[Federal Register Volume 60, Number 22 (Thursday, February 2, 1995)]
[Proposed Rules]
[Pages 6632-6635]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-2115]




[[Page 6631]]

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Part VI





Department of





Transportation





_______________________________________________________________________



Federal Aviation Administration



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14 CFR Part 25, et al.



Fuel System Vent Fire Protection; Proposed Rule

  Federal Register / Vol. 60, No. 22 / Thursday, February 2, 1995 / 
Proposed Rules   

[[Page 6632]]


DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 25, 121, 125, and 135

[Docket No. 24251; Notice No. 847-17A]
RIN 2120-AA49


Fuel System Vent Fire Protection

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking.

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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 

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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 

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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]
BILLING CODE 4910-13-M