition to the two accidents 

discussed above, multiple incidents and 

accidents that have occurred over the 

years illustrate the types of wire 

malfunctions that can affect flight 

safety. A discussion of some of those, 

titled ‘‘EAPAS NPRM Supplemental 

Material, Other Incidents and Accidents 

Involving Electrical Wiring,’’ is 

included in the docket for this NPRM. 

C. FAA Aging Transport Nonstructural 

Systems Plan 

After the Flight 800 accident, at the 

recommendation of the White House 

Commission on Aviation Safety and 

Security (WHCSS), the FAA expanded 

its Aging Aircraft Program, which in the 

past had focused on structures, to cover 

nonstructural systems. We formed a 

team to study aging nonstructural 

systems and conduct detailed physical 

evaluations of aging airplanes. We 

reviewed the report from that study 

team, along with information from 

meetings with FAA principal inspectors 

and representatives of major airplane 

manufacturers, as well as an analysis of 

airplane service histories. From this 

combined information, we developed 

the Aging Transport Nonstructural 

Systems Plan (included in the docket for 

this NPRM). The plan’s primary focus is 

on electrical wiring systems. There are 

other on-going research and 

development activities that address 

mechanical and avionics systems. 

The July 1998 Aging Transport 

Nonstructural Systems Plan includes 

results of the evaluation of five transport 

category airplanes considered 

representative of the ‘‘aging fleet of 

transport airplanes.’’ The FAA found 

conditions similar to those the NTSB 

found during its investigation of the 

TWA Flight 800 accident. Those 

conditions included: 

• Deterioration of wiring and related 

components. 

• Stiff and cracked wire. 

• Contamination of wire bundles with 

metal shavings, dust, and fluids. 

• Corrosion on connector pins. 

• Improper wire installation and 

repairs. 

The FAA also found, as had NTSB 

investigators, that wires contained in 

wire bundles are difficult to inspect. 

The conclusions reached from this 

evaluation were that: 

• Current maintenance practices do 

not adequately address wiring 

components. 

• Wire inspection criteria are too 

general. 

• Unacceptable conditions, such as 

improper repairs and installations, are 

not described in enough detail in 

maintenance instructions. 

• Repair instructions and data are 

difficult to extract from SWPMs. 

• The information that maintenance 

personnel are given for wire 

replacement may not be adequate. 

• Current incident/maintenance 

reporting procedures do not allow for 

easy identification of failures. 

The NTSB agreed with these 

conclusions. 

The Aging Transport Nonstructural 

Systems Plan detailed several tasks and 

associated subtasks aimed at correcting 

these problems, including: 

• Improving wiring inspection 

criteria and providing more detailed 

descriptions of undesirable conditions. 

• Improving inspector training to 

ensure that it adequately addresses the 

recognition and repair of aging wiring 

components. 

• Developing new methods for 

nondestructive testing of wiring. 

The NTSB responded to the issues 

defined in the Aging Transport 

Nonstructural Systems Plan. They 

concluded that they are important safety 

issues and must be fully addressed 

through rulemaking or other means. 

Specifically addressed by the NTSB 

(NTSB Recommendation No. A–00–108, 

included in the docket) were the need 

for: 

• Improved training of maintenance 

personnel to ensure adequate 

recognition and repair of potentially 

unsafe wiring conditions; 

• Improved documentation and 

reporting of potentially unsafe electrical 

wiring conditions; 1 and 

• Incorporation of the use of new 

technology, such as arc-fault circuit 

breakers and automated wire test 

equipment. 

The NTSB also recommended (NTSB 

Recommendation A–00–106, included 

in the docket) that the FAA review the 

design specifications for aircraft wiring 

systems of all U.S.-certified aircraft and 

then: 

• Identify which systems are critical 

to safety; and 

• Require revisions, as necessary, to 

ensure that adequate separation is 

provided for the wiring related to those 

critical systems. 

Finally, the NTSB recommended that 

the FAA ensure that all part 25 transport 

category airplanes, regardless of 

whether they are operated under parts 

91, 121, 125, or 135, be included in the 

review of aging transport airplane 

systems and structures (NTSB 

Recommendation A–00–119, contained 

in the docket). 

The FAA Administrator established a 

formal advisory committee (the Aging 

Transport Systems Rulemaking 

Advisory Committee, or ATSRAC) in 

1998. Its purpose was to facilitate 

actions recommended by the Aging 

Transport Nonstructural Systems Plan 

(FAA Order 11110.127, Aging Transport 

Systems Rulemaking Advisory 

Committee, dated Jan. 19, 1999, 

included in the docket). This committee 

is made up of representatives of aircraft 

manufacturers, transport airplane 

operators, aerospace and industry 

associations, and governmental 

agencies. 

In January 1998, the FAA assigned 

five tasks to ATSRAC. These included 

collecting data on aging wiring systems 

through airplane inspections, reviewing 

58512 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

2The IIWG was a separate but parallel group 

within the Aging Systems Task Force (ASTF). The 

Air Transport Association (ATA) formed the ASTF 

in June 1998 to review the effectiveness of 

maintenance on electrical wiring systems and 

assess the condition of those systems on aircraft 

with type certificates (TC) older than 20 years. 

When ATSRAC was formed in 1998, it continued 

the work started under the ASTF. 

airplane manufacturers’ service 

information, reviewing operators’

maintenance programs, and providing 

the FAA with recommendations to 

improve the safety of those systems. 

ATSRAC’s work on those tasks focused 

on transport category airplanes. 

The ATSRAC review of data (The 

‘‘Aging Systems Task Force Aging 

Transport Systems Task 1 and Task 2 

Final Report,’’ included in the docket) 

yielded the following wiring-related 

findings: 

• Nine B–727 airplanes inspected; 

276 discrepancies found. 

• Nine B–737 airplanes inspected; 

399 discrepancies found. 

• Seven B–747 airplanes inspected; 

238 discrepancies found. 

• Fourteen DC–8 airplanes inspected; 

974 discrepancies found. 

• Fifteen DC–9 airplanes inspected; 

116 discrepancies found. 

• Fourteen DC–10 airplanes 

inspected; 714 discrepancies found. 

• Three L–1011 airplanes inspected; 

247 discrepancies found. 

• Ten A–300 airplanes inspected; 408 

discrepancies found. 

The results from those five initial 

tasks showed that problems related to 

wiring systems on aging airplanes were 

not entirely related to degradation over 

time. Inadequate installation and 

maintenance practices were identified 

as factors that can lead to what is 

commonly referred to as an ‘‘aging 

system’’ problem. As a result, the scope 

of ATSRAC’s work was expanded to 

include improving the continued 

airworthiness of airplane systems, 

particularly wiring systems. 

In May 2001, the FAA assigned four 

new tasks to the committee to carry out 

the ATSRAC recommendations on the 

first five tasks (66 FR 29203). These next 

tasks were to accomplish the following: 

• Address the need for new wire 

system certification requirements. 

• Propose changes to the standard 

wiring practices manual. 

• Develop a training program for wire 

systems. 

• Develop maintenance criteria for 

wire systems. 

The results discussed earlier from 

ATSRAC’s review of the eight models of 

large transport category airplanes had 

heightened concern about whether 

similar conditions existed in small 

transport category airplanes (airplanes 

with a 6- to 30-passenger seating 

capacity). As a result, in March 2002 (67 

FR 9799), the FAA assigned another task 

to ATSRAC—to investigate and develop 

recommendations to improve the safety 

of electrical wiring systems in transport 

category airplanes certificated for fewer 

than 30 passengers. In response to this 

task, ATSRAC examined the 

applicability of their previous 

recommendations to this group of 

airplanes and identified issues unique 

to electrical wiring systems on small 

transport category airplanes. ATSRAC’s 

work in this area is continuing. 

Another investigative group 

functioning within ATSRAC, whose 

wiring inspections extended to the 

laboratory, was the Intrusive Inspection 

Working Group (IIWG).2 The IIWG 

subjected selected wire installations on 

six decommissioned airplanes to an 

intensive, detailed visual inspection, 

followed by destructive testing and 

laboratory analysis (an intrusive 

inspection). They studied the results to 

assess the state of wire on aged 

airplanes as a function of wire type and 

service history. In addition, the results 

from the visual inspections were 

compared with the nondestructive 

testing and laboratory analysis to 

determine the efficacy of visual 

inspections for the detection of agerelated deterioration. 

The findings from the IIWG were 

documented in the ‘‘Transport Aircraft 

Intrusive Inspection Project (An 

Analysis of the Wire Installations of Six 

Decommissioned Aircraft) Final 

Report,’’ issued on December 29, 2000 

(from now on referred to as ‘‘Intrusive 

Inspection Report’’). A copy is included 

in the docket. The findings showed that 

wire-related failures have multiple 

causes. These include: 

• Localized heat damage. 

• Breaches in wire insulation. 

• Wire embrittlement. 

• Charred wire insulation. 

• Missing insulation. 

• Chafing. 

• Arcing. 

• Arc tracking. 

• Reduced insulation resistance in 

certain wires. 

• Defective and broken connectors. 

• Damage to connector backshells. 

Both the nonintrusive, visual 

inspections on the airplane and the 

intrusive inspections found most wiring 

discrepancies were in areas of frequent 

maintenance activity. In addition, fluid 

contamination and dust and dirt 

accumulations were common in those 

areas. 

The Intrusive Inspection Report 

identified several areas that required 

special emphasis. Three areas—the 

cockpit, electrical power centers, and 

power feeder cables—were considered 

critical. This is because chafing on 

wiring in these areas, combined with 

flammable materials close by, can result 

in severe outcomes, such as wire-tostructure or wire-to-wire shorting and 

arcing. Since a fire in these areas could 

present a high risk to continued safe 

flight and landing, the IIWG 

recommended more detailed 

inspections for those three areas. The 

intent was to ensure potential problems 

are identified and corrected. This effort 

led to the development of an enhanced 

zonal analysis procedure (EZAP) to 

assess risk for fire so that maintenance 

programs developed for wire systems in 

such critical areas would require more 

detailed inspections. An EZAP is a 

specific wire-focused version of the 

zonal analysis procedure widely used to 

analyze an airplane’s physical areas or 

zones. It’s used for developing 

maintenance tasks. One version of an 

EZAP is described in proposed AC 120–

XX, ‘‘Program to Enhance Transport 

Category Airplane Electrical Wiring 

Interconnection System Maintenance.’’

ATSRAC made a number of 

recommendations to the FAA. Those 

recommendations and the FAA’s 

responses to them are included in the 

docket in the document titled ‘‘ATSRAC 

Recommendations for Rulemaking.’’

ATSRAC working groups also produced 

four proposed advisory circulars (AC) as 

guidance for their recommended 

rulemaking. These proposed ACs are on 

the topics of wiring system 

maintenance, training, standard wiring 

practices manuals, and the proposed 

subpart H, and will be briefly discussed 

at the end of this preamble under the 

heading ‘‘Advisory Circulars.’’

D. Fuel Tank Safety Rule 

In addition to the activities described 

earlier, in response to the TWA 800 

accident, the FAA has developed an 

extensive program to address safety 

problems associated specifically with 

fuel tanks. As mentioned previously, on 

May 7, 2001, the FAA issued a final rule 

entitled, ‘‘Transport Airplane Fuel Tank 

System Design Review, Flammability 

Reduction, and Maintenance and 

Inspection Requirements.’’ This 

discussion refers to that final rule as the 

‘‘Fuel Tank Safety Rule.’’ The Fuel Tank 

Safety Rule was issued to address 

unforeseen failure modes and the lack of 

specific maintenance procedures that 

could result in degrading the design 

safety features intended to preclude 

ignition of fuel tank vapors. 

One part of the Fuel Tank Safety Rule, 

Special Federal Aviation Regulation 88, 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58513 

(SFAR 88) applies to design approval 

holders of certain turbine-powered 

transport category airplanes, and any 

person who modifies those airplanes 

later. SFAR 88 requires these regulated 

parties to perform safety assessments to 

confirm if the design of the fuel tank 

system precludes the existence of 

ignition sources in the fuel tank system. 

SFAR 88 also requires development of 

design changes and maintenance and 

inspection instructions to assure the 

safety of the fuel tank system. 

Other sections of the Fuel Tank Safety 

Rule (referred to as the ‘‘operational 

rules’’) require that operators of those 

airplanes include fuel tank safety 

maintenance and inspection 

instructions in their existing 

maintenance or inspection programs. 

The requirements of those sections 

address two areas: 

(i) The fuel tank systems of the 

‘‘baseline’’ airplane (as originally made 

by the TC holder); and 

(ii) The ‘‘actual configuration’’ of the 

fuel tank systems of each affected 

airplane (as modified or altered after 

original manufacture). 

As discussed later, one purpose of 

this rulemaking is to make sure that the 

implementation of this proposal for 

wiring is aligned with the 

implementation of the Fuel Tank Safety 

Rule. 

E. Existing Wiring Certification 

Regulations 

Traditionally, wire has not been 

looked upon as having the same 

importance to safety as the rest of the 

systems for which it provides the 

electrical interconnection. Whereas a 

particular piece of electrical equipment 

may be the focus of intense scrutiny 

regarding its design, installation, and 

maintenance, the wires that provide the 

electrical interconnection to that 

equipment have not received the same 

amount of attention, except for the 

wiring on engines. Additionally, in the 

past, system safety assessments usually 

addressed only the effect of a wire 

failure on the system itself. The safety 

assessments have not usually identified 

the effect of wire failures on other 

systems or on the airplane. 

Existing regulations fall short of 

providing specific wiring-related 

requirements that we now recognize 

should be included. For example, 

current rules do not adequately address 

requirements for wires in system 

separation, safety assessments, 

component selection, component 

identification, protection in cargo and 

baggage compartments, and accessibility 

for inspection, maintenance, and repair. 

This quote from FAA Wiring Policy 

ANM–01–04 supports the need for more 

specific wiring information: ‘‘The FAA 

expects the applicant to provide 

engineering drawings instead of merely 

statements such as ‘install in accordance 

with industry standard practices,’ or 

‘install in accordance with AC 43.13 

[‘‘Acceptable Methods, Techniques, and 

Practices—Aircraft Inspection and 

Repair’’].’ The FAA considers such 

statements inadequate because the 

standard practices cannot define the 

location or routing of the wiring to the 

level needed to ensure that new/ 

modified wiring does not invalidate 

previous certification findings for 

existing airplane systems.’’

III. General Discussion of the Proposal 

A. Nature of the Problem 

Electrical wiring systems perform 

roles essential to the safety of the entire 

airplane. They distribute power 

throughout the airplane, transmit 

signals for control, and send data. Over 

time, as more sophisticated 

computerized systems have been 

introduced into airplane controls, their 

electrical wires, cables, and associated 

components have become increasingly 

important to safe flight. 

Historically, manufacturers have been 

required to provide maintenance-related 

information for airplane systems. 

However, there has never been a 

requirement for maintenance 

information specifically addressing 

wiring systems. Since January 28, 1981, 

design approval holders have been 

required to provide ICA for the airplane. 

ICA must be prepared in accordance 

with Appendix H to part 25. In 

developing ICA, the applicant must 

include certain information. This 

includes a description of the airplane 

and its systems, servicing information, 

and maintenance instructions, including 

the frequency and extent of inspections 

necessary to provide for the continued 

airworthiness of the airplane. Currently, 

§ 25.1529 includes a requirement for an 

FAA-approved Airworthiness 

Limitations section in the ICA. This 

section must list those mandatory 

inspections, inspection intervals, 

replacement times, and related 

procedures approved under §§ 25.571 

and 25.981. There are no requirements 

for specific information related to 

wiring. 

Airplanes must be continually 

maintained and inspected, and the 

information contained in the ICA is 

used as a basis for developing a 

maintenance program. Yet the 

examinations of large transport 

airplanes discussed earlier revealed 

many anomalies in electrical wiring 

systems and their components, as well 

as contamination by dirt and debris. 

Section 43.13(b) requires anyone 

performing maintenance or alteration to 

do the work in such a manner and use 

materials of such a quality that the 

condition of the aircraft, airframe, 

aircraft engine, propeller, or appliance 

worked on will be at least equal to its 

original or properly altered condition 

(with regard to aerodynamic function, 

structural strength, resistance to 

vibration and deterioration, and other 

qualities affecting airworthiness). 

Anyone performing maintenance must 

use methods, techniques, and practices 

prescribed in the current manufacturer’s 

maintenance manual or ICA prepared by 

the manufacturer, or methods, 

techniques, and practices referred to in 

§ 43.13(a) as acceptable to the 

Administrator. However, current 

practice has shown that, when wiring is 

inspected as part of the maintenance 

program or following alterations, it is 

not always cleaned appropriately for the 

inspection being performed. Generally, 

neither FAA inspectors nor airline 

maintenance workers have been fully 

aware of the vulnerable and critical 

condition of wire and fuel tank systems. 

Little focus has been placed on the 

importance of cleaning electrical wiring 

during maintenance or alteration. The 

result has been to hasten the aging of 

wiring. 

Extensive research by the FAA, in 

partnership with the aviation industry 

and other government agencies, has 

shown that electrical wiring on 

transport category airplanes is subject to 

a breakdown of physical and functional 

properties. This is not just a function of 

time, but also because of many stresses 

on the wiring. These stressors include 

chafing, vibration, contamination, and 

temperature variation, all of which can 

cause cumulative damage. Each airplane 

maintenance procedure or modification, 

whether performed on the wiring 

system itself or on surrounding 

components, introduces possibilities for 

unintentional damage, changes to the 

previously approved wire design, or 

contamination of the wiring systems by 

fluids, foreign objects, and debris. As 

the aviation industry matures, there are 

more older airplanes in service, and the 

wiring in those airplanes has had more 

years of exposure to all these factors. 

Electrical wiring system malfunctions 

resulting from inadequate design, 

alteration, maintenance, inspection, and 

repair practices can cause incidents and 

accidents involving smoke, fire, and/or 

loss of function. 

Wire contamination is a major 

concern, especially in older airplanes, 

58514 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

and it occurs in many ways. Dust, dirt, 

and lint from airplane carpets and seats, 

lavatory waste products, hydraulic 

fluid, engine oil, corrosion prevention 

compounds, and galley spills all collect 

over time. Liquids can corrode 

connectors and other wiring 

components and degrade wire 

insulation. In addition, electrical 

current flow in the wiring attracts dust, 

dirt, and lint, and they are deposited on 

the wiring system and surrounding 

airplane structure by cabin airflow. 

Leakage of fluid lines and spills make 

the wiring grimy, so more dust, dirt, and 

lint are attracted to them. 

To fully understand why wiring 

system contamination is a major 

problem and a potential fire hazard that 

could prevent the safe operation of an 

airplane, it is necessary to understand 

the ‘‘fire triangle’’ of combustion. The 

fire triangle symbolizes three 

elements—oxygen, heat or ignition 

source, and fuel. All three are necessary 

for fire to occur. 

In an airplane, oxygen, the first 

element of the triangle, is always 

present, because the heating and airconditioning system must provide a 

suitable environment for passengers. 

Wiring can act as an ignition source 

(second element), especially if damage, 

such as cracked insulation or chafing, 

causes a short to ground or to another 

conductor, or if it causes arcing. Fuel for 

fire (third element) can be present in the 

form of dust, dirt, lint, hydraulic fluid, 

engine oil, engine fuel, and corrosion 

prevention compound. Eliminating or 

mitigating any of these elements will 

help remove the fire threat. 

For obvious reasons, oxygen cannot 

be eliminated from an airplane. Wiring 

systems provide critical functions, so 

they cannot be eliminated either. But 

their ability to act as a fire ignition 

source can be mitigated by proper 

design, maintenance, and repair. The 

easiest element to alleviate is fuel for 

fire. The improved maintenance 

requirements in this proposal, as well as 

the more rigorous design standards, are 

intended to address the fuel and 

ignition elements of the fire triangle of 

combustion. 

This NPRM also addresses the 

requirement that certain operators 

incorporate ICA for their fuel tank 

systems into their maintenance or 

inspection programs, to ensure the 

continued safe operation of those design 

features that minimize the potential for 

an ignition source in the fuel tank 

system. Although there are existing 

regulations that require these ICA, the 

FAA believes, based on lessons learned 

from SFAR 88 and industry comments, 

that the existing operational rules need 

to address several issues that have 

arisen since they were adopted. Also, 

because there are elements in the fuel 

tank system that include wiring, those 

ICA could conflict with the 

requirements for electrical systems in 

this proposal. Additionally, the FAA 

believes that the compliance times for 

the regulations for those two systems, 

wiring systems and fuel tank systems, 

should be aligned. 

B. Relationship of This Proposal to 

Other Aging Aircraft Initiatives 

The FAA, as part of a broader review 

and realignment of its Aging Airplane 

Program, has determined that certain 

compliance dates in existing rules and 

pending proposals could be better 

aligned, so that operators can comply 

more efficiently with the requirements 

during scheduled maintenance. 

Compliance dates could also impact our 

ability to schedule oversight programs 

efficiently. In addition, based on our 

review, we have determined that certain 

substantive changes are needed to 

improve the cost-effectiveness of these 

rules and proposals. Therefore, we have 

decided to revise these requirements 

and proposals and align the compliance 

schedules as practically as possible. 

Notice of these changes and a 

description of our Aging Airplane 

Program review appeared in the Federal 

Register on July 30, 2004 (69 FR 45936). 

The actions affected by these revisions 

are this proposal and three others: 

• Transport Airplane Fuel Tank 

System Design Review, Flammability 

Reduction, and Maintenance and 

Inspection Requirements Special 

Federal Aviation Regulation (Fuel Tank 

Safety Rule) (final rule). 

• Aging Airplane Safety (interim final 

rule). 

• Widespread Fatigue Damage 

(pending proposal). 

To prevent any conflicts within this 

proposal, which affects fuel tank wiring 

issues, changes to the operational 

requirements of the Fuel Tank Safety 

Rule requiring the incorporation of fuel 

tank system maintenance and 

inspection tasks are proposed as part of 

this rulemaking. 

C. Alternatives to Rulemaking 

Before proposing new rulemaking, the 

FAA must consider alternative ways to 

solve the safety issues under 

consideration. Following is a brief 

discussion of two of the alternatives we 

considered during deliberations on this 

rulemaking proposal. 

No new regulatory action. The FAA 

believes that the result of no action 

would be continued incidents and 

accidents resulting from wiring system 

failures. We would continue to address 

these situations ‘‘reactively’’ on a caseby-case basis (as they occur) by issuing 

airworthiness directives. This is 

unacceptable from a safety standpoint. 

Improved certification regulations, 

inspection and maintenance programs, 

and ICA for wiring systems are needed 

to address the potential for similar 

problems arising on existing and future 

designs, and to ensure their long-term 

safety. 

Rely on voluntary compliance with 

the intent of the rule by affected parties. 

Some in industry have suggested simply 

issuing ACs to give guidance on the 

changes that need to be made. Issuing 

ACs would depend on voluntary 

compliance, and would not be 

enforceable. While certain members of 

the industry would proceed with 

voluntary programs, others would not. 

The use of ACs alone would ensure 

neither consistent results nor the 

achievement of the safety objectives of 

this proposal for the current and future 

fleet. Previous voluntary safety 

assessments, such as those relating to 

the thrust reverser and cargo door 

reviews, have been difficult to complete 

in a timely manner because they lacked 

enforceability. The proposed rules 

provide an enforceable means to require 

timely completion of the actions 

identified as necessary to address aging 

electrical wiring systems. 

IV. Overview of Proposal 

The FAA proposes several rule 

changes that collectively provide a more 

proactive management of wiring 

systems. These changes would require 

development and implementation of 

ICA for wiring systems and subsequent 

incorporation of those ICA into the 

operators’ maintenance or inspection 

program. We are also proposing changes 

in the certification rules to require, 

during design and installation of 

airplane systems, more attention to 

conditions that could compromise wire 

safety and accessibility. 

The result of these changes to the 

maintenance and certification programs 

would be to remove, as far as possible, 

sources of ignition and fuel for fire from 

the wiring systems. In addition, a new 

part 25 subpart dedicated to wiring 

systems would be created. The current 

part 25 regulations for wire would be 

moved into this new subpart and 

combined with new regulations. An 

alignment of the compliance times for 

incorporation of the wire and fuel tank 

ICA would also occur to enable a more 

comprehensive treatment of those ICA 

and accomplishment of the maintenance 

instructions at time intervals consistent 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58515 

3 ‘‘Final Report to President Clinton, February 12, 

1997,’’ a copy of which is in the docket. 

4 ‘‘Review of Federal Programs for Wire System 

Safety,’’ November 2000, in the docket. 

with typical airplane maintenance 

checks. 

The FAA believes that traditional 

ways of addressing wiring are no longer 

enough. Because wire damage or 

degradation can be the result of 

successive and interactive factors 

introduced over time, the approach to 

ensuring wiring safety must be 

analytical, multilayered, and proactive, 

rather than reactive. An analytical 

approach means assessing logically the 

possibilities for fire occurring. A 

multilayered approach means 

addressing multiple layers of stressors, 

like chafing, vibration, temperature 

change, and modification that act on 

wiring in succession or concurrently 

and can cause cumulative damage to an 

electrical system. A proactive approach 

means addressing conditions affecting 

safe flight that we know can happen—

before they happen. Causes of wire 

degradation must be addressed 

separately and collectively, and 

analyzed in relation to the entire 

airplane. Based on the findings and 

research described earlier in this 

document, the FAA has determined that 

air carriers, operators, TC holders, 

supplemental type certificate (STC) 

holders, repair stations, and certificated 

maintenance personnel need to place 

more emphasis on wiring and fuel tank 

systems when performing maintenance 

and alterations. Currently, other than 

the visual inspections required by 

maintenance or inspection programs, 

maintenance is not normally performed 

on these systems unless an obvious 

discrepancy is identified. This proposal 

is designed to heighten awareness of the 

criticality of wiring systems and to 

change the current approach to 

maintaining and modifying them. 

Maintenance personnel need to be 

aware that current industry practice for 

maintenance and inspection of these 

systems is inadequate and must be 

improved, as provided by this proposal. 

The changes proposed in this NPRM 

were derived from the maintenance, 

inspection, design, and alteration best 

practices developed through extensive 

research by ATSRAC and other groups, 

including the White House Commission 

on Aviation Safety and Security,3 the 

National Science and Technology 

Council Committee on Technology Wire 

System Safety Interagency Working 

Group,4 the IIWG, and safety reviews 

required in accordance with SFAR 88. 

The following table summarizes the 

proposed regulatory changes that are 

discussed in detail in this section. 

SUMMARY OF PROPOSED RULEMAKING IN THIS NPRM 

Affected part of 14 CFR Description of proposal Applies to 

1 ........................................... Adds the abbreviation ‘‘EWIS’’.

25 ......................................... Harmonization rules ........................................................ Applicants for type, amended, and supplemental type 

certificates 

25 ......................................... New subpart H containing: New and revised wire-related certification requirements including requirements to develop ICA for electrical wiring interconnection systems.Applicants for type, amended, and supplemental type 

certificates 

25 ......................................... New subpart I containing: New requirements to develop 

ICA for electrical wiring interconnection systems in 

accordance with proposed § 25.1539 and the revised 

Appendix H for the current specified fleet.

Type certificate holders for large transport category airplanes and certain applicants for type, amended and 

supplemental type certificates 

Parts 121/129 ....................... Requirement to incorporate new EWIS ICA into maintenance program (included in new subparts for Continued Airworthiness).U.S. certificate holders and foreign persons operating 

U.S. registered large transport category airplanes 

Parts 91/121/125/129 ........... New subparts (L, Y, M, and B respectively) for Continued Airworthiness containing parts 121/129 EWIS 

ICA requirements (above) and: 

• Requirement to incorporate fuel tank ICA into maintenance program.

• Redesignation of other existing requirements into 

these new subparts 

U.S. certificate holders and foreign persons operating 

U.S. registered large transport category airplanes. 

Currently, part 25 does not have a 

separate subpart governing wiring. 

Certification rules that apply to wiring 

appear throughout the regulations, 

under the headings ‘‘Design and 

Construction,’’ ‘‘Powerplant,’’ and 

‘‘Equipment.’’ In some of these rules, 

the term ‘‘wiring’’ is not specifically 

used. 

The discussion of proposed changes 

to part 25 is broken into four parts: 

• Part 25 Subpart H—Electrical 

Wiring Interconnection Systems (EWIS). 

• Part 25 Subpart I—Continued 

Airworthiness. 

• Other Proposed Changes to Part 25. 

• Part 25 Electrical System 

Harmonization Rules. 

ATSRAC recommended placing part 

25 wiring-related regulations into one 

section. This change would increase the 

visibility of these regulations and 

facilitate a comprehensive process for 

the design and certification of wire 

systems. ATSRAC reviewed the current 

part 25 to identify each regulation that 

related to wiring, either directly or 

indirectly. Each wire-related regulation 

was then reviewed to determine if it 

should be moved (in whole or in part) 

into the proposed new subpart. As a 

result of ATSRAC’s recommendations, 

this NPRM would change some existing 

wire requirements, add new ones, and 

compile all of them into a new subpart: 

subpart H of part 25. 

No single regulation was moved in its 

entirety to the new subpart, but 

applicable portions of regulations were 

moved. Some regulations easily lent 

themselves to division into wire and 

non-wire portions, while others did not. 

In some cases it was difficult to remove 

the wire-related portion and maintain 

the continuity of the existing regulation. 

In those cases, the regulation was not 

moved to subpart H. Instead, the current 

regulation remained in place and a new 

subpart H regulation was created to state 

the importance of wiring systems to the 

safe design of the system that is the 

subject of the existing regulation. 

Portions of some current regulations 

that were moved to the new subpart 

were divided and distributed among 

58516 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

several new subpart H sections to follow 

the logical structure of the new subpart. 

Accordingly, there is not always a oneto-one correspondence between the 

existing regulations and the new subpart 

H regulations. A table showing the 

correlation between proposed new 

regulations and the existing regulations 

can be found in APPENDIX B. The table 

in APPENDIX C compares the existing 

regulations to the proposed new ones. 

The APPENDIX D table shows which of 

the current wire-related rules must be 

changed to accommodate the new 

subpart and which will remain the 

same. 

Adoption of the proposed new and 

revised requirements and advisory 

material would help prevent future 

occurrences of the types of incidents 

and accidents described in this NPRM. 

The creation of a new part 25 subpart 

for all existing, revised, and new wire 

system certification requirements would 

strengthen the role of properly designed, 

installed, and maintained wire systems 

in increasing the safety of flight. It 

would also provide the regulatory tools 

to help ensure this outcome and locate 

all applicable regulations in a single 

place that is easy to reference and use. 

Certain vintage airplanes type 

certificated before 1958, the beginning 

of the jet age, would be excluded from 

the requirements of this proposal. They 

are named in paragraph (f) of § 25.1805 

and in the final paragraph of each of the 

proposed fuel tank and EWIS operating 

rules. There are no known 

reciprocating-powered transport 

category airplanes currently in 

scheduled passenger service, and the 

few remaining in cargo service would be 

excluded. Compliance is not required 

for these specific older airplanes 

because their advanced age or small 

numbers would likely make compliance 

economically impractical. 

V. Section-by-Section Discussion of 

Proposed Rules 

The FAA proposes to add the 

abbreviation for electrical wiring 

interconnection systems (EWIS) to 14 

CFR part 1—Definitions and 

Abbreviations. The purpose of this 

addition is to ensure the use of a 

common term for EWIS throughout the 

regulations. More detailed analysis of 

the other proposed changes and 

additions is outlined below. 

A. Part 25 Subpart H—Electrical Wiring 

Interconnection Systems (EWIS) 

The proposed subpart H consists of 

relocated, revised, and new regulations 

about EWIS. Unless we say otherwise, 

our purpose in moving requirements to 

subpart H is to ensure their application 

to EWIS. We do not intend to change 

their legal effect in any other way. 

Section 25.1701 Definition 

Proposed § 25.1701 would define 

what constitutes an EWIS for the 

purposes of complying with the 

proposed subpart H requirements and 

other EWIS-related requirements of 

parts 25, 121, and 129. 

Current regulations do not provide a 

definition of a wiring system. Without 

this definition, the proposed rules could 

be inconsistently applied to various 

wire-related components. To completely 

address the safety issues associated with 

wiring systems, requirements must 

address not only the wiring itself, but 

also components and devices that are 

required to adequately install and 

identify each wire. Various components 

and devices needed to route and 

identify wires are critical in ensuring 

that a proper electrical interconnection 

is made and maintained. 

For the purposes of this NPRM, the 

term ‘‘wire’’ means bare and/or 

insulated wire used for the purpose of 

electrical energy transmission, 

grounding, or bonding. This includes 

electrical cables, coaxial cables, ribbon 

cables, power feeders, and databuses. 

A proper electrical interconnection 

between two or more points requires 

more than just wire. Making the 

connection in a manner that ensures 

both functionality and safety requires 

various types of components, of which 

wire is one. Therefore, a clear definition 

of an electrical interconnection is 

necessary. The proposed regulation 

provides this and at the same time 

introduces the term ‘‘electrical wiring 

interconnection system (EWIS)’’ to 

describe that interconnection. The term 

EWIS means any wire, wiring device, or 

combination of these, including 

termination devices, installed in the 

airplane for transmitting electrical 

energy between two or more termination 

points. The proposed regulation 

expands on this basic statement to 

clearly identify which wire-related 

components are included in the EWIS 

definition and which are not. Most 

wires are routed with other wires that 

make up wire bundles and cable 

assemblies (or ‘‘looms,’’ as they are 

sometimes called). A single wire may 

also be routed separately. The same 

definition of an EWIS is applied to a 

single wire or to a bundle containing 

hundreds of wires. 

To complete an electrical connection, 

various types of connectors are 

necessary. Examples are MS connectors 

(MS means military specification), Dsubminiature connectors, and rack and 

panel connectors. Any connector used 

to complete an electrical connection is 

included in the EWIS definition. The 

exception to this is the mating 

connection on those devices that are 

excluded from the proposed definition. 

The excepted devices are addressed 

later in this discussion. 

Connector accessories fall under the 

definition of EWIS. Such accessories 

include, but are not limited to, 

backshells, strain reliefs, grommets, and 

sealing plugs. Electrical connections to 

devices such as relays, interrupters, 

switches, contactors, terminal blocks, 

and feed-through connectors are parts of 

an EWIS. For example, the connection 

device on a relay is considered part of 

the EWIS, but the relay mechanism is 

not, because it is a termination point. A 

splice can be considered an electrical 

connector because it performs the same 

role as other connection devices by 

providing an electrical connection 

between two or more wires. The failure 

of a splice or relay connection could 

create a hazardous situation by exposing 

bare conductors or impairing system 

functionality. 

Although a bus bar is not a 

‘‘connector’’ in the traditional sense, it 

is a collector and distribution device for 

electrical energy and thus must be 

treated as part of an EWIS. 

Wire or wire bundles require devices 

to physically route and support them, 

such as clamps, brackets, standoffs, and 

other such components. These are 

included in the EWIS definition. Cable 

ties are included because they are used 

to hold multiple wires together and in 

place. The failure of one or more of 

these EWIS components could affect the 

ability of the wire to perform its 

intended function. It could cause 

collateral damage to other wires in the 

same or adjacent bundles or cause the 

bundle to fail in a way that would cause 

structural damage or ignite flammable 

material, fluid, or vapors in the area. 

Some wires must pass through 

pressure bulkheads, so a pressure seal is 

needed. Failure of a pressure seal could 

cause damage to the wires in the wire 

bundle and affect the functioning of the 

system they support. Some wire bundles 

use shields or braids to protect them 

from electromagnetic radiation, 

lightning, abrasion, and other types of 

physical damage. Failure of the shields 

or braid could cause, or allow, the wires 

to be damaged. It could also allow 

unwanted electrical energy to be 

coupled into systems and cause system 

malfunction. Thus, shields, braids, and 

pressure seals must be considered part 

of the EWIS and treated as such. 

Sometimes adequate physical 

separation distance is not possible, and 

some sort of protective sleeving may be 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58517 

used. Since the sleeving is used to 

achieve separation, it must be 

considered part of the EWIS. 

Conduits are included in the proposal 

because they are used to provide 

protection for wires as well as provide 

physical separation. Conduits that have 

electrical termination for bonding are 

considered part of an EWIS because the 

failure of the bonding could create a 

hazardous situation. 

The definition of an EWIS includes 

labels or other means used for 

identification. This supports the 

proposed § 25.1711 requiring new 

identification criteria for wires and 

other EWIS components. Discussion of 

the proposed labeling requirements 

appears under the heading for § 25.1711. 

The proposed regulation does not 

cover portable, carry-on, or other 

electrical equipment not certified for 

installation on the airplane under part 

25. Examples of items not included are 

laptop computers and portable audio 

and/or video or other consumer devices 

typically carried on-board by passengers 

for personal use. Increasingly, flight and 

cabin crew are using laptop computers 

in the performance of their duties. As 

stated, laptops are not part of the EWIS 

definition, but any electrical connection 

used to support power and/or signal 

transmission that is part of the airplane 

TC, and that is used for the laptop or 

other carry-on items, is covered by the 

proposed definition. 

The proposed EWIS definition does 

not cover fiber optic cable because fiber 

optic cable does not transmit electrical 

energy. But since fiber optics can 

provide functions (for example, data 

transmission) similar to those provided 

by wire, it is being expressly eliminated 

from the EWIS definition to avoid 

confusion. 

The proposed definition excludes 

electrical wiring interconnection system 

components inside avionics equipment 

(high-frequency communication radio or 

flight data recorder, for instance), or the 

mating electrical connectors mounted 

on that equipment. Such equipment is 

produced by various manufacturers for 

use on a broad range of airplane models 

and is designed and built to various 

performance and environmental 

specifications. Environmental testing, 

either by means of RTCA (Radio 

Technical Commission for Aeronautics) 

Document No. RTCA DO–160, 

EUROCAE 55 specification 

(specification of the European 

Organization for Civil Aviation 

Equipment), or other environmental 

qualification procedures approved by 

the FAA, ensures that the EWIS 

contained within avionics equipment is 

robust and well suited for the airborne 

environments in which it will be 

operated. 

This proposal also does not apply to 

miscellaneous electrical equipment if 

that equipment has been adequately 

qualified to environmental conditions 

and testing procedures approved by the 

FAA, unless that equipment is 

specifically included in the proposed 

§ 25.1701 as discussed in the following 

paragraph. 

The definition of EWIS includes 

electrical wiring interconnection system 

components inside shelves, panels, 

racks, junction boxes, distribution 

panels, back-planes of equipment racks 

including circuit board back-planes, and 

wire integration units. We have 

included the components in this type of 

equipment because it, unlike avionics 

equipment, is typically designed and 

made for a particular airplane model or 

series of models. The same requirements 

that apply to airplane EWIS components 

must also be applied to the components 

inside that equipment. Avionics 

components must be sent back to their 

manufacturer or a specialized repair 

shop for service. But this type of 

equipment is maintained, repaired, and 

modified by the same personnel who 

maintain, repair, and modify the EWIS 

in the rest of the airplane. In an 

electrical distribution panel system, for 

example, separation must be designed 

and maintained within the panel just as 

in the EWIS leading up to that panel. 

Identification of components inside the 

panel is just as important as for those 

outside the panel since the wiring 

inside the panel is treated much the 

same. Also, while this type of 

equipment is designed for its intended 

function and is manufactured and 

installed to the same standards as other 

EWIS, it is typically not qualified to an 

environmental standard such as RTCA 

DO–160. 

Section 25.1703 Function and 

Installation: EWIS 

Proposed § 25.1703 would require 

that applicants select EWIS components 

that are of a kind and design appropriate 

to their intended function. Factors such 

as the components’ design limitations, 

functionality, and susceptibility to arc 

tracking and moisture must be 

considered when selecting EWIS 

components. 

Section 25.1301 requires that each 

item of installed equipment be of a kind 

and design appropriate to its intended 

function, be labeled (identified), be 

installed according to any limitations 

specified for it, and function properly 

when installed. This is a general ‘‘catchall’’ regulation applicable to equipment 

and systems certified under subpart F. 

Because of its generality and the fact 

that the FAA has not published any 

advisory circular for this rule, § 25.1301 

has not been applied in a standardized 

way. Currently, § 25.1301 is applicable 

to wire and its associated components 

but it does not provide sufficient wirespecific requirements to ensure proper 

function and installation of EWIS. It 

does not adequately cover all factors 

that need to be considered when 

selecting, identifying, and installing 

wiring components. 

The requirements of § 25.1301 are the 

basis for the new § 25.1703, but those 

requirements are supplemented by new 

ones. Requirements from other existing 

sections are also moved into the new 

regulation, so that the proposed rule 

would specifically apply to EWIS 

components. Adoption would ensure 

that the selection of wires and other 

EWIS components, and their 

installation, are carried out in a safe, 

consistent, and standardized manner. 

Section 25.1703(a)(1) would require 

that each EWIS component be of a kind 

and design appropriate to its intended 

function. While § 25.1301(a) contains 

the same requirements, § 25.1703(a)(1) 

is specific to EWIS components. In this 

context, the requirement means that 

components must be qualified for 

airborne use, or otherwise specifically 

assessed as acceptable for their intended 

use. To be ‘‘appropriate’’ means that the 

equipment is used in a manner for 

which it was designed. For example, a 

wire rated at 150 degrees Celsius would 

not be appropriate for installation in an 

airplane zone where the temperature 

exceeds 150 degrees Celsius. Wire and 

other components made for household 

or consumer products use would not be 

appropriate for airborne use because 

they are manufactured for the consumer 

market and not for use in an airborne 

environment. Exceptions to this would 

be wire or other consumer components 

shown to comply with all the applicable 

airworthiness requirements of part 25. 

In the past this showing of compliance 

has proven to be difficult because 

manufacturers of consumer products 

have been reluctant to modify their 

designs to accommodate aviation use. 

Aviation use of consumer products 

represents too small a market. 

Other factors that must be considered 

for EWIS component selection are 

mechanical strength, voltage drop, 

required bend radius, and expected 

service life. Expected service life means 

the expected service lifetime of the 

EWIS. This is not normally less than the 

expected service life of the aircraft 

structure. If the expected service life 

requires that all or some of the EWIS 

components be replaced at certain 

58518 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

intervals, then these intervals must be 

specified in the ICA as required by 

§ 25.1529. 

Section 25.1703(a)(2) requires that 

EWIS components be installed 

according to their limitations. As used 

here, limitations means the design and 

installation requirements of the 

particular EWIS component. Examples 

of EWIS component limitations are 

maximum operating temperature, degree 

of moisture resistance, voltage drop, 

maximum current-carrying capability, 

and tensile strength. Section 25.1301(c) 

contains that requirement, but fails to 

specifically address the unique 

characteristics of EWIS. EWIS 

component selection and installation 

design must take into account various 

environmental factors including, but not 

limited to, vibration, temperature, 

moisture, exposure to the elements or 

chemicals (de-icing fluid, for instance), 

insulation type, and type of clamp. For 

example, wire bundle adhesive clamps 

are known to work loose during aircraft 

operation. Attention must be given to 

the selection of and methods of affixing 

this type of wire bundle support and it 

must be shown that this type of clamp 

is appropriate for the environment in 

which it will be used. 

Section 25.1703(a)(3) would require 

that EWIS function properly when 

installed. This is the same requirement 

as § 25.1301(d). However, the 

§ 25.1301(d) requirement is so general 

that it is applied in a nonstandardized 

manner. Sometimes the term ‘‘function 

properly when installed’’ has been 

interpreted to mean that even nonsafety-related functions of a given 

system must function in the manner for 

which it was designed. The key word in 

understanding the intent of this 

proposed section is ‘‘properly,’’ as that 

relates to airworthiness of the airplane 

in which the electrical wiring 

interconnection systems are installed. 

For an EWIS component to function 

properly means that it must be capable 

of safely performing the function for 

which it was designed. For example, the 

fact that an airplane’s in-flight 

entertainment (IFE) system fails to 

deliver satisfactory picture or sound 

quality is not what the term ‘‘properly’’

refers to and is not a certification issue. 

However, the failure of an EWIS 

component has the potential for being a 

safety hazard whether it is part of a 

safety-related system or an IFE system. 

Therefore, EWIS components must 

always function properly when 

installed, no matter what system they 

are part of. The guidance material being 

prepared to accompany the proposed 

subpart H, AC 25,17XX, ‘‘Certification 

of Electrical Wiring Interconnection 

Systems on Transport Category 

Airplanes,’’ will clarify these 

distinctions. 

Section 25.1703(a)(4) is a new 

requirement to ensure that EWIS 

components be designed and installed 

so mechanical strain is minimized. This 

means the EWIS installation must be 

designed such that strain on the wires 

would not be so great as to cause wire 

or other components to fail. This 

requirement would ensure that adequate 

consideration is given to mechanical 

strain when selecting wire and cables, 

clamps, strain reliefs, stand-offs, and 

other devices used to route and support 

the wire bundle. 

Proposed § 25.1703(b) would require 

that selection of wires for installation 

takes into account known characteristics 

of different wire types in relation to 

each specific application, to minimize 

risk of damage. It is important to select 

the aircraft wire type whose 

construction matches the application 

environment. The wire type selected 

must be constructed for the most severe 

environment likely to be encountered in 

service. Among other things, the 

proposed section would ensure that 

insulation types susceptible to arc 

tracking be used only in environments 

that will minimize the likelihood of that 

phenomenon. Arc tracking is a 

phenomenon in which a conductive 

carbon path forms across an insulating 

surface. A breach in the insulation 

allows arcing. The arcing carbonizes the 

insulation. The carbon residue is 

electrically conductive. The carbon path 

then provides a short circuit path 

through which current can flow. This 

can occur on either dry or wet wires. 

Certain types of wire insulation are 

more susceptible to arc tracking than 

others. Wire insulated with aromatic 

polyimide is one type that is susceptible 

to arc tracking. While this type of 

insulation is well suited for use in very 

low or high temperature environments, 

it generally should not be used in areas 

of an airplane prone to excessive 

moisture or vibration, such as those 

areas designated as severe wind and 

moisture problem (SWAMP) areas 

without taking into account this 

insulation property’s unique 

characteristics. Installations exposed to 

vibration and constant flexing in a 

moisture-prone area would need wire 

type suitable for that environment. 

Proposed § 25.1703(c) would require 

that design and installation of the main 

power cables allow for a reasonable 

degree of deformation and stretching 

without failure. This requirement now 

resides in § 25.869(a)(3). 

Proposed § 25.1703(d) requires that 

EWIS components located in areas of 

known moisture build-up be adequately 

protected to minimize moisture’s 

hazardous effects. This is to ensure that 

all practical means are used to ensure 

damage from fluid contact with 

components does not occur. Wires 

routed near a lavatory, galley area, 

hydraulic lines, severe wind and 

moisture problem areas such as wheel 

wells and wing trailing edges, and any 

other area of the airplane where 

moisture collection could be a concern 

must be adequately protected from 

possible adverse effects of exposure to 

the types of moisture in these areas. 

If a TC includes subpart H in its 

certification basis, the TC holder would 

have to show compliance with the 

proposed EWIS requirements. For future 

modifications of those TCs, use of the 

same design practices as those used by 

the TC holder will enable the modifier 

to substantiate compliance with the 

subpart H requirements based on a 

comparison with the TC holder’s 

methods. If modifiers choose to deviate 

from those design practices, they would 

have to substantiate compliance 

independently. They would also have to 

consider the design practices used by 

the TC holder in order to justify their 

own choice of components. 

In summary, these new rules would 

require the designer and installer to be 

careful in wire type choices, system 

design, and installation design. The 

existing § 25.1301 would be amended to 

contain a reference to § 25.1703 for 

EWIS component requirements. 

Section 25.1705 System Safety: EWIS 

Proposed § 25.1705 would require 

applicants to perform a system safety 

assessment of the EWIS. The safety 

assessment must consider the effects 

that both physical and functional 

failures of EWIS would have on the 

airplane’s safety. Based on that safety 

assessment, it must be shown that each 

EWIS failure considered to be hazardous 

is extremely remote. Each EWIS failure 

considered to be catastrophic must be 

shown to be extremely improbable and 

not result from a single failure. 

The current regulation requiring 

system safety assessments is § 25.1309. 

But current § 25.1309 practice does not 

lead to the type of analysis that fully 

ensures all EWIS failure conditions 

affecting airplane-level safety are 

considered. This is because the current 

§ 25.1309(a) only covers systems and 

equipment that are ‘‘required by this 

subchapter,’’ and wiring for nonrequired 

systems is sometimes ignored. The 

current safety analysis requirements of 

§ 25.1309(b) and (d) have not always 

been applied to wire associated with the 

airplane systems that are covered by the 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58519 

same rule. When they are, there is 

evidence of inadequate and inconsistent 

application. This is especially true for 

miscellaneous electrical equipment that 

is not required, such as IFE systems. 

Traditional thinking about these 

nonrequired systems has been that, 

since they are not required, and the 

function they provide is not necessary 

for the safety of the airplane, their 

failure could not affect the safety of the 

airplane. This is not a valid assumption 

because failure of an electrical wire can 

have hazardous or even catastrophic 

results regardless of the system it is 

associated with. Wire failure can cause 

serious physical and functional damage 

whether the wire or other EWIS 

components are associated with an 

autoland system or an IFE system. An 

example of this is arcing from a shorted 

wire cutting through flight control 

cables. 

The Aviation Rulemaking Advisory 

Committee (ARAC), based on the work 

of its System Design and Analysis 

Harmonization Working Group, has 

made recommendations to the FAA for 

changes to the current § 25.1309. We are 

evaluating those recommendations. (A 

copy of those recommendations has 

been placed in the docket for reference.) 

We have considered the ARAC 

recommendations in developing the 

proposed § 25.1705. 

One of the factors we considered in 

developing the proposed § 25.1705 is 

that the proposed ARAC revisions to 

§ 25.1309 would exempt certain 

airplane systems, including the EWIS 

components associated with those 

systems, from having to comply with its 

requirements. Specifically, ARAC 

recommends that jamming of flight 

control surfaces or pilot controls 

covered by § 25.671(c)(3) be exempt 

from the requirements of § 25.1309. 

Single failures covered by § 25.735(b)(1) 

and the failure effects covered by 

§§ 25.810(a)(1)(v) and 25.812 would also 

be excepted from the revision to 

§ 25.1309(b) recommended by ARAC. 

This includes wiring or other EWIS 

components associated with those 

systems. In part, proposed § 25.1705 

would ensure coverage of the EWIS 

associated with those systems. 

There are many examples of 

inadequate EWIS designs that have later 

been determined to be unsafe. Adoption 

of proposed § 25.1705 would help 

ensure that those unsafe design 

practices are not repeated in the future 

by requiring that EWIS failure 

conditions affecting airplane-level safety 

are fully considered. The current 

§ 25.1309 does not provide that 

assurance. 

The FAA has issued over 100 wirerelated airworthiness directives (AD) 

since 1998. Over 50 of those were issued 

since 1999 to correct wiring deficiencies 

on the Model MD–11 airplane as 

delivered by the manufacturer. 

Airplanes as delivered from all transport 

category airplane manufacturers have 

been the subject of mandatory corrective 

action to correct safety-related wiring 

problems. 

Similarly, the FAA has issued many 

ADs to correct unsafe EWIS installations 

because of postdelivery modifications. 

One example of this involves the IFE 

system installed on the Swissair MD–11 

airplane that crashed off the coast of 

Nova Scotia and was discussed 

previously in this document. That 

modification is a clear case of not 

considering the effect that EWIS failures 

can have on airplane safety. The 

airplane was modified using the 

supplemental type certification process 

to add the IFE system. That system 

contained roughly 750 separate 

electronic boxes and was installed 

without an adequate safety assessment 

per § 25.1309. Although this IFE system 

consumed relatively large amounts of 

electrical power and its components and 

wiring were distributed throughout, 

below, and above the entire passenger 

cabin, the applicant did not thoroughly 

address the safety implications of 

routing the system wire in the same 

bundles as wire from other airplane 

systems, thus raising a concern for 

common cause failure to multiple 

essential systems. In many instances the 

applicant could not identify what 

airplane systems were associated with 

the wire in the bundles modified to 

route the IFE wiring. With the adoption 

of the proposed § 25.1705, this IFE 

system, as designed and installed on an 

airplane with the proposed subpart H in 

its type certification basis, would be 

subjected to a more rigorous safety 

assessment that would identify any 

inappropriate routing and force a design 

change. 

Many other examples of type design 

modifications provide evidence that 

modifiers do not always give due 

consideration to the impact on safety 

that installation of a new or modified 

system may have. Modifiers continue to 

route the EWIS needed for 

modifications with, or in close 

proximity to, wiring from other airplane 

systems without identifying protection 

mechanisms for those systems. The 

current § 25.1309 and revisions to it 

recommended by ARAC do not contain 

sufficient requirements to ensure such 

modifications maintain the level of 

safety intended by the regulation. 

Accordingly, a more comprehensive 

and specific safety assessment 

regulation for EWIS is necessary. The 

objective of the proposed § 25.1705 is to 

focus attention on EWIS and the safety 

issues associated with them by using the 

concepts of § 25.1309 to provide for 

consistent use of a more thorough and 

structured analysis of aircraft wiring 

and its associated components. 

The integrated nature of wiring and 

the potential severity of failures demand 

a more structured safety analysis 

approach than that traditionally used 

under the current, or the ARAC’s 

proposed revision to, § 25.1309. There 

are more failure modes that need to be 

addressed than have been addressed 

previously with traditional analyses 

(arcing events that occur without 

tripping circuit breakers, resulting in 

complete wire bundle failures and fire; 

or wire bundle failures that lead to 

structural damage, for example). Current 

§ 25.1309 system safety assessments 

typically evaluate effects of wire failures 

on system functions. But they have not 

considered physical wire failure as a 

cause of the failure of other wires within 

the EWIS. The traditional assessments 

look at external factors like rotor burst, 

lightning, and hydraulic line rupture, 

but not at internal factors, like a single 

wire chafing or arcing event, as the 

cause of the failure of functions 

supported by the EWIS. Compliance 

with the proposed § 25.1705 would 

require addressing those failure modes 

at the airplane level. This means that 

EWIS failures would need to be 

analyzed to determine what effect they 

would have on the safe operation of the 

airplane. 

The proposed rule language is 

consistent with § 25.1309 and is meant 

to work in conjunction with the 

§ 25.1309 assessments performed on 

airplane systems. It would require that 

the probability of a hazardous failure 

condition be extremely remote and that 

the probability of a catastrophic failure 

condition be extremely improbable and 

not result from a single failure. The 

terminology and meaning of the 

classifications of EWIS failure 

conditions are identical to those 

proposed by ARAC in August 2002. The 

proposed AC produced by that working 

group discussing this, titled ‘‘System 

Design and Analysis,’’ is in the docket 

for this NPRM. The following table 

identifies and explains the failure 

condition terms. 

58520 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

CLASSIFICATION OF FAILURE CONDITIONS

Term Explanation 

No Safety Effect .............................. Failure conditions that would have no effect on safety; for example failure conditions that would not affect 

the operational capability of the airplane or increase flightcrew workload. 

Minor ............................................... Failure conditions that would not significantly reduce airplane safety, and involve flightcrew actions that are 

well within their capabilities. Minor failure conditions may include, for example: 

• a slight reduction in safety margins or functional capabilities; 

• a slight increase in flightcrew workload, such as routine flight plan changes; or 

• some physical discomfort to passengers or cabin crew. 

Major ............................................... Failure conditions that would reduce the capability of the airplane or the ability of the flightcrew to cope 

with adverse operating conditions to the extent that there would be, for example: 

• a significant reduction in safety margins or functional capabilities; 

• a significant increase in flightcrew workload or in conditions impairing flightcrew efficiency; 

• discomfort to the flightcrew; or 

• physical distress to passengers or cabin crew, possibly including injuries. 

Hazardous ....................................... Failure conditions that would reduce the capability of the airplane or the ability of the flightcrew to cope 

with adverse operating conditions to the extent that there would be, for example: 

• a large reduction in safety margins or functional capabilities; or 

• physical distress or excessive workload such that the flightcrew cannot be relied upon to perform their 

tasks accurately or completely; or 

• serious or fatal injuries to a relatively small number of persons other than the flightcrew. 

Catastrophic .................................... Failure conditions that would result in multiple fatalities, usually with the loss of the airplane. (Note: A catastrophic failure condition was defined differently in previous versions of § 25.1309 and in accompanying 

advisory material as ‘‘a failure condition that would prevent continued safe flight and landing.’’) 

The proposed § 25.1705 would 

complement the § 25.1309 assessments 

by raising the quality of the safety 

assessment with respect to EWIS 

failures that would not be identified 

using the traditional methods of 

compliance with § 25.1309. The analysis 

required to show compliance with the 

proposed regulation is based on a 

qualitative approach to assessing EWIS 

safety as opposed to a numerical 

probability-based quantitative analysis. 

The intent is not to examine each 

individual wire and its relation to other 

wires, but rather to ensure that there are 

no unacceptable hazards to the airplane. 

This does not preclude the possibility 

that, should the analysis identify a 

failure in a given wire bundle or 

component(s) that may lead to a 

catastrophic failure condition, the 

design mitigation process may lead to 

performing a complete analysis of each 

wire in the relevant bundle. 

The type of analysis used to show 

compliance with the proposed § 25.1705 

can vary depending on the knowledge of 

the designers or modifiers of an EWIS. 

As stated earlier, it is important that 

there is thorough knowledge of what 

systems and functions the other wires in 

the same and surrounding bundles 

support. In the case of a post-TC 

modification, without this information 

it would be impossible to state that the 

modified system could not fail in a way 

that would cause a hazardous or 

catastrophic event. If this information is 

not available to the modifier, then the 

EWIS system must be designed to 

accommodate this lack of knowledge. 

This would typically mean that wire 

being added for the modification would 

need to be routed separately from 

existing airplane wiring. 

Flowchart 1 and Flowchart 2, 

contained in Appendix E of this notice, 

illustrate the type of analysis necessary 

to show compliance with the proposed 

§ 25.1705. Two separate cases are 

considered. Flowchart 1 is applicable to 

pre-type-certification work and to TCs 

and STCs when the modifier has all the 

data necessary to perform the analysis. 

If the analysis is conducted according to 

this flowchart, the available data must 

include identification of systems 

supported by the EWIS under 

consideration for modification and the 

functions associated with them. The 

original aircraft manufacturer has most 

of this data and would normally follow 

the Flowchart 1 method. However, this 

may not always be the case when the 

manufacturer modifies an airplane that 

has been previously modified by 

another party. 

The analysis depicted in Flowchart 2 

would apply to modifiers for post-TC 

modification who cannot identify the 

systems or functions contained in EWIS 

being considered for modification. 

In both analyses, EWIS functional and 

physical failures are addressed. It is the 

physical portion that has been neglected 

in past system safety analyses. The 

proposed regulation would require an 

applicant to identify any physical 

failure of EWIS that can cause damage 

to co-located EWIS or other surrounding 

systems or structure, or injury to people. 

Once those physical failures are 

identified, their severity can be 

determined and design mitigation 

strategies can be developed and applied. 

The process is repeated until all known 

unsafe features are eliminated. The 

difference between the processes 

identified in the two flowcharts is that 

in Flowchart 1, all the systems and 

associated functions whose wires are in 

a bundle are known. In Flowchart 2, 

new wire is routed separately from 

existing wire. Otherwise, the analysis is 

the same. 

In summary, the need for this new 

regulation is shown by experience on 

the part of the FAA and other 

governmental regulatory authorities and 

by service histories. Many wire-related 

incidents and accidents have occurred. 

Post-TC modifications have repeatedly 

introduced wiring safety problems. 

Airplane manufacturers have delivered 

airplanes that have wiring problems 

when they leave the factory, or such 

problems have later developed in 

service, as evidenced by resulting 

mandatory corrective actions. Adoption 

of this proposal would ensure that such 

problems are fully considered and 

addressed as part of the type 

certification process. 

Section 25.1709 System Separation: 

EWIS 

Proposed § 25.1709 would require 

applicants to design EWIS with 

appropriate separation to minimize the 

possibility of hazardous effects upon the 

airplane or its systems. 

Safe operation of airplanes depends in 

part on the safe transfer of electrical 

energy, a function provided by airplane 

EWIS. If an EWIS failure should occur, 

the separation between the failed EWIS 

and other EWIS and airplane systems 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58521 

plays an important role in ensuring that 

any hazardous effects of the failure are 

mitigated to an acceptable level. Thus, 

it is vital to design and install wiring 

systems with adequate separation from 

those systems whose interaction with 

the wire could create hazardous effects. 

Currently, part 25 certification rules do 

not adequately address wire system 

separation. The rules currently used to 

require system separation are 

§ 25.1353(a), (b), and (c), but service 

experience has shown that compliance 

with these requirements, with regard to 

wiring systems, has not always been 

adequate. This is due in part to their 

lack of specific wording about which 

wiring systems are covered and which 

systems those wires are meant to be 

separated from. The proposed rule 

corrects these inadequacies by stating 

specifically that it applies to each EWIS 

on the airplane, and mandating specific 

separation requirements for certain 

airplane systems known to have 

potential for creating a hazardous 

condition. The term ‘‘hazardous 

condition’’ in this proposed rule is used 

in a different context than it is used in 

the proposed § 25.1705. Proposed 

§ 25.1705 uses the terms ‘‘hazardous’’

and ‘‘catastrophic’’ in the context of 

assigning a numerical probability to 

failures that can cause a failure 

condition. Hazardous failure conditions 

and catastrophic failure conditions are 

defined in the discussion of the 

proposed § 25.1705. In proposed 

§ 25.1709, the term hazardous condition 

means that the applicant must perform 

a qualitative design assessment of the 

installed EWIS. This assessment would 

involve using reasonable engineering 

and manufacturing judgment and 

assessing relevant service history to 

decide whether an EWIS, any other type 

of system, or any structural component 

could fail in such a way that a condition 

affecting the airplane’s ability to 

continue safe operation could result. A 

numerical probability assessment may 

still be required under the requirements 

of the proposed § 25.1705 if the 

airplane-level functional hazard 

assessment identifies failures that could 

affect safe operation of the airplane. 

To illustrate the type of assessment 

required by proposed § 25.1709, 

consider the following simple example 

involving the use of wire bundle 

clamps. Clamps are used to secure a 

wire bundle to structure in order to hold 

the bundle in place and route the 

bundle from one location to another 

along a predetermined path. An airplane 

manufacturer, using the criteria 

contained in the proposed advisory 

material for 25.1709, determines that a 

2-inch separation from hydraulic lines 

is necessary. The manufacturer further 

decides that one clamp every 10 inches 

is needed to maintain that separation. 

However, there is one localized area 

where a single clamp failure would 

potentially create a hazard. This is 

because the area in question is a high 

vibration, high temperature area, subject 

to exposure to moisture. So the clamp 

in this particular area is exposed to 

severe environmental conditions that 

could lead to its accelerated 

degradation. The manufacturer decides 

that using just a single clamp every 10 

inches in this area would not suffice to 

preclude a hazardous event. The 

manufacturer prescribes use of double 

clamps every 10 inches in that area. 

The requirements of proposed 

§ 25.1709 do not preclude use of valid 

component failure rates if the applicant 

chooses to use a probability argument in 

addition to the design assessment to 

demonstrate compliance. It also does 

not preclude the FAA from requiring 

such an analysis if the applicant cannot 

adequately demonstrate that hazardous 

conditions will be prevented solely by 

using the qualitative design assessment. 

As used in the proposed rule, the term 

‘‘separation’’ is a measure of physical 

distance. The purpose of separation is to 

prevent hazards of arcing between wires 

in a single bundle, between two or more 

bundles, or between an electrical bundle 

and a non-electrical system or structure. 

In some cases, the proposal would allow 

separation to be achieved with a barrier 

or other means shown to be at least 

equivalent to the necessary physical 

distance. However, distance separation 

is preferred because service experience 

shows that use of barriers such as 

conduits can cause wire damage or lead 

to maintenance errors. In some cases, 

wire bundle sleeving is used to provide 

separation, although the sleeving itself 

is susceptible to the same types of 

damage as wire insulation. 

Determining the necessary amount of 

physical separation distance is essential. 

However, the proposed rule does not 

mandate specific separation distances 

because each system design and 

airplane model can be unique, and 

because manufacturers have differing 

design standards and installation 

techniques. Instead it requires that the 

chosen separation be adequate so that 

an EWIS component failure will not 

create a hazardous condition. The 

following factors must be considered 

when determining the separation 

distance: 

(1) The electrical characteristics, 

amount of power, and severity of failure 

condition of the system functions 

performed by the signals in the EWIS 

and adjacent EWIS. 

(2) Installation design features, 

including the number, type, and 

location of support devices along the 

wire path. 

(3) The maximum amount of slack 

wire resulting from wire bundle build 

tolerances and other wire bundle 

manufacturing variabilities. 

(4) Probable variations in the 

installation of the wiring and adjacent 

wiring, including position of wire 

support devices and amount of wire 

slack possible. 

(5) The intended operating 

environment, including amount of 

deflection or relative movement 

possible and the effect of failure of a 

wire support or other separation means. 

(6) Maintenance practices as defined 

by the airplane manufacturer’s standard 

wiring practices manual and the ICA 

required by § 25.1529 and proposed 

§ 25.1739. 

(7) The maximum temperature 

generated by adjacent wire/wire bundles 

during normal and fault conditions. 

The FAA recognizes that some 

airplane models may have localized 

areas where maintaining the minimum 

physical separation distance is not 

feasible. In those cases, other means of 

ensuring equivalent minimum physical 

separation may be acceptable, if testing 

or analysis demonstrates that safe 

operation of the airplane is not 

jeopardized. The testing or analysis 

program must be conservative and 

consider the worst possible conditions. 

Paragraphs (a), (b), (c), and (d) of 

proposed § 25.1709 contain EWISrelated requirements derived from the 

existing regulations applying to 

electrical power generation systems and 

electrical equipment and installations 

(§§ 25.1351 and 25.1353). Section 

25.1351 does not need any revision to 

support the proposed § 25.1709, but 

§ 25.1353 is amended to reference 

§ 25.1709. 

The proposed requirements of 

§ 25.1709(a) were derived from existing 

§ 25.1353(a). While the requirements of 

§ 25.1353(a) are retained, the portion of 

that requirement applicable to wiring 

has been moved to the proposed 

§ 25.1709(a). Further clarification of the 

requirement is also included in the 

proposal. Section 25.1353(a) states 

‘‘* * * wiring must be installed so that 

operation of any one unit or system of 

units * * *.’’ Proposed section 

25.1709(a) expands on the term 

‘‘operation’’ to state that it means 

‘‘operation under normal and failure 

conditions as defined by § 25.1309.’’

Proposed section 25.1709(b) would 

require that each EWIS be designed and 

58522 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

5The JAA is the Joint Aviation Authority of 

Europe and the JAR is its Joint Aviation 

Requirements, the equivalent of our Federal 

Aviation Regulations. In the time since these 

proposals were developed, in 2003, the European 

Aviation Safety Agency (EASA) was formed. EASA 

is now the principal aviation regulatory agency in 

Europe, and we intend to continue to work with 

them to ensure our proposal is also harmonized 

with its Certification Specifications (CS). But since 

the harmonization efforts involved in developing 

this proposal occurred before EASA was formed, it 

was the JAA that was involved with them. So while 

the JAR and CS are essentially equivalent, and in 

the future we will be focusing on the CS, it is the 

JAR that will be referred to in the historical 

background discussions in this proposal. 

installed so that any electrical 

interference likely to be present in the 

airplane will not result in hazardous 

effects on the airplane or its systems. 

This proposed requirement is based on 

new text recently added to § 25.1353(a) 

to harmonize part 25 with the existing 

text of the JAA JAR 25.1353(a).5 The text 

of JAR 25.1353(a) requires that any 

electrical interference likely to be 

present in the airplane must not result 

in hazardous effects on the airplane or 

its systems except under extremely 

remote conditions. The proposed 

§ 25.1709(b) is recognition of the fact 

that electrical interference can be 

introduced into airplane systems and 

wiring by coupling between electrical 

cables or between cables and coaxial 

lines, as well as by the other equipment 

that is the subject of § 25.1353(a). The 

proposed requirement does not adopt 

the JAR clause ‘‘except under extremely 

remote conditions.’’ This is because the 

intent of the requirement is not to 

require a numerical probability 

assessment of the likelihood of electrical 

interference or its consequences as 

described previously. Rather it is meant 

to convey that under failure conditions 

that may be caused by electrical 

inference, the resultant effects should 

not be such as to prevent continued safe 

flight of the airplane. 

Proposed section 25.1709(c) contains 

the wire-related requirements of the 

current § 25.1353(b). These 

requirements have been expanded to 

add that not only wires and cable 

carrying heavy current are covered, but 

their associated EWIS components are 

covered as well. The proposal prescribes 

that any required physical separation 

must be achieved either by separation 

distance or by barrier or other means 

shown to be at least equivalent to an 

adequate separation distance. 

Proposed section 25.1709(d) contains 

wire-related requirements of existing 

§§ 25.1351(b)(1) and (b)(2) and would 

introduce additional requirements. To 

show compliance with § 25.1709(d), 

EWIS components associated with the 

generating system must be considered 

with the same degree of attention as 

other components of the system, such as 

the electrical generators. The proposal 

prescribes that any required physical 

separation must be achieved either by 

separation distance or by a barrier or 

other means shown to be at least 

equivalent to an adequate separation 

distance. Paragraph (d)(1) would 

introduce a requirement to prohibit the 

airplane’s independent electrical power 

sources from sharing a common ground 

terminating location. Paragraph (d)(2) 

would prohibit the airplane’s static 

grounds from sharing a common ground 

terminating location with any of the 

airplane’s independent electrical power 

sources. These two new requirements 

would help to ensure the independence 

of separate electrical power sources and 

to prevent introduction of unwanted 

interference into airplane electrical 

power systems from other airplane 

systems. 

Paragraphs (e), (f), (g), and (h) of 

proposed § 25.1709 contain EWISrelated requirements from 

§ 25.1353(d)(3). These paragraphs 

contain specific separation requirements 

for the airplane’s fuel, hydraulic, 

oxygen, and waste/water systems. They 

require that EWIS have adequate 

separation from those systems except to 

the extent necessary to provide any 

required electrical connection to them. 

These paragraphs require that EWIS be 

designed and installed with adequate 

separation so a failure of an EWIS 

component will not create a hazardous 

condition and any leakage from those 

systems (i.e., fuel, hydraulic, oxygen, 

waste/water) onto EWIS components 

will not create a hazardous condition. 

The proposed requirements recognize 

the potential catastrophic hazard that 

could occur should an arcing fault ignite 

a flammable fluid like fuel or hydraulic 

fluid. An arcing fault has the potential 

to puncture a line associated with those 

systems if adequate separation is not 

maintained. If there is leakage from one 

of those systems and an arcing event 

occurs, fire or explosion could result. 

Similarly, leakage from the water/waste 

system can cause damage to EWIS 

components and adversely affect their 

integrity. An EWIS arcing event that 

punctures a water or waste line could 

also introduce fluids into other airplane 

systems and create a hazardous 

condition. 

To prevent chafing, jamming, or other 

types of interference or other failures 

that may lead to loss of control of the 

airplane, EWIS in general and wiring in 

particular must be physically separated 

from flight or other control cables. 

Mechanical cables have the potential to 

cause chafing of electrical wire if the 

two come into contact. This can occur 

either through vibration of the EWIS 

and/or mechanical cable or because of 

cable movement in response to a system 

command. A mechanical cable could 

also damage other EWIS components, 

such as a wire bundle support, in a way 

that would cause failure of that 

component. Also, if not properly 

designed and installed, a wire bundle or 

other EWIS component could interfere 

with movement of a mechanical control 

cable by causing jamming or otherwise 

restricting the cable’s movement. An 

arcing fault could damage or sever a 

control cable, or a control cable failure 

could cause damage to EWIS if not 

adequately separated. Therefore, 

proposed paragraph (i) would require an 

adequate separation distance or barrier 

between EWIS and flight or other 

mechanical control systems cables and 

their associated system components. It 

would further require that failure of an 

EWIS component must not create a 

hazardous condition and that the failure 

of any flight or other mechanical control 

systems cables or systems components 

must not damage EWIS and create a 

hazardous condition. 

EWIS in general and wiring in 

particular must be routed away from 

high-temperature equipment, hot air 

ducts, and hydraulic, fuel, water, and 

other lines. There must be adequate 

separation distance in order to prevent 

damage to the EWIS caused by extreme 

temperatures and so that an EWIS 

failure will not damage the equipment, 

ducts, or lines. High temperatures can 

deteriorate wire insulation and other 

parts of EWIS components, and if the 

wire or component type is not carefully 

selected, this deterioration could lead to 

wire or component failure. Similarly, 

should an arcing event occur, the arc 

could penetrate a hot air duct or line 

and allow the release of high pressure, 

high temperature air. Such a release 

could damage surrounding components 

associated with various airplane 

systems and potentially lead to a 

hazardous situation. Paragraph (j) would 

require that EWIS be designed and 

installed with an adequate separation 

distance or barrier between the EWIS 

components and heated equipment, hot 

air ducts, and lines. 

The needed reliability of some 

airplane systems, such as an autoland 

system, requires that independent, 

redundant systems be used. Loss of one 

channel of a redundant system would 

not decrease the ability to continue safe 

operation. However, if both channels of 

a two-channel system were lost because 

of a common failure, the results could 

be catastrophic. To maintain the 

independence of redundant systems and 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58523 

equipment so that safety functions 

required for safe operation are 

maintained, adequate separation and 

electrical isolation between these 

systems must be ensured. Paragraph (k) 

would require that EWIS associated 

with any system that requires 

redundancy to meet certification 

requirements be separated with an 

adequate separation distance or barrier. 

Paragraph (l) of proposed § 25.1709 

would require that EWIS be designed 

and installed so they are adequately 

separated from aircraft structure and 

protected from sharp edges and corners. 

The purpose of this proposal is to 

minimize the potential for abrasion/ 

chafing, vibration damage, and other 

types of mechanical damage. Such 

protection is necessary because over 

time the insulation on a wire that is 

touching a rigid object, such as an 

equipment support bracket, will fail and 

expose bare wire. This can potentially 

lead to arcing that could destroy that 

wire and other wires in its bundle. 

Depending on the amount of electrical 

energy being carried by the failed wire, 

structural damage may also occur. 

Section 25.1711 Component 

Identification: EWIS 

Proposed § 25.1711 would require 

applicants to identify EWIS components 

using consistent methods that facilitate 

easy identification of the component, its 

function, and its design limitations. For 

EWIS associated with flight-essential 

functions, identification of the EWIS 

separation requirement would also be 

required. 

An important aspect of ensuring safe 

operation of airplanes is making sure 

that EWIS components are properly 

identified. This is necessary so that 

modification designers, maintenance 

personnel, and inspectors can easily 

determine the function of the associated 

system, together with any associated 

separation requirements and design 

limitations. Clear labeling of EWIS 

components and easy-to-understand 

identification aids allow installers, 

inspectors, and maintainers to readily 

ascertain that correct system 

components are installed as designed, 

and allow modifiers to add systems with 

due regard to the existing protection and 

separation requirements. 

The current part 25 certification 

requirement for equipment 

identification is § 25.1301(b) and it is 

applicable to ‘‘each item of installed 

equipment.’’ This rule is inadequate for 

EWIS because it does not provide the 

specific requirements that have been 

determined necessary for identifying 

EWIS components. Specific EWIS 

component identification needs to be 

done to prevent modifiers from 

unintentionally introducing unsafe 

design or installation features on 

previously certified airplanes when they 

install new or modified systems. 

Component identification would also 

make those performing maintenance 

and inspections more aware of what 

systems are associated with specific 

EWIS in the areas undergoing 

maintenance or inspection. 

When the FAA first certifies an 

airplane type design, its systems are 

designed and installed to ensure safe 

operation of the airplane. Systems 

essential to that safe operation are often 

designed and installed to ensure 

redundancy of the system function. 

They have two or more circuits, or 

channels, that can perform the same 

function in case one of them 

malfunctions. Separate circuits 

(channels) typically have their own 

sensors, wiring, and equipment. This 

helps ensure that a common failure 

cannot cause failure of the entire 

system. 

An example of this is the autoland 

system on modern transport category 

airplanes. The autoland system allows 

airplanes to land during adverse 

weather conditions that would 

otherwise prevent landing with manual 

techniques that rely on the flightcrew’s 

ability to see the runway. Typically the 

autoland system has three channels that 

are physically separated and electrically 

segregated, so if one channel fails, the 

airplane can safely continue the 

autoland procedure. The failure of an 

autoland system at a critical phase of 

flight can be catastrophic to the airplane 

and its passengers. The integrity of an 

autoland system’s design could be 

compromised by systems installed after 

certification of the autoland system. One 

way to prevent this is to clearly identify 

EWIS associated with the autoland in a 

way that makes it easy to see that it is 

associated with a critical system. Such 

identification would aid the designers 

and installers of the new system by 

alerting them to the presence of the 

critical system and allow appropriate 

design and installation decisions, 

preventing degradation of the safety of 

the autoland system. 

The reverse is also true. For example, 

suppose an in-flight entertainment 

system is installed on an airplane and, 

after that installation, an autoland 

system is to be installed. The designers 

and installers of the autoland system 

would need to be able to identify EWIS 

associated with the IFE system so they 

do not mix IFE system EWIS with the 

autoland system EWIS. The IFE system 

is a passenger convenience item and its 

functionality is not important to the 

continued safe operation of the airplane. 

When the zone containing the autoland 

system EWIS is undergoing inspections 

or maintenance, easy identification of 

the EWIS will alert inspection or 

maintenance personnel to use extra 

caution in the area. 

Proposed § 25.1711(a) uses language 

that is similar to existing § 25.1301(b) 

but is specifically applicable to EWIS 

components. The proposal adds the 

word ‘‘consistent’’ to stress the need for 

consistency in EWIS identification to 

avoid confusion and mistakes during 

airplane manufacturing, modification, 

and maintenance. This means the FAA 

expects airplane manufacturers to 

develop an EWIS identification method 

that facilitates easy identification of the 

systems that any specific EWIS 

component supports and use that 

identification method in a consistent 

manner throughout the airplane. The 

consistent identification method must 

be used for new type certifications and 

changes to those designs. Proposed 

§ 25.1711(e) would require that 

modifications to type designs use EWIS 

identification methods that are 

consistent with the identification 

method of the original type design. The 

proposed requirements of paragraph (e) 

are discussed later in this document. 

Paragraph (b) would impose 

additional requirements for 

identification detail, when assessed in 

accordance with the proposed 

requirements of § 25.1705, for EWIS 

components associated with: 

• Systems required for safe flight and 

landing. 

• Systems required for egress. 

• Systems with potential to affect the 

flightcrew’s ability to cope with adverse 

operating conditions. 

Paragraph (c) would require that 

identifying markings required by 

paragraphs (a) and (b) of the proposal 

remain legible throughout the design 

life of the component. As most wire 

installations are designed to remain on 

the airplane throughout the airplane’s 

service life, this means the 

identification marks must be able to be 

read to support the intended purpose of 

the markings for the life of the airplane. 

The method of marking must take into 

account the environment in which the 

EWIS component will be installed. 

Paragraph (d) would require that the 

means used to identify an EWIS 

component does not have an adverse 

effect on the component’s performance 

throughout its design life. Certain wire 

marking methods have the potential to 

damage the wire’s insulation. Hot-stamp 

marking is one such method. According 

to SAE (Society of Automotive 

Engineers) aerospace information report 

58524 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

AIR5575, ‘‘Hot Stamp Wire Marking 

Concerns for Aerospace Vehicle 

Applications,’’ a copy of which is 

included in the docket, the hot-stamp 

marking method is not well suited for 

today’s generation of aircraft wiring. As 

noted in the SAE document, wire 

insulation has become markedly thinner 

over the years since the procedure was 

first introduced in the 1940s. Because of 

this, problems have arisen over wire 

damage from excessive penetration by 

the hot-stamp process. The document 

further states: ‘‘The frequent need for 

adjustments in temperature, pressure, 

and swell time inherent to achieving 

legible hot stamp wire marking provides 

many opportunities for error. The 

controls, methods, and guidance 

necessary to achieve satisfactory 

performance with hot stamp marking 

are often not made available to operators 

in smaller wire shops.’’

The FAA concurs with this 

assessment. If damage to the insulation 

occurs during the marking process, it 

may fail later in service after it has been 

exposed to the sometimes-harsh 

environmental conditions of aircraft 

use. While the proposed regulation does 

not prohibit use of hot-stamp marking, 

its use is not encouraged. To comply 

with this paragraph, if the hot stamp 

marking process is used, the guidelines 

of SAE recommended practice 

ARP5369, ‘‘Guidelines for Wire 

Identification Marking Using the Hot 

Stamp Process’’ or equivalent must be 

followed. A copy of this document is in 

the docket. 

In some cases it may not be 

practicable to mark an EWIS component 

directly, because of component size or 

identification requirements. In this case 

other methods of identification such as 

a label or sleeve must be used. 

Paragraph (e) would require that 

EWIS modifications to the type design 

take into consideration the 

identification scheme of the original 

type design. This is to ensure that the 

consistency required by proposed 

§ 25.1711(a) is maintained when a 

modification is installed. The intent of 

this requirement is to provide 

continuity in the methods used for 

EWIS identification on a particular 

model. It is not the intent of the 

requirement to impose on the modifier 

the exact wire identification methods of 

the airplane manufacturer. However, 

since the purpose of proposed § 25.1711 

is to make it easy to identify those 

airplane systems essential to the safe 

operation of the airplane, it is in the best 

interest of safety that designers of any 

modifications to the original design 

consider the approved type design 

identification methods. For example it 

would not be appropriate for a modifier 

to use purple wire to identify a specific 

flight critical system when the approved 

type design used the color green, 

especially if the type design already 

uses purple wire to identify nonessential systems. Such a scheme could 

cause confusion and lead future 

modifiers or maintainers to believe that 

the routing of purple wires with green 

wires is acceptable. This is just an 

example and should not be construed to 

say that flight critical systems should 

use green wire or non-essential systems 

purple wire. The regulation does not 

prescribe a particular method for 

identification, but is meant to ensure 

that the consistency of the identification 

method required by paragraph (a) is 

maintained throughout the life of the 

airplane. 

Section 25.1713 Fire Protection: EWIS 

Proposed § 25.1713 would require 

that EWIS components meet the 

applicable fire and smoke protection 

requirements of § 25.831(c). It would 

further require that EWIS located in 

designated fire zones be at least fire 

resistant. Insulation on electrical wires 

and cables would also be required to be 

self-extinguishing when tested in 

accordance with the applicable portions 

of Appendix F, Part I, of part 25. 

During an emergency situation it is 

important that airplane systems needed 

by the flightcrew to effectively deal with 

the emergency be operative. To help 

ensure this, § 25.869 requires that 

electrical systems components meet 

certain flammability requirements and 

be designed and installed to minimize 

probability of ignition of flammable 

fluids and vapors. Currently, § 25.869(a) 

is applicable to wiring. The proposal is 

to move the requirements of § 25.869(a) 

related to protection of wiring from fire 

and put them into the proposed 

§ 25.1713. This will allow easy 

identification of the requirements for 

fire protection of EWIS, because they 

will be found in the proposed new 

subpart H, which is dedicated to EWIS 

regulations. Requirements of § 25.869 

dealing with isolation from flammable 

fluid lines have been moved to the new 

§ 25.1709 and requirements for 

allowance for deformation and 

stretching have been moved to 

§ 25.1703. As a result, we are amending 

§ 25.869 to accommodate this change. 

Section 25.1717 Electrical Bonding 

and Protection Against Static Electricity: 

EWIS 

Proposed § 25.1717(a) would require 

that EWIS used for electrical bonding 

and protection against static electricity 

meet the requirements of § 25.899. 

Proposed § 25.1717(b) would require 

that EWIS components used for any 

electrical bonding purposes (not just 

that used for protection against static 

electricity) provide an adequate 

electrical return path under both normal 

and fault conditions. 

The buildup and subsequent 

discharge of static electricity has the 

potential to create hazardous conditions 

for both airplane systems and people. 

Static electricity can injure people. It 

can also interfere with installed 

electrical/electronic equipment and 

cause ignition of flammable vapors. We 

are proposing to adopt § 25.899 (as 

discussed in the section headed 

‘‘Electrical System Harmonization 

Rules’’) to highlight the importance of 

considering electrical bonding and static 

electricity as a full aircraft requirement 

and to prevent hazardous effects of 

static electricity. The proper design and 

installation of EWIS components used 

to accomplish such protection is critical 

to ensure the hazardous effects of static 

discharge are minimized. For example, 

the cross-sectional area of bonding paths 

used for primary bonding paths is 

important in ensuring that a low 

electrical impedance is obtained, as is 

the method in which the bonding 

connection is made to the airplane 

structure. Thus, EWIS must be fully 

considered when designing and 

installing protection from the adverse 

effects of static electricity. The proposed 

§ 25.1717 highlights the importance 

EWIS has in providing this protection 

and requires that EWIS components 

meet the same requirements as other 

components used to show compliance 

with § 25.899. 

The ARAC Electrical Systems 

Harmonization Working Group 

recommended the adoption of JAR 

25.1353(e) as paragraph (e) of § 25.1353. 

The JAR requires that electrical bonding 

provide an adequate electrical return 

path under both normal and fault 

conditions on airplanes with grounded 

electrical systems. ATSRAC 

recommended that the requirements of 

JAR 25.1353(e) be moved in their 

entirety to the proposed subpart H. We 

agree with that recommendation and, 

instead of adopting JAR 25.1353(e) as 

§ 25.1353(e), we are proposing to adopt 

it as § 25.1717(b). 

Section 25.1719 Systems and 

Functions: EWIS 

Proposed § 25.1719 would require 

that EWIS components be considered in 

showing compliance with the 

certification requirements of specific 

airplane systems. Many of the current 

part 25 sections contain system specific 

requirements that apply to EWIS in an 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58525 

indirect way. The EWIS associated with 

such systems play an integral role in 

ensuring the safe operation of the 

system and of the airplane. In general, 

the EWIS associated with any airplane 

system needs to be considered an 

integral part of that system and must be 

given the same design and installation 

attention as the rest of the system. The 

proposed § 25.1719(a) contains this 

general requirement, while paragraph 

(b) of the proposal identifies specific 

sections of part 25 that are associated 

with airplane systems where wire and 

its associated components play an 

important part in ensuring safety. These 

specific part 25 sections contain 

requirements that do not lend 

themselves to creating a separate EWISbased Subpart H requirement. 

It is the intent of the proposed 

§ 25.1719 to require that EWIS be 

designed and installed to support 

systems required for type certification or 

by operating rules, including those 

systems addressed by the regulations 

specifically listed in paragraph (b) of the 

proposal. They must be considered part 

of those systems, and be given the same 

design and installation considerations 

as the rest of the system. While 

paragraphs (a) and (b) may seem 

redundant, we have listed specific 

sections in (b) to ensure that applicants 

are aware of the need to give EWIS 

associated with those systems the same 

consideration as the other components 

of those systems. We consider the 

general requirements of (a) necessary 

because there may be other regulations 

where EWIS must be considered in 

showing compliance with those 

regulations. It also ensures that EWIS is 

given full consideration for any systemrelated regulation adopted in the future. 

Section 25.1721 Circuit Protective 

Devices: EWIS 

Proposed § 25.1721 would require 

that electrical wires and cable be 

compatible with the circuit protective 

devices required by § 25.1357. 

We recently adopted § 25.1353(d)(1) 

based on recommendations of ARAC, as 

part of the effort to harmonize the 

requirements of JAA JAR 25 and FAA 14 

CFR part 25. Paragraph (d)(1) requires 

that electrical cables be 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. That requirement would be 

moved from § 25.1353(d)(1) into the 

proposed § 25.1721 in its entirety. The 

proposal also adds the word ‘‘wire’’ to 

the requirement. This is because this 

requirement applies to all sizes of wire, 

not just heavy-current-carrying cables. 

Section 25.1723 Instruments Using a 

Power Supply: EWIS 

The proposed § 25.1723 would 

require that EWIS components 

associated with flight and navigation 

instruments using a power supply be 

designed and installed so that 

compliance with § 25.1331 is ensured. 

Section 25.1331 requires that flight 

and navigation instruments using a 

power supply must, in the event of the 

failure of one power source, be supplied 

by another power source. No change is 

proposed to the wording of that section. 

Section 25.1725 Accessibility 

Provisions: EWIS 

The proposed new § 25.1725 would 

require that means be provided to allow 

for inspection of EWIS and replacement 

of their components as necessary for 

continued airworthiness. 

Currently, § 25.611 requires that 

means must be provided to allow 

inspection, replacement of parts, 

adjustment, and lubrication as necessary 

for principal structural elements and 

control systems. While wiring systems 

are not specifically referred to in the 

existing rule, the ‘‘accessibility’’ concept 

is easily applied to EWIS. Many of the 

wiring systems on airplanes today are 

very difficult to access and inspect. We 

now have an increased awareness of the 

importance of inspecting wiring for 

separation and for contamination and 

damage in order to ensure proper 

functioning, maintenance, and safety. 

We also know that when adjacent 

structures must be removed to allow 

access to wire installations, new 

possibilities for contamination, chafing, 

and other types of damage are 

introduced. Section 25.611 would be 

amended to specify that EWIS must 

meet the accessibility requirements of 

§ 25.1725. 

The intent of proposed § 25.1725 is to 

ensure that EWIS components be 

installed so that inspections, tests, 

repairs, and replacements can be 

undertaken, and that these can be 

carried out with a minimum of aircraft 

disassembly. This proposal would 

facilitate the proposed implementation 

of the new wiring inspection programs 

developed under proposed § 25.1739 

and the operating rules contained in this 

proposal. 

Section 25.1727 Protection of EWIS 

Proposed § 25.1727 would require 

that cargo or baggage compartments not 

contain any EWIS whose failure would 

adversely affect safe operation. It would 

also require that all EWIS be protected 

from damage by movement of people. 

Section 25.855(e) requires that no 

cargo or baggage compartments may 

contain any controls, wiring, lines, 

equipment, or accessories whose 

damage or failure would affect safe 

operation of the airplane unless they are 

protected so that they cannot be 

damaged by movement of cargo in the 

compartment and their breakage or 

failure will not create a fire hazard. The 

proposed regulations would remove the 

word ‘‘wiring’’ from the current 

language and move those requirements, 

as they apply to EWIS, to the proposed 

§ 25.1727(a). Proposed § 25.855(j) would 

mandate that cargo or baggage 

compartment EWIS components must 

meet the requirements of § 25.1727(a). 

The proposed § 25.1727(b) and (c) are 

new EWIS requirements that currently 

don’t exist in part 25. Paragraph (b) 

would require that EWIS be designed so 

that damage and risk of damage from 

movement of people in the airplane 

during all phases of flight, maintenance, 

and service, be minimized. Paragraph 

(c) would require designers to minimize 

damage and risk of damage to EWIS by 

items carried onto the airplane by 

passengers, cabin crew, and flightcrew. 

These two new requirements are 

justified by service experience that 

shows wires can easily be damaged by 

movement of people on the airplane and 

by items carried on board. 

Paragraph (b) would require that 

EWIS designers and installers consider 

such things as the routing of wires that 

could be damaged by personnel in the 

cargo compartments. For example, EWIS 

would have to be designed and installed 

in ways that prevent their use as handor footholds as much as practicable. It 

would further require that EWIS be 

protected from damage by people in the 

cabin or flight deck. More and more 

wiring is being routed to passenger seats 

to support increasingly complex 

passenger convenience features. If an 

airplane is equipped with seat-back 

monitors, for example, the electronic 

components necessary to support the 

monitor are typically mounted 

underneath the seat. This requires wire 

routing to the seats, usually through the 

seat tracks (structural channels used to 

fasten the seats to the floor) or from the 

side wall directly next to the seat. Many 

wires mounted on or under the seats 

have been damaged by passengers. In 

one case an airplane was operated with 

wires lying on the floor in the area 

where a passenger would put his feet. 

The wires had become dislodged from 

the seat track. This not only exposed the 

wires to damage but also posed a 

potential electrical shock risk to the 

passenger. In other cases, wires have 

been routed to the seats through holes 

cut into the cabin side wall, exposing 

them to damage from both passengers 

58526 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

and carry-on items stored beneath the 

seat or between the side wall and seat. 

Section 25.1729 Flammable Fluid Fire 

Protection: EWIS 

The proposed § 25.1729 would 

require that EWIS components be 

considered a potential ignition source in 

each area where flammable fluid or 

vapors might escape by leakage of a 

fluid system and must meet the 

requirements of § 25.863. 

The current § 25.863 mandates that, in 

each area where flammable fluids or 

vapors might escape by leakage of a 

fluid system, there must be means to 

minimize the probability of ignition, 

and resultant hazards if ignition does 

occur. Possible ignition sources, 

including overheating of equipment, 

malfunctioning of protective devices, 

and electrical faults must be considered 

in showing compliance with this rule. 

Many types of electrical faults could 

cause ignition. Among them are sparks 

emitting from an avionics component, 

overheated electrical component 

surfaces, and arcing from electrical 

wiring. The wording of § 25.863 would 

not change. 

Section 25.1731 Powerplants: EWIS 

The proposed § 25.1731 specifies that 

EWIS associated with any powerplant 

must be designed and installed so that 

failure of an EWIS component will not 

prevent continued safe operation of the 

remaining powerplants or require 

immediate action by any crewmember 

for continued safe operation, in 

accordance with § 25.903(b). It would 

also mandate that design precautions be 

taken to minimize hazards to the 

airplane because of EWIS damage in the 

event of a powerplant rotor failure or a 

fire originating in the powerplant that 

burns through the powerplant case, in 

accordance with § 25.903(d)(1). The 

purpose of this section is to ensure 

proper consideration of EWIS in 

evaluating powerplant installation 

designs. 

The current § 25.903(b) requires, 

among other things, that powerplants be 

arranged and isolated from each other to 

allow operation, in at least one 

configuration, so that failure or 

malfunction of any engine, or of any 

system that can affect the engine, will 

not prevent continued safe operation of 

the remaining engines or require 

immediate action by any crewmember 

for continued safe operation. Section 

25.901(d)(1) requires that design 

precautions be taken to minimize 

hazards to the airplane in the event of 

an engine rotor failure or a fire 

originating within the engine that burns 

through the engine case. 

Section 25.1733 Flammable Fluid 

Shutoff Means: EWIS 

Proposed § 25.1733 would require 

that EWIS associated with each 

flammable fluid shutoff means and 

control be ‘‘fireproof’’ (as defined in 

§ 1.1) or located and protected so that 

any fire in a fire zone will not affect 

operation of the flammable fluid shutoff 

means, in accordance with § 25.1189. 

Section 25.1189 requires that each 

engine installation and fire zone have a 

means to shut off or otherwise prevent 

hazardous quantities of fuel, oil, deicer, 

and other flammable fluids from flowing 

into or through any designated fire zone. 

No change is proposed for that section. 

Section 25.1735 Fire Detector Systems, 

General: EWIS 

Proposed § 25.1735 would require 

that EWIS associated with any installed 

fire protection system be considered in 

showing compliance with the applicable 

requirements for that particular system. 

This would be a new requirement. It 

does not currently exist in part 25. The 

current part 25 regulations contain fire 

detection system requirements for 

powerplants (§ 25.1203), lavatories 

(§ 25.854), and cargo compartments 

(§§ 25.855, 25.857 and 25.858). Each fire 

detection system requires electrical 

wire. Failure of this wire could lead to 

inability of the detection system to 

function properly. The wire and other 

associated EWIS components must be 

considered an integral part of the fire 

detection system and meet the 

requirements of the applicable 

regulation. The proposal would apply to 

all required fire protection systems with 

the exception of powerplants and APUs. 

Requirements for EWIS associated with 

powerplant and APU fire detection 

systems are contained in proposed 

§ 25.1737. 

Section 25.1737 Powerplant and APU 

Fire Detector System: EWIS 

Proposed § 25.1737 would require 

that EWIS that are part of a fire or 

overheat detector system located in a 

fire zone be at least fire-resistant, as 

defined in § 1.1. It would also require 

that EWIS components of any fire or 

overheat detector system for any fire 

zone may not pass through another fire 

zone unless: 

• They are protected against the 

possibility of false warning caused by 

fire in the zone through which they 

pass, or 

• Each zone involved is 

simultaneously protected by the same 

detector or extinguishing system. 

In addition, the proposal would 

require that EWIS that are part of a fire 

or overheat detector system in a fire 

zone meet the requirements of 

§ 25.1203. 

The current § 25.1203 requires 

approved, quick acting fire or overheat 

detectors in each designated fire zone, 

and in the combustion, turbine, and 

tailpipe sections of turbine engine 

installations, to provide prompt 

indication of fire in those zones. The 

present rule does contain requirements 

for wire used in the fire detection 

systems. But to increase visibility of the 

related EWIS requirements and to gather 

them into one central place, a new rule 

devoted specifically to fire detector 

system EWIS is proposed. 

Existing § 25.1203 would be amended 

to reference the new § 25.1737, thus 

effectively closing the loop on 

requirements. 

Section 25.1739 Instructions for 

Continued Airworthiness: EWIS 

Proposed § 25.1739 would require 

that applicants prepare EWIS ICA in 

accordance with the requirements of 

Appendix H to part 25. The proposed 

EWIS ICA requirements are discussed in 

the next section of this document. 

B. Part 25 Subpart I—Continued 

Airworthiness and Related Part 25 

Changes 

As discussed below, the following 

proposals are applicable to holders of 

existing TCs for transport category 

airplanes and applicants for approval of 

design changes to those certificates. On 

July 12, 2005, we issued policy 

statement PS–ANM110–7–12–2005, 

‘‘Safety—A Shared Responsibility—New 

Direction for Addressing Airworthiness 

Issues for Transport Airplanes’’ (70 FR 

40166). The policy states, in part, 

‘‘Based on our evaluation of more 

effective regulatory approaches for 

certain types of safety initiatives and the 

comments received from the Aging 

Airplane Program Update (July 30, 

2004), the FAA has concluded that we 

need to adopt a regulatory approach 

recognizing the shared responsibility 

between design approval holders (DAH) 

and operators. When we decide that 

general rulemaking is needed to address 

an airworthiness issue, and believe the 

safety objective can only be fully 

achieved if the DAHs provide operators 

with the necessary information in a 

timely manner, we will propose 

requirements for the affected DAHs to 

provide that information by a certain 

date.’’

We believe that the safety objectives 

contained in this proposal can only be 

reliably achieved and acceptable to the 

FAA if the DAHs provide the operators 

with the EWIS- and fuel-tank-systemVerDate Aug<31>2005 16:39 Oct 05, 2005 Jkt 208001 PO 00000 Frm 00020 Fmt 4701 Sfmt 4702 E:\FR\FM\06OCP2.SGM 06OCP2
Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58527 

related maintenance information 

required by the proposed operational 

rules for parts 91, 121, 125, and 129. 

Our determination that DAH 

requirements are necessary to support 

the initiatives contained in this proposal 

is based on several factors: 

• Developing EWIS and fuel tank 

system ICA is complex. Only the 

airplane manufacturer, or DAH, has 

access to all the necessary type design 

data needed for the timely and efficient 

development of the required EWIS and 

fuel tank system maintenance tasks. 

• FAA-approved EWIS and fuel tank 

system ICA need to be available in a 

timely manner. Due to the complexity of 

these ICA, we need to ensure that the 

DAHs submit them for approval on 

schedule. This will allow the FAA 

Oversight Office having approval 

authority to ensure that the ICA are 

acceptable, are available on time, and 

can be readily implemented by the 

affected operators. Additionally, 

accurate and timely information is 

necessary to ensure alignment with the 

requirements of the Fuel Tank Safety 

Rule (FTSR). The compliance deadline 

for the operational requirements of the 

FTSR was extended to facilitate this 

alignment, as stated in the Federal 

Register notice ‘‘ Fuel Tank Safety 

Compliance Extension (Final Rule) and 

Aging Airplane Program Update 

(Request for Comments)’’ (69 FR 45936). 

• The proposals in this NPRM affect 

a large number of different types of 

transport airplanes. Because the safety 

issues addressed by this proposal are 

common to many airplanes, we need to 

ensure that technical requirements are 

met consistently and the processes of 

compliance are consistent. This will 

ensure that the proposed safety 

enhancements are implemented in a 

standardized manner. 

• The safety objectives of this 

proposal need to be maintained for the 

operational life of the airplane. We need 

to ensure that future design changes to 

the type design of the airplane do not 

degrade the safety enhancements 

achieved by the initial incorporation of 

EWIS and fuel tank system ICA. We 

need to be aware of future changes to 

the type designs to ensure that these 

changes do not invalidate the 

maintenance tasks assigned to a 

particular type design when the ICA are 

first developed under the requirements 

of this proposal. 

Based on the above reasons and the 

stated safety objectives of FAA policy 

PS–ANM110–7–12–2005, we are 

proposing to implement DAH 

requirements applicable to EWIS and 

fuel tank system ICA. 

In the past, we have issued a similar 

requirement in the form of a special 

federal aviation regulation (SFAR). But 

SFARs appear in various places in the 

CFR and are difficult to reference as a 

whole. The FAA believes that placing 

these types of requirements in a new 

subpart of part 25, which contains the 

airworthiness standards for transport 

category airplanes, would provide a 

single, readily accessible location for 

this type of requirement. Therefore, we 

are proposing new subpart I to part 25 

to contain these requirements. 

In preliminary discussions with 

foreign airworthiness authorities of the 

concept of this new subpart, they have 

expressed concerns that their regulatory 

systems may not be able to 

accommodate these types of 

requirements in their counterparts to 

part 25. While agreeing on the need for 

these types of requirements, they have 

suggested that it may be more 

appropriate to place them in part 21 or 

another location. As discussed below, 

because we expect these new subpart I 

requirements to be similar to new part 

25 airworthiness standards, we have 

tentatively decided to place them in part 

25. However, we specifically request 

comments on the appropriate location of 

these requirements, particularly from 

the foreign authorities. If, based on 

comments received, we conclude that 

another location is more appropriate, we 

may move them in the final rule. 

Because such a move would not affect 

the substance of the requirements 

themselves, we would not consider this 

to be an expansion of the scope of this 

rulemaking that would require 

additional notice and comment 

procedures. 

Section 25.1 Applicability 

As stated in § 25.1, part 25 currently 

prescribes airworthiness standards for 

issuance of TCs, and changes to those 

certificates, for transport category 

airplanes. As discussed in more detail 

above, with this NPRM the FAA is 

proposing to expand the coverage of 

part 25 to include a new subpart I 

containing requirements that must be 

complied with by current holders of 

these certificates. Therefore, we are 

proposing to amend § 25.1, 

‘‘Applicability,’’ to state that part 25 

also includes requirements for holders 

of these design certificates. As discussed 

in the FAA’s final rule, ‘‘Fuel Tank 

Safety Compliance Extension and Aging 

Airplane Program Update’’ (69 FR 

45936), this NPRM is one of several 

proposals for adoption of these kinds of 

requirements for current holders of type 

certificates. 

A theme common to this and other 

possible subpart I proposed rules is that 

the rulemaking projects include 

proposals for changes to operational 

rules to require operators to implement 

programs or take other actions that the 

FAA has determined are necessary for 

safety. In several recent rules we have 

adopted operational requirements 

without a corresponding requirement 

for design approval holders to develop 

and provide the necessary data and 

documents to support the operators’

compliance. The difficulty encountered 

by operators in complying with these 

rules has convinced us that the 

corresponding design approval holder 

requirements are necessary to enable 

operators to comply by the regulatory 

deadlines. 

Section 25.2 Special Retroactive 

Requirements 

Section 25.2 currently contains 

‘‘special retroactive requirements.’’

These requirements are ‘‘retroactive’’ in 

the sense that they require applicants 

for changes to TCs to comply with 

requirements that were not applicable to 

the original TC. As discussed below, 

proposed subpart I would have a similar 

effect, in that it would impose new 

requirements on both existing design 

certificate holders and applicants for 

changes to those certificates. Therefore, 

we are proposing to amend § 25.2 to 

make reference to proposed subpart I. 

Section 25.1801 Purpose and 

Definition 

Paragraph (a) of this section states that 

this subpart would establish 

requirements for holders of TCs to take 

actions necessary to address particular 

safety concerns or to support the 

continued airworthiness of transport 

category airplanes. Such actions may 

include, but are not limited to, 

performing assessments, making design 

changes, developing revisions to ICA, 

and making necessary documentation 

available to affected persons. 

The specific applicability of each 

subpart I rule will be established as part 

of the rulemaking adopting each rule. 

Generally this subpart would also apply 

to applicants for type certificates and 

changes that are pending as of the 

effective date of this rule. It would also 

apply to future applicants for changes to 

existing type certificates. Under 

§ 21.101, the FAA may determine that it 

is not appropriate to require such 

applicants to comply with new 

airworthiness standards, such as 

proposed new subpart H. However, it is 

appropriate for them to comply with the 

same requirements as existing certificate 

holders. Otherwise, the safety 

58528 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

improvements that result from type 

certificate holder compliance with these 

requirements could be undone by later 

modifications. 

For example, in the case of this 

proposed rule, as discussed below, 

operators would be required to revise 

their maintenance programs based on 

EWIS ICA developed by the type 

certificate holder. Unless future STC 

applicants are required to provide 

similar ICA for their modifications, the 

TC holder’s ICA could become obsolete 

or, in some cases, even provide 

incorrect and potentially unsafe 

information as applied to the STC 

holder’s modification. In other cases, 

because subpart I rules accompany 

corresponding operating requirements, 

failure of an STC applicant to comply 

with a subpart I rule could make it 

impossible for an operator to comply 

with the corresponding operating 

requirement. Subpart I does not apply to 

future applicants for TCs, because those 

applicants will be covered by other 

proposed changes to part 25, including 

Appendix H. 

Therefore, adoption of a new subpart 

I rule would also necessitate new 

requirements for certification of changes 

to TCs that are in addition to the 

requirements that are specified under 

§ 21.101. Under that section, if a change 

is ‘‘significant’’ and certain other criteria 

are met, the applicant would have to 

show compliance with the latest 

airworthiness requirements. For 

example, an applicant applying for such 

a change after this final rule becomes 

effective would have to comply with the 

proposed EWIS requirements in subpart 

H. Even if we determine that these 

broader regulations do not apply, the 

applicant for a change must still comply 

with the subpart I rule. 

Paragraph (b) of this section provides 

a definition of the term ‘‘FAA Oversight 

Office.’’ The FAA Oversight Office is the 

aircraft certification office or office of 

the Transport Airplane Directorate with 

oversight responsibility for the relevant 

TC or STC, as determined by the 

Administrator. As stated later in the 

discussion of the proposed operating 

rules, the primary means for operators 

to comply with those requirements 

would be by implementing programs or 

taking other actions developed by the 

TC and STC holders under this 

proposed subpart. In each case, to 

ensure compliance with the relevant 

subpart I rule, the TC and STC holder’s 

compliance documentation (for 

example, in this case, EWIS ICA) must 

be submitted to the FAA Oversight 

Office. Because we expect this will be 

a standard approach to compliance with 

the requirements of this subpart, we are 

including this definition in this section 

to avoid having to repeat it in each 

section within this subpart. 

Section 25.1805 Electrical Wiring 

Interconnection Systems (EWIS) 

Maintenance Program 

This proposal would apply to holders 

of TCs and to applicants for new TCs, 

amended TCs, and supplemental TCs if 

the application was filed before the 

effective date of this rule and the 

certificate was issued on or after the 

effective date of this rule. It would also 

apply to future applicants for approval 

of changes to existing TCs. 

Paragraph (a) states that this rule 

would apply, with some exceptions, to 

transport category turbine-powered 

airplanes with a maximum typecertificated capacity of 30 or more 

passengers, or a maximum payload 

capacity of 7500 pounds or more 

resulting from the original certification 

of the airplane or later increase in 

capacity. This would result in the 

coverage of airplanes where the safety 

benefits and the public interest are the 

greatest. 

The reference to the originally 

certificated capacity, or later increase in 

capacity, is intended to address two 

situations: 

• In the past, some designers and 

operators have tried to avoid applying 

requirements mandated only for 

airplanes over specified capacities by 

getting a design change approval for a 

slightly lower capacity. By referencing 

the capacity resulting from original 

certification, this proposal would 

remove this possible means of avoiding 

compliance. 

• It is also possible that an airplane 

design could be originally certified with 

a capacity slightly lower than the 

minimum specified in this section, but 

through later design changes, the 

capacity could be increased above this 

minimum. The reference to later 

increases in capacity would ensure that, 

if this occurs, the design would have to 

meet the requirements of this section. 

Compliance is not proposed for 

airplanes with a certificated passenger 

capacity of fewer than 30 passengers, or 

having a maximum capacity of less than 

7500 pounds payload resulting from 

original certification, because it is not 

clear at this time that the possible 

benefits for those airplanes would be 

proportionate to the cost involved. The 

FAA intends to evaluate the merits of 

applying these requirements to those 

airplanes. We are currently working 

with ATSRAC to assess how these 

issues might be addressed in those 

transport category airplanes. We request 

comments on the feasibility and benefits 

of requiring holders of TCs for those 

airplanes to comply with these 

requirements. 

This proposed rule, as it applies to 

EWIS, is not applicable to holders of 

existing (already issued) STCs. Often, 

the wire design for STC installations of 

EWIS was based on operator or repair 

station standard practices and therefore 

details of the installation are not 

available. In the cases where such 

information is available, it would 

usually indicate that the wiring for the 

modification follows the same path, or 

is in the same airplane zone, as the 

wiring in the original type design. We 

anticipate that operators would inspect 

those areas while performing the TC 

holder’s EZAP program. We also expect 

that any possible discrepancies will be 

further mitigated by operators 

incorporating applicable EWIS 

maintenance tasks into the maintenance 

program for that zone. Accordingly, the 

FAA has decided not to require 

compliance with this section for 

existing STCs. However, if an existing 

STC is amended, this section would 

apply to the amendment. 

TC holders, who design EWIS on 

airplanes, are the technical experts who 

possess information about those 

systems. This proposal would apply to 

the following: 

• TC holders. 

• Applicants for TCs and for approval 

of design changes to existing TCs whose 

applications are pending when this rule 

becomes effective. 

• Future applicants for approval of 

design changes to existing TCs. 

Section 25.1805(b) would require TC 

holders to complete a comprehensive 

assessment of the EWIS of each 

‘‘representative’’ airplane for which they 

hold a TC, develop inspection and 

maintenance instructions for them, and 

incorporate those instructions into the 

airplane’s ICA. The ‘‘representative’’

airplane is defined as the configuration 

of each model series airplane that 

incorporates all the variations of EWIS 

used on that model, and that includes 

all TC-holder-designed modifications 

mandated by AD, as of the effective date 

of this rule. 

For example, for the Boeing Model 

737, the representative airplane would 

be the configuration of each of the 

airplane series, 737–100 through 737–

900 that incorporates all the variations 

of EWIS used in producing each 

airplane series. The purpose of this 

definition is to ensure that the TC 

holder considers the full range of EWIS 

configurations that may affect the 

results of the EZAP. Further, AD 99–03–

04 applies to all Boeing Model 737–100, 

–200, –300, –400, and –500 series 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58529 

airplanes. It requires installation of 

components to provide shielding and 

separation of the fuel system wiring 

from adjacent wiring. It also requires 

installation of flame arrestors and 

pressure relief valves in the fuel vent 

system. Boeing would be required to 

develop ICA for each of those series 

airplanes as modified by installation of 

these components and all other 

modifications mandated by ADs. 

The purpose of including these 

mandated design changes is to ensure 

that the TC holder’s EZAP addresses the 

existing configuration of airplanes in the 

operating fleet, rather than just the 

configuration produced and delivered 

by the manufacturer. 

Applicants for approval of design 

changes would be required to evaluate 

the effect of their proposed change on 

the EWIS ICA developed by the TC 

holder for the representative airplane 

and to develop EWIS ICA to address 

those effects. For TC holders, this 

requirement would apply to any design 

changes that may affect the ICA for the 

representative airplane. This includes 

service bulletins describing such design 

changes. Under § 21.113, these design 

changes are amendments to the TC. 

A description of what must be 

included in those ICA, and the EZAP 

that must be used to develop them, is 

contained in the section of this 

preamble discussing the proposed 

revision to Appendix H, part 25. 

The requirement for ICA was effective 

on January 28, 1981. TC holders whose 

application was dated before that date 

are not subject to that requirement. This 

proposal would require TC holders who 

do not have ICA for specific airplane 

models to create EWIS ICA for them. As 

discussed below, air carriers and 

operators of those airplanes would then 

be required to revise their maintenance 

or inspection programs based on the 

new ICA for EWIS and fuel tank 

systems. 

As discussed earlier, SFAR 88 

requires TC holders to develop 

maintenance and inspection 

instructions to assure the safety of the 

fuel tank system. Proposed § 25.1805(b) 

would require that TC holders align the 

fuel tank system instructions with the 

results of the EZAP applied to EWIS to 

ensure compatibility and minimize 

redundancies. All EWIS would be 

subject to review in developing the 

EWIS ICA, and the appropriate 

instructions for their maintenance and 

inspection would be required. But some 

EWIS are also part of the fuel tank 

system. The requirements for their 

maintenance and inspection might be 

more specific than those for wiring in 

general, and might contain additional 

requirements. That is why the two must 

be reviewed for compatibility. 

As discussed later in this section, the 

ICA for fuel tank system electrical 

wiring required by SFAR 88 will be 

determined in accordance with 

guidance provided by Policy Statement 

ANM100–2004–1129, ‘‘Process for 

Developing Instructions for 

Maintenance and Inspection of Fuel 

Tank Systems Required by SFAR 88’’ (a 

copy of which may be found in the 

docket), or other acceptable process. 

Compliance with Subpart I will require 

ICA for the same wire to be determined 

using an EZAP. While these processes 

have similarities, they may result in 

identification of different tasks and 

intervals. The ICA maintenance tasks 

and intervals that result from these 

determinations are expected to be 

additive. If there is a conflict in the task 

or interval, for purposes of this section, 

the FAA Oversight Office will resolve 

the conflict. 

The ICA should be reviewed to ensure 

that any maintenance tasks for EWIS do 

not compromise fuel tank system wire 

requirements, such as separation or 

configuration specifications. If there is 

an inspection or maintenance 

requirement for EWIS and the fuel tank 

system within the same zone, there 

must be an effort to align the task 

interval. In addition, design certificate 

holder’s existing documents containing 

EWIS and fuel tank system ICA should 

be reviewed to either remove or crossreference redundant information. 

The compliance plan required by this 

proposal must include identification of 

those common locations in the airplane 

where EWIS and fuel tank ICA apply. 

The considerations for compatibility 

and minimization of redundancy for the 

two systems will be reviewed and 

approved by the FAA Oversight Office. 

The plan for documenting the required 

ICA for EWIS and fuel tank system will 

also be reviewed as part of the 

compliance plan. These documents are 

critical to the effort that will be required 

of operators to show compliance with 

the operational rules contained in this 

proposal. We intend that the ICA 

information, both in content and format, 

will be readily usable by the affected 

operators for developing proposed 

changes to their maintenance or 

inspection programs. Generally, the 

information contained in the ICA for the 

fuel tank system required by SFAR 88 

would include: 

• The location of the fuel tank system 

components to be maintained or 

inspected and any access requirements. 

• Any unique procedures required, 

such as special, detailed inspections or 

dual sign-off of maintenance records. 

• Specific task information, such as 

inspections defined by pictures or 

schematics. 

• Intervals for any repetitive tasks. 

• Methods, techniques, and practices 

required to perform the task. 

• Criteria for passing inspections. 

• Any special equipment or test 

apparatus required. 

• Critical Design Configuration 

Control Limitations—for example, wire 

separation or pump impeller material 

specifications—that cannot be altered, 

except in accordance with the 

applicable limitation. 

The information for EWIS ICA would 

generally include: 

• Identification of each zone of the 

airplane. 

• Identification of each zone that 

contains EWIS. 

• Identification of each zone 

containing EWIS that also contains 

combustible material. 

• Identification of each zone in which 

EWIS is in close proximity to both 

primary and back-up hydraulic, 

mechanical, or electrical flight controls 

and lines. 

• The location of the EWIS 

components to be maintained or 

inspected and any access requirements. 

• Any unique procedures required, 

such as special, detailed inspections, or 

a dual sign-off of maintenance records. 

• Specific task information, such as 

inspections defined by pictures or 

schematics. 

• Intervals for any repetitive tasks. 

• Methods, techniques and practices 

required to perform the task. 

• Criteria for passing inspections. 

• Any special equipment or test 

apparatus required. 

• Instructions for protection and 

caution information that will minimize 

contamination and accidental damage to 

EWIS during performance of 

maintenance, alterations, or repairs. 

• Guidelines for identifying wiring 

discrepancies and assessing what effect 

such discrepancies, if found, could have 

on adjacent systems, particularly if 

these include wiring. 

• Critical Design Configuration 

Control Limitations—for example, wire 

separation specifications—that cannot 

be altered, except in accordance with 

the applicable limitation. 

Policy Statement No. PS–ANM100–

2004–10029 provides guidance on 

acceptable processes for developing fuel 

tank system ICA as required by SFAR 

88. The FAA expects that engineers 

from aircraft certification offices or from 

the Transport Airplane Directorate will 

review and approve the results of the 

EZAP. 

The three groups whose compliance 

with this proposal would be required, 

58530 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

and their required compliance dates, 

indicated in paragraph (c), are as 

follows: 

• Existing TC holders: No later than 

December 16, 2007. 

• Current applicants for TCs and 

amendments to TCs (including service 

bulletins describing design changes) 

whose applications are pending and 

future applicants for TC amendments: 

No later than December 16, 2007, or the 

date of approval of their application, 

whichever is later. 

• Pending and future applicants for 

STCs: No later than June 16, 2008, or the 

date of the approval of their application, 

whichever is later. 

Future applicants for changes to TCs 

that comply with proposed § 25.1739 

would not be required to comply with 

this section. As discussed previously, 

under § 21.101, applicants for 

‘‘significant’’ changes that meet certain 

criteria must comply with the latest 

airworthiness requirements. If this 

NPRM is adopted as a final rule, such 

a future applicant would have to 

comply with § 25.1739. Because the 

proposed requirements of that section 

are more extensive than the proposed 

requirements of § 25.1805, requiring 

compliance with this section would be 

redundant. 

In determining the compliance 

schedules for the requirements covered 

in this proposal, the FAA balanced the 

safety-related reasons for the rule 

against the need to give industry enough 

time to comply with it. Therefore, before 

setting the proposed compliance times 

for the TC holders to complete their 

analysis of their representative type 

design, the FAA considered the 

following: 

• Input from industry. 

• Current or planned compliance 

periods of several aging-related 

rulemakings, such as the pending Aging 

Airplane Safety proposed rule, Fuel 

Tank System safety initiatives (69 FR 

45936, 66 FR 23086), and the pending 

Widespread Fatigue Damage proposal. 

• Safety improvements that will 

result from compliance with this rule. 

• Industry’s current efforts to 

incorporate some of these safety 

initiatives. 

ATSRAC recommended a compliance 

time of 24 months for TC holders to 

develop these ICA. To align this 

proposal with other rules in the aging 

airplane program, the FAA has adjusted 

the time frame to that of other rules 

discussed earlier, so that operators can 

more efficiently comply with 

requirements to revise their 

maintenance programs. To support this 

realignment, compliance dates that 

allow an 18-month time frame for TC 

holders to develop the EWIS ICA and 12 

months for operators to implement them 

were determined to be appropriate and 

were included in this proposal. We 

believe these time frames are supported 

by the experience gained from the 

EZAPs already performed. Since 

ATSRAC made its recommendation, 

several manufacturers have applied an 

EZAP to their type design airplanes and 

have completed those reviews. 

When we initially drafted this 

proposal, we assumed the final rule 

would be adopted by mid-2006. As a 

result, we set the compliance dates in 

the proposal using the mid-2006 time 

frame as the baseline. However, the 

proposed rulemaking process took 

longer than we had anticipated. 

Consequently, we expect that the time 

frame for adoption of the final rule will 

be sometime after mid-2006. We 

recognize that this delay will adversely 

impact the compliance dates we 

propose for TC holders and operators 

and we may need to adjust them. 

Therefore, we request and will consider 

your comments on revising the 

proposed compliance dates. Once the 

ICA are approved by the FAA Oversight 

Office, the submitter must make the ICA 

available to affected persons as required 

by § 21.50. 

Because this proposal sets a precedent 

in introducing part 25 requirements for 

holders of existing TCs, it is the FAA’s 

expectation that they will work closely 

with the FAA Oversight Office in 

putting together a compliance plan for 

developing the required ICA. Proposed 

section 25.1805(d) would require that 

the compliance plan be approved by the 

FAA Oversight Office as sufficient basis 

for showing compliance with the 

proposed § 25.1805. 

The following table lists the FAA 

Oversight Offices, as currently 

determined by the Administrator, that 

oversee issuance of type certificates and 

amended type certificates for 

manufacturers of transport category 

airplanes with a passenger capacity of 

30 passengers or a payload capacity of 

7500 pounds or greater. 

Airplane manufacturer FAA Oversight Office 

Aerospatiale .............................................................................................. Transport Airplane Directorate, International Branch, ANM–116. 

Airbus ........................................................................................................ Transport Airplane Directorate, International Branch, ANM–116. 

BAE ........................................................................................................... Transport Airplane Directorate, International Branch, ANM–116. 

Boeing ....................................................................................................... Seattle Aircraft Certification Office. 

Bombardier ............................................................................................... New York Aircraft Certification Office. 

CASA ........................................................................................................ Transport Airplane Directorate, International Branch, ANM–116. 

deHavilland ............................................................................................... New York Aircraft Certification Office. 

Dornier ...................................................................................................... Transport Airplane Directorate, International Branch, ANM–116. 

Embraer .................................................................................................... Transport Airplane Directorate, International Branch, ANM–116. 

Fokker ....................................................................................................... Transport Airplane Directorate, International Branch, ANM–116. 

Lockheed .................................................................................................. Atlanta Aircraft Certification Office. 

McDonnell-Douglas .................................................................................. Los Angeles Certification Office. 

SAAB ........................................................................................................ Transport Airplane Directorate, International Branch, ANM–116. 

Development of a compliance plan is 

necessary to ensure that TC holders 

thoroughly understand the requirements 

of this proposal and produce on time 

appropriate ICA that are acceptable in 

content and format in addressing the 

maintenance and inspection tasks for 

EWIS and the fuel tank system. Integral 

to the compliance plan will be the 

inclusion of procedures to allow the 

FAA to monitor progress towards 

compliance. These aspects of the plan 

will help ensure that the expected 

outcomes will be acceptable and on 

time for incorporation by the affected 

operators in accordance with the 

operational rules contained in this 

proposal. 

To help ensure that TC holders are 

fully informed of what is necessary to 

show compliance with these 

requirements, as previously discussed, 

we are issuing AC 120.XX, and have 

issued a policy statement that describes 

an acceptable means, but not the only 

means, of complying with these 

requirements for developing EWIS ICA 

and the fuel tank system ICA required 

by SFAR 88. AC 120-XX, ‘‘Program to 

Enhance Transport Category Airplane 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58531 

Electrical Wiring Interconnection 

System Maintenance,’’ provides an 

enhanced zonal analysis procedure 

(EZAP) for completing a review of the 

representative airplane covering all 

areas, including the flight deck (or 

cockpit), electrical power center, fuel 

tank wiring, and powerfeeder cables. 

Policy Statement ANM100–2004–10029, 

‘‘Process for Developing Instructions for 

Maintenance and Inspection of Fuel 

Tank Systems Required by SFAR 88,’’

provides guidance for identifying ICA, 

including any airworthiness limitations, 

as a result of the fuel tank system review 

required by SFAR 88 and compliance 

with Amendment 102 to part 25 

Appendix H and § 25.981. 

Proposed § 25.1805(d) is intended to 

provide TC holders, applicants with 

pending TC-amendment or STC 

applications, and the FAA with 

assurance that they understand what 

means of compliance are acceptable and 

have taken necessary actions, including 

assigning sufficient resources, to 

achieve compliance with this section. 

This paragraph is based substantially on 

‘‘The FAA and Industry Guide to 

Product Certification,’’ which describes 

a process for developing project-specific 

certification plans for type certification 

programs. A copy of this guide may be 

found in the docket. This planning 

requirement would not apply to future 

applicants for TC amendments or STCs 

because, as described in the guide, this 

type of planning routinely occurs at the 

beginning of the certification process. 

The guide recognizes the importance 

of ongoing communication and 

cooperation between applicants and the 

FAA. Section 25.1805, while regulatory 

in nature, is intended to encourage 

establishment of the same type of 

relationship in the process of complying 

with this section. In particular, in 

addition to other necessary information, 

paragraph (d)(3) makes it clear that, to 

the extent that they intend to use means 

of compliance different from those 

already identified as acceptable by the 

FAA, it is imperative that they identify 

those differences at the earliest possible 

stage so any compliance issues can be 

resolved without risk of unnecessary 

expenditure of resources or, ultimately, 

noncompliance. 

Proposed § 25.1805(d) would require 

TC holders and applicants to submit to 

the FAA Oversight Office the following 

within 90 days after the effective date of 

the rule: 

• A proposed project schedule, 

identifying all major milestones, for 

meeting the compliance dates of this 

rule. 

• A proposed means of compliance 

with this section, identifying all 

required deliverables, including all 

compliance items and all data to be 

developed to substantiate compliance. If 

any affected person has already initiated 

compliance, the FAA Oversight Office 

will review the results of those efforts to 

ensure that the results are acceptable. 

• A detailed explanation of how the 

proposed means will be shown to 

comply with this section if the affected 

person proposes a means of compliance 

that differs from that described in FAA 

advisory material. 

• A proposal for how the approved 

ICA will be made available to affected 

persons. 

It should be noted that this section 

applies not only to domestic TC holders 

and applicants, but also to foreign TC 

holders and applicants. In this sense, 

this section is different from most type 

certification programs, where foreign 

applicants typically work with their 

responsible certification authority, and 

the FAA relies on that authority’s 

findings of compliance under bilateral 

airworthiness agreements. Since this 

rulemaking is not harmonized in all 

cases, the FAA will make all the 

necessary compliance determinations, 

and where appropriate we may accept 

findings of compliance made by the 

appropriate foreign authorities using 

procedures developed under the 

bilateral agreements. The compliance 

planning provisions of this section are 

equally important for domestic and 

foreign TC holders and applicants, and 

we will work with the foreign 

authorities to ensure that their TC 

holders and applicants perform the 

planning necessary to comply with the 

requirements of this section. 

One of the items required in the plan 

is, ‘‘If the proposed means of 

compliance differs from that described 

in FAA advisory material, a detailed 

explanation of how the proposed means 

will comply with this section.’’ FAA 

advisory material is never mandatory 

because it describes one means, but not 

the only means of compliance. In the 

area of type certification, applicants 

frequently propose acceptable 

alternatives to the means described in 

advisory circulars. But when an 

applicant chooses to comply by an 

alternative means, it is important to 

identify this as early as possible in the 

certification process to provide an 

opportunity to resolve any issues that 

may arise that could lead to delays in 

the certification schedule. 

The same is true for this requirement. 

As discussed earlier, TC holder 

compliance with this section on time is 

necessary to enable operators to comply 

with the operational requirements of 

this NPRM. Therefore, this item in the 

plan would enable the FAA Oversight 

Office to identify and resolve any issues 

that may arise with the TC holder’s 

proposal without jeopardizing the TC 

holder’s ability to comply with this 

section by the compliance time. 

As of the date of this proposal, certain 

TC holders have voluntarily started to 

develop the EWIS EZAP that would be 

required by proposed § 25.1805. An 

EZAP has been completed on certain 

transport category airplanes. Although 

the EZAP used by those TC holders may 

not be the version outlined in AC120- 

XX, it is similar. The FAA would expect 

that after issuance of the final rule, these 

TC holders would either submit a plan 

proposing revisions to the EZAP for 

those model airplanes to be consistent 

with the guidance given in AC120-XX, 

or use the planning process to show that 

their EZAP complies with this section. 

The FAA Oversight Office will then 

review the results of those efforts to 

ensure that the results are acceptable for 

compliance with this section. 

Section 25.1805(e) requires that TC 

holders and applicants correct a 

deficient plan, or deficiencies in 

implementing the plan, in a manner 

identified by the FAA Oversight Office. 

Before the FAA formally notifies a TC 

holder or applicant of deficiencies, 

however, we will have communicated 

with them to try to achieve a complete 

mutual understanding of the 

deficiencies and means of correcting 

them. Therefore, the notification 

referred to in this paragraph should 

document the agreed corrections. 

Because operators’ ability to comply 

with the applicable operational rules 

will be dependent on TC holders’ and 

applicants’ compliance with § 25.1805, 

the FAA will carefully monitor their 

compliance and take appropriate action 

if they fail to achieve compliance. 

Failure to comply within the specified 

time would constitute a violation of the 

requirements and may subject the 

violator to certificate action to amend, 

suspend, or revoke the affected 

certificate in accordance with 49 U.S.C. 

§ 44709. In accordance with 49 U.S.C. 

46301, it may also subject the violator 

to a civil penalty of not more than 

$25,000 per day per TC until § 25.1805 

is complied with. 

C. Other Proposed Changes to Part 25 

As explained in the preamble 

discussion of the proposed subpart H, 

some existing rules applying to EWIS 

would need revision in order to support 

the proposed new subpart. Those rules 

that would be changed by this proposal 

are: 

• 25.611 

• 25.855 

58532 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

• 25.869 

• 25.1203 

• 25.1301 

• 25.1309 

• 25.1353 

• 25.1357 

The changes proposed for them are 

discussed in the section-by-section 

discussion for proposed subpart H. In 

addition, this NPRM includes a number 

of other changes to part 25 requirements 

for electrical systems discussed later in 

the section headed ‘‘Electrical System 

Harmonization Rules.’’ The remaining 

changes to part 25 are discussed below. 

Section 25.1357(f) System Power 

Removal 

ATSRAC has proposed adding a 

requirement that airplane systems 

normally requiring power removal have 

a power switch to accomplish this, 

instead of relying on using the circuit 

breaker. The FAA has decided that this 

requirement belongs in § 25.1357. 

It is not the intent of the proposal to 

require that every electrically powered 

system in the airplane have a means to 

remove power from them other than a 

circuit breaker. ATSRAC used the 

phrase ‘‘normally requiring power 

removal’’ to distinguish between 

airplane systems normally turned on 

and off during normal operations, such 

as passenger convenience systems, and 

those systems normally powered at all 

times, such as the flightdeck multifunction displays or the flight 

management computer. But if, for 

example, the flight-management 

computer did require power cycling 

regularly, for whatever reason, this 

system would then be required to have 

a means to do this other than using the 

circuit breakers. 

For systems requiring this power 

removal design feature, power should be 

removed from the system as closely as 

practical to the source of power instead 

of simply deactivating the outputs of the 

systems power supplies. 

The ability to quickly remove power 

from an airplane system not required for 

the airplane’s safe operation is 

important if an emergency situation 

demands isolation of a known or 

unknown source of fire or smoke. One 

of the first things flightcrews are 

instructed to do when faced with a fire 

or smoke emergency is to remove power 

from the known source or from all 

unnecessary systems if the source is 

unknown. This is to stop the fire or 

smoke from spreading. Currently, part 

25 regulations do not require systems to 

have a separate shutoff feature. But the 

need for the flightcrew to be able to shut 

off unnecessary systems was tragically 

illustrated during the investigation of 

the fatal accident on September 3, 1998, 

of a Swissair Model MD–11, discussed 

earlier in this document. 

After that accident, the FAA 

conducted a special certification review 

(SCR) on the IFE system installed on the 

airplane, and published its report 

(‘‘Federal Aviation Administration 

Special Certification Review Team 

Report on: Santa Barbara Aerospace, 

STC ST00236LA–D, Swissair Model 

MD–11 Airplane, In-flight 

Entertainment System,’’ June 9, 2000. A 

copy of this report is contained in the 

docket). One of the team’s findings was 

that the design of the IFE system did not 

allow the flightcrew or cabin crew to 

completely remove electrical power in 

any other way than by pulling the 

system’s circuit breakers. The FAA 

decided that this was an unsafe 

condition, and we issued an 

airworthiness directive prohibiting 

operation of MD–11 airplanes with that 

particular IFE system installed. The 

FAA expanded its investigation and 

reviewed previously issued STCs that 

had approved installation of IFE 

systems on transport category airplanes. 

That investigation identified over 20 

STC IFE installations that had the same 

design characteristics as the one on the 

accident MD–11 airplane (no means to 

remove power other than by pulling the 

circuit breaker). We issued ADs to 

correct those inadequate IFE system 

designs. As more IFE systems with the 

same design characteristic are 

identified, ADs will be issued to correct 

the identified unsafe condition. 

On September 18, 2000, the FAA 

issued a policy memorandum stating 

that a newly certified IFE system should 

have a way for the flightcrew or cabin 

crew to disconnect it from its source of 

power other than by using circuit 

breakers. A copy of this memorandum, 

titled ‘‘Interim Policy Guidance for 

Certification of In-Flight Entertainment 

Systems on Title 14 CFR Part 25 Aircraft 

(Policy Number 00–111–160),’’ is in the 

docket. Most airplane manufacturers are 

now equipping IFE systems on their 

newly delivered airplanes with a power 

source disconnection means. 

Subsequent policy covering cabin video 

surveillance systems also contains the 

same guidance (Policy Number 01–111–

196, ‘‘Interim Summary of Policy and 

Advisory Material Available for Use in 

the Certification of Cabin Mounted 

Video Cameras Systems with Flight 

Deck Displays on Title 14 CFR Part 25 

Aircraft,’’ included in the docket). 

ATSRAC (as recommended by the 

ATSRAC Wire Systems Harmonization 

Working Group and the ARAC Electrical 

Systems Harmonization Working Group) 

believes that this philosophy should be 

applied to any airplane system that 

requires having its power removed or 

reset during normal operations. The 

FAA agrees with this recommendation. 

The proposed § 25.1357(f) would 

require that airplane systems needing a 

capability for having their power 

removed or reset during normal 

operations must be designed so that 

circuit breakers are not the primary 

means to do that. This is a new 

regulation whose requirements have not 

previously existed within part 25 and is 

a recognition that any airplane system, 

including an IFE system, that requires 

regular power removal or resetting 

needs to have a means to do so. 

Appendix H to Part 25—Instructions for 

Continued Airworthiness 

As previously noted, improper 

maintenance, repair, and modifications 

often hasten the ‘‘aging’’ of EWIS. To 

properly maintain, repair, and modify 

airplane EWIS, certain information must 

be available to the designer, modifier, 

and installer. This information should 

be part of the ICA as required by current 

§ 25.1529 and the proposed § 25.1739. 

This proposal would amend 

Appendix H by adding a new section, 

H25.5, to require TC applicants to 

develop maintenance information for 

EWIS as part of the ICA as a 

requirement for getting a design 

approval. The proposed rule would also 

apply to applicants for design change 

approvals (supplemental TCs and 

amended TCs). 

The proposal would require 

applicants for TCs to prepare ICA for 

EWIS that are approved by the FAA 

Oversight Office, in the form of a 

document that is easily recognizable as 

an EWIS ICA. To prepare these 

instructions, they must use an EZAP 

such as the one described in AC120-XX, 

‘‘Program to Enhance Aircraft Electrical 

Wiring Interconnection System 

Maintenance’’ to perform a review of 

their representative airplane covering all 

areas, including the flightdeck (also 

known as the cockpit), electrical power 

center, fuel tank wiring and 

powerfeeder cables, as well as the 

engine. Applicants for design change 

approvals would have to perform a 

similar review for their proposed design 

changes. 

A zonal analysis procedure is an 

assessment of the structures and 

systems within each physical zone of 

the airplane. It is used to develop an 

inspection program to assess the general 

condition and security of attachment of 

all system components and structures 

items contained in the zone, using 

general visual inspections (GVI). An 

enhanced zonal analysis procedure 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58533 

(EZAP) is an enhanced version of the 

zonal analysis procedure. It focuses on 

EWIS components. An EZAP-generated 

inspection program might call for the 

use of stand-alone GVI and detailed 

inspections (DET). A stand-alone GVI is 

one that is performed separately from 

the regularly scheduled GVI (typically 

more frequently) and is focused on a 

particular area or component. In this 

case, the focus would be wiring. So 

while the zonal analysis procedure 

would result in a regularly scheduled 

GVI for the entire zone, in which each 

of its systems and structures are 

inspected at the same time, the EZAP 

could result in additional GVIs or DETs 

for the EWIS in that zone, which occur 

more frequently. These inspection 

techniques are discussed later in this 

section. 

An EZAP identifies the physical and 

environmental conditions contained in 

each zone of an airplane, analyzes their 

effects on electrical wiring, and assesses 

the possibilities for smoke and fire. 

From such an analysis, maintenance 

tasks can be developed to prevent 

ignition sources and to minimize the 

possibilities for combustion by 

minimizing the accumulation of 

combustible materials. Such a 

procedure would involve dividing the 

airplane into physical areas, or zones, 

including actual physical boundaries 

such as wing spars, bulkheads, and 

cabin floor, and access provisions for 

the zone, and identifying which of those 

zones contain EWIS components. For 

those zones with EWIS components, 

characteristics and components of all 

systems installed in the zone would be 

listed. The EWIS in the zone would be 

described, including information on the 

full range of power levels carried in the 

zone. And the presence or possibilities 

for ignition sources or accumulation of 

combustibles would be noted. 

Combustibles are any materials that 

could cause a fire to be sustained in the 

event of an ignition source. Examples of 

combustible materials would be dust or 

lint accumulation, contaminated 

insulation blankets, and fuel or other 

combustible liquids or vapors. Wire 

contaminants are foreign materials that 

are likely to cause degradation of 

wiring. Wire contaminants can also be 

combustibles. Some commonly used 

airplane liquids, like engine oils, 

hydraulic fluids, and corrosion 

prevention compounds, might be 

readily combustible, but only in vapor 

or mist form. In that case, an assessment 

must be made of conditions that could 

exist within the zone that would convert 

the liquid to that form. Combustibles 

appearing as a result of any single 

failure must be considered. An example 

would be leaks from connection sites of 

unshrouded pipes. For the purposes of 

this new requirement, the term 

combustible does not refer to material 

that will burn when subjected to a 

continuous source of heat as occurs 

when a fire develops. Combustibles, as 

used here, will sustain a fire without a 

continuous ignition source. 

An EZAP must address: 

• Ventilation conditions in the zone 

and the density of the installations that 

would affect the presence and build-up 

of combustibles and the possibilities for 

combustion. Avionics and instruments 

located in the flightdeck and equipment 

bays, which generate heat and have 

relatively tightly packed installations, 

require cooling air flow. The air blown 

into the area for that cooling tends to 

deposit dust and lint on the equipment 

and EWIS components. 

• Liquid contamination on wiring. 

Most synthetic oils and hydraulic fluids, 

while they might not be combustibles by 

themselves, could be an aggravating 

factor for accumulation of dust or lint. 

This accumulation could then present 

fuel for fire. Moisture on wiring may 

increase the probability of arcing from 

small breaches in the insulation, which 

could cause a fire. Moisture on wires 

that contain insulation breaches can 

also lead to ‘‘arc tracking.’’ As discussed 

previously, arc tracking is a 

phenomenon in which an electrical arc 

forms a conductive carbon path across 

an insulating surface. The carbon path 

then provides a short circuit path 

through which current can flow. Short 

circuit current flow from arc tracking 

can lead to loss of multiple airplane 

systems, structural damage, and fire. 

• EWIS in close proximity to both 

primary and back-up hydraulic, 

mechanical, or electrical flight controls. 

• The type of wiring discrepancies 

that must be addressed if they are 

identified by general visual or detailed 

inspections. A listing of typical wiring 

discrepancies that should be detectable 

during EZAP-derived EWIS inspections 

is given in AC120-XXX, Section B 

‘‘Guidance for Zonal Inspections.’’

• Proper cleaning methods for EWIS 

components. 

Once information about such 

contaminants and combustibles within 

an airplane zone is collected, each 

identified possibility for combustion 

would then be addressed to determine 

whether a specific task could be 

performed to reduce that possibility. An 

example of a specific task to reduce 

build-up of combustibles on EWIS 

components is the use of temporary 

protective covers (such as plastic 

sheeting) over EWIS components in a 

zone where corrosion prevention fluids 

are being used. This would minimize 

the amount of fluid contamination of 

the EWIS components. Preventing fluid 

contamination reduces the probability 

of other contaminants, like dust and 

dirt, accumulating on the EWIS 

components. If no task can be developed 

to prevent accumulation of 

combustibles in a zone, such as the dust 

blown through the air by cooler fans, 

then tasks must be developed to 

minimize their buildup, such as 

scheduled cleaning. 

Developing an ICA to define such 

tasks would include assessing whether 

particular methods of cleaning would 

actually damage the EWIS components. 

Although regular cleaning to prevent 

potential combustible build-up would 

be the most obvious task for an EWIS 

ICA, other procedures might also be 

called for. A detailed inspection of a 

hydraulic pipe might be appropriate, for 

instance, if high-pressure mist from a 

pinhole caused by corrosion could 

accumulate on a wire bundle in a low 

ventilation area, creating a possibility 

for electrical arcing. 

Proximity of EWIS to both primary 

and back-up hydraulic, mechanical, or 

electrical flight controls within a zone 

would affect the criticality of 

inspections needed, their level of detail, 

and their frequency. Even in the absence 

of combustible material, wire arcing 

could adversely affect continued safe 

flight and landing if hydraulic pipes, 

mechanical cables, or wiring for fly-bywire controls are routed close to other 

wiring. 

The EZAP-generated ICA must be 

produced in the form of a single 

document, easily recognizable as EWIS 

ICA for that specific airplane model. 

The single document is relevant to the 

maintenance and inspection aspects of 

the ICA, and not the standard wiring 

practices manual or electrical load 

analysis, etc. 

The ICA must define applicable and 

effective tasks, and the intervals for 

performing them, to: 

• Minimize accumulation of 

combustible materials. 

• Detect wire contaminants. 

• Detect wiring discrepancies that 

may not otherwise be reliably detected 

by inspections contained in existing 

maintenance programs. 

As noted earlier, among the types of 

tasks to be developed from an EZAP are 

general visual inspections (GVI) and 

detailed inspections (DET). A GVI is 

defined as a visual examination of an 

interior or exterior area, installation, or 

assembly to detect obvious damage, 

failure, or irregularity. This level of 

inspection is made from within 

touching distance of the inspected 

58534 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

object unless otherwise specified. It is 

made under normally available lighting 

conditions such as daylight, hangar 

lighting, flashlight, or droplight and 

may require removal or opening of 

access panels or doors. It may be 

necessary to use a mirror to improve 

visual access to all exposed surfaces in 

the inspection area. Stands, ladders, or 

platforms may be required to gain 

proximity to the area being checked. It 

is expected that the area to be inspected 

is clean enough to minimize the 

possibility that accumulated dirt, grease, 

or other contaminants might hide 

unsatisfactory conditions that would 

otherwise be obvious. It is also 

expected, as an outcome of the EZAP 

applied to EWIS, that any cleaning 

considered necessary would be 

performed in accordance with 

procedures that minimize the possibility 

of the cleaning process itself 

introducing anomalies. The EZAP must 

identify guidelines to assist personnel 

performing a GVI in identifying wiring 

discrepancies and in assessing what 

effect such discrepancies, if found, 

could have on adjacent systems, 

particularly if these include wiring. As 

discussed previously, a list of typical 

wiring discrepancies that should be 

addressed is contained in proposed 

AC120–XX, Section B, ‘‘Guidance for 

Zonal Inspections.’’

A DET is an intensive examination of 

a specific item, installation, or assembly 

to detect damage, failure, or irregularity. 

Available lighting is normally 

supplemented with a direct source of 

good lighting at an intensity considered 

appropriate. Inspection aids, such as 

mirrors, magnifying lenses, or other 

means, may be necessary. Surface 

cleaning and elaborate access 

procedures may be required. A DET can 

be more than just a visual inspection. It 

may include tactile assessment to check 

a component or assembly for tightness 

and security. Such an inspection may be 

needed to ensure the continued integrity 

of installations such as bonding 

jumpers, terminal connectors, etc. 

A DET would be required when the 

developer of the EZAP determines that 

a GVI is inadequate to reliably detect 

anomalies or degradation of EWIS 

components. Any detected 

discrepancies must be corrected 

according to the operator’s approved 

maintenance procedures. It is not 

intended that the EZAP ICA identify 

how to correct detected discrepancies. 

To prevent improper modification 

and repair of existing EWIS or the 

improper installation of a new EWIS, 

modification designers and modification 

personnel must know the applicable 

standard wiring practices, EWIS 

identification requirements, and 

electrical load data for the airplane 

undergoing modification. The proposed 

Appendix H 25.5 would also require 

that the following information be 

included in ICA applicable to EWIS: 

• Standard wiring practices data. 

• Wire separation design guidelines. 

• Information to explain the 

airplane’s EWIS identification method 

required by the proposed § 25.1711. 

• Electrical load data and instructions 

for updating that data. Such information 

will help ensure that those modifying, 

repairing, or installing new EWIS will 

not perform any action that will 

adversely affect previously certified 

systems and unintentionally introduce 

potential hazards. 

Standard wiring practices are defined 

as standards developed by the specific 

airplane manufacturer or industry-wide 

standards for the repair and 

maintenance of EWIS. They include 

procedures and practices for the 

installation, repair, and removal of 

EWIS components, including 

information about wire splices, methods 

of bundle attachment, connectors and 

electrical terminal connections, 

bonding, and grounding. Although a 

standard wiring practices manual is not 

a design manual, and those designing a 

new EWIS modification for a specific 

model airplane should not use it as 

such, it does provide the designer with 

insight into the types of EWIS 

components used by the TC holder and 

the procedures recommended by the 

manufacturer for maintenance or repair 

that supports continued airworthiness 

of the components. 

EWIS separation guidelines are 

important for maintaining the safe 

operation of the airplane. Maintenance 

and repair personnel need to be aware 

of the type certificate holders’

separation requirements so they do not 

compromise separation in previously 

certified systems. In fuel tank systems, 

the separation of certain wires may be 

critical design configuration control 

items and therefore qualify as an 

airworthiness limitation. Maintenance 

personnel need to be aware of these 

guidelines and limitations because 

many times wire bundles must be 

moved or removed to perform necessary 

maintenance. They must be able to 

readily identify EWIS associated with 

systems essential to the safe operation of 

the airplane. 

Similarly, those who design and 

install new EWIS need to be aware of 

separation requirements so they can use 

the same methods to develop the 

required separation for the EWIS they 

are adding to the airplane. This would 

help to ensure both that newly added 

EWIS is adequately separated from other 

EWIS, airplane system components, and 

structure so they do not damage the 

added EWIS, and that the addition of 

the new EWIS does not invalidate 

separation for previously certified 

EWIS. 

Electrical load data and the 

instructions for updating that data are 

necessary to help ensure that future 

modifications or additions of equipment 

that consume electrical power do not 

exceed the generating capacity of the 

onboard electrical generation and 

distribution system. The existing 

§ 25.1351(a)(1) mandates that the 

required generating capacity, and the 

number and kinds of power sources, 

must be determined by an electrical 

load analysis. Typically, after an 

airplane is delivered and enters service, 

it is modified numerous times 

throughout its service life. Each 

addition or deletion of an electricalpower-consuming system changes the 

electrical load requirements. The only 

way to ensure that the capacity of the 

overall generating and distribution 

system, as well as individual electrical 

buses, is not exceeded is to have an upto-date electrical load analysis. The best 

way to ensure that an up-to-date 

electrical load analysis is maintained is 

for the type certificate holder to include 

such data in the ICA provided with the 

airplane when it is first delivered to a 

customer, along with recommended 

practices for keeping it updated as 

electrical loads are deleted and added. 

D. Part 25 Electrical System 

Harmonization Rules 

At the time the EWIS certification 

requirements contained in this proposal 

were being developed, several existing 

part 25 certification requirements were 

also undergoing revision under a 

separate joint harmonization effort with 

the European JAA. The FAA had tasked 

ARAC to develop recommendations for 

harmonized rules (64 FR 66522). The 

intent of that harmonization effort was 

to develop a common set of standards 

between 14 CFR part 25 and JAR–25. As 

mentioned previously, JAR–25 is the 

European counterpart to part 25. 

When ATSRAC began developing the 

EWIS requirements proposed in this 

NPRM, the process of developing 

harmonized proposals was essentially 

complete, although NPRMs had not yet 

been published in the Federal Register. 

So ATSRAC worked on the assumption 

that the harmonized rules would be in 

effect by the time this proposal was 

published, and used the new proposed 

harmonized part 25 as the baseline for 

the proposed EWIS requirements. This 

NPRM revises several of the harmonized 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58535 

rules to accommodate the proposed new 

EWIS requirements. 

Three of those harmonized part 25 

proposals, § 25.869(a), § 25.1353(a), 

(c)(5), (c)(6), (d), and § 25.1431(d), have 

already been adopted as final rules (69 

FR 12526). We’re revising the new 

25.1353(a) in this NPRM. Some of the 

remaining harmonized rules have been 

published as NPRMs. But several others 

have not. Therefore, to ensure 

consistency in the proposed EWIS 

requirements, those harmonized 

requirements on which ATSRAC 

recommendations are based, and which 

have not yet been published as final 

rules, are included in this NPRM. These 

are: §§ 25.899, 25.1309, 25.1310, 

25.1357, 25.1360, 25.1362, and 25.1365. 

The following discusses the proposed 

harmonization rules that must be 

adopted to support the addition of the 

proposed part 25 EWIS certification 

requirements. We believe the public 

should be aware of the background and 

full reasoning behind each change to 

these standards. 

Section 25.899 Electrical Bonding and 

Protection Against Static Electricity 

Proposed § 25.899 would contain 

requirements for electrical bonding and 

protection against static electricity. 

Current §§ 25.581, 25.954, and 25.1316 

contain requirements for protecting the 

airplane and its systems from the effects 

of lightning strikes. But the current 

requirements do not address the hazards 

that could occur because of the 

accumulation of electrostatic charge. 

Static electricity can cause electrical 

shock hazards to people, ignite fuel 

vapors, and cause electromagnetic 

interference of airplane systems. 

Proposed § 25.899 would require that 

electrical bonding and protection 

against static electricity be designed to 

minimize accumulation of electrostatic 

charge that could cause human injury 

from electric shock, ignition of 

flammable vapors, or interference with 

electrical and electronic equipment. 

Compliance could be shown by bonding 

the components properly to the airframe 

or by incorporating other acceptable 

means to dissipate static charge. 

This proposal would adopt a modified 

version of the current proposed JAR 

25X899. As currently written, the JAR 

duplicates some of the lightning 

protection requirements of JARs 25.581, 

25.985, and 25.1316. That proposed JAR 

25X899 will be revised as well, and 

those duplications removed, for the 

purposes of this harmonization. 

There is currently no § 25.899. This 

new requirement is necessary to ensure 

electrical bonding and static protection 

is fully addressed as a design standard. 

Proposed § 25.899 maintains the same 

level of safety as currently exists 

because it reflects and codifies current 

industry practices. The proposed change 

would affect airplane manufacturers by 

requiring compliance with the new 

sections of the regulations. However, 

this would have a minimal effect in 

practice because airframe manufacturers 

must comply with proposed standards 

when seeking joint FAA–JAA 

certification of their products, so there 

would be little change required from the 

standards they have been using to 

comply with the existing proposed JAR 

25X899. 

The FAA has developed advisory 

material about the requirements for 

bonding and static electricity protection 

in transport category airplanes. This 

material is contained in proposed AC 

25.899–1. 

Section 25.1309 Equipment, Systems, 

and Installations and Section 25.1310 

Power Source Capacity and 

Distribution. 

Proposed new § 25.1310 is composed 

of material now covered in § 25.1309(e) 

and (f). The current standards define an 

‘‘essential load’’ on the power supply 

and the conditions under which those 

loads must be supplied. An ‘‘essential 

load’’ is each equipment installation 

whose function is required for type 

certification or by operating rules and 

that requires a power supply. These 

paragraphs require that power sources 

must be able to supply those loads 

under a number of specified failure 

conditions. These requirements are not 

directly related to the safety and 

analysis requirements of § 25.1309. For 

that reason, and to make them more 

accessible, we propose to move them to 

a new section where they would stand 

alone. There is no current § 25.1310. 

The goal of harmonization was to 

‘‘envelope’’ to the more stringent 

requirements, which in this case are 

those contained in the current 

§ 25.1309(e) and (f). The proposal is to 

adopt as § 25.1310 the more stringent 

current § 25.1309(e) and (f). The JAA 

has agreed to adopt the same 

requirements in a new JAR 25.1310 (JAR 

NPA25df-317). Current § 25.1309(g) 

would be redesignated as § 25.1309(e). 

The proposed new § 25.1310 and JAR 

25.1310 would not be completely 

harmonized because JAR 25.1310 

contains requirements for maintenance 

of airworthiness essential services after 

failure of any two engines on a threeengined airplane and makes reference to 

two JAR Advisory Circular Joint 

materials (ACJ). But the proposed 

standard maintains the same level of 

safety as the current regulations. It is in 

line with current design practices and 

will have a minimum effect on the 

airplane operators and manufacturers. 

There is no current published FAA 

advisory material for the proposed rule. 

ARAC has recommended that the JAR 

ACJ to 25.1310(a) be adopted as FAA 

advisory material because it provides a 

useful, acceptable means of compliance. 

The FAA plans to adopt it. 

Section 25.1357 Circuit Protective 

Devices 

Section 25.1357 specifies standards 

for use, functional requirements, and 

installation requirements for electrical 

circuit protective devices. These 

standards protect the airplane’s wiring 

from electrical faults or malfunctions. 

JAR paragraph 25.1357(d) contains a 

requirement to provide sufficient spare 

fuses, formerly located in paragraph (f). 

The reason the JAA moved this text 

from paragraph (f) to (d) was to make it 

clear that the spare fuse requirement 

does not apply to fuses that are 

inaccessible in flight. We propose to 

revise § 25.1357 to move the spare fuse 

requirement of paragraph (f) to 

paragraph (d) to harmonize with the JAR 

requirement. 

The proposed standard continues to 

address the underlying safety issue by 

providing protection for the airplane’s 

electrical system from wiring faults or 

malfunctions, and by ensuring that there 

is no confusion about use of spare fuses 

in flight. It would maintain the same 

level of safety relative to the current 

regulations and is in line with current 

industry practice. 

Manufacturers and operators of 

transport category airplanes could be 

affected by the proposed change. But 

since it is in line with current industry 

practice and does not result in any 

practical changes in requirements or 

practice, such effects would not be 

significant. 

The JAR paragraph 25.1357(a) 

references advisory material, ACJ 

25.1357(a), which states that the effects 

of variations in ambient temperatures on 

either the protective device or the 

equipment it protects must not result in 

hazards. We intend to revise our current 

AC 25–1357 to include this ACJ 

material. The announcement of a new 

AC on the effects of temperature 

variations will be published in the 

Federal Register once it is available to 

the public. Comments on the proposed 

AC will be invited in that notice. 

Section 25.1360 Precautions Against 

Injury 

Also to harmonize with the standards 

of JAR, the FAA proposes to add a new 

section, § 25.1360, concerning electric 

58536 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

shock and burn protection. Currently, 

there is no part 25 requirement for 

precautions against injury from 

electrical shock and burns. Adding the 

JAR requirement to part 25 would 

increase safety. The proposed JAR 

25X1360, with its related ACJ material, 

would require that the electrical system 

and equipment must be designed to 

minimize risk of electrical shock and 

burns to the crew, passengers, and 

maintenance and servicing personnel 

during normal operations. The ACJ 

provides advisory material for high 

voltages and high temperatures and a 

means of compliance to the 

requirements. 

The proposed action is to harmonize 

the regulations by the adoption of JAR 

25X1360 and its ACJ material in its 

entirety. The proposed standard is more 

stringent for part 25 because it adds a 

new requirement and new advisory 

material. But it is in line with current 

industry practice, and therefore would 

maintain the level of safety. 

The FAA intends to publish advisory 

material that adopts the existing JAA 

advisory material. 

Section 25.1362 Electrical Supplies for 

Emergency Conditions. 

The FAA proposes to add a new 

section, § 25.1362, about electrical 

supplies for emergency conditions. 

There is no part 25 standard addressing 

electrical supplies for emergency 

conditions equivalent to JAR 25.1362. 

Partial coverage is provided by 

§§ 25.1189, 25.1195, 25.1309, and 

25.1585. 

The JAR 25.1362 and associated ACJ 

material were created to ensure that 

electrical supplies for emergency 

functions (such as fuel and hydraulic 

shut-off valves) are maintained so they 

are operable after the flight crew has 

switched off the main power sources. 

This is necessary so emergency 

procedures can be performed. Since 

there is no equivalent standard to JAR 

25.1362 in part 25, but partial coverage 

is provided by §§ 25.1189, 25.1195, 

25.1309, and 25.1585, application of 

JAA standards by U.S. manufacturers 

and aircraft operators has sometimes 

resulted in different designs for the 

powering of appropriate emergency 

functions. 

The proposed action would adopt a 

new § 25.1362 harmonized to a revised 

JAR 25.1362. The new harmonized 

standard would provide for a consistent 

application of the standards. The ACJ 

would be revised and adopted as a new 

AC by the FAA. This proposed rule and 

advisory material would provide 

flexibility by allowing either an 

appropriate airplane flight manual 

(AFM) procedure or design 

implementation to achieve compliance 

with the standards. 

This proposal addresses the 

underlying safety issue by ensuring that 

appropriate electrical power supplies 

are maintained to emergency services 

after the main power sources have been 

switched off by the flightcrew. The 

proposal increases the level of safety by 

focusing on appropriate methods to 

ensure that electrical power is provided 

for emergency functions during 

emergency landing or ditching 

conditions. It is in line with current 

industry practice. Another option 

considered was to adopt the existing 

JAR and ACJ into 14 CFR. But revising 

the JAR and the ACJ material and 

creating a new § 25.1362 and AC 25–

1362 results in a harmonized standard 

that would provide greater flexibility for 

compliance. 

Since this proposed change is in line 

with current design practices, the effect 

is considered to be minimal for aircraft 

operators and manufacturers affected by 

this change. 

There is no FAA advisory material 

available. This proposal would create a 

new AC 25–1362 harmonized with ACJ 

25X1362. 

Section 25.1365 Electrical Appliances, 

Motors, and Transformers 

The FAA proposes to add a new 

section, § 25.1365, within the 

‘‘Miscellaneous Equipment’’ section of 

subpart F, concerning design and 

installation of domestic appliances. The 

term ‘‘domestic appliance’’ is used to 

refer to those items placed on the 

airplane to provide service amenities to 

passengers. Examples of domestic 

appliances are cooktops, ovens, 

microwave ovens, coffee makers, water 

heaters, refrigerators, and toilet flush 

systems. In turn, domestic systems are 

those such as lavatories or galleys, that 

may contain one or more domestic 

appliances. IFE equipment, however, is 

not considered equipment that falls 

under the definition of a domestic 

appliance. Proposed § 25.1365 is now 

covered by § 25.1309(b), which does not 

specifically address electrical appliance 

motors and transformers. 

The proposed § 25.1365 would 

require that domestic appliances be 

designed and installed so that in the 

event of failures, the requirements of 

§§ 25.1309(b), (c), and (d) would be 

satisfied. It would further require that 

galleys and cooking appliances be such 

as to minimize risk of overheating or fire 

and that they be installed to prevent 

damage or contamination of other 

equipment from fluids or vapors 

resulting from spillage during use of the 

appliances. It would also require that 

electric motors and transformers be 

provided with a thermal protection 

device unless it can be shown that the 

circuit protective device required by 

§ 25.1357(a) would be sufficient to show 

compliance with the requirements of 

§ 25.1309(b). 

Adoption of the proposal would 

address concerns that faulty galley 

heating equipment (ovens) often cause 

smoke or fire in the cabin, and that 

circuit protection devices used in motor 

power supplies for those appliances 

have not always provided enough 

protection against failures. 

The proposed standard would be an 

improvement over current safety 

practices because current part 25 does 

not specifically address electrical 

appliance motors and transformers. The 

FAA considers that a new § 25.1365 

specifically addressing domestic 

appliances is the most appropriate way 

to increase the level of safety. The JAA 

is adopting the same requirement as JAR 

25.1365. 

Aircraft operators and manufacturers, 

together with suppliers of galley and 

electrical equipment, could be affected 

by this change. Since newly certificated 

aircraft may have to be supplied with 

newly designed galley equipment, 

airplane operators may elect to 

introduce the same new equipment into 

their existing fleet to maintain fleet 

commonality. 

A new AC 25–1365 will be developed 

and an announcement of its availability 

for comment will be published in the 

Federal Register. 

E. Proposed Changes to Part 91, 121, 

125, and 129 Operating Rules for Fuel 

Tank Systems and EWIS and Other 

Existing Continued-AirworthinessRelated Rules 

As discussed earlier, the proposed 

alignment of the ICA requirements for 

EWIS and the fuel tank system is a 

result of an FAA review and 

realignment of the Aging Airplane 

Program. We have determined that 

certain compliance dates in the existing 

rules and pending proposals could be 

better aligned. Other changes to the 

rules and proposals are necessary to 

increase the cost-effectiveness of these 

rules and proposals. Therefore, we have 

decided to revise those requirements 

and proposals and to align the 

compliance schedules as nearly as 

possible. This effort also includes a 

proposal to create new subparts in parts 

25 (subpart I, discussed earlier), 91, 121, 

125, and 129. These new subparts 

would contain certain rules in this 

proposal and other existing and future 

rules that pertain to the support of 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58537 

continued airworthiness, in particular, 

rules addressing aging airplane issues. 

The FAA believes that inclusion of 

certain rules under the new subparts 

will improve the reader’s ability to 

readily identify rules pertinent to 

continued airworthiness. 

The table below illustrates what 

proposed and existing requirements will 

be included in these new subparts. Each 

of these new subparts is titled 

‘‘Continued Airworthiness.’’ The 

proposed new subparts consist of 

relocated, revised, and new regulations 

pertaining to continued airworthiness of 

the airplane. Unless we say otherwise, 

our purpose in moving requirements to 

these new subparts is to ensure easy 

visibility of those requirements 

applicable to the continued 

airworthiness of the airplane. We do not 

intend to change their legal effect in any 

other way. 

NEW CONTINUED AIRWORTHINESS SUBPARTS FOR PARTS 25, 91, 121, 125, AND 129 

Part 25 new/relocated rules 

within proposed 

Subpart I 

Part 91 new/relocated 

rules within proposed 

Subpart L 

Part 121 new/relocated 

rules within proposed 

Subpart Y 

Part 125 new/relocated 

rules within proposed 

Subpart M 

Part 129 new/relocated 

rules within proposed 

Subpart B 

§ 25.1801—Purpose and 

definition (new).

§ 91.1501—Purpose and 

definition (new).

§ 121.901—Purpose and 

definition (new).

§ 125.501—Purpose and 

definition (new).

(Proposed Subpart A 

would contain a revised 

§ 129.1 and all of existing part 129 except 

§§ 129.16, 129.32, and 

129.33). 

§ 25.1803—Reserved ........ § 91.1503—Reserved ........ § 121.903—Reserved ........ § 125.503—Reserved ........ § 129.101—Purpose and 

definition (new). 

§ 25.1805—Electrical wiring interconnection systems (EWIS) maintenance program (new).§ 91.1505—Repairs assessment for pressurized fuselages (formerly 

§ 91.410(a)).

§ 121.905—Aging airplane 

inspections and records 

reviews (formerly 

§ 121.368).

§ 125.505—Repairs assessment for pressurized fuselages (formerly 

§ 125.248(a)).

§ 129.103—Reserved. 

§ 91.1507—Fuel tank system maintenance program (new) (replaces requirements of 

§ 91.410(b)).

§ 121.907—Repairs assessment for pressurized fuselages (formerly 

§ 121.370(a)).

§ 125.507—Fuel tank system inspection program 

(new) (replaces requirements of § 125.248(b)).

§ 129.105—Aging airplane 

inspections and records 

reviews for U.S.-registered multiengine aircraft (formerly § 129.33). 

§ 121.909—Supplemental 

inspections (formerly 

§ 121.370a).

........................................... § 129.107—Repairs assessment for pressurized fuselages (formerly 

§ 129.32(a)). 

§ 121.911—Electrical wiring interconnection systems (EWIS) maintenance program (new)............................................ § 129.109—Supplemental 

inspections for U.S.-registered aircraft (formerly 

§ 129.16). 

§ 121.913—Fuel tank system maintenance program (new) (replaces requirements of 

§ 121.370(b)).

........................................... § 129.111—Electrical wiring interconnection systems (EWIS) maintenance program (new). 

§ 129.113—Fuel tank system maintenance program (new) (replaces requirements of 

§ 129.32(b)). 

As previously stated, other future 

rules pertaining to the support of 

continued airworthiness would also be 

contained in these proposed new 

subparts. Several such proposals are 

currently under development. But 

because of uncertainties in the timing of 

adoption of final rules, it is not always 

possible to estimate which of the 

proposals currently being developed 

will reach final rule stage first. In order 

to ensure that the proposed new 

subparts for continued airworthiness 

have been established in 14 CFR to 

contain whichever of several new 

continuing airworthiness proposals is 

adopted, the FAA has decided to use a 

‘‘building block’’ strategy to establish 

the new subparts. 

Until the new subparts have been 

established in 14 CFR as part of a final 

rule, each of several proposals 

containing new continued airworthiness 

rules will include language needed to 

set up the proposed subparts. Once one 

of those proposals becomes final, and 

the new continued airworthiness 

subparts are thus established, then other 

continued-airworthiness-related 

proposals will delete any language 

relating to setting up the new subparts. 

They will retain only the rule language 

pertinent to that specific proposal. 

A result of this ‘‘building block’’

strategy of proposed rulemaking is the 

possibility that two or more NPRMs may 

appear in the Federal Register 

proposing the same new continued 

airworthiness subparts for 14 CFR at the 

same time. The language setting up the 

operational rule subparts will be the 

same in each rulemaking. But the 

language setting up subpart I of part 25 

will vary slightly because of differences 

in the applicability of each rule. The 

proposed applicability in proposed 

§§ 25.1 and 25.1801 will be correct for 

each NPRM. Otherwise, commenters 

addressing each NPRM might be 

confused by an inconsistency between 

the applicability of the subpart and the 

applicability of the individual proposed 

rule sections. And until final decisions 

are made on the content of each later 

NPRM, it would be inappropriate and 

potentially misleading for this NPRM to 

propose that content. 

If this NPRM, which has the 

narrowest applicability of several 

58538 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

proposals in development, is adopted 

first, then as each of the other final rules 

is adopted, §§ 25.1 and 25.1801 would 

be amended to expand the applicability 

to cover what’s added in the new rule. 

For instance, one proposal might cover 

holders of existing supplemental type 

certificates (STCs), so § 25.1 and 

§ 25.1801, as adopted in this NPRM, 

would be amended to reference those 

holders. If a proposal applying to them 

is adopted first, then when this proposal 

is adopted, we can remove the proposed 

§ 25.1 and § 25.1801 from the final rule, 

because those provisions would already 

be included in the previously adopted 

rule. 

When all the proposals currently 

under development are issued as final 

rules, § 25.1 and § 25.1801 will be as 

broad as they need to be to cover all of 

the rules. If any of those rules currently 

under development is not issued, then 

those sections would be only as broad 

as is needed for the rules that are 

adopted. Because the language in each 

NPRM will have been appropriate for 

that specific NPRM, the public will have 

been given adequate notice for all of the 

provisions in the final versions of those 

sections. 

Paragraph (a) of the ‘‘Purpose and 

definition’’ sections of part 91, subpart 

L, part 121, subpart Y, part 125, subpart 

M, and part 129, subpart B generally 

describes the applicability of these 

subparts and states that the purpose of 

the various sections in these subparts is 

to prescribe requirements to support 

continued airworthiness. While most of 

the requirements of these subparts 

would address the need for improved 

maintenance, these subparts may also 

include requirements to modify 

airplanes or take other actions that we 

consider necessary for continued 

airworthiness. 

Historically, the only means used by 

the FAA to impose these types of 

requirements was the AD process. 

Under part 39, ADs address unsafe 

conditions that we determine are likely 

to exist or develop on other products of 

the same type design. In recent years, 

the FAA has identified a number of 

fleet-wide continued airworthiness 

issues, particularly relating to aging 

airplanes, that are not limited to 

particular type designs. Under these 

circumstances, general rulemaking may 

be a more efficient and appropriate way 

to address these types of problems than 

ADs. These new subparts provide 

locations for these types of 

requirements. 

Paragraph (b) of these sections 

provides a definition of the term ‘‘FAA 

Oversight Office.’’ As stated in the 

discussion of proposed § 25.1801, the 

FAA Oversight Office is the aircraft 

certification office or office of the 

Transport Airplane Directorate with 

oversight responsibility for the relevant 

type certificate or supplemental type 

certificate, as determined by the 

Administrator. As discussed previously, 

the primary means for operators to 

comply with the requirements of these 

subparts would be by implementing 

programs or taking other actions 

developed by the TC and STC holders 

under proposed subpart I of part 25. In 

each case, to ensure compliance with 

the relevant subpart I rule, the TC and 

STC holder deliverables must be 

approved by the FAA Oversight Office. 

Because we expect this will be a 

standard approach to compliance with 

the requirements of these subparts, we 

are including this definition in these 

sections to avoid having to repeat it in 

each section within these subparts. 

Proposed Changes to Parts 121 (Subpart 

Y) and 129 (Subpart B)—EWIS 

Maintenance Programs 

Paragraph (a) states that these sections 

would apply to transport category, 

turbine powered airplanes with a 

maximum type certificated passenger 

capacity of 30 or more, or having a 

maximum payload capacity of 7500 

pounds or more resulting from the 

original certification of the airplane or 

later increase in capacity. This 

applicability provision coincides with 

that of proposed § 25.1805 and is 

intended to ensure that, if a TC or STC 

holder is required to develop EWIS ICA 

for an airplane design, the operator of 

that airplane is required to implement 

them. As discussed previously, certain 

vintage airplanes would be excluded 

from these requirements. This 

applicability would result in the 

coverage of airplanes where the safety 

benefits and the public interest are the 

greatest. This action would affect 

approximately 7,000 U.S. registered 

airplanes in parts 121 and 129 

operations. 

Paragraph (b) of these sections would 

add requirements for maintenance 

programs for EWIS for part 121 

certificate holders and part 129 foreign 

air carriers and foreign operators of U.S. 

registered aircraft. Paragraph (c) would 

require them to develop a maintenance 

program for EWIS based on ICA for 

EWIS prepared by TC or STC holders. 

As discussed previously, the changes to 

part 25 would require both holders of 

existing TCs and future applicants for 

TCs and design changes to provide 

affected operators with these ICA. 

The compliance date for adopting 

these maintenance program changes is 

December 16, 2008. Assuming this 

proposal is adopted by mid-2006, this 

proposal would give operators 30 

months after the effective date of the 

final rule to make these changes. 

Because the proposed compliance date 

in § 25.1805 for holders of existing TCs 

is December 16, 2007, operators would 

have one year after that date to comply 

with this section. 

For pending and future design 

changes approved after December 16, 

2008, operators incorporating such a 

change would have to revise their 

maintenance program to incorporate 

EWIS ICA before returning the airplane 

to service. 

Paragraph (d) would require that 

operators keep their EWIS maintenance 

programs current as they modify their 

airplanes. As discussed earlier, the 

proposed changes to part 25 would 

ensure that, for modifications affecting 

EWIS, the applicant for the design 

approval will provide necessary 

revisions to the ICA. This paragraph 

would ensure that operators installing 

those modifications on their airplanes 

would revise their maintenance program 

to incorporate these ICA revisions. 

Paragraph (e) would require that the 

maintenance program changes required 

by these sections be approved by the 

operator’s principal inspector. We are in 

the process of developing guidance for 

principal inspectors to ensure that their 

reviews are consistent and focused on 

the key implementation issues. 

Assuming this proposal is adopted by 

mid-2006, this proposal would give the 

affected air carriers and operators 30 

months after the effective date of the 

final rule to incorporate those ICA for 

EWIS into their manuals. Thereafter, 

inspections and maintenance of EWIS 

and fuel tank systems must be carried 

out at the intervals specified in the 

operator’s maintenance program. 

Many problems caused by inadequate 

wire maintenance practices have been 

discussed previously in this document. 

Much effort has been devoted to 

identifying the maintenance practices 

that could either prevent such incidents 

and accidents from occurring again or 

mitigate their causes. The purpose of 

this new section is to ensure that 

enhanced EWIS and fuel tank system 

maintenance techniques are put into 

practice on a continuing basis in 

airplane maintenance programs. Proper 

use of existing methods, techniques, and 

practices, combined with knowledge 

gained through ATSRAC activities, 

service history, research, and analysis, 

will result in improved wire system 

safety. 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58539 

Proposed Changes to Parts 91 (Subpart 

L), 121 (Subpart Y), 125 (Subpart M), 

and 129 (Subpart B)—Fuel Tank 

Maintenance Programs 

These proposals would require part 

91 and part 125 operators, part 121 

certificate holders, and part 129 foreign 

air carriers and foreign persons 

operating U.S. registered airplanes to 

incorporate fuel tank system ICA into 

their inspection or maintenance 

programs. As discussed earlier, one of 

the main objectives of this rulemaking is 

to align the operational requirements for 

fuel tank maintenance programs with 

the proposed requirements for EWIS 

maintenance programs. To that end, 

except as discussed below, the current 

fuel tank requirements would be revised 

to be parallel with the EWIS operational 

requirements discussed earlier. We 

provide the justification for these 

parallel provisions in the earlier 

discussion of the EWIS proposal, and it 

is not repeated here. 

Part 91 and part 125 operators are 

required to have an inspection program. 

Part 121 air carriers are required to have 

an inspection program and a program 

covering maintenance, preventive 

maintenance, and alterations for their 

airplanes. As provided by § 43.13(a), 

operators may choose to follow the 

maintenance instructions developed by 

the TC holder or they may develop their 

own maintenance instructions, as long 

as they are acceptable to the 

Administrator. But they must comply 

with the airworthiness limitations 

section of the ICA. Foreign persons or 

foreign air carriers operating a U.S. 

registered aircraft are required to have a 

maintenance program approved by the 

Administrator. 

Because of the Fuel Tank Safety Rule, 

the above-listed operators and air 

carriers must now incorporate 

instructions for inspection and 

maintenance of the fuel tank system into 

their inspection or maintenance 

programs. These instructions must 

address the actual configuration of the 

fuel tank systems and they must be 

approved by the FAA aircraft 

certification office (ACO) having 

cognizance over the TC for the affected 

airplane. The compliance time for 

incorporation of the fuel tank system 

instructions for inspection and 

maintenance into the inspection or 

maintenance programs was changed on 

July 30, 2004 to December 16, 2008. The 

reasons for that change were briefly 

outlined earlier in this document in the 

discussions about rule alignment. This 

proposal would change the current 

requirements for the instructions for 

fuel tank inspections and maintenance 

that must be incorporated into 

operators’ and air carriers’ inspection or 

maintenance programs in the following 

ways: 

• The FAA Oversight Office must 

approve ICA for the fuel tank system, 

and the operator’s principal inspector or 

Flight Standards District Office (FSDO) 

must approve the operator’s program 

changes incorporating those ICA. 

The current rule requires the ACO to 

approve individual operator fuel tank 

maintenance programs. The FAA 

recognizes that, as long as the ICA are 

approved by the ACO, ACO approval of 

the operators’ maintenance program 

changes incorporating those ICA 

imposes unnecessary burdens on both 

the operators and the ACOs. With this 

proposed change, principal inspectors 

or the cognizant FSDO would be 

responsible for reviewing and approving 

program changes to address fuel tank 

safety. But, as stated, the ICA on which 

the operator’s program is based must be 

approved by the FAA Oversight Office. 

• The instructions for fuel tank 

maintenance and inspection developed 

by the TC holders will be referenced as 

the ‘‘fuel tank ICA.’’ The previous rule 

language referred to ‘‘instructions for 

maintenance and inspection of the fuel 

tank system,’’ even though it was widely 

understood throughout the industry that 

these instructions would be contained 

in the ICA. Because these requirements 

are now being aligned with the 

proposed requirements for EWIS to 

facilitate operator compliance, and the 

EWIS requirements refer to ICA as the 

place where EWIS maintenance 

instructions may be found, the FAA 

believes that using a consistent term to 

refer to the required information in both 

rules would clarify the common intent 

of the requirements and make them 

easier for operators to understand. 

• The fuel tank ICA must address the 

fuel tank system as defined by the 

airplane’s TC, any supplemental TCs, 

and any field approved incorporated 

auxiliary fuel tank systems. The current 

requirements mandate that the ICA must 

be developed for the ‘‘actual 

configuration of the fuel tank systems of 

each affected airplane.’’ That wording, 

however, proved to be unclear to many 

in the industry. The changed language 

is proposed to clarify the original intent. 

To further clarify what STCs should 

be included, the FAA has created a list 

by airplane model of STCs affected by 

this proposed rule. That list has been 

placed in the docket for this rulemaking 

and may also be viewed at http:// 

qps.airweb.faa.gov/QuickPlace/ 

sfar88ops/Main.nsf. 

The holders of those STCs, as well as 

the TC holders for the affected airplane 

models, must develop the ICA as 

required by SFAR 88. We are also 

proposing to make it clear that the 

operator is required to develop the 

maintenance instructions for fieldapproved auxiliary fuel tanks. Because 

there is no other design approval holder 

for these tanks, there is no other person 

in a better position to develop these 

instructions. As with the original 

requirements of the Fuel Tank Safety 

Rule, we expect that operators who do 

not have the expertise to develop these 

instructions will be able to contract with 

experts to help them. 

The proposed operational rules also 

make it clear that they apply to ICA 

developed under SFAR 88, to ICA 

developed for new or amended 

certificates under § 25.1529 Amendment 

102, and to any later revisions to those 

ICA. These proposed operational rules 

would require that operators revise their 

maintenance and inspection programs 

to incorporate ICA changes associated 

with alterations affecting the fuel tank 

ICA. This is necessary because an 

alteration may invalidate existing fuel 

tank system ICA, and compromise the 

safety objectives of the proposed rules. 

H. Advisory Circulars 

As indicated in the discussion of 

ATSRAC recommendations that 

appeared earlier in this document, the 

advisory committee has produced four 

guidance documents as products of the 

working group activities that have 

contributed to this proposed rule. Those 

guidance documents are on 

maintenance, training, and standard 

wiring practices manuals, as well as on 

the proposed new subpart H. We have 

used these documents as the basis for 

developing the accompanying advisory 

circulars. Notices of availability for 

comment for the training, standard 

wiring practices, and subpart H ACs are 

published elsewhere in the Federal 

Register. Notice of availability for the 

maintenance AC will be published as 

soon as possible. 

Advisory materials for the design 

approval holder (DAH) requirements of 

subpart I and for the part 25 electrical 

system harmonization rules are also 

made available in notices of availability 

for comment published elsewhere in the 

Federal Register. 

In addition, guidance material 

entitled ‘‘Process for Developing 

Instructions for Maintenance and 

Inspection of Fuel Tank Systems 

Required by SFAR 88’’ was made 

available as a policy statement on May 

28, 2004 at http://www.airweb.faa.gov/ 

rgl. Comments have been received and 

are being reviewed. Advisory Circular 

25.981–1B, ‘‘Fuel Tank Ignition Source 

58540 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

Prevention Guidelines,’’ gives guidance 

on showing compliance to certification 

requirements for prevention of ignition 

sources within the fuel tanks of 

transport category airplanes. It also 

gives guidance on developing ICA for 

fuel tank systems. It can be found in the 

docket for this NPRM. 

VI. Regulatory Analyses and Notices 

Authority for This Rulemaking 

The FAA’s authority to issue rules 

regarding aviation safety is found in 

Title 49 of the United States Code. 

Subtitle I, section 106 describes the 

authority of the FAA Administrator. 

Subtitle VII, Aviation Programs, 

describes in more detail the scope of the 

agency’s authority. This rulemaking is 

promulgated under the authority 

described in subtitle VII, part A, subpart 

III, section 44701, ‘‘General 

requirements.’’ Under that section, the 

FAA is charged with promoting safe 

flight of civil aircraft in air commerce by 

prescribing—

• Minimum standards required in the 

interest of safety for the design and 

performance of aircraft; 

• Regulations and minimum 

standards in the interest of safety for 

inspecting, servicing, and overhauling 

aircraft; and 

• Regulations for other practices, 

methods, and procedures the 

Administrator finds necessary for safety 

in air commerce. 

This regulation is within the scope of 

that authority because it prescribes—

• New safety standards for the design 

of transport category airplanes, and 

• New requirements that are 

necessary for safety for the design, 

production, operation, and maintenance 

of those airplanes, and for other 

practices, methods and procedures 

relating to those airplanes. 

Paperwork Reduction Act 

This proposal contains the following 

new information collection 

requirements. As required by the 

Paperwork Reduction Act of 1995 (44 

U.S.C. 3507(d)), the Department of 

Transportation has submitted the 

information requirements associated 

with this proposal to the Office of 

Management and Budget for its review. 

Title: Enhanced Airworthiness 

Program for Airplane Systems/Fuel 

Tank Safety (EAPAS/FTS). 

Summary: This proposal consists of 

regulatory changes applying to wiring 

systems and fuel tank systems in 

transport category airplanes. Some of 

those changes would require new 

information collection. The proposed 

new information requirements and the 

persons who would be required to 

provide that information are described 

below. 

Required Information, Use, and 

Respondents 

(1) Proposed § 25.1711 would require 

that electrical wiring interconnection 

systems (EWIS) components be labeled 

to identify the component, its function, 

and its design limitations, if any. If the 

EWIS is part of a system that requires 

redundancy, the labeling would also 

include component part number, 

function, and separation requirements 

for bundles. This specificity of labeling 

would be required to ensure that 

maintenance can be handled properly 

and with the appropriate caution for 

maintaining the safety features the 

wiring system was designed to provide. 

The information marked on the wires 

would be used by maintenance 

personnel for repair and cautionary 

tasks, and by modifiers so that original 

safety features are retained during 

modifications. The future airplane 

manufacturer and anyone who modifies 

the airplane would bear the burden of 

this labeling requirement. 

(2) Proposed § 25.1805 would require 

that existing TC holders develop 

Instructions for Continued 

Airworthiness (ICA) for EWIS. 

Applicants for approval of design 

changes would be required to develop 

revisions to those EWIS ICA for any 

modifications to the airplane that might 

affect them. Proposed § 25.1739 and 

Appendix H would apply the 

requirement for EWIS ICA to future 

applicants for TCs. EWIS ICA would be 

used by operators to prepare their 

maintenance programs. This 

requirement would be necessary to 

ensure that wiring is properly 

maintained and inspected to avoid 

problems that could affect safety. 

(3) Proposed subpart I would also 

require that TC holders submit to the 

FAA a plan detailing how they intend 

to comply with its requirements. This 

information would be used by the FAA 

to assist the TC holder in complying 

with requirements. The compliance 

plan would be necessary to ensure that 

TC holders fully understand the 

requirements, correct any deficiencies 

in planning in a timely manner, and are 

able to provide the information needed 

by the operators for the operators’

timely compliance with the rule. 

(4) Anyone operating an airplane 

under part 121 would be required to 

revise their existing maintenance 

program to incorporate the maintenance 

and inspection tasks for EWIS contained 

in the EWIS ICA required by subpart I. 

The information incorporated into the 

maintenance program would be used by 

maintenance personnel to maintain the 

integrity of airplane wiring systems. 

This requirement would be necessary to 

ensure that wiring is properly 

maintained and inspected to avoid 

problems that could affect safety. 

(5) As a result of the revised 

maintenance programs that would be 

required for airplanes operating under 

part 121, maintenance personnel will be 

performing inspections and 

maintenance procedures to address 

safety issues specific to wiring systems. 

Although this NPRM does not 

specifically require new training, 

existing § 121.375 requires that 

certificate holders or persons 

performing maintenance have a training 

program to ensure that persons 

determining the adequacy of such work 

(including inspectors) are fully 

informed about the procedures and 

techniques involved and are competent 

to perform them. To comply with this 

requirement in relation to proposals for 

revised maintenance programs for EWIS 

included in this NPRM, certificate 

holders would be required to develop 

any additional training program needed 

to ensure that the appropriate personnel 

are adequately prepared to carry out the 

revised maintenance programs. 

(6) The proposed revision to part 25 

Appendix H would require that future 

manufacturers include acceptable EWIS 

practices in their ICA, presented in a 

standard format. This information 

would be used by maintenance 

personnel for wiring maintenance and 

repairs. The requirement is necessary 

because information about cautionary 

tasks during maintenance that can 

prevent situations that could 

compromise safety need to be available 

to maintenance personnel. Standard 

wiring practices manuals, in which this 

information is presented, often differ 

from manufacturer to manufacturer and 

so are difficult for maintenance 

personnel to find specific information 

in. The requirement for a standard 

format is meant to correct this. Because 

of this proposal, manufacturers would 

change their Standard Wiring Practices 

Manuals (SWPM). 

Annual Burden Estimate 

To provide estimates for the burden 

associated with this NPRM, the FAA 

developed categories corresponding to 

information collection impacts of 

requirements contained in the proposal. 

The summary table below contains the 

impacted entities, average annual hours 

and hardware costs, and the 

corresponding average annual cost. 

Details of the estimates are in the 

paragraphs below. 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58541 

Entities impacted Proposed requirement Hardware cost Average 

annual hours 

Average 

annual cost 

Airplane Manufacturers ............................. Wire identification (30 seconds per label) .................................... 12,046 $430,524 

Airplane Manufacturers ............................. Label ......................................................... 5 cents per label ....... ........................ 72,275 

Airplane Modifiers ..................................... Wire identification (30 seconds per label) .................................... 18,417 658,224 

Airplane Modifiers ..................................... Label ......................................................... 5 cents per label ....... ........................ 110,500 

Existing TC Holders .................................. Develop ICA ............................................. .................................... 15,743 868,699 

Future TC Applicants ................................ Develop ICA ............................................. .................................... 3,578 197,434 

Future STC Applicants .............................. Develop ICA ............................................. .................................... 57,828 3,190,949 

Airplane Manufacturers ............................. Revise SWPM .......................................... .................................... 1,035 57,111 

Airplane Manufacturers ............................. Develop Compliance Plan ........................ .................................... 132 7,284 

Airplane Operators .................................... Revise Maintenance Program .................. .................................... 2,744 151,414 

Airplane Operators .................................... Develop Training Program ....................... .................................... 2,376 131,108 

Total ................................................... ................................................................... .................................... 113,899 5,875,522 

Proposed § 25.1711 would affect 

airplane manufacturers by requiring 

additional labeling. Over the 25-year 

period of analysis, manufacturers would 

label on average 413 airplanes yearly. 

The FAA estimates that an additional 

3,500 labels might be added to wires in 

each part 25 airplane, for 1,445,500 

labels annually. The additional 

identification requirement would take 

roughly 30 seconds, requiring 

approximately 12,046 annual hours. 

Using the fully burdened hourly cost of 

a mechanic ($35.74), the average annual 

hourly burden for the wire 

identification requirement on 

manufacturers is $430,524. 

The estimated cost resulting from 

information collection from TC holders 

also considers the additional cost of 

labels. The additional manufacturer 

identification requirements would 

require roughly 1,445,500 labels 

annually. Industry representatives 

provided the FAA with cost estimates 

for each label of approximately 5 cents. 

The estimated annual corresponding 

cost is $72,275. 

Section 25.1711 would also affect 

airplane modifiers when electrical 

wiring supplemental type certificates 

(STC) are installed on airplanes. The 

FAA estimates there would be an 

additional 200 labels added each time 

an affected STC is installed on an 

airplane. Using 170 as the average 

annual affected number of STCs, and 65 

as the number of installations per STC, 

the corresponding total annual number 

of labels for STCs is 2,210,000. The 

identification requirement would take 

about 30 seconds for each additional 

label, requiring an annual burden of 

roughly 18,417 hours. Using the fully 

burdened hourly cost of a mechanic 

($35.74), the annual burden on airplane 

modifiers for the wire identification 

requirement is $658,224. 

Estimated costs resulting from 

information collection from STC 

applicants consider the additional cost 

of labels. The additional STC 

identification requirements would 

require roughly 2,210,000 labels 

annually. With the cost of each label 

approximately 5 cents, the estimated 

average annual corresponding cost is 

$110,500. 

The proposal would require that 

existing TC holders develop ICA for 

EWIS. Over the period of analysis, the 

FAA estimates the proposal would 

require 15,743 average annual 

engineering hours, resulting in an 

average annual cost of $868,699 (using 

the fully burdened hourly rate of $55.18 

for an engineer). 

Proposed §25.1805 would also require 

future TC applicants to develop ICA for 

EWIS. The FAA estimates roughly .5 

part 25 TCs yearly, with average annual 

estimated labor hours to perform the 

analysis of 3,578. This would result in 

average annual costs of $197,434. 

The proposal would require future 

applicants for STCs to develop ICA for 

EWIS as well. Over the period of 

analysis, the FAA estimates it would 

take 948 annual STC applicants 61 

hours to perform the analysis. With 

engineering costs of $55.18 per hour, the 

average annual burden would be 

$3,190,949. 

Because of this proposal, 

manufacturers would change their 

Standard Wiring Practices Manual 

(SWPM). The FAA calculates 1,035 as 

the average annual hours required to 

update manuals, resulting in an average 

annual burden of roughly $57,111. 

Manufacturers would present a plan 

for approval describing how they intend 

to comply with the requirements. The 

FAA believes the data contained in this 

plan would be submitted electronically 

with no cost to submit the plan. We 

estimate 60 labor hours (per airplane 

model) to develop a plan and submit 

data to the FAA. We estimate 3,300 

hours for roughly 55 models. The 

average annual hours are 132, with 

corresponding average annual costs of 

$7,284 (using the fully burdened hourly 

cost of $55.18). 

Operators would be required to revise 

their existing maintenance program to 

incorporate the maintenance and 

inspection tasks for EWIS contained in 

the EWIS ICA. Over the period of 

analysis, the FAA estimates 68,607 total 

hours, or 2,744 average annual hours 

required to revise existing maintenance 

programs. Using the fully burdened 

labor cost for an engineer, the average 

annual planning cost would be 

$151,414. 

The estimated cost to develop training 

considers the industry’s standard 

training factor of 200 hours per one hour 

of prepared training material. 600 hours 

is the estimated training development 

time for the 3-hour training course for 

each operator. When combined with 99 

operators, the total hours would be 

59,400 or 2,376 annually. Combined 

with the burdened hourly cost of 

$55.18, the average annual cost for 

training development would be 

$131,108. 

The agency is soliciting comments to 

(1) evaluate whether the proposed 

collection of information is necessary 

for the proper performance of the 

functions of the agency, including 

whether the information will have 

practical utility; (2) evaluate the 

accuracy of the agency’s estimate of the 

burden; (3) enhance the quality, utility, 

and clarity of the information to be 

collected; and (4) minimize the burden 

of the collection of information on those 

who are to respond, including through 

the use of appropriate automated, 

electronic, mechanical, or other 

technological collection techniques or 

other forms of information technology 

(for example, permitting electronic 

submission of responses). 

Individuals and organizations may 

submit comments on the information 

collection requirement by December 5, 

2005, and should direct them to the 

address listed in the ADDRESSES section 

of this document. 

According to the regulations 

implementing the Paperwork Reduction 

58542 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

Act of 1995, (5 CFR Part 

1320.8(b)(2)(vi)), an agency may not 

conduct or sponsor, and a person is not 

required to respond to, a collection of 

information unless it displays a 

currently valid OMB control number. 

The OMB control number for this 

information collection will be published 

in the Federal Register after it is 

approved by the Office of Management 

and Budget. 

International Compatibility 

In keeping with U.S. obligations 

under the Convention on International 

Civil Aviation, it is FAA policy to 

comply with International Civil 

Aviation Organization (ICAO) Standards 

and Recommended Practices to the 

maximum extent practicable. The FAA 

has determined that there are no ICAO 

Standards and Recommended Practices 

that correspond to these proposed 

regulations. 

Regulatory Evaluation Summary 

This portion of the preamble 

summarizes the FAA’s analysis of the 

economic impacts of this NPRM. It also 

includes summaries of the initial 

regulatory flexibility determination. We 

suggest readers seeking greater detail 

read the full regulatory evaluation, a 

copy of which we have placed in the 

docket for this rulemaking. 

Changes to Federal regulations must 

undergo several economic analyses. 

First, Executive Order 12866 directs that 

each Federal agency shall propose or 

adopt a regulation only upon a reasoned 

determination that the benefits of the 

intended regulation justify its costs. 

Second, the Regulatory Flexibility Act 

of 1980 requires agencies to analyze the 

economic impact of regulatory changes 

on small entities. Third, the Trade 

Agreements Act (19 U.S.C. 2531–2533) 

prohibits agencies from setting 

standards that create unnecessary 

obstacles to the foreign commerce of the 

United States. In developing U.S. 

standards, this Trade Act requires 

agencies to consider international 

standards and, where appropriate, to be 

the basis of U.S. standards. Fourth, the 

Unfunded Mandates Reform Act of 1995 

(Pub. L. 104–4) requires agencies to 

prepare a written assessment of the 

costs, benefits, and other effects of 

proposed or final rules that include a 

Federal mandate likely to result in the 

expenditure by State, local, or tribal 

governments, in the aggregate, or by the 

private sector, of $100 million or more 

annually (adjusted for inflation). 

In conducting these analyses, FAA 

has determined this proposal: Has 

benefits that justify its costs, is not an 

economically ‘‘significant regulatory 

action’’ as defined in section 3(f) of 

Executive Order 12866, and is 

‘‘significant’’ as defined in DOT’s 

Regulatory Policies and Procedures; 

would not have a significant economic 

impact on a substantial number of small 

entities; would not have an effect on 

international trade; and would not 

impose an unfunded mandate on state, 

local, or tribal governments, or on the 

private sector. These analyses, available 

in the docket, are summarized below. 

Total Costs and Benefits of This 

Rulemaking 

The estimated cost of this NPRM is 

$474.4 million ($209.2 million present 

value) over 25 years. The total estimated 

benefits are $755.3 million ($340.7 

million present value) over 25 years. 

Who Is Potentially Affected by This 

Rulemaking? 

• Manufacturers of part 25 airplanes. 

• Operators of large transport 

category airplanes operating under FAR 

Parts 121 & 129. 

• Applicants for amended type 

certificates and supplemental type 

certificates. 

Cost Assumptions and Sources of 

Information 

Discount rate—7% 

Period of analysis—25 Years, 2005 

through 2029 

Burdened labor rate (as shown in key 

assumptions & labor rates in 

regulatory evaluation)—

• Aerospace engineers—$55.18/hour 

• Maintenance personnel—$35.74/ 

hour 

Value of fatality avoided—$3.0 million 

(Source: ‘‘Revised Departmental 

Guidance, Treatment of Value of Life 

and Injuries in Preparing Economic 

Evaluations,’’ Office of the Secretary 

of Transportation Memorandum’’, 

January 29, 2002) 

Fleet—FAA Flight Standards (SPAS 

Database) 

Fleet Growth (3.82% per year) & 

Passenger Occupancy Rates 

(75%)—FAA Aerospace Forecasts 

Years 2003–2014 

Failures, Incidents and Accidents—

The National Aviation Safety Data 

Analysis Center 

Aircraft Value—Economic Values for 

Evaluation of Federal Aviation 

Administration Investment and 

Regulatory Programs 1998 

Articles Referenced 

Wright, T.P. ‘‘American Methods of 

Aircraft Production,’’ 1939. 

Wojcik, Leonard A., ‘‘Models To 

Understand Airline and Air Traffic 

Management Authority DecisionMaking Interactions in Schedule 

Disruptions: From Simple Games to 

Agent-Based Models,’’ Handbook of 

Airline Strategy, 1992. 

Irrgang, M.E., ‘‘Airline Irregular 

Operations,’’ Handbook of Airline 

Economics, 1995. 

Alternatives We Considered 

Alternative 1—Require operators to 

clean & inspect each airplane every Ccheck or every three years, causing an 

additional $192.5 million ($79.9 million 

present value) in cleaning and 

inspection costs, and an additional 

$104.0 million ($38.6 million present 

value) in downtime. 

This option would result in additional 

costs of $296.5 million ($118.5 million 

present value) with no commensurate 

increase in benefits. 

Alternative 2—Require EWIS training 

for four groups of people in addition to 

maintenance workers. The groups and 

additional costs are: 

• Electrical/avionic engineers—$4.0 

million ($2.4 million present value). 

• Individuals involved in engineering 

or planning work—$0.4 million ($0.4 

million present value). 

• Flight deck crew—$260.0 million 

($126.1 million present value). 

• Cabin crew-$91.5 million ($44.4 

million present value). 

To train these individuals, operators 

would develop additional courses. The 

FAA estimates an additional $25.2 

million ($24.1 million present value) to 

develop the necessary training material. 

The total estimated additional cost of 

this alternative is approximately $381.1 

million ($197.4 million present value) 

with no commensurate increase in 

benefits. 

Benefits of This Rulemaking 

The FAA estimates $755.3 million 

($340.7 million present value) as the 

total benefits of this proposal. 

In the table below, categories of 

benefits are shown. The middle column 

gives the nominal values of quantified 

benefits, while the right-hand column 

gives the total incremental present value 

benefits broken down by category type. 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58543 

Benefits 

Nominal 

values 

(millions) 

Present value 

(millions) 

Non Fatal & Fatal Accidents: 

Non Fatal events .............................................................................................................................................. $56.0 $26.1 

Fatal events ...................................................................................................................................................... 507.0 236.3 

Total ........................................................................................................................................................... 563.0 262.4 

EWIS Operational Improvements: 

Averted delays .................................................................................................................................................. 21.2 8.3 

Averted unscheduled landings ......................................................................................................................... 152.4 62.4 

Averted IFE failures .......................................................................................................................................... 18.7 7.6 

Total ........................................................................................................................................................... 192.3 78.3 

Total—All Benefits .............................................................................................................................. 755.3 340.7 

Costs of This Rulemaking 

The FAA estimates $474.3 million 

($209.2 million present value) as the 

total cost of this proposal. 

In the table below, the left-hand 

column specifies the cost component by 

14 CFR part, the middle column gives 

the nominal cost, and the right-hand 

column gives the total incremental 

present value costs by 14 CFR part. 

Cost component 

Nominal 

values 

(millions) 

Present 

value 

(millions) 

Part 25 Harmonization ............................................................................................................................................. 0 0 

Part 25 Subpart H .................................................................................................................................................... $131.9 $53.8 

Part 25 Subpart I ..................................................................................................................................................... 23.3 20.3 

Part 121 ICA ............................................................................................................................................................ 319.1 135.1 

Parts 91/121/125—Fuel Tank .................................................................................................................................. (*) 

Total ..................................................................................................................................................................... 474.3 209.2 

* De minimus. 

Initial Regulatory Flexibility 

Determination 

The Regulatory Flexibility Act of 1980 

(RFA) establishes ‘‘as a principle of 

regulatory issuance that agencies shall 

endeavor, consistent with the objective 

of the rule and of applicable statutes, to 

fit regulatory and informational 

requirements to the scale of the 

business, organizations, and 

governmental jurisdictions subject to 

regulation.’’ To achieve that principle, 

the RFA requires agencies to solicit and 

consider flexible regulatory proposals 

and to explain the rationale for their 

actions. The RFA covers a wide-range of 

small entities, including small 

businesses, not-for-profit organizations, 

and small governmental jurisdictions. 

Agencies must perform a review to 

determine whether a proposed or final 

rule will have a significant economic 

impact on a substantial number of small 

entities. If the agency determines that it 

will, the agency must prepare a 

regulatory flexibility analysis as 

described in the Act. 

However, if an agency determines that 

a proposed or final rule is not expected 

to have a significant economic impact 

on a substantial number of small 

entities, section 605(b) of the 1980 RFA 

provides that the head of the agency 

may so certify and a regulatory 

flexibility analysis is not required. The 

certification must include a statement 

providing the factual basis for this 

determination, and the reasoning should 

be clear. 

This proposed rule would not have a 

significant economic impact on a 

substantial number of small entities for 

the following reasons. 

Entities potentially affected by this 

proposal include part 25 manufacturers, 

applicants for future amended and 

supplemental type certificates, and part 

121 operators of large transport category 

airplanes. 

The FAA uses the size standards from 

the Small Business Administration for 

Air Transportation and Aircraft 

Manufacturing, which specify 

companies having less than 1,500 

employees as small entities. 

The current United States part 25 

airplane manufacturers include: Boeing, 

Cessna Aircraft, Gulfstream Aerospace, 

Learjet (owned by Bombardier), 

Lockheed Martin, McDonnell Douglas (a 

wholly-owned subsidiary of The Boeing 

Company), Raytheon Aircraft, and 

Sabreliner Corporation. These 

manufacturers would incur type 

certificate (TC) and amended TC costs. 

Because all U.S. transport-aircraft 

category manufacturers have more than 

1,500 employees, none are considered 

small entities. 

Future supplemental type certificate 

(STC) applicants would incur additional 

compliance costs. These STC applicants 

would incur the cost only if the 

expected revenue from the STC would 

exceed the expected cost. While future 

STC costs would be passed on to 

airplane operators, it is not possible to 

determine when and which operator 

would purchase and install such a 

future STC. Because a future STC 

applicant would incur the additional 

compliance cost only if the STC would 

generate profits, the FAA believes there 

would not be a significant impact on a 

substantial number of STC applicants. 

The FAA calculated the economic 

impact on small-business part 121 

operators by dividing the annual 

compliance cost by the firm’s annual 

revenue. The annual estimated average 

annual cost of the proposal would 

approach 1⁄2 of 1 percent for only two 

small entities. For the others, the cost 

impact would be a few hundredths of 1 

percent of revenue. 

58544 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

The FAA has determined that: No part 

25 manufacturers are small entities, 

there would not be a significant impact 

on a substantial number of amended TC 

or STC applicants, the estimated 

operator compliance cost as a percent of 

annual revenue would not be 

significant. 

Accordingly, pursuant to the 

Regulatory Flexibility Act, 5 U.S.C. 

605(b), the Federal Aviation 

Administration certifies that this 

proposed rule would not have a 

significant impact on a substantial 

number of small entities. 

Initial International Trade Impact 

Assessment 

The Trade Agreement Act of 1979 

prohibits Federal agencies from 

establishing any standards or engaging 

in related activities that create 

unnecessary obstacles to the foreign 

commerce of the United States. 

Legitimate domestic objectives, such as 

safety, are not considered unnecessary 

obstacles. The statute also requires 

consideration of international standards 

and, where appropriate, that they be the 

basis for U.S. standards. The FAA has 

assessed the potential effect of this 

proposed rule and determined that it 

would impose the same costs on 

domestic and international entities and, 

thus, would have a neutral trade impact. 

Initial Unfunded Mandates Assessment 

The Unfunded Mandates Reform Act 

of 1995 (the Act) is intended, among 

other things, to curb the practice of 

imposing unfunded Federal mandates 

on State, local, and tribal governments. 

Title II of the Act requires each Federal 

agency to prepare a written statement 

assessing the effects of any Federal 

mandate in a proposed or final agency 

rule that may result in an expenditure 

of $100 million or more (adjusted 

annually for inflation) in any one year 

by State, local, and tribal governments, 

in the aggregate, or by the private sector; 

such a mandate is deemed to be a 

‘‘significant regulatory action.’’ The 

FAA currently uses an inflationadjusted value of $120.7 million in lieu 

of $100 million. This proposed rule 

does not contain such a mandate. 

Therefore, the requirements of Title II of 

the Unfunded Mandates Reform Act of 

1995 do not apply. 

Executive Order 13132, Federalism 

The FAA has analyzed this proposed 

rule under the principles and criteria of 

Executive Order 13132, Federalism. We 

determined that this action would not 

have a substantial direct effect on the 

States, on the relationship between the 

national Government and the States, or 

on the distribution of power and 

responsibilities among the various 

levels of government, and therefore 

would not have federalism implications. 

Plain English 

Executive Order 12866 (58 FR 51735, 

Oct. 4, 1993) requires each agency to 

write regulations that are simple and 

easy to understand. We invite your 

comments on how to make these 

proposed regulations easier to 

understand, including answers to 

questions such as the following: 

• Are the requirements in the 

proposed regulations clearly stated? 

• Do the proposed regulations contain 

unnecessary technical language or 

jargon that interferes with their clarity? 

• Would the regulations be easier to 

understand if they were divided into 

more (but shorter) sections? 

• Is the description in the preamble 

helpful in understanding the proposed 

regulations? 

Please send your comments to the 

address specified in the ADDRESSES

section. 

Environmental Analysis 

FAA Order 1050.1E identifies FAA 

actions that are categorically excluded 

from preparation of an environmental 

assessment or environmental impact 

statement under the National 

Environmental Policy Act in the 

absence of extraordinary circumstances. 

The FAA has determined this proposed 

rulemaking action qualifies for the 

categorical exclusion identified in 

paragraph 312f and involves no 

extraordinary circumstances. 

Regulations That Significantly Affect 

Energy Supply, Distribution, or Use 

The FAA has analyzed this NPRM 

under Executive Order 13211, Actions 

Concerning Regulations that 

Significantly Affect Energy Supply, 

Distribution, or Use (May 18, 2001). We 

have determined that it is not a 

‘‘significant energy action’’ under the 

executive order because it is not a 

‘‘significant regulatory action’’ under 

Executive Order 12866, and it is not 

likely to have a significant adverse effect 

on the supply, distribution, or use of 

energy. 

The following Appendices will not appear 

in the Code of Federal Regulations. 

Appendix A 

List of Acronyms 

AC—Advisory Circular 

ACJ—Advisory Circular Joint 

ACO—Aircraft certification office 

AD—Airworthiness directive 

AFM—Airplane flight manual 

ARAC—Aviation Rulemaking Advisory 

Committee 

ASTF—Aging Systems Task Force 

ATA—Air Transport Association 

ATSRAC—Aging Transport Systems 

Rulemaking Advisory Committee 

CFR—Code of Federal Regulations 

CS—Certification Specifications 

CWT—Center wing fuel tank 

DET—detailed inspection 

EAPAS—Enhanced Airworthiness Program 

for Airplane Systems 

EASA—European Aviation Safety Agency 

EUROCAE—European Organization for Civil 

Aviation Equipment 

EWIS—Electrical wiring interconnection 

systems 

EZAP—Enhanced zonal analysis procedure 

FAA—Federal Aviation Administration 

FQIS—Fuel quantity indicating system 

FSDO—Flight Standards District Office 

GVI—General visual inspection 

ICA—Instructions for Continued 

Airworthiness 

ICAO—International Civil Aviation 

Organization 

IFE—In-flight entertainment 

IIWG—Intrusive Inspection Working Group 

JAA—Joint Aviation Authority 

JAR—Joint Aviation Requirements 

MS—Military specification 

NPRM—notice of proposed rulemaking 

NTSB—National Transportation Safety Board 

OMB—Office of Management and Budget 

RTCA—Radio Technical Commission for 

Aeronautics 

SAE—Society of Automotive Engineers 

SCR—Special certification review 

SFAR—Special federal aviation regulation 

SFAR 88—Special Federal Aviation 

Regulation 88—Fuel Tank System Fault 

Tolerance Evaluation Requirements—TCand STC-holder requirements included in 

the FTSR 

STC—Supplemental type certificate 

SWAMP—Severe wind and moisture 

problem 

SWPM—Standard wiring practices manual 

TC—Type certificate 

TSB—Transportation Safety Board of Canada 

WHCSS—White House Commission on 

Aviation Safety and Security 

Appendix B 

CORRELATION BETWEEN PROPOSED NEW PART 25 REGULATIONS AND EXISTING REGULATIONS

Proposed new regulation and title Section Based on existing 

requirements in 

§ 25.1701 Definition ....................................................................................................................... (a) .............................. none 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58545 

CORRELATION BETWEEN PROPOSED NEW PART 25 REGULATIONS AND EXISTING REGULATIONS—Continued 

Proposed new regulation and title Section Based on existing 

requirements in 

(b) .............................. none 

(c) .............................. none 

(d) .............................. none 

§ 25.1703 Function and installation: EWIS ................................................................................... (a)(1) .......................... § 25.1301(a) 

(a)(2) .......................... § 25.1301(c) 

(a)(3) .......................... § 25.1301(d) 

(a)(4) .......................... none 

(b) .............................. none 

(c) .............................. § 25.869(a)(3) 

(d) .............................. none 

§ 25.1705 System safety: EWIS .................................................................................................... (a)(1) .......................... § 25.1309(b)(1) 

(a)(2) .......................... § 25.1309(b)(1) 

(b) .............................. § 25.1309(b)(2) 

§ 25.1709 System separation: EWIS ............................................................................................ (a) .............................. § 25.1353(a) 

(b)(1) .......................... § 25.1353(a) 

(b)(2) .......................... none 

(c) .............................. § 25.1353(b) 

(d)(1) .......................... § 25.1351(b)(1) 

(d)(2) .......................... § 25.1351(b)(2) 

(e)(1) .......................... § 25.869(a)(3)(i) 

(e)(2) .......................... § 25.869(a)(3)(ii) 

§ 25.1353(d)(3) 

(f)(1) ........................... § 25.869(a)(3)(i) 

(f)(2) ........................... § 25.869(a)(3)(ii) 

§ 25.1353(d)(3) 

(g) .............................. § 25.1353(d)(3) 

(h)(1) .......................... § 25.1353(d)(3) 

(h)(2).

(i)(1) ........................... § 25.1353(d)(3) 

(i)(2).

(i)(3).

(j)(1) ........................... § 25.1353(d)(3) 

(j)(2).

(k) .............................. none 

(l) ............................... § 25.1353(d)(3) 

§ 25.1711 Component identification: EWIS.

(a) .............................. § 25.1301(b) 

(b)(1) .......................... none 

(b)(2) .......................... none 

(c) .............................. § 25.1353(d)(2) 

(d) .............................. none 

(e) .............................. none 

§ 25.1713 Fire protection: EWIS ................................................................................................... (a) .............................. § 25.869(a)(1) 

(b) .............................. § 25.869(a)(2) 

(c) .............................. § 25.869(a)(4) 

§ 25.1717 Electrical bonding and protection against static electricity: EWIS ............................... (a) .............................. § 25.899 

(b) .............................. none 

§ 25.1719 Systems and functions: EWIS ...................................................................................... (a) .............................. none 

(b)(1) .......................... § 25.773(b)(2) 

(b)(2) .......................... § 25.981 

(b)(3) .......................... § 25.1165 

(b)(4) .......................... § 25.1310 

(b)(5) .......................... § 25.1316 

(b)(6) .......................... § 25.1351 

(b)(7) .......................... § 25.1355 

(b)(8) .......................... § 25.1360 

(b)(9) .......................... § 25.1362 

(b)(10) ........................ § 25.1365 

(b)(11) ........................ § 25.1431(c) 

§ 25.1431(d) 

§ 25.1721 Circuit protection devices: EWIS .................................................................................. .................................... § 25.1353(d)(1) 

§ 25.1723 Instruments using a power supply: EWIS .................................................................... .................................... § 25.1331(a)(2) 

§ 25.1303(b) 

§ 25.1725 Accessibility provisions: EWIS ..................................................................................... ............................... § 25.611 

§ 25.1727 Protection of EWIS ....................................................................................................... (a)(1) .......................... § 25.855(e)(1) 

(a)(2) .......................... § 25.855(e)(2) 

(b) .............................. none 

(c) .............................. none 

§ 25.1729 Flammable fluid fire protection: EWIS .......................................................................... .................................... § 25.863(b)(3) 

§ 25.1731 Powerplants: EWIS ....................................................................................................... (a) .............................. § 25.903(b) 

(b) .............................. § 25.903(d)(1) 

58546 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

CORRELATION BETWEEN PROPOSED NEW PART 25 REGULATIONS AND EXISTING REGULATIONS—Continued 

Proposed new regulation and title Section Based on existing 

requirements in 

§ 25.1733 Flammable fluid shutoff means: EWIS ......................................................................... .................................... § 25.1189(d) 

§ 25.1735 Fire detector systems, general: EWIS ......................................................................... ............................... none 

§ 25.1737 Powerplant and APU fire detector system: EWIS ........................................................ (a) .............................. § 25.1203(e) 

(b)(1) .......................... § 25.1203(f)(1) 

(b)(2) .......................... § 25.1203(f)(2) 

§ 25.1739 Instructions for Continued Airworthiness: EWIS .......................................................... .................................... § 25.1529 

The term ‘‘none’’ in the above table indicates that the section in the proposed regulation is a new rule. 

Appendix C 

CORRELATION BETWEEN EXISTING PART 25 REGULATIONS AND PROPOSED NEW REGULATIONS

Existing regulation and title Section Proposed new 

regulation 

§ 25.611 Accessibility provisions ................................................................................................... .................................... § 25.1725 

§ 25.773 Pilot compartment view .................................................................................................. (b)(2) .......................... § 25.1719(b)(1) 

§ 25.855 Cargo or baggage compartments .................................................................................. (e)(1) .......................... § 25.1727(a)(1) 

(e)(2) .......................... § 25.1727(a)(2) 

§ 25.863 Flammable fluid fire protection ....................................................................................... (b)(3) .......................... § 25.1729 

§ 25.869 Fire protection: systems ................................................................................................. (a)(1) .......................... § 25.1713(a) 

(a)(2) .......................... § 25.1713(b) 

(a)(4) .......................... § 25.1713(c) 

(a)(3)(i) ....................... § 25.1709(e)(1) 

(a)(3)(ii) ...................... § 25.1709(e)(2) 

§ 25.1709(f)(1) 

§ 25.1709(f)(2) 

(a)(4) .......................... § 25.1713(c) 

§ 25.899 Electrical bonding and protection against static electricity ........................................... .................................... § 25.1717(a) 

§ 25.903 Engines ........................................................................................................................... (b) .............................. § 25.1731(a) 

(d)(1) .......................... § 25.1731(b) 

§ 25.1165 Engine ignition systems ................................................................................................ .................................... § 25.1719(b)(3) 

§ 25.1189 Shutoff means .............................................................................................................. (d) .............................. § 25.1733 

§ 25.1203 Fire detector system ..................................................................................................... (e) .............................. § 25.1737(a) 

(f)(1) ........................... § 25.1737(b)(1) 

(f)(2) ........................... § 25.1737(b)(2) 

§ 25.1301 Function and installation ............................................................................................... (a) .............................. § 25.1703(a)(1) 

(c) .............................. § 25.1703(a)(2) 

(b) .............................. § 25.1711(a) 

(d) .............................. § 25.1703(a)(3) 

§ 25.1303 Flight and navigation instruments ................................................................................ (b) .............................. § 25.1723 

§ 25.1309 Equipment, systems, and installations ......................................................................... (b)(1) .......................... § 25.1705(a)(1) 

§ 25.1705(a)(2) 

(b)(2) .......................... § 25.1705(b) 

(e) .............................. § 25.1707 

(f) ............................... § 25.1707 

§ 25.1316 System lightning protection .......................................................................................... .................................... § 25.1719(b)(5) 

§ 25.1331 Instruments using a power supply ............................................................................... (a)(2) .......................... § 25.1723 

§ 25.1351 General ......................................................................................................................... (b)(1) .......................... § 25.1709(d)(1) 

(b)(2) .......................... § 25.1709(d)(2) 

§ 25.1353 Electrical equipment and installations .......................................................................... (a) .............................. § 25.1709(b)(1) 

(a) .............................. § 25.1709(a) 

(b) .............................. § 25.1709(c) 

(d)(1) .......................... § 25.1721 

(d)(2) .......................... § 25.1711(c) 

(d)(3) .......................... § 25.1709(e)(1) 

§ 25.1709(e)(2) 

(d)(3) .......................... § 25.1709(f)(1) 

§ 25.1709(f)(2) 

(d)(3) .......................... § 25.1709(g) 

(d)(3) .......................... § 25.1709(h)(1) 

§ 25.1709(h)(2) 

(d)(3) .......................... § 25.1709(i)(1) 

§ 25.1709(i)(2) 

§ 25.1709(i)(3) 

(d)(3) .......................... § 25.1709(j)(1) 

§ 25.1709(j)(2) 

(d)(3) .......................... § 25.1709(l) 

§ 25.1355 Distribution system ....................................................................................................... .................................... § 25.1719(b)(5) 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58547 

CORRELATION BETWEEN EXISTING PART 25 REGULATIONS AND PROPOSED NEW REGULATIONS—Continued 

Existing regulation and title Section Proposed new 

regulation 

§ 25.1360 Precautions against injury ............................................................................................ .................................... § 25.1719(b)(6) 

§ 25.1362 Electrical supplies for emergency conditions ............................................................... .................................... § 25.1719(b)(7) 

§ 25.1365 Electrical appliances, motors, and transformers .......................................................... .................................... § 25.1719(b)(8) 

§ 25.1431 Electronic equipment .................................................................................................... (c) .............................. § 25.1719(b)(9) 

(d) ..............................

§ 25.1529 Instructions for Continued Airworthiness ...................................................................... .................................... § 25.1739 

Appendix D 

The tables below indicate which of the 

current rules will need to be changed to 

accommodate the new certification 

requirements and which will remain the 

same. 

EXISTING PART 25 REQUIREMENTS REQUIRING REVISION TO SUPPORT NEW PROPOSED REGULATIONS

Existing regulation 

Revision to existing 

regulation 

required? 

§ 25.611 .......................................................................................................................................................................... Yes. 

§ 25.773 .......................................................................................................................................................................... No. 

§ 25.855 .......................................................................................................................................................................... Yes. 

§ 25.863 .......................................................................................................................................................................... No. 

§ 25.869 .......................................................................................................................................................................... Yes. 

§ 25.899 .......................................................................................................................................................................... No. 

§ 25.903 .......................................................................................................................................................................... No. 

§ 25.1165 ........................................................................................................................................................................ No. 

§ 25.1189 ........................................................................................................................................................................ No. 

§ 25.1203 ........................................................................................................................................................................ Yes. 

§ 25.1301 ........................................................................................................................................................................ Yes. 

§ 25.1309 ........................................................................................................................................................................ Yes. 

§ 25.1310 ........................................................................................................................................................................ No. 

§ 25.1316 ........................................................................................................................................................................ No. 

§ 25.1331 ........................................................................................................................................................................ No. 

§ 25.1351 ........................................................................................................................................................................ No. 

§ 25.1353 ........................................................................................................................................................................ Yes. 

§ 25.1355 ........................................................................................................................................................................ No. 

§ 25.1357 ........................................................................................................................................................................ Yes. 

§ 25.1360 ........................................................................................................................................................................ No. 

§ 25.1362 ........................................................................................................................................................................ No. 

§ 25.1365 ........................................................................................................................................................................ No. 

§ 25.1431 ........................................................................................................................................................................ No. 

§ 25.1529 ........................................................................................................................................................................ No. 

BILLING CODE 4910–13–P 

58548 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 


EP06OC05.000</GPH>
Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58549 

BILLING CODE 4910–13–C 


EP06OC05.001</GPH>
58550 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

Discussion of the EWIS Safety Analysis 

Process as Depicted in Flowcharts 1 

and 2 (Excerpt From Proposed AC 

25.17XX, ‘‘Certification of Electrical 

Wiring Interconnection Systems on 

Transport Category Airplanes’’) 

The analysis described here is based 

on a qualitative approach to assessing 

EWIS safety as opposed to numerical, 

probability-based quantitative analysis. 

The intent is not to examine each 

individual wire and its relation to other 

wires. Rather, it is to ensure that there 

are no hazardous combinations. 

However, in case the ‘‘top down’’

analysis process described in this AC 

determines that a failure in a given 

bundle may lead to a catastrophic 

failure condition, the mitigation process 

may lead to performing a complete 

analysis of each wire in the relevant 

bundle. 

The analysis described may be 

accomplished in conjunction with the 

required aircraft system safety 

assessments of §§ 25.1309, 25.671, etc. 

The classification of failure 

conditions is given in Table 1 (found in 

the section-by-section discussion of 

proposed § 25.1705). 

There are two flowcharts contained in 

this appendix: 

• Flowchart 1 applies to applicants 

for pre-TC work and for amended TCs, 

and STCs when the applicant has all 

data necessary to perform the analysis 

per Flowchart 1. If Flowchart 1 is used 

for post-TC modifications the available 

data must include identification of the 

systems in the EWIS under 

consideration for modification and the 

system functions associated with that 

EWIS. 

• Flowchart 2 applies to applicants 

for post-TC modifications when the 

applicant cannot identify the systems or 

systems functions contained in EWIS 

under consideration for modification 

The analysis process is initiated by a 

functional hazard analysis performed at 

aircraft level identifying catastrophic 

and hazardous failure events. 

The processes in both Flowcharts 1 

and 2 identify two aspects: physical and 

functional failures. 

Note: For this discussion the following 

definitions apply: 

Validation: Determination that 

requirements for a product are sufficiently 

correct and complete. 

Verification: Evaluation to determine that 

requirements have been met. 

Physical Failure Analysis: Only single 

common cause events or failures need to 

be addressed during the physical failure 

analysis as described in this AC and 

shown on the left hand sides of 

Flowcharts 1 and 2. The objective of the 

physical analysis is to protect against 

single common cause events or failures 

that may involve single or multiple 

physical failures. Multiple common 

cause events or failures need not be 

addressed. 

In relation to physical effects, it 

should be assumed that wires are 

carrying electrical energy and, in the 

case of an EWIS failure, as defined in 

the preceding paragraph, this energy 

may result in hazardous or catastrophic 

effects directly or when combined with 

other factors (fuel, oxygen, hydraulic 

fluid, or damage by passengers, for 

example). These failures, for example, 

may result in fire, smoke, emission of 

toxic gases, and damage to co-located 

systems and structural elements or 

injury to personnel. This analysis 

considers all EWIS from all systems 

regardless of criticality, (autopilot, auto 

throttle, PA system, IFE system, etc.). 

Functional Failure Analysis: The 

functional failure analysis assumes that 

electrical wires are carrying power, 

signal, or information data. Failure of 

EWIS under these circumstances may 

lead to aircraft system degradation 

effects. 

Descriptive Text for Flowchart 1 

Box A 

The functional hazard assessment 

(FHA) referred to in this box is not a 

stand-alone separate document 

specifically created to show compliance 

with § 25.1705. It is the aircraft level 

FHA that the applicant will have 

developed in compliance with § 25.1309 

to help demonstrate acceptability of a 

design concept, identify potential 

problem areas or desirable design 

changes, or determine the need for and 

scope of any additional analyses (refer 

to AC/ACJ 25.1309–1B). 

Physical Failures 

Box B 

EWIS Characteristics: Use the results 

of the FHA (BOX A) to identify EWIS 

installation criteria and definitions of 

component characteristics. Results of 

BOX B are fed into the preliminary 

system safety analysis (PSSA) and 

system safety analysis (SSA) of BOX J. 

Boxes C, D, and E 

Validation and Verification of 

Installation Criteria: Ensure that the 

EWIS component qualification satisfies 

the design requirements and that 

components are selected, used, and 

installed according to their qualification 

characteristics and the aircraft 

constraints linked to their location. 

Using available information (e.g., 

digital mockup, physical mockup, 

aircraft, historical data), inspections and 

analyses (e.g., 1st article inspection, 

design review, particular risks, zonal 

safety assessments, zonal inspections, 

common mode analysis, as applicable) 

should be performed to validate that 

design and installation criteria are 

adequate to the zone/function, 

including multi-systems impact. Also, 

the inspections and analyses should be 

used to assess whether design and 

installation criteria were correctly 

applied. Special consideration should 

be given to those areas of the airplane 

that are known problem areas based on 

service history and historical data (e.g., 

arcing, smoke, loose clamps, chafing, 

arc tracking, interference with other 

systems, etc.). Special considerations 

should also be given to cases where new 

(previously unused) material or other 

technologies are used. 

Deviations from installation and 

component selection criteria identified 

by these activities should be evaluated 

and a determination made about their 

acceptability. Alternative mitigation 

strategies should be developed as 

necessary. 

Boxes F & G 

Development and Validation of 

Mitigation Strategy: Identify and 

develop a mitigation strategy for the 

physical failures and their adverse 

effects identified in BOXES D and E. 

• Validation and verification of the 

mitigation solution should ensure that: 

• Hazardous failure conditions are 

extremely remote. 

• Catastrophic failure conditions do 

not result from a single common cause 

event or failure. 

• This mitigation solution does not 

introduce any new potential failure 

conditions. 

Box H 

Incorporate newly developed 

mitigation strategies (BOX F) into 

guidelines (BOX B) for further design 

and inspection and analysis process. 

Box I 

From the EWIS physical failure 

analysis, document the physical failures 

that were addressed, their effects, and 

the mitigation strategies that were 

developed. This information supports 

the final analysis documentation (BOX 

P). 

Functional Failures 

Box J 

System Safety Assessment: Use results 

of the aircraft level FHA (BOX A) to 

guide the system level FHA (BOX J). 

EWIS failures identified by § 25.1705 

are to be incorporated into the system 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58551 

level and aircraft level FHA, as 

necessary, the PSSA, the common cause 

analysis (CCA), and the SSA. These 

analyses are performed to satisfy 

requirements of § 25.1309. 

Use results of these analyses to update 

the EWIS definition (BOX B). 

Boxes K, L, and M 

Hazardous and Catastrophic Failure 

Conditions: Use the analyses in BOX J 

to determine if the EWIS associated 

with the system under analysis can 

contribute (in whole or in part) to the 

failure condition under study. A 

determination needs to be made about 

whether the EWIS failure needs to be 

mitigated. If yes, a mitigation strategy 

needs to be developed, validated, and 

verified. If no, the appropriate safety 

assessment should be completed (e.g., 

per § 25.1309, § 25.671, etc.). 

Boxes N and O 

Development and Validation of 

Mitigation Strategy: Identify and 

develop a mitigation strategy for the 

functional failures and adverse effects 

identified in BOX J. 

Validation and verification of the 

mitigation solution should determine if 

initial objective is fully reached and 

confirm that this mitigation solution is 

compatible with existing installations 

and installation criteria. If the EWIS was 

the failure cause, the subsequent 

mitigation strategy developed may 

introduce new adverse effects not 

previously identified by the analysis. A 

check for any new adverse effects 

should be accomplished and the aircraft 

level FHA and other system safety 

assessments should be updated as 

necessary. 

Box P 

After the mitigation strategies have 

been validated and verified, document 

the results of the § 25.1705 analysis. 

Update as necessary the aircraft level 

FHA that has been developed in support 

of certification of the proposed 

modification, in compliance with 

§ 25.1309, (BOX A). 

Descriptive Text for Flowchart 2 

The main objectives are to ensure that 

the proposed modification will be 

correctly designed and installed and 

will not adversely affect existing 

systems. 

As far as EWIS is concerned, correct 

incorporation of the modification 

should be ensured by both good 

knowledge of original aircraft 

manufacturer (OAM) installation 

practices and their correct 

implementation or by adequate 

separation of the added EWIS from 

existing EWIS. In either case, physical 

analyses should be performed (similar 

to the physical failures part of 

Flowchart 1). 

Box A 

Aircraft level effects must be 

considered for modified systems or 

systems added to the aircraft. If the 

applicant has the aircraft level FHA it 

should be examined to determine the 

airplane-level effect of the proposed 

modification. If the applicant doesn’t 

have the aircraft level FHA, then the 

applicant must generate an aircraft level 

FHA based on the proposed 

modification. This aircraft level FHA 

would be limited to just those aircraft 

systems affected by the proposed 

modification. If it is determined that no 

aircraft level functional effects are 

introduced, a statement to this effect 

and the supporting data is sufficient to 

satisfy BOX A. 

Physical Failures 

Box B 

EWIS Characteristics: Use results of 

the aircraft level FHA (BOX A) to 

identify EWIS installation criteria and 

definitions of component 

characteristics. Results of BOX B are fed 

into the PSSA and SSA of BOX J. 

Box C 

Separate the EWIS to be added from 

other existing airplane EWIS since it 

cannot be determined what systems or 

system functions are contained in the 

existing EWIS. Physical separation 

between the new and existing EWIS 

must be achieved through separation 

distance or an appropriate barrier or 

other means shown to be at least 

equivalent to the physical separation 

distance when allowed by § 25.1709. 

Methods given in the proposed advisory 

material for § 25.1709 provide an 

acceptable way to determine adequate 

separation. 

In cases where separation cannot be 

maintained because of physical 

constraints (e.g., terminal strips and 

connectors, etc.), the applicant should 

accomplish the appropriate analysis to 

show that no adverse failure conditions 

exist because of sharing the common 

device. This requires that the applicant 

have knowledge of the systems or 

system functions sharing the common 

device (e.g. terminal strips and 

connectors etc.). 

Boxes D and E 

Validation and Verification of 

Installation Criteria 

Ensure that the EWIS component 

qualification satisfies the design 

requirements and that components are 

selected, used, and installed according 

to their qualification characteristics and 

the aircraft constraints linked to their 

location. 

Using available information (e.g., 

digital mockup, physical mockup, 

aircraft, historical data), inspections and 

analyses (e.g. 1st article inspection, 

design review, particular risks, zonal 

safety assessments, zonal inspections, 

common mode analysis, as applicable) 

should be performed to validate that 

design and installation criteria are 

adequate to the zone/function, 

including multi-systems impact. Also, 

inspections and analyses should be used 

to assess whether design and 

installation criteria were correctly 

applied. Special consideration should 

be given to those areas of the airplane 

that are known problem areas based on 

service history and historical data (e.g., 

arcing, smoke, loose clamps, chafing, 

arc tracking, interference with other 

systems, etc.). Special consideration 

should also be given to cases where new 

(previously unused) material or other 

technologies are used. 

Deviation from installation and 

component selection criteria identified 

by these activities should be evaluated 

and a determination made about their 

acceptability. Alternative mitigation 

strategies should be developed as 

necessary. 

Boxes F and G 

Development & Validation of Mitigation 

Strategy 

Identify and develop a mitigation 

strategy for the physical failures and 

their adverse effects identified in Boxes 

D and E. 

Validation and verification of the 

mitigation solution should ensure that: 

• Hazardous failure conditions are 

extremely remote. 

• Catastrophic failure conditions do 

not result from a single common cause 

event or failure. 

• This mitigation solution does not 

introduce any new potential failure 

conditions. 

Box H 

Incorporate newly developed 

mitigation strategies (Box F) into 

guidelines (Box B) for further design 

and inspection and analysis process. 

Box I 

From the EWIS physical failure 

analysis, document the physical failures 

that were addressed, their effects, and 

mitigation strategies that were 

developed. This information supports 

the final analysis documentation (Box 

P). 

58552 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

Functional Failures 

Box J 

System Safety Assessment 

Use the results of the aircraft level 

FHA (Box A) to guide the system level 

FHA (Box J). 

EWIS failures identified by § 25.1705 

are to be incorporated into the system 

level and aircraft level FHA, as 

necessary, the PSSA, the CCA, and the 

SSA. These analyses are performed to 

satisfy requirements of § 25.1309. 

Use results of these analyses to update 

the EWIS definition (Box B). 

Boxes K, L, and M 

Hazardous and Catastrophic Failure 

Conditions 

Use the analyses in Box J to determine 

if the EWIS associated with the system 

under analysis can contribute (in whole 

or in part) to the failure condition under 

study. A determination needs to be 

made about whether the EWIS failure 

needs to be mitigated. If yes, a 

mitigation strategy needs to be 

developed, validated, and verified. If no, 

the appropriate safety assessment 

should be completed (e.g., per 

§ 25.1309, § 25.671, etc.). 

Boxes N and O 

Development and Validation of 

Mitigation Strategy 

Identify and develop a mitigation 

strategy for the functional failures and 

adverse effects identified in Box J. 

Validation and verification of the 

mitigation solution should determine if 

initial objective is fully reached and 

confirm that this mitigation solution is 

compatible with existing installations 

and installation criteria. If the EWIS was 

the failure cause, the subsequent 

mitigation strategy developed may 

introduce new adverse effects not 

previously identified by the analysis. A 

check for any new adverse effects 

should be accomplished and the aircraft 

level FHA and other system safety 

assessments should be updated as 

necessary. 

Box P 

After the mitigation strategies have 

been validated and verified, document 

the results of the § 25.1705 analysis. 

Update as necessary the aircraft level 

FHA that has been developed in support 

of certification of the proposed 

modification, in compliance with 

§ 25.1309, (Box A). 

List of Subjects 

14 CFR Part 1 

Air Transportation. 

14 CFR Parts 25, 91, 125 

Aircraft, Aviation safety, Reporting 

and recordkeeping requirements. 

14 CFR Parts 121, 129 

Air carriers, Aircraft, Aviation safety, 

Reporting and recordkeeping 

requirements. 

The Proposed Amendments 

In consideration of the foregoing, the 

Federal Aviation Administration 

proposes to amend Chapter I of Title 14, 

Code of Federal Regulations parts 1, 25, 

91, 121, 125, and 129 as follows: 

PART 1—DEFINITIONS AND 

ABBREVIATIONS 

1. The authority citation for part 1 

continues to read as follows: 

Authority: 49 U.S.C. 106(g), 40113, 44701. 

2. Amend § 1.2 to add the following 

abbreviation in alphabetical order: 

§ 1.2 Abbreviations and symbols. 

* * * * * 

EWIS means electrical wiring 

interconnection system. 

* * * * * 

PART 25—AIRWORTHINESS 

STANDARDS: TRANSPORT 

CATEGORY AIRPLANES 

3. The authority citation for part 25 

continues to read as follows: 

Authority: 49 U.S.C. 106(g), 40113, 44701, 

44702 and 44704. 

4. Amend § 25.1 by adding a new 

paragraph (c) to read as follows: 

§ 25.1 Applicability. 

* * * * * 

(c) This part also establishes 

requirements for holders of type 

certificates and changes to those 

certificates to take actions necessary to 

support the continued airworthiness of 

transport category airplanes. 

5. Amend § 25.2 by adding a new 

paragraph (d) to read as follows: 

§ 25.2 Special retroactive requirements. 

* * * * * 

(d) In addition to the requirements of 

this section, subpart I of this part 

contains requirements that apply to—

(1) Holders of type certificates; and 

(2) Applicants for type certificates, 

changes to type certificates (including 

service bulletins describing design 

changes), and supplemental type 

certificates. 

6. Amend § 25.611 by designating the 

existing paragraph as paragraph (a) and 

adding new paragraph (b) to read as 

follows: 

§ 25.611 Accessibility provisions. 

(a) * * * 

(b) EWIS must meet the accessibility 

requirements of § 25.1725. 

7. Amend § 25.855 by removing the 

word ‘‘wiring’’ from paragraph (e) 

introductory text and adding new 

paragraph (j) as follows: 

§ 25.855 Cargo or baggage compartments. 

* * * * * 

(j) Cargo or baggage compartment 

electrical wiring interconnection system 

components must meet the 

requirements of § 25.1727. 

8. Amend § 25.869 by removing 

paragraph (a)(4) and revising paragraphs 

(a)(2) and (a)(3) as follows: 

§ 25.869 Fire protection: systems. 

(a) * * * 

(1) * * * 

(2) Equipment that is located in 

designated fire zones and is used during 

emergency procedures must be at least 

fire resistant. 

(3) EWIS components must meet the 

requirements of § 25.1713. 

* * * * * 

9. Amend part 25 by adding a new 

§ 25.899 to read as follows: 

§ 25.899 Electrical bonding and protection 

against static electricity. 

(a) Electrical bonding and protection 

against static electricity must be 

designed to minimize accumulation of 

electrostatic charge that would cause—

(1) Human injury from electrical 

shock, 

(2) Ignition of flammable vapors, or 

(3) Interference with installed 

electrical/electronic equipment. 

(b) Compliance with paragraph (a) of 

this section may be shown by—

(1) Bonding the components properly 

to the airframe; or 

(2) Incorporating other acceptable 

means to dissipate the static charge so 

as not to endanger the airplane, 

personnel, or operation of the installed 

electrical/electronic systems. 

10. Amend § 25.1203 by revising 

paragraph (e) and adding a new 

paragraph (h) as follows: 

§ 25.1203 Fire detector system. 

* * * * * 

(e) Components of each fire or 

overheat detector system in a fire zone 

must be at least fire-resistant. 

* * * * * 

(h) EWIS for each fire or overheat 

detector system in a fire zone must meet 

the requirements of § 25.1727. 

11. Amend § 25.1301 by designating 

the introductory text as paragraph (a), 

redesignating paragraphs (a) through (d) 

as (1) through (4), and adding a new 

paragraph (b) as follows: 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58553 

§ 25.1301 Function and installation. 

* * * * * 

(b) EWIS must meet the requirements 

of subpart H of this part. 

12. Amend § 25.1309 by removing 

paragraph (e) and redesignating 

paragraph (g) as paragraph (e) and 

revising paragraph (f) as follows: 

§ 25.1309 Equipment, systems, and 

installations. 

* * * * * 

(f) EWIS must be assessed in 

accordance with the requirements of 

§ 25.1705. 

13. Amend part 25 by adding a new 

§ 25.1310, to read as follows: 

§ 25.1310 Power source capacity and 

distribution. 

(a) Each installation whose 

functioning is required for type 

certification or under operating rules 

and that requires a power supply is an 

‘‘essential load’’ on the power supply. 

The power sources and the system must 

be able to supply the following power 

loads in probable operating 

combinations and for probable 

durations: 

(1) Loads connected to the system 

with the system functioning normally. 

(2) Essential loads, after failure of any 

one prime mover, power converter, or 

energy storage device. 

(3) Essential loads after failure of—

(i) Any one engine on two-engine 

airplanes; and 

(ii) Any two engines on three-or-moreengined airplanes. 

(4) Essential loads for which an 

alternate source of power is required, 

after any failure or malfunction in any 

one power supply system, distribution 

system, or other utilization system. 

(b) In determining compliance with 

paragraphs (a) (2) and (3) of this section, 

the power loads may be assumed to be 

reduced under a monitoring procedure 

consistent with safety in the kinds of 

operation authorized. Loads not 

required in controlled flight need not be 

considered for the two-engineinoperative condition on airplanes with 

three or more engines. 

14. Amend § 25.1353 by revising 

paragraphs (a), (b), and (d) as follows: 

§ 25.1353 Electrical equipment and 

installations. 

(a) Electrical equipment and controls 

must be installed so that operation of 

any one unit or system of units will not 

adversely affect the simultaneous 

operation of any other electrical unit or 

system essential to safe operation. Any 

electrical interference likely to be 

present in the airplane must not result 

in hazardous effects on the airplane or 

its systems. 

(b) EWIS components must meet the 

requirements of § 25.1357, § 25.1703, 

§ 25.1709, § 25.1711, and § 25.1721. 

(c) * * * 

(d) Electrical bonding must provide 

an adequate electrical return path under 

both normal and fault conditions, on 

airplanes having grounded electrical 

systems. 

15. Amend § 25.1357 by revising 

paragraphs (d) and (f) to read as follows: 

§ 25.1357 Circuit protective devices. 

* * * * * 

(d) If the ability to reset a circuit 

breaker or replace a fuse is essential to 

safety in flight, that circuit breaker or 

fuse must be located and identified so 

that it can be readily reset or replaced 

in flight. Where fuses are used, there 

must be spare fuses for use in-flight 

equal to at least 50% of the number of 

fuses of each rating required for 

complete circuit protection. 

* * * * * 

(f) For airplane systems for which the 

ability to remove or reset power during 

normal operations is necessary, the 

system must be designed so that circuit 

breakers are not the primary means to 

remove or reset system power unless 

specifically designed for use as a switch. 

* * * * * 

16. Amend part 25 by adding a new 

§ 25.1360 to read as follows: 

§ 25.1360 Precautions against injury. 

(a) Shock. The electrical system must 

be designed to minimize risk of electric 

shock to crew, passengers, and servicing 

personnel and to maintenance 

personnel using normal precautions. 

(b) Burns. The temperature of any part 

that may be handled by a crewmember 

during normal operations must not 

cause dangerous inadvertent movement 

by the crewmember or injury to the 

crewmember. 

17. Amend part 25 by adding a new 

§ 25.1362 to read as follows: 

§ 25.1362 Electrical supplies for 

emergency conditions. 

A suitable electrical supply must be 

provided to those services required for 

emergency procedures after an 

emergency landing or ditching. The 

circuits for these services must be 

designed, protected, and installed so 

that the risk of their causing a fire under 

these emergency conditions is 

minimized. 

18. Amend part 25 by adding a new 

§ 25.1365 to read as follows: 

§ 25.1365 Electrical appliances, motors, 

and transformers. 

(a) Domestic appliances must be 

designed and installed so that in the 

event of failures of the electrical supply 

or control system, the requirements of 

§ 25.1309(b), (c), and (d) will be 

satisfied. Domestic appliances are items 

such as cooktops, ovens, coffee makers, 

water heaters, refrigerators, and toilet 

flush systems that are placed on the 

airplane to provide service amenities to 

passengers. 

(b) Galleys and cooking appliances 

must be installed in a way that 

minimizes risk of overheat or fire. 

(c) Domestic appliances, particularly 

those in galley areas, must be so 

installed or protected as to prevent 

damage or contamination of other 

equipment or systems from fluids or 

vapors which may be present during 

normal operation or as a result of 

spillage, if such damage or 

contamination may create a hazardous 

condition. 

(d) Unless compliance with 

§ 25.1309(b) is provided by the circuit 

protective device required by 

§ 25.1357(a), electric motors and 

transformers, including those installed 

in domestic systems, must have a 

suitable thermal protection device to 

prevent overheating under normal 

operation and failure conditions, if 

overheating would create a smoke or fire 

hazard. 

19. Amend part 25 by adding new 

subpart H to read as follows: 

Subpart H—Electrical Wiring 

Interconnection Systems (EWIS) 

Sec. 

25.1701 Definition. 

25.1703 Function and installation: EWIS. 

25.1705 System safety: EWIS. 

25.1707 [Reserved] 

25.1709 System separation: EWIS. 

25.1711 Component identification: EWIS. 

25.1713 Fire protection: EWIS. 

25.1715 [Reserved] 

25.1717 Electrical bonding and protection 

against static electricity: EWIS. 

25.1719 Systems and functions: EWIS. 

25.1721 Circuit protective devices: EWIS. 

25.1723 Instruments using a power supply: 

EWIS. 

25.1725 Accessibility provisions: EWIS. 

25.1727 Protection of EWIS. 

25.1729 Flammable fluid fire protection: 

EWIS. 

25.1731 Powerplants: EWIS. 

25.1733 Flammable fluid shutoff means: 

EWIS. 

25.1735 Fire detector systems, general: 

EWIS. 

25.1737 Powerplant and APU fire detector 

system: EWIS. 

25.1739 Instructions for Continued 

Airworthiness: EWIS. 

Subpart H—Electrical Wiring 

Interconnection Systems (EWIS) 

§ 25.1701 Definition. 

(a) As used in this chapter, electrical 

wiring interconnection system (EWIS) 

58554 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

means any wire, wiring device, or 

combination of these, including 

termination devices, installed in any 

area of the airplane for the purpose of 

transmitting electrical energy between 

two or more intended termination 

points. Except as provided for in 

paragraph (c) of this section, this 

includes: 

(1) Wires and cables. 

(2) Bus bars. 

(3) The termination point on electrical 

devices, including those on relays, 

interrupters, switches, contactors, 

terminal blocks and circuit breakers, 

and other circuit protection devices. 

(4) Connectors, including feedthrough connectors. 

(5) Connector accessories. 

(6) Electrical grounding and bonding 

devices and their associated 

connections. 

(7) Electrical splices. 

(8) Materials used to provide 

additional protection for wires, 

including wire insulation, wire sleeving, 

and conduits that have electrical 

termination for the purpose of bonding. 

(9) Shields or braids. 

(10) Clamps and other devices used to 

route and support the wire bundle. 

(11) Cable tie devices. 

(12) Labels or other means of 

identification. 

(13) Pressure seals. 

(b) The definition in paragraph (a) of 

this section covers EWIS components 

inside shelves, panels, racks, junction 

boxes, distribution panels, and backplanes of equipment racks, including, 

but not limited to, circuit board backplanes and wire integration units. 

(c) Except for the equipment indicated 

in paragraph (b) of this section, EWIS 

components inside the following 

equipment, and the external connectors 

that are part of that equipment, are 

excluded from the definition in 

paragraph (a) of this section: 

(1) Electrical equipment or avionics 

that are qualified to environmental 

conditions and testing procedures when 

those conditions and procedures are-(i) 

Appropriate for the intended function 

and operating environment, and 

(ii) Acceptable to the FAA. 

(2) Portable electrical devices that are 

not part of the type design of the 

airplane. This includes personal 

entertainment devices and laptop 

computers. 

(3) Fiber optics. 

§ 25.1703 Function and installation: EWIS. 

(a) Each EWIS component installed in 

any area of the aircraft must: 

(1) Be of a kind and design 

appropriate to its intended function. 

(2) Be installed according to 

limitations specified for the EWIS 

components. 

(3) Function properly when installed. 

(4) Be designed and installed in a way 

that will minimize mechanical strain. 

(b) Selection of wires must take into 

account known characteristics of the 

wire in relation to each installation and 

application to minimize the risk of wire 

damage, including any arc tracking 

phenomena. 

(c) The design and installation of the 

main power cables, including generator 

cables, must allow for a reasonable 

degree of deformation and stretching 

without failure. 

(d) EWIS components located in areas 

of known moisture accumulation must 

be adequately protected to minimize 

any hazardous effects due to moisture. 

§ 25.1705 System safety: EWIS. 

Each EWIS must be designed and 

installed so that: 

(a) Each catastrophic failure 

condition—

(1) Is extremely improbable; and 

(2) Does not result from a single 

failure. 

(b) Each hazardous failure condition 

is extremely remote. 

§ 25.1707 [Reserved] 

§ 25.1709 System separation: EWIS. 

(a) Each EWIS must be designed and 

installed so that under normal 

conditions and failure conditions as 

defined by § 25.1309(b)(1) and (b)(2), it 

will not adversely affect the 

simultaneous operation of any other 

systems necessary for continued safe 

flight, landing, and egress. Unless 

otherwise stated, for the purposes of this 

section, adequate physical separation 

must be achieved by separation distance 

or by a barrier that provides protection 

equivalent to that separation distance. 

(b) Each EWIS must be designed and 

installed so that any electrical 

interference likely to be present in the 

airplane will not result in hazardous 

effects upon the airplane or its systems. 

(c) Wires and cables carrying heavy 

current, and their associated EWIS 

components, must be designed and 

installed to ensure adequate physical 

separation and electrical isolation so 

that damage to essential circuits will be 

minimized under fault conditions. 

(d) Each EWIS associated with 

independent airplane power sources 

must be designed and installed to 

ensure adequate physical separation and 

electrical isolation so that a fault in any 

one airplane power source EWIS will 

not adversely affect any other 

independent power sources. In addition: 

(1) Airplane independent electrical 

power sources must not share a 

common ground terminating location. 

(2) Airplane system static grounds 

must not share a common ground 

terminating location with any of the 

airplane’s independent electrical power 

sources. 

(e) Except to the extent necessary to 

provide electrical connection to the fuel 

systems components, the EWIS must be 

designed and installed with adequate 

physical separation from fuel lines and 

other fuel system components, so that: 

(1) Any EWIS component failure will 

not create a hazardous condition. 

(2) Any fuel leakage onto EWIS 

components will not create a hazardous 

condition. 

(f) Except to the extent necessary to 

provide electrical connection to the 

hydraulic systems components, EWIS 

must be designed and installed with 

adequate physical separation from 

hydraulic lines and other hydraulic 

system components, so that: 

(1) Any EWIS component failure will 

not create a hazardous condition. 

(2) Any hydraulic fluid leakage onto 

EWIS components will not create a 

hazardous condition. 

(g) Except to the extent necessary to 

provide electrical connection to the 

oxygen systems components, EWIS 

must be designed and installed with 

adequate physical separation from 

oxygen lines and other oxygen system 

components, so that any EWIS 

component failure will not create a 

hazardous condition. 

(h) Except to the extent necessary to 

provide electrical connection to the 

water/waste systems components, EWIS 

must be designed and installed with 

adequate physical separation from 

water/waste lines and other water/waste 

system components, so that: 

(1) Any EWIS component failure will 

not create a hazardous condition. 

(2) Any water/waste leakage onto 

EWIS components will not create a 

hazardous condition. 

(i) EWIS must be designed and 

installed with adequate physical 

separation between the EWIS and flight 

or other mechanical control systems 

cables and associated system 

components, so that: 

(1) Chafing, jamming, or other 

interference are prevented. 

(2) Any EWIS component failure will 

not create a hazardous condition. 

(3) Failure of any flight or other 

mechanical control systems cables or 

systems components will not damage 

the EWIS and create a hazardous 

condition. 

(j) EWIS must be designed and 

installed with adequate physical 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58555 

separation between the EWIS 

components and heated equipment, hot 

air ducts, and lines, so that: 

(1) Any EWIS component failure will 

not create a hazardous condition. 

(2) Any hot air leakage or heat 

generated onto EWIS components will 

not create a hazardous condition. 

(k) For systems for which redundancy 

is required, by certification rules, by 

operating rules, or as a result of the 

assessment required by § 25.1705, EWIS 

components associated with those 

systems must be designed and installed 

with adequate physical separation. 

(l) Each EWIS must be designed and 

installed so there is adequate physical 

separation between it and aircraft 

structure, and so that the EWIS is 

protected from sharp edges and corners, 

to minimize potential for abrasion/ 

chafing, vibration damage, and other 

types of mechanical damage. 

§ 25.1711 Component identification: EWIS. 

(a) EWIS components must be labeled 

or otherwise identified using a 

consistent method that facilitates 

identification of the wire, its function, 

and its design limitations, if any. 

(b) For systems for which redundancy 

is required, by certification rules, by 

operating rules, or as a result of the 

assessment required by § 25.1705, , 

EWIS components associated with those 

systems must be specifically identified 

with component part number, function, 

and separation requirement for bundles. 

(1) The identification must be placed 

along the wire, cable, or wire bundle at 

appropriate intervals and in areas of the 

airplane where it is readily visible to 

maintenance, repair, or alteration 

personnel. 

(2) If an EWIS component cannot be 

marked physically, then other means of 

identification must be provided. 

(c) The identifying markings required 

by paragraphs (a) and (b) of this section 

must remain legible throughout the 

expected service life of the EWIS 

component. 

(d) The means used for identifying 

each EWIS component as required by 

this section must not have an adverse 

effect on the performance of that 

component throughout its expected 

service life. 

(e) Identification for EWIS 

modifications to the type design must be 

consistent with the identification 

scheme of the original type design. 

§ 25.1713 Fire protection: EWIS. 

(a) All EWIS components must meet 

the applicable fire and smoke protection 

requirements of § 25.831(c) of this part. 

(b) EWIS components that are located 

in designated fire zones and are used 

during emergency procedures must be at 

least fire resistant. 

(c) Insulation on electrical wire and 

electrical cable, and materials used to 

provide additional protection for the 

wire and cable, installed in any area of 

the airplane, must be self-extinguishing 

when tested in accordance with the 

applicable portions of Appendix F, part 

I, of 14 CFR part 25. 

§ 25.1715 [Reserved] 

§ 25.1717 Electrical bonding and 

protection against static electricity: EWIS. 

(a) EWIS components used for 

electrical bonding and protection 

against static electricity must meet the 

requirements of § 25.899. 

(b) Electrical bonding provided by 

EWIS components must provide an 

adequate electrical return path under 

both normal and fault conditions, on 

airplanes having grounded electrical 

systems. 

§ 25.1719 Systems and functions: EWIS. 

(a) EWIS associated with systems 

required for type certification or by 

operating rules must be considered an 

integral part of that system and must be 

considered in showing compliance with 

the applicable requirements for that 

system. 

(b) For systems to which the following 

rules apply, the components of EWIS 

associated with those systems must be 

considered an integral part of that 

system or systems and must be 

considered in showing compliance with 

the applicable requirements for that 

system. 

(1) § 25.773(b)(2) Pilot compartment 

view. 

(2) § 25.981 Fuel tank ignition 

prevention. 

(3) § 25.1165 Engine ignition systems. 

(4) § 25.1310 Power source capacity 

and distribution. 

(5) § 25.1316 System lightning 

protection. 

(6) § 25.1351 General. 

(7) § 25.1355 Distribution system. 

(8) § 25.1360 Precautions against 

injury. 

(9) § 25.1362 Electrical supplies for 

emergency conditions. 

(10) § 25.1365 Electrical appliances, 

motors, and transformers. 

(11) § 25.1431(c) and (d) Electronic 

equipment. 

§ 25.1721 Circuit protective devices: EWIS. 

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. 

§ 25.1723 Instruments using a power 

supply: EWIS. 

EWIS components associated with 

any instrument required by § 25.1303(b) 

that uses a power supply must be 

designed and installed so that failure of 

the EWIS components would not affect 

that instrument’s compliance with 

§ 25.1331(a)(2). 

§ 25.1725 Accessibility provisions: EWIS. 

Access must be provided to allow 

inspection and replacement of any 

EWIS component as necessary for 

continued airworthiness. 

§ 25.1727 Protection of EWIS. 

(a) No cargo or baggage compartment 

may contain any EWIS whose damage or 

failure may affect safe operation, unless 

the EWIS is protected so that: 

(1) It cannot be damaged by 

movement of cargo or baggage in the 

compartment. 

(2) Its breakage or failure will not 

create a fire hazard. 

(b) EWIS must be designed and 

installed to minimize damage and risk 

of damage to EWIS by movement of 

people in the airplane during all phases 

of flight, maintenance, and servicing. 

(c) EWIS must be designed and 

installed to minimize damage and risk 

of damage to EWIS by items carried onto 

the aircraft by passengers or cabin crew. 

§ 25.1729 Flammable fluid fire protection: 

EWIS. 

EWIS components located in each 

area where flammable fluid or vapors 

might escape by leakage of a fluid 

system must be considered to be a 

potential ignition source and must meet 

the requirements of § 25.863. 

§ 25.1731 Powerplants: EWIS. 

(a) EWIS associated with any 

powerplant must be designed and 

installed so that the failure of an EWIS 

component will not prevent the 

continued safe operation of the 

remaining powerplants or require 

immediate action by any crewmember 

for continued safe operation, in 

accordance with the requirements of 

§ 25.903(b). 

(b) Design precautions must be taken 

to minimize hazards to the airplane due 

to EWIS damage in the event of a 

powerplant rotor failure or a fire 

originating within the powerplant that 

burns through the powerplant case, in 

accordance with the requirements of 

§ 25.903(d)(1). 

§ 25.1733 Flammable fluid shutoff means: 

EWIS. 

EWIS associated with each flammable 

fluid shutoff means and control must be 

fireproof or must be located and 

58556 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

protected so that any fire in a fire zone 

will not affect operation of the 

flammable fluid shutoff means, in 

accordance with the requirements of 

§ 25.1189. 

§ 25.1735 Fire detector systems, general: 

EWIS. 

EWIS associated with any installed 

fire protection system must be 

considered an integral part of the system 

in showing compliance with the 

applicable requirements for that system. 

§ 25.1737 Powerplant and APU fire 

detector system: EWIS. 

(a) EWIS that are part of each fire or 

overheat detector system in a fire zone 

must be at least fire-resistant. 

(b) No EWIS component of any fire or 

overheat detector system for any fire 

zone may pass through another fire 

zone, unless: 

(1) It is protected against the 

possibility of false warnings resulting 

from fires in zones through which it 

passes; or 

(2) Each zone involved is 

simultaneously protected by the same 

detector and extinguishing system. 

(c) EWIS that are part of each fire or 

overheat detector system in a fire zone 

must meet the requirements of 

§ 25.1203. 

§ 25.1739 Instructions for Continued 

Airworthiness: EWIS. 

The applicant must prepare 

Instructions for Continued 

Airworthiness applicable to EWIS in 

accordance with Appendix H sections 

H25.4 and H25.5 to this part that are 

approved by the FAA. 

20. Amend part 25 by adding new 

subpart I to read as follows. 

Subpart I—Continued Airworthiness and 

Safety Improvements 

Sec. 

25.1801 Purpose and definition. 

25.1803 [Reserved] 

25.1805 Electrical wiring interconnection 

systems (EWIS) maintenance program. 

Subpart I—Continued Airworthiness 

and Safety Improvements 

§ 25.1801 Purpose and definition. 

(a) This subpart establishes 

requirements for support of the 

continued airworthiness of transport 

category airplanes. These requirements 

may include performing assessments, 

developing design changes, developing 

revisions to Instructions for Continued 

Airworthiness, and making necessary 

documentation available to affected 

persons. This subpart applies to the 

following persons, as specified in each 

section of this subpart: 

(1) Holders of type certificates. 

(2) Applicants for type certificates and 

changes to type certificates (including 

service bulletins describing design 

changes). Applicants for changes to type 

certificates must comply with the 

requirements of this subpart in addition 

to the airworthiness requirements 

determined applicable under § 21.101 of 

this subchapter. 

(b) For purposes of this subpart, the 

‘‘FAA Oversight Office’’ is the aircraft 

certification office or office of the 

Transport Airplane Directorate with 

oversight responsibility for the relevant 

type certificate or supplemental type 

certificate, as determined by the 

Administrator. 

§ 25.1803 [Reserved] 

§ 25.1805 Electrical wiring interconnection 

systems (EWIS) maintenance program. 

(a) Except as provided in paragraph (f) 

of this section, this section applies to 

transport category, turbine-powered 

airplanes with a type certificate issued 

after January 1, 1958, that, as a result of 

the original certification, or later 

increase in capacity, have—

(1) A maximum type-certificated 

passenger capacity of 30 or more or 

(2) A maximum payload capacity of 

7,500 pounds or more. 

(b) Each person identified in 

paragraph (c) of this section must 

develop and submit for review and 

approval by the FAA Oversight Office 

Instructions for Continued 

Airworthiness for the representative 

airplane’s EWIS in accordance with 

Appendix H paragraphs H25.5(a)(1) and 

(b) of this part in effect on [effective date 

of final rule] for each affected type 

design. For purposes of this section, the 

‘‘representative airplane’’ is the 

configuration of each model series 

airplane that incorporates all variations 

of EWIS used on that series airplane, 

and that includes all TC-holderdesigned modifications mandated by 

airworthiness directive as of the 

effective date of this rule. Each person 

specified in paragraph (c) of this section 

must also review any fuel tank system 

Instructions for Continued 

Airworthiness developed by that person 

to comply with SFAR 88 to ensure 

compatibility with the EWIS 

Instructions for Continued 

Airworthiness, including minimizing 

redundant requirements. 

(c) The following persons must 

comply with the requirements of 

paragraph (b) of this section before the 

dates specified. 

(1) Holders of type certificates (TC): 

December 16, 2007. 

(2) Applicants for TCs, and 

amendments to TCs (including service 

bulletins describing design changes), if 

the date of application was before 

[effective date of final rule] and the 

certificate was issued on or after 

[effective date of final rule]: December 

16, 2007, or the date the certificate is 

issued, whichever occurs later. 

(3) Unless compliance with § 25.1739 

of this part is required or elected, 

applicants for amendments to TCs, if the 

application was filed after [effective 

date of final rule]: December 16, 2007, 

or the date of approval of the 

application, whichever occurs later. 

(4) Applicants for supplemental type 

certificates (STC), if the date of 

application was before [effective date of 

final rule] and the certificate was issued 

on or after [effective date of final rule]: 

June 16, 2008, or the date of approval 

of the application, whichever occurs 

later. 

(5) Unless compliance with § 25.1739 

of this part is required or elected, 

applicants for STCs, if the application 

was filed after [effective date of final 

rule]: June 16, 2008, or the date of 

approval of the application, whichever 

occurs later. 

(d) Each person identified in 

paragraphs (c)(1), (c)(2), and (c)(4) of 

this section must submit to the FAA 

Oversight Office for approval a 

compliance plan by [insert date 90 days 

after effective date of final rule]. The 

compliance plan must include the 

following information: 

(1) A proposed project schedule, 

identifying all major milestones, for 

meeting the compliance dates specified 

in paragraph (c) of this section. 

(2) A proposed means of compliance 

with this section, identifying all 

required submissions, including all 

compliance items as mandated in 

Appendix H paragraphs H25.5(a)(1) and 

(b) of this part in effect on [effective date 

of this final rule], and all data to be 

developed to substantiate compliance. 

(3) If the affected person proposes a 

means of compliance that differs from 

that described in FAA advisory 

material, a detailed explanation of how 

the proposed means will be shown to 

comply with this section. 

(4) A proposal for submitting a draft 

of all compliance items required by 

paragraph (d)(2) of this section for 

review by the FAA Oversight Office not 

less than 60 days before the compliance 

time specified in paragraph (c) of this 

section. 

(5) A proposal for how the approved 

Instructions for Continued 

Airworthiness will be made available to 

affected persons. 

(e) Each affected person must 

implement the compliance plan as 

approved in compliance with paragraph 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58557 

(d) of this section. If either paragraph 

(e)(1) or (2) of this section applies, the 

affected person must submit a corrected 

plan to the FAA Oversight Office and 

implement the corrected plan within 30 

days after such notification. 

(1) The FAA Oversight Office notifies 

the affected person of deficiencies in the 

proposed compliance plan and how to 

correct them. 

(2) The FAA Oversight Office notifies 

the affected person of deficiencies in the 

person’s implementation of the plan and 

how to correct them. 

(f) This section does not apply to the 

following airplane models: 

(1) Convair CV–240, 340, 440, if 

modified to include turbine engines. 

(2) Lockheed L–188 

(3) Vickers Armstrong Viscount 

(4) Douglas DC–3, if modified to 

include turbine engines 

(5) Bombardier CL–44 

(6) Mitsubishi YS–11 

(7) British Aerospace BAC 1–11 

(8) Concorde 

(9) deHavilland D.H. 106 Comet 4C 

(10) VFW-Vereinigte Flugtechnische 

Werk VFW–614 

(11) Illyushin Aviation IL 96T 

(12) Bristol Aircraft Britannia 305 

(13) Handley Page Herald Type 300 

(14) Avions Marcel Dassault—Breguet 

Aviation Mercure 100C 

(15) Airbus Caravelle 

APPENDIX H TO PART 25—

INSTRUCTIONS FOR CONTINUED 

AIRWORTHINESS 

21. Amend H25.1 by revising 

paragraph (a) to read as follows: 

H25.1 General. 

(a) This appendix specifies requirements 

for preparation of Instructions for Continued 

Airworthiness as required by §§ 25.1529, 

25.1739, and applicable provisions of subpart 

I of this part. 

* * * * * 

22. Amend H25.4 by revising 

paragraph (a)(1) and adding new 

paragraph (a)(3) to read as follows: 

H25.4 Airworthiness Limitations section. 

(a) * * * 

(1) Each mandatory replacement time, 

structural inspection interval, and related 

structural inspection procedures approved 

under § 25.571. 

(2) * * * 

(3) Any mandatory replacement time of 

EWIS components as defined in section 

25.1701. 

* * * * * 

23. Amend Appendix H to part 25 by 

adding new paragraph H25.5 to read as 

follows: 

H25.5 Electrical Wiring 

Interconnection System (EWIS) 

Instructions for Continued 

Airworthiness. 

(a) The applicant must prepare Instructions 

for Continued Airworthiness applicable to 

EWIS as defined by § 25.1701 that are 

approved by the FAA and include the 

following: 

(1) Maintenance and inspection 

requirements for the EWIS developed with 

the use of an enhanced zonal analysis 

procedure that includes: 

(i) Identification of each zone of the 

airplane. 

(ii) Identification of each zone that 

contains EWIS. 

(iii) Identification of each zone containing 

EWIS that also contains combustible 

materials. 

(iv) Identification of each zone in which 

EWIS is in close proximity to both primary 

and back-up hydraulic, mechanical, or 

electrical flight controls and lines. 

(v) Identification of—

(A) Tasks, and the intervals for performing 

those tasks, that will reduce the likelihood of 

ignition sources and accumulation of 

combustible material, and 

(B) Procedures, and the intervals for 

performing those procedures, that will 

effectively clean the EWIS components of 

combustible material if there is not an 

effective task to reduce the likelihood of 

combustible material accumulation. 

(vi) Instructions for protections and 

caution information that will minimize 

contamination and accidental damage to 

EWIS, as applicable, during performance of 

maintenance, alteration, or repairs. 

(2) Acceptable EWIS maintenance practices 

in a standard format. 

(3) Wire separation requirements as 

determined under § 25.1709. 

(4) Information explaining the EWIS 

identification method and requirements for 

identifying any changes to EWIS under 

§ 25.1711. 

(5) Electrical load data and instructions for 

updating that data. 

(b) The Instructions for Continued 

Airworthiness must be in the form of a 

document appropriate for the information to 

be provided, and they must be easily 

recognizable as EWIS Instructions for 

Continued Airworthiness. 

PART 91—GENERAL OPERATING AND 

FLIGHT RULES 

24. The authority for part 91 

continues to read as follows: 

Authority: 49 U.S.C. 106(g), 1155, 40103, 

40113, 40120, 44101, 44111, 44701, 44709, 

44711, 44712, 44715, 44716, 44717, 44722, 

46306, 46315, 46316, 46504, 46506–46507, 

47122, 47508, 47528–47531, articles 12 and 

29 of the Convention on International Civil 

Aviation (61 stat. 1180). 

25. Amend part 91 by adding new 

Subpart L as follows: 

Subpart L—Continued Airworthiness and 

Safety Improvements 

Sec. 

91.1501 Purpose and definition. 

91.1503 [Reserved] 

91.1505 [Reserved] 

91.1507 Fuel tank system maintenance 

program. 

Subpart L—Continued Airworthiness 

and Safety Improvements 

§ 91.1501 Purpose and definition. 

(a) This subpart requires operators to 

support the continued airworthiness of 

each airplane. These requirements may 

include, but are not limited to, revising 

the inspection program, incorporating 

design changes, and incorporating 

revisions to Instructions for Continued 

Airworthiness. 

(b) For purposes of this subpart, the 

‘‘FAA Oversight Office’’ is the aircraft 

certification office or office of the 

Transport Airplane Directorate with 

oversight responsibility for the relevant 

type certificate or supplemental type 

certificate, as determined by the 

Administrator. 

§ 91.1503 [Reserved] 

§ 91.1505 [Reserved] 

§ 91.1507 Fuel tank system maintenance 

program. 

(a) Except as provided in paragraph 

(g) of this section, this section applies to 

transport category, turbine-powered 

airplanes with a type certificate issued 

after January 1, 1958, that, as a result of 

original type certification or later 

increase in capacity, have—

(1) A maximum type-certificated 

passenger capacity of 30 or more, or 

(2) A maximum payload capacity of 

7,500 pounds or more. 

(b) For each airplane on which an 

auxiliary fuel tank is installed under a 

field approval, before December 16, 

2007, the operator must submit to the 

FAA Oversight Office proposed 

maintenance instructions for the tank 

that meet the requirements of Special 

Federal Aviation Regulation No. 88 

(SFAR 88) of this chapter. 

(c) After December 16, 2008, no 

operator may operate an airplane 

identified in paragraph (a) of this 

section unless the inspection program 

for that airplane has been revised to 

include inspections, procedures, and 

limitations for fuel tank systems. 

(d) The proposed fuel tank system 

inspection program revisions must be 

based on the following documents: 

(1) The applicable type-certificateholder-developed fuel tank Instructions 

for Continued Airworthiness, developed 

under SFAR 88, or under § 25.1529 in 

58558 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

effect on June 6, 2001, approved by the 

FAA Oversight Office. 

(2) The applicable supplemental-typecertificate-holder-developed fuel tank 

Instructions for Continued 

Airworthiness, if any, developed under 

SFAR 88, or Instructions for Continued 

Airworthiness developed in accordance 

with § 25.1529 in effect on June 6, 2001, 

approved by the FAA Oversight Office. 

(3) The applicable operator-developed 

inspection instructions for fieldapproved auxiliary fuel tanks, if any, 

approved by the FAA Oversight Office 

for the type certificate. 

(e) After December 16, 2008, before 

returning an airplane to service after any 

alterations for which fuel tank 

Instructions for Continued 

Airworthiness are developed under 

SFAR 88, or under § 25.1529 in effect on 

June 6, 2001, the operator must include 

in the inspection program for the 

airplane inspections and procedures for 

the fuel tank system based on those 

Instructions for Continued 

Airworthiness. 

(f) The fuel tank system inspection 

program changes identified in 

paragraphs (d) and (e) of this section 

and any later fuel tank system revisions 

must be submitted to the cognizant 

Flight Standards District Office (FSDO) 

for review and approval. 

(g) This section does not apply to the 

following airplane models: 

(1) Convair CV–240, 340, 440, if 

modified to include turbine engines. 

(2) Lockheed L–188 

(3) Vickers Armstrong Viscount 

(4) Douglas DC–3, if modified to 

include turbine engines 

(5) Bombardier CL–44 

(6) Mitsubishi YS–11 

(7) British Aerospace BAC 1–11 

(8) Concorde 

(9) deHavilland D.H. 106 Comet 4C 

(10) VFW-Vereinigte Flugtechnische 

Werk VFW–614 

(11) Illyushin Aviation IL 96T 

(12) Bristol Aircraft Britannia 305 

(13) Handley Page Herald Type 300 

(14) Avions Marcel Dassault—Breguet 

Aviation Mercure 100C 

(15) Airbus Caravelle 

26. Designate the text of current 

§ 91.410 as new § 91.1505, removing 

and reserving paragraph (b), and 

revising the section heading to read as 

follows: 

§ 91.1505 Repairs assessment for 

pressurized fuselages. 

§ 91.410 [Reserved] 

27. § 91.410 is reserved. 

PART 121—OPERATING 

REQUIREMENTS: DOMESTIC, FLAG, 

AND SUPPLEMENTAL OPERATIONS 

28. The authority citation for part 121 

continues to read: 

Authority: 49 U.S.C. 106(g), 40113, 40119, 

41706, 44101, 44701–44702, 44705, 44709–

44711, 44713, 44716–44717, 44722, 44901, 

44903–44904, 44912, 45101–45105, 46105, 

46301. 

29. Amend part 121 by adding new 

subpart Y to read as follows: 

Subpart Y—Continued Airworthiness and 

Safety Improvements 

Sec. 

121.901 Purpose and definition. 

121.903 [Reserved] 

121.905 [Reserved] 

121.907 [Reserved] 

121.909 [Reserved] 

121.911 Electrical wiring interconnection 

systems (EWIS) maintenance program. 

121.913 Fuel tank system maintenance 

program. 

Subpart Y—Continued Airworthiness 

and Safety Improvements 

§ 121.901 Purpose and definition. 

(a) This subpart requires persons 

holding an air carrier or operating 

certificate under part 119 of this chapter 

to support the continued airworthiness 

of each airplane. These requirements 

may include, but are not limited to, 

revising the maintenance program, 

incorporating design changes, and 

incorporating revisions to Instructions 

for Continued Airworthiness. 

(b) For purposes of this subpart, the 

‘‘FAA Oversight Office’’ is the aircraft 

certification office or office of the 

Transport Airplane Directorate with 

oversight responsibility for the relevant 

type certificate or supplemental type 

certificate, as determined by the 

Administrator. 

§ 121.903 [Reserved] 

§ 121.905 [Reserved] 

§ 121.907 [Reserved] 

§ 121.909 [Reserved] 

§ 121.911 Electrical wiring interconnection 

systems (EWIS) maintenance program. 

(a) Except as provided in paragraph (f) 

of this section, this section applies to 

transport category, turbine-powered 

airplanes with a type certificate issued 

after January 1, 1958, that, as a result of 

original type certification or later 

increase in capacity, have—

(1) A maximum type-certificated 

passenger capacity of 30 or more, or 

(2) A maximum payload capacity of 

7500 pounds or more. 

(b) After December 16, 2008, no 

certificate holder may operate an 

airplane identified in paragraph (a) of 

this section unless the maintenance 

program for that airplane includes 

inspections and procedures for 

electrical wiring interconnection 

systems (EWIS). 

(c) The proposed EWIS maintenance 

program changes must be based on the 

following documents: 

(1) The applicable EWIS Instructions 

for Continued Airworthiness, developed 

by the type certificate holder and 

approved by the FAA Oversight Office. 

(2) The applicable EWIS Instructions 

for Continued Airworthiness, if any, 

developed for supplemental type 

certificates, approved by the FAA 

Oversight Office. 

(d) After December 16, 2008, before 

returning an airplane to service after any 

alterations for which EWIS Instructions 

for Continued Airworthiness are 

developed, the certificate holder must 

include in the airplane’s maintenance 

program inspections and procedures for 

EWIS based on those Instructions for 

Continued Airworthiness. 

(e) The EWIS maintenance program 

changes identified in paragraphs (c) and 

(d) of this section and any later EWIS 

revisions must be submitted to the 

Principal Inspector for review and 

approval. 

(f) This section does not apply to the 

following airplane models: 

(1) Convair CV–240, 340, 440, if 

modified to include turbine engines. 

(2) Lockheed L–188 

(3) Vickers Armstrong Viscount 

(4) Douglas DC–3, if modified to 

include turbine engines 

(5) Bombardier CL–44 

(6) Mitsubishi YS–11 

(7) British Aerospace BAC 1–11 

(8) Concorde 

(9) deHavilland D.H. 106 Comet 4C 

(10) VFW-Vereinigte Flugtechnische 

Werk VFW–614 

(11) Illyushin Aviation IL 96T 

(12) Bristol Aircraft Britannia 305 

(13) Handley Page Herald Type 300 

(14) Avions Marcel Dassault—Breguet 

Aviation Mercure 100C 

(15) Airbus Caravelle 

§ 121.913 Fuel tank system maintenance 

program. 

(a) Except as provided in paragraph 

(g) of this section, this section applies to 

transport category, turbine-powered 

airplanes with a type certificate issued 

after January 1, 1958, that, as a result of 

original type certification or later 

increase in capacity, have—

(1) A maximum type-certificated 

passenger capacity of 30 or more, or 

(2) A maximum payload capacity of 

7500 pounds or more. 

(b) For each airplane on which an 

auxiliary fuel tank is installed under a 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58559 

field approval, before December 16, 

2007, the certificate holder must submit 

to the FAA Oversight Office proposed 

maintenance instructions for the tank 

that meet the requirements of Special 

Federal Aviation Regulation No. 88 

(SFAR 88) of this chapter. 

(c) After December 16, 2008, no 

certificate holder may operate an 

airplane identified in paragraph (a) of 

this section unless the maintenance 

program for that airplane has been 

revised to include inspections, 

procedures, and limitations for fuel 

tanks systems. 

(d) The proposed fuel tank system 

maintenance program revisions must be 

based on the following documents: 

(1) The applicable type-certificateholder-developed fuel tank Instructions 

for Continued Airworthiness, developed 

under SFAR 88 or under § 25.1529 in 

effect on June 6, 2001, approved by the 

FAA Oversight Office. 

(2) The applicable supplemental-typecertificate-holder-developed fuel tank 

Instructions for Continued 

Airworthiness, if any, developed under 

SFAR 88, or under § 25.1529 in effect on 

June 6, 2001, approved by the FAA 

Oversight Office. 

(3) The applicable certificate-holderdeveloped maintenance instructions for 

field-approved auxiliary fuel tanks, if 

any, approved by the FAA Oversight 

Office for the type certificate. 

(e) After December 16, 2008, before 

returning an aircraft to service after any 

alteration for which fuel tank 

Instructions for Continued 

Airworthiness are developed under 

SFAR 88 or under § 25.1529 in effect on 

June 6, 2001, the certificate holder must 

include in the maintenance program for 

the airplane inspections and procedures 

for the fuel tank system based on those 

Instructions for Continued 

Airworthiness. 

(f) The fuel tank system program 

changes identified in paragraphs (d) and 

(e) of this section and any later fuel tank 

system revisions must be submitted to 

the Principal Inspector for review and 

approval. 

(g) This section does not apply to the 

following airplane models: 

(1) Convair CV–240, 340, 440, if 

modified to include turbine engines. 

(2) Lockheed L–188 

(3) Vickers Armstrong Viscount 

(4) Douglas DC–3, if modified to 

include turbine engines 

(5) Bombardier CL–44 

(6) Mitsubishi YS–11 

(7) British Aerospace BAC 1–11 

(8) Concorde 

(9) deHavilland D.H. 106 Comet 4C 

(10) VFW-Vereinigte Flugtechnische 

Werk VFW–614 

(11) Illyushin Aviation IL 96T 

(12) Bristol Aircraft Britannia 305 

(13) Handley Page Herald Type 300 

(14) Avions Marcel Dassault—Breguet 

Aviation Mercure 100C 

(15) Airbus Caravelle 

§ 121.368 [Redesignated as § 121.905] 

30. Redesignate § 121.368 as new 

§ 121.905 and reserve §121.368. 

§ 121.368 [Reserved] 

31. § 121.368 is reserved. 

32. Designate the text of current 

§ 121.370 as new § 121.907, removing 

and reserving paragraph (b), and 

revising the section heading to read as 

follows: 

§ 121.907 Repairs assessment for 

pressurized fuselages. 

§ 121.370 [Reserved] 

33. § 121.370 is reserved. 

§ 121.370a [Redesignated as §121.909] 

34. Redesignate § 121.370a as new 

§121.909 and reserve § 121.370a. 

§ 121.370a [Reserved] 

35. § 121.370a is reserved. 

PART 125—CERTIFICATION AND 

OPERATIONS: AIRPLANES HAVING A 

SEATING CAPACITY OF 20 OR MORE 

PASSENGERS OR A MAXIMUM 

PAYLOAD CAPACITY OF 6,000 

POUNDS OR MORE; AND RULES 

GOVERNING PERSONS ON BOARD 

SUCH AIRCRAFT 

36. The authority citation for part 125 

continues to read: 

Authority: 49 U.S.C. 106(g), 40113, 44701–

44702, 44705, 44710–44711, 44713, 44716–

44717, 44722. 

37. Amend part 125 by adding new 

subpart M to read as follows: 

Subpart M—Continued Airworthiness and 

Safety Improvements 

Sec. 

125.501 Purpose and definition. 

125.503 [Reserved] 

125.505 [Reserved] 

125.507 Fuel tank system inspection 

program. 

Subpart M—Continued Airworthiness 

and Safety Improvements 

§ 125.501 Purpose and definition. 

(a) This subpart requires operators to 

support the continued airworthiness of 

each airplane. These requirements may 

include, but are not limited to, revising 

the inspection program, incorporating 

design changes, and incorporating 

revisions to Instructions for Continued 

Airworthiness. 

(b) For purposes of this subpart, the 

‘‘FAA Oversight Office’’ is the aircraft 

certification office or office of the 

Transport Airplane Directorate with 

oversight responsibility for the relevant 

type certificate or supplemental type 

certificate, as determined by the 

Administrator. 

§ 125.503 [Reserved] 

§ 125.505 [Reserved] 

§ 125.507 Fuel tank system inspection 

program. 

(a) Except as provided in paragraph 

(g) of this section, this section applies to 

transport category, turbine-powered 

airplanes with a type certificate issued 

after January 1, 1958, that, as a result of 

original type certification or later 

increase in capacity, have—

(1) a maximum type-certificated 

passenger capacity of 30 or more, or 

(2) a maximum payload capacity of 

7500 pounds or more. 

(b) For each airplane on which an 

auxiliary fuel tank is installed under a 

field approval, before December 16, 

2007, the certificate holder must submit 

to the FAA Oversight Office proposed 

maintenance instructions for the tank 

that meet the requirements of Special 

Federal Aviation Regulation No. 88 

(SFAR 88) of this chapter. 

(c) After December 16, 2008, no 

certificate holder may operate an 

airplane identified in paragraph (a) of 

this section unless the inspection 

program for that airplane has been 

revised to include inspections, 

procedures, and limitations for fuel tank 

systems. 

(d) The proposed fuel tank system 

inspection program revisions must be 

based on the following documents: 

(1) The applicable type-certificateholder-developed fuel tank Instructions 

for Continued Airworthiness, developed 

under SFAR 88, or under § 25.1529 in 

effect on June 6, 2001, approved by the 

FAA Oversight Office. 

(2) The applicable supplemental-typecertificate-holder-developed fuel tank 

Instructions for Continued 

Airworthiness, if any, developed under 

SFAR 88, or under § 25.1529 in effect on 

June 6, 2001, approved by the FAA 

Oversight Office. 

(3) The applicable certificate-holderdeveloped inspection instructions for 

field-approved auxiliary fuel tanks, if 

any, approved by the FAA Oversight 

Office for the type certificate. 

(e) After December 16, 2008, before 

returning an aircraft to service after any 

alteration for which fuel tank 

Instructions for Continued 

Airworthiness are developed under 

SFAR 88, or under § 25.1529 in effect on 

June 6, 2001, the certificate holder must 

include in the inspection program for 

58560 Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 

the airplane inspections and procedures 

for the fuel tank system based on those 

Instructions for Continued 

Airworthiness. 

(f) The fuel tank system program 

changes identified in paragraphs (d) and 

(e) of this section and any later fuel tank 

system revisions must be submitted to 

the Principal Inspector for review and 

approval. 

(g) This section does not apply to the 

following airplane models: 

(1) Convair CV–240, 340, 440, if 

modified to include turbine engines. 

(2) Lockheed L–188 

(3) Vickers Armstrong Viscount 

(4) Douglas DC–3, if modified to 

include turbine engines 

(5) Bombardier CL–44 

(6) Mitsubishi YS–11 

(7) British Aerospace BAC 1–11 

(8) Concorde 

(9) deHavilland D.H. 106 Comet 4C 

(10) VFW-Vereinigte Flugtechnische 

Werk VFW–614 

(11) Illyushin Aviation IL 96T 

(12) Bristol Aircraft Britannia 305 

(13) Handley Page Herald Type 300 

(14) Avions Marcel Dassault—Breguet 

Aviation Mercure 100C 

(15) Airbus Caravelle 

38. Designate the text of current 

§ 125.248 as new § 125.505, removing 

and reserving paragraph (b), and 

revising the section heading to read as 

follows: 

§ 125.505 Repairs assessment for 

pressurized fuselages. 

§ 125.248 [Reserved] 

39. § 125.248 is reserved. 

PART 129—OPERATIONS: FOREIGN 

AIR CARRIERS AND FOREIGN 

OPERATORS OF U.S.-REGISTERED 

AIRCRAFT ENGAGED IN COMMON 

CARRIAGE 

40. The authority citation for part 129 

continues to read: 

Authority: 49 U.S.C. 1372, 40113, 40119, 

44101, 44701–44702, 44705, 44709–44711, 

44713, 44716–44717, 44722, 44901–44904, 

44906, 44912, 46105, Pub. L. 107–71 sec. 

104. 

41. Amend part 129 by: 

A. Designating the existing sections, 

except §§ 129.16, 129.32, and 129.33, as 

‘‘Subpart A—General’’; 

B. Revising paragraph (b) of § 129.1; 

C. Redesignating §§ 129.16, 129.32, 

and 129.33 as §§ 129.109, 129.107, and 

129.105, respectively, and revising the 

heading for newly designated § 129.107 

and removing and reserving paragraph 

(b); and 

D. Adding a new subpart B. 

The revisions and additions read as 

follows: 

Subpart A—General 

§ 129.1 Applicability and definitions. 

* * * * * 

(b) Operations of U.S.-registered 

aircraft solely outside the United States. 

In addition to the operations specified 

under paragraph (a) of this section, 

§§ 129.14 and 129.20 and subpart B of 

this part also apply to U.S.-registered 

aircraft operated solely outside the 

United States in common carriage by a 

foreign person or foreign air carrier. 

* * * * * 

Subpart B—Continued Airworthiness and 

Safety Improvements 

Sec. 

129.101 Purpose and definition. 

129.103 [Reserved] 

129.105 Aging airplane inspections and 

records reviews for U.S.-registered 

multiengine aircraft. 

129.107 Repairs assessment for pressurized 

fuselages. 

129.109 Supplemental inspections for U.S.- 

registered aircraft. 

129.111 Electrical wiring interconnection 

systems (EWIS) maintenance program. 

129.113 Fuel tank system maintenance 

program. 

Subpart B—Continued Airworthiness 

and Safety Improvements 

§ 129.101 Purpose and definition. 

(a) This subpart requires a foreign 

person or foreign air carrier operating a 

U.S. registered airplane in common 

carriage to support the continued 

airworthiness of each airplane. These 

requirements may include, but are not 

limited to, revising the maintenance 

program, incorporating design changes, 

and incorporating revisions to 

Instructions for Continued 

Airworthiness. 

(b) For purposes of this subpart, the 

‘‘FAA Oversight Office’’ is the aircraft 

certification office or office of the 

Transport Airplane Directorate with 

oversight responsibility for the relevant 

type certificate or supplemental type 

certificate, as determined by the 

Administrator. 

§ 129.103 [Reserved] 

§ 129.105 [Redesignated from § 129.33] 

§ 129.107 [Redesignated from § 129.32] 

§ 129.109 [Redesignated from §129.16] 

§ 129.111 Electrical wiring interconnection 

systems (EWIS) maintenance program. 

(a) Except as provided in paragraph (f) 

of this section, this section applies to 

transport category, turbine-powered 

airplanes with a type certificate issued 

after January 1, 1958, that, as a result of 

original type certification or later 

increase in capacity, have—

(1) A maximum type-certificated 

passenger capacity of 30 or more, or 

(2) A maximum payload capacity of 

7500 pounds or more. 

(b) After December 16, 2008, no 

foreign person or foreign air carrier may 

operate an airplane identified in 

paragraph (a) of this section unless the 

maintenance program for that airplane 

includes inspections and procedures for 

EWIS. 

(c) The proposed EWIS maintenance 

program changes must be based on the 

following documents: 

(1) The applicable EWIS Instructions 

for Continued Airworthiness, developed 

by the type certificate holder and 

approved by the FAA Oversight Office. 

(2) The applicable EWIS Instructions 

for Continued Airworthiness, if any, 

developed for supplemental type 

certificates, approved by the FAA 

Oversight Office. 

(d) After December 16, 2008, before 

returning an airplane to service after any 

alterations for which EWIS Instructions 

for Continued Airworthiness are 

developed, the foreign person or foreign 

air carrier must include in the 

maintenance program for that airplane 

inspections and procedures for EWIS 

based on those Instructions for 

Continued Airworthiness. 

(e) The EWIS maintenance program 

changes identified in paragraphs (c) and 

(d) of this section and any later EWIS 

revisions must be submitted to the 

Principal Inspector or cognizant Flight 

Standards International Field Office for 

review and approval. 

(f) This section does not apply to the 

following airplane models: 

(1) Convair CV–240, 340, 440, if 

modified to include turbine engines. 

(2) Lockheed L–188 

(3) Vickers Armstrong Viscount 

(4) Douglas DC–3, if modified to 

include turbine engines 

(5) Bombardier CL–44 

(6) Mitsubishi YS–11 

(7) British Aerospace BAC 1–11 

(8) Concorde 

(9) deHavilland D.H. 106 Comet 4C 

(10) VFW-Vereinigte Flugtechnische 

Werk VFW–614 

(11) Illyushin Aviation IL 96T 

(12) Bristol Aircraft Britannia 305 

(13) Handley Page Herald Type 300 

(14) Avions Marcel Dassault-Breguet 

Aviation Mercure 100C 

(15) Airbus Caravelle 

§ 129.113 Fuel tank system maintenance 

program. 

(a) Except as provided in paragraph 

(g) of this section, this section applies to 

transport category, turbine-powered 

airplanes with a type certificate issued 

after January 1, 1958, that, as a result of 

Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / Proposed Rules 58561 

original type certification or later 

increase in capacity, have—

(1) A maximum type-certificated 

passenger capacity of 30 or more, or 

(2) A maximum payload capacity of 

7500 pounds or more. 

(b): For each airplane on which an 

auxiliary fuel tank is installed under a 

field approval, before December 16, 

2007, the foreign person or foreign air 

carrier operating the airplane must 

submit to the FAA Oversight Office 

proposed maintenance instructions for 

the tank that meet the requirements of 

Special Federal Aviation Regulation No. 

88 (SFAR 88) of this chapter. 

(c) After December 16, 2008, no 

foreign person or foreign air carrier may 

operate an airplane identified in 

paragraph (a) of this section unless the 

maintenance program for that airplane 

has been revised to include inspections, 

procedures, and limitations for fuel 

tanks systems. 

(d) The proposed fuel tank system 

maintenance program revisions must be 

based on the following documents: 

(1) The applicable type-certificateholder-developed fuel tank Instructions 

for Continued Airworthiness, developed 

under SFAR 88, or under § 25.1529 in 

effect on June 6, 2001, approved by the 

FAA Oversight Office. 

(2) The applicable supplemental-typecertificate-holder-developed fuel tank 

Instructions for Continued 

Airworthiness, if any, developed under 

SFAR 88, or Instructions for Continued 

Airworthiness developed in accordance 

with § 25.1529 in effect on June 6, 2001, 

approved by the FAA Oversight Office. 

(3) The applicable maintenance 

instructions for field-approved auxiliary 

fuel tanks, if any, developed by the 

foreign person or foreign air carrier 

operating the airplane and approved by 

the FAA Oversight Office for the type 

certificate. 

(e) After December 16, 2008, before 

returning an airplane to service after any 

alteration for which fuel tank 

Instructions for Continued 

Airworthiness are developed under 

SFAR 88, or under § 25.1529 in effect on 

June 6, 2001, the foreign person or 

foreign air carrier must include in the 

maintenance program for the airplane 

inspections and procedures for the fuel 

tank system based on those Instructions 

for Continued Airworthiness. 

(f) The fuel tank system program 

changes identified in paragraphs (d) and 

(e) of this section and any later fuel tank 

system revisions must be submitted to 

the Principal Inspector or cognizant 

Flight Standards International Field 

Office for review and approval. 

(g) This section does not apply to the 

following airplane models: 

(1) Convair CV–240, 340, 440, if 

modified to include turbine engines. 

(2) Lockheed L–188 

(3) Vickers Armstrong Viscount 

(4) Douglas DC–3, if modified to 

include turbine engines 

(5) Bombardier CL–44 

(6) Mitsubishi YS–11 

(7) British Aerospace BAC 1–11 

(8) Concorde 

(9) deHavilland D.H. 106 Comet 4C 

(10) VFW-Vereinigte Flugtechnische 

Werk VFW–614 

(11) Illyushin Aviation IL 96T 

(12) Bristol Aircraft Britannia 305 

(13) Handley Page Herald Type 300 

(14) Avions Marcel Dassault—Breguet 

Aviation Mercure 100C 

(15) Airbus Caravelle 

Issued in Washington, DC on September 

22, 2005. 

James J. Ballough, 

Director, Flight Standards Service. 

John J. Hickey, 

Director, Aircraft Certification Service. 

[FR Doc. 05–19419 Filed 10–5–05; 8:45 am] 

BILLING CODE 4910–13–P