Fuel System Vent Fire Protection

SUMMARY: This notice proposes an amendment to the airworthiness

standards for transport category airplanes to require fuel system vent

protection during post-crash ground fires. This proposal is the result

of information obtained from public hearings on aircraft fire safety,

and recommendation by the Special Aviation Fire and Explosion Reduction

(SAFER) Advisory Committee, and is intended to provide protection

against a fuel tank explosion following a post-crash ground fire. The

proposed amendment would apply to air carriers, air taxi operators, and

commercial operators of transport category airplanes, as well as the

manufacturers of such airplanes.

DATES: Comments must be received on or before June 2, 1995.

ADDRESSES: Comments on this proposal may be mailed in triplicate to:

Federal Aviation Administration, Office of the Chief Counsel,

Attention: Rules Docket (AGC-200), Docket No. 24251, 800 Independence

Avenue SW., Washington, D.C. 20591, or delivered in triplicate to: Room

915G, 800 Independence Avenue SW., Washington, D.C. Comments must be

marked: Docket No. 24251. Comments may be inspected in Room 915G

weekdays, except Federal holidays, between 8:30 a.m. and 5:00 p.m. In

addition, the FAA is maintaining an information docket of comments in

the Office of the Assistant Chief Counsel (ANM-7), Federal Aviation

Administration, Northwest Mountain Region, 1601 Lind Avenue SW, Renton,

Washington 98055-4056. Comments in the information docket may be

inspected in the Office of the Assistant Chief Counsel weekdays, except

Federal holidays, between 7:30 a.m. and 4:00 p.m.

FOR FURTHER INFORMATION CONTACT:

Mike McRae, FAA, Airframe and Propulsion Branch (ANM-112), Transport

Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue

SW., Renton, Washington 98055-4056; telephone (206) 227-2133.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in this proposed

rulemaking by submitting such written data, views, or arguments as they

may desire. Comments relating to the environmental, energy, or economic

impact that might result from adopting the proposals contained in this

notice are invited. Substantive comments should be accompanied by cost

estimates. Commenters should identify the regulatory docket or notice

number and submit comments, in triplicate, to the Rules Docket address

specified above. All comments received on or before the closing date

for comments will be considered by the Administrator before taking

action on this proposed rulemaking. The proposals contained in this

notice may be changed in light of comments received. All comments will

be available in the Rules Docket, both before and after the closing

date for comments, for examination by interested persons. A report

summarizing each substantive public contact with FAA personnel

concerning this rulemaking will be filed in the docket. Commenters

wishing the FAA to acknowledge receipt of their comments must submit

with those comments a self-addressed, stamped postcard on which the

following statement is made: ``Comments to Docket No. 24251.'' The

postcard will be date stamped and returned to the commenter.

Availability of NPRM

Any person may obtain a copy of this NPRM by submitting a request

to the Federal Aviation Administration, Office of Public Affairs,

Attention: Public Information Center, APA-230, 800 Independence Avenue

SW., Washington, D.C. 20591, or by calling (202) 267-3484.

Communications must identify the notice number of this NPRM. Persons

interested in being placed on a mailing list for future rulemaking

documents should also request a copy of Advisory Circular No. 11-2A,

Notice of Proposed Rulemaking Distribution System, which describes the

application procedures.

Background

Section 25.954 (14 CFR 25.954) of the current airworthiness

standards for transport category airplanes requires, in part, that any

fuel system vents be designed to protect the fuel system from ignition

by lightning strikes or electrostatic phenomenon. However, fuel system

vents are not required to protect the fuel system from ignition during

a post-crash ground fire. Improved fuel system vent fire protection is

the subject of this NPRM.

To investigate the feasibility of reducing the severity or

occurrence of airplane fires and explosions, the FAA held two public

hearings in 1977. The first, in June, considered fire and explosion

hazard reduction. The second, in November, dealt with the flammability

of compartment interior materials. From the information obtained at

those 1977 hearings, the FAA concluded that pending rulemaking actions

on fuel tank explosion protection and flammability, toxicity, and smoke

production concerning cabin materials were premature. The FAA decided

to reexamine the technologies involved in reducing those hazards before

going forward with any new rules.

To focus advice from the industry and the public at large for this

review of available technology, the FAA formed the Special Aviation

Fire and Explosion Reduction (SAFER) Advisory Committee on June 26,

1978. The committee consisted of a chairman and executive director,

plus 24 representatives spanning the spectrum of international aviation

interests.

The SAFER Committee's advice and recommendations to the FAA are

embodied in a final report, FAA-ASF-80-4, dated June 26, 1980, Final

Report of the Special Aviation Fire and Explosion Reduction (SAFER)

Advisory Committee. This notice responds to the recommendation of the

SAFER Committee concerning fuel system vent protection. Recommendations

made in other areas are the subject of other rulemaking actions and are

not relevant to this notice.

The SAFER Committee reviewed worldwide transport airplane accidents

involving post-crash fuel tank explosions that had occurred since 1964

and concluded that with existing technology, the potential for post-

crash explosion hazards could be reduced. The Committee considered that

fuel system vent flame arrestors or surge tank explosion suppression

systems used in some current airplanes to protect against lightning-

induced ignition at fuel vent outlets might also be able to delay

propagation of ground fires and the subsequent explosions, to provide

additional time for safe evacuation of passengers. They also considered

that a design practice in use on some current airplanes that provides

for closure of both fuel tank-to-engine and engine fuel control shutoff

valves during normal engine shutdown would also maximize the

probability of engine fuel supply shutoff in post-crash fire accidents.

On the basis of these

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considerations, the SAFER Committee made the following regulatory

recommendations to the FAA:

1. Amend 14 CFR part 25 to require fuel tank vent protection from

ground fires by adding a new Sec. 25.975(a)(7) to read: ``Each vent to

atmosphere must be designed to minimize the possibility of external

ground fires being propagated through the vent line to the tank vapor

space, providing that the tank and vent structure remain intact.''

2. Amend part 25 to require design practices that maximize the

probability of engine fuel supply shutoff in potential fire situations.

To implement the SAFER propulsion system recommendations,

preliminary rulemaking action was initiated. Advance Notice of Proposed

Rulemaking (ANPRM) No. 84-17 was published in the Federal Register (49

FR 38078, September 26, 1984) for the purpose of obtaining public

comments, information, and data relative to adding new airworthiness

standards applicable to transport category airplane fuel systems. The

objective of the rulemaking proposed in Notice 84-17 was to develop

airworthiness standards that would provide protection against fuel tank

explosions following a post-crash ground fire, and that would assure

engine and auxiliary power unit fuel supply shutoff to reduce the fire

hazard from spilled fuel.

Comments were received from the general public, airplane

manufacturers, and other interested organizations in the United States

and Europe. Eight of the commenters, including the Airline Pilots

Association (ALPA), Aerospace Industries Association of America (AIAA),

and the Air Transport Association of America (ATA), support the

proposed rule change regarding fuel system vent fire protection,

whereas five commenters object to the proposal. The ATA response

indicates that while comments received from their member airlines

generally support the ``aircraft design enhancements'' discussed in the

ANPRM, some remain unconvinced that the specific proposals will produce

the desired results. They state, however, that even with minimal

justification for such changes, it appears sufficiently promising to

proceed with a more detailed cost-benefit analysis.

In general, commenters opposing the proposal argue that the added

cost and complexity of the installed fuel system vent fire protection

would exceed the very small safety benefits that might accrue from the

installation. Further, they express concern that the critical vent

system performance might be compromised by the installation of a flame

arrestor. They believe the costs would not be commensurate with the

benefits, although they submitted no facts or figures to support their

contention. One commenter states that the occurrence of only two

incidents in a 20-year period, only one of which would have been

mitigated if the airplane had met the proposed fire protection

standards, is not sufficient justification for requiring new standards.

As discussed below, the FAA concludes that the projected benefits from

this proposal are sufficient to warrant further action. Further, the

costs and risks to vent performance are expected to be relatively

small, since the majority of transport category airplanes currently

incorporate flame arrestors in the fuel system vents. Many of these

arrestor installations were expressly designed to provide protection

from ground fires and have demonstrated the ability to safeguard vent

system performance.

A preliminary regulatory evaluation was completed in November 1985.

Although the analysis showed that the costs exceeded the benefits, it

was noted that the analysis did not properly account for the potential

magnitude of a hazardous situation created by a post-crash ground fire

and a fuel tank explosion. As discussed below, to address these factors

a new regulatory evaluation was completed that demonstrates that the

benefits exceed the costs. Therefore, in light of the comments received

in response to Notice 84-17, the SAFER Committee conclusions and

recommendations, and the fact that public safety would be enhanced, the

FAA finds the proposed changes to 14 CFR parts 25, 121, 125, and 135

are in the interest of public safety and should be promulgated.

Nevertheless, the comments received in response to the advance notice

were considered during the development of the regulatory evaluation for

this notice.

While the regulatory evaluation for this notice was being prepared,

Congress enacted Public Law 100-591, ``Aviation Safety Research Act of

1988.'' Section 9(a) of that Act resulted in the FAA publication of

Advance Notice of Proposed Rulemaking (ANPRM) No. 89-11 (54 FR 18824,

May 2, 1989). Notice 89-11 requested new information on the feasibility

of installing ``crashworthy fuel systems.'' The comments received

indicate that although additional information is needed, improvements

in fuel system crashworthiness beyond those envisioned by the SAFER

committee recommendation on fuel feed shutoff are feasible. Therefore,

the fuel feed shutoff provisions of Notice 84-17 are being incorporated

into the regulatory evaluation prepared for the proposed rulemaking

resulting from Notice 89-11, which the FAA anticipates will more

completely address the threat from fuel leakage following a survivable

crashlanding.

Discussion

To minimize the possibility of propagation of external ground fires

through the vent system, it would be necessary to design a flame

arrestor or flame suppression device or system to prevent flame

penetration and propagation through the airplane fuel tank vent system

for a finite period of time. This time period should be no less than

the time required for an external fire to heat fuel and vapors in a

wing tank to its auto ignition temperature, or for an external fire to

penetrate the undersurface of an empty wing tank, whichever is greater.

Typically, this tank material is at least fire resistant; therefore, a

period of protection of five (5) minutes is considered consistent with

the currently accepted criteria for fire resistant materials. The FAA

proposes to adopt a new Sec. 25.975(a)(7) to require that each fuel

tank be designed to prevent the propagation of flames from external

fires through the fuel tank vents and any other external openings to

fuel tank vapor spaces for a minimum of five minutes after a survivable

crash landing when the fuel tank and the vent system remain intact.

In order to maximize the net potential benefits by increasing

safety during survivable post-crash evacuations, the FAA considers it

appropriate to require that the proposed changes to part 25 be

incorporated in all transport category airplanes that are used in air

carrier, air taxi, or commercial service under the provisions of 14 CFR

parts 121, 125, or 135 as soon as practicable. Currently, about 75

percent of the fleet have a flame arrestor device that may comply with

proposed Sec. 25.975(a)(7). For airplanes manufactured after the

effective date of the rule, compliance would be required within one

year. For all other airplanes in operation, compliance would be

required within two years. The FAA considers this timeframe to be

sufficient to allow manufacturers and operators to design and install a

fuel vapor flame suppression device that meets the new requirements.

Parts 121, 125, and 135 would be revised accordingly.

Regulatory Evaluation

This section summarizes the full regulatory evaluation prepared by

the FAA that provides more detailed estimates of the economic

consequences of this proposed regulatory action. This summary and the

full evaluation

[[Page 6634]]

quantify, to the extent practicable, estimated costs and anticipated

benefits to the private sector, consumers, and Federal, State, and

local governments.

Proposed 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.

Finally, the Office of Management and Budget directs agencies to assess

the effects of regulatory changes on international trade. In conducting

these analyses, the FAA has determined that this rule: (1) Would

generate benefits that would justify its costs and is not a

``significant regulatory action'' as defined in the Executive Order;

(2) is not significant as defined in Department of Transportation

Regulatory Policies and Procedures; (3) would not have a significant

impact on a substantial number of small entities; and (4) would not

have a negative impact on international trade. These analyses,

available in the docket, as summarized below.

As discussed earlier, several commenters to the ANPRM claim that

the benefits of fuel system vent protection would not outweigh the

costs. The FAA disagrees with these claims. The Special Aviation Fire

and Explosion Reduction (SAFER) Advisory Committee identified four

accidents worldwide in which effective fuel vent fire protection could

have prevented or delayed post-crash fires (Malaysian Airways Comet 4,

Singapore, 1964; TWA 707, Rome, 1964; BOAC 707, London, 1968; and

Seaboard World DC-8, Stockton, 1969. After sustaining relatively minor

impact damage, all four airplanes were destroyed by fire and

explosions, resulting in 53 fatalities and 55 serious injuries. As

summarized below, the number of fuel tank fires that this proposed rule

might prevent is expected to be low, but the expected value of averting

a single incident would exceed the estimated compliance costs.

Costs

The FAA assumes that manufacturers and operators would use vent

flame arrestors as the most effective and economical means of

compliance. For a representative large transport airplane, the FAA

estimates that non-recurring costs would be approximately $700 and that

recurring operating costs would be approximately $51 per year.

Corresponding estimates for a representative small transport airplane

are approximately $400 in non-recurring costs and $51 in recurring

costs.

Section 25.954 currently requires, in part, that fuel systems be

designed to prevent ignition within the fuel system by lightning

strikes and other electrostatic phenomena. Flame arrestors and

suppressors are offered as standard or optional equipment on most U.S.

transport airplanes in current production. Approximately 75 percent of

the transport airplane fleet currently have devices that might meet the

criteria of the proposed rule. Until actual testing and evaluation is

performed, however, it cannot be determined whether these devices would

qualify. For purposes of this cost analysis, therefore, all relevant

airplanes are assumed to be affected.

Based on this premise, approximately 11,048 airplanes would be

affected during the first ten years following the effective date of the

rule. applying the unit costs summarized above to this number of

airplanes yields a total cost of $18.8 million (constant dollars), or

$11.5 million discounted to present value. The average annualized costs

per airplane are $142 for large transport airplanes and $120 for small

transport airplanes.

Benefits

Since the four accidents identified by the SAFER Advisory

Committee, there have been no known accidents in which fuel vent fire

protection would have prevented or delayed post-crash fires. This is

attributable in part to regulatory and voluntary initiatives aimed

aircraft fire safety, such as the use of less volatile fuels, and

improve safety performance that reduced the opportunities for post-

crash fires.

Notwithstanding the absence of fuel tank fires in recent years and

lacking other sufficient bases upon which to estimate the risks of

future fires, the merits of the proposed rule can be assessed by

considering the number of incidents that would need to be prevented to

offset the costs of the rule. For large passenger-configured transport

airplanes, the prevention of one fuel tank fire during the operating

lives of such airplanes affected during the first ten years of the rule

would yield expected benefits of approximately $106 million, or $40.1

million discounted to present value. This estimate reflects an accident

involving a representative large transport airplane with 130 occupants

and 20 percent fatality and 20 percent serious injury rates.

Corresponding estimates for small passenger-configured and cargo-

configured transport airlines would be $15 million ($5.7 million

discounted) and $16 million ($6.0 million discounted), respectively.

Summary of Costs and Benefits

The FAA finds the proposed rule to be cost beneficial because the

expected benefits of preventing just one post-crash fire outweigh the

expected costs ($40.1 million in benefits versus $7.3 million in costs

for large passenger-configured transport airplanes; $5.7 million in

benefits versus $4.2 million in costs for small passenger-configured

transport airplanes; and $6.0 million in benefits versus $5.7 million

in costs for cargo-configured transport airplanes). If this action is

not taken, a hazard would continue to exist, even though effective and

low-cost means are available to minimize or eliminate it. To the extent

that existing devices might satisfy the proposed criteria, the total

incremental costs would be less than those summarized above.

Regulatory Flexibility Determination

The Regulatory Flexibility Act of 1980 (RFA) was enacted by

Congress to ensure that small entities are not unnecessarily or

disproportionately burdened by government regulations. The RFA requires

agencies to evaluate alternative remedies when a rule would have a

``significant economic impact on a substantial number of small

entities.'' The FAA has determined that the proposed rule would not

have a significant impact on a substantial number of small entities.''

Trade Impact Statement

The proposed rule would have no impact on trade opportunities for

U.S. firms doing business in foreign markets and foreign firms doing

business in the U.S. market.

Federalism Implications

The regulations proposed herein would not have substantial direct

effects 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. Therefore, in

accordance with Executive Order 12612, it is determined that this

proposal would not have sufficient federalism implications to warrant

the preparation of a Federalism Assessment.

Conclusion

Because the installation of fuel system vent protection equipment

is not expected to result in a substantial economic cost, the FAA has

determined that this proposed regulation is not significant under

Executive Order 12866. In addition, the FAA has

[[Page 6635]]

determined that this action is not significant as defined in Department

of Transportation Regulatory Policies and Procedures (44 FR 11034,

February 26 1979). Under the criteria of the Regulatory Flexibility

Act, the FAA certifies that this proposed regulation, if adopted, would

not have a significant economic impact, positive or negative, on a

substantial number of small entities. A copy of the initial regulatory

evaluation prepared for this proposal may be examined in the public

docket or obtained from the person identified under the caption, FOR

FURTHER INFORMATION CONTACT.

List of Subjects

14 CFR Part 25

Aircraft, Aviation safety, Reporting and recordkeeping

requirements.

14 CFR Part 121

Air carriers, Aircraft, Airmen, Aviation safety, Charter flights,

Reporting and recordkeeping requirements, Safety, Transportation.

14 CFR Part 125

Aircraft, Airmen, Aviation Safety, Reporting and recordkeeping

requirements.

14 CFR Part 135

Air taxis, Aircraft, Airmen, Aircraft safety, Reporting and

recordkeeping requirements.

The Proposed Amendments

Accordingly, the Federal Aviation Administration (FAA) proposes to

amend 14 CFR parts 25, 121, 125, and 135 of the Federal Aviation

Regulations (FAR) as follows:

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

1. The authority citation for part 25 continues to read as follows:

Authority: 49 U.S.C. app. 1344, 1354(a), 1355, 1421, 1423, 1424,

1425, 1428, 1429, 1430; 49 U.S.C. 106(g); and 49 CFR 1.47(a).

2. By amending Sec. 25.975 by removing the word ``and'' at the end

of paragraph (a)(5), by removing the period at the end of paragraph

(a)(6) and adding ``; and'' in its place, and by adding a new paragraph

(a)(7) to read as follows:

Sec. 25.975 Fuel tank vents and carburetor vapor vents.

(a) * * *

(7) Each fuel tank vent must be designed to prevent the propagation

of flames from external ground fires through the fuel tank vents and

any other external openings to fuel tank vapor spaces for a minimum of

five minutes after a survivable crash landing, when the fuel tank and

the vent system remain intact.

* * * * *

PART 121--CERTIFICATION AND OPERATIONS: DOMESTIC FLAG, AND

SUPPLEMENTAL AIR CARRIERS AND COMMERCIAL OPERATORS OF LARGE

AIRCRAFT

3. The authority citation for part 121 continues to read as

follows:

Authority: 49 U.S.C. app. 1354(a), 1355, 1356, 1357, 1401, 1421-

1430, 1472, 1485, and 1502; 49 U.S.C. 106(g).

4. By revising Sec. 121.316 to read as follows:

Sec. 121.316 Fuel systems.

(a) No person may operate a turbine-powered transport category

airplane after October 30, 1991, unless it meets the fuel tank access

cover criteria of Sec. 25.963(e) of this chapter in effect on October

30, 1989.

(b) After [a date 1 year after the effective date of the

amendment], no person may operate a transport category airplane

manufactured on or after that date unless it is equipped with a fuel

vapor flame suppression device that meets the requirements of

Sec. 25.975(a)(7) of this chapter.

(c) After [a date 2 years after the effective date of the

amendment], no person may operate any other transport category airplane

unless it is equipped with a fuel vapor flame suppression device that

meets the requirements of Sec. 25.975(a)(7) of this chapter.

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

5. The authority citation for part 125 continues to read as

follows:

Authority: 49 U.S.C. 1354, 1421 through 1430, and 1502; 49

U.S.C. 106(g), (Revised Pub. L. 97-449, January 12, 1983).

6. By adding a new Sec. 125.214 to read as follows:

Sec. 125.214 Fuel systems.

(a) After [a date 1 year after the effective date of the

amendment], no person may operate a transport category airplane

manufactured on or after that date unless it is equipped with a fuel

vapor flame suppression device that meets the requirements of

Sec. 25.975(a)(7) of this chapter.

(b) After [a date 2 years after the effective date of the

amendment], no person may operate any other transport category airplane

unless it is equipped with a fuel vapor flame suppression device that

meets the requirements of Sec. 25.975(a)(7) of this chapter.

PART 135--AIR TAXI OPERATORS AND COMMERCIAL OPERATORS

7. The authority citation for part 135 continues to read as

follows:

Authority: 49 U.S.C. app. 1354(a), 1355(a), 1421 through 1431,

and 1502; 49 U.S.C. 106(g); and 49 CFR 1.47(a).

8. By adding a new Sec. 135.187 to subpart C to read as follows:

Sec. 135.187 Fuel systems.

(a) After [a date 1 year after the effective date of the

amendment], no person may operate a transport category airplane

manufactured on or after that date unless it is equipped with a fuel

vapor flame suppression device that meets the requirements of

Sec. 25.975(a)(7) of this chapter.

(b) After [a date 2 years after the effective date of the

amendment], no person may operate any other transport category airplane

unless it is equipped with a fuel vapor flame suppression device that

meets the requirements of Sec. 25.975(a)(7) of this chapter.

Issued in Washington, D.C., on January 20, 1995.

Elizabeth Yoest,

Acting Director, Aircraft Certification Service.

[FR Doc. 95-2115 Filed 2-1-95; 8:45 am]

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