[Federal Register Volume 59, Number 248 (Wednesday, December 28, 1994)]
[Unknown Section]
[Page ]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-31913]


[Federal Register: December 28, 1994]


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Part VII





Department of Transportation





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Federal Aviation Administration



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14 CFR Part 23



Powerplant Instruments; Fuel Pressure Indication; Proposed Rule
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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. 28011; Notice No. 94-37]
RIN 2120-AF41


Powerplant Instruments; Fuel Pressure Indication

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to amend the certification requirement 
for fuel pressure indicators on pump fed engines of small airplanes to 
permit regulatory alternatives to warn pilots of fuel system problems. 
A fuel pressure indicator is not the only means available to the pilot 
of indicating a fuel system problem. The proposed change would allow 
airplanes to be certificated with means that indicate fuel flow, or 
that monitor the fuel system and warn the pilot of a trend that could 
lead to engine failure. New technology that would be incorporated as 
means of compliance with the revised rule could improve engine 
operation and reduce airplane operating costs.

DATES: Comments must be received on or before February 27, 1995.

ADDRESSES: Comments on this document should be mailed in triplicate to: 
Federal Aviation Administration, Office of the Chief Counsel, 
Attention: Rules Docket (AGC-10), Docket No. 28011, 800 Independence 
Avenue SW., Washington, DC 20591. Comments delivered must be marked 
Docket No. 28011. Comments may be inspected in room 915G weekdays 
between 8:30 a.m. and 5 p.m., except on Federal holidays.
    In addition, the FAA is maintaining an information docket of 
comments in the Office of the Assistant Chief Counsel, ACE-7, Federal 
Aviation Administration, Central Region, 601 East 12th Street, Kansas 
City, Missouri 64106. Comments in the information docket may be 
inspected in the Office of the Assistant Chief Counsel weekdays, except 
Federal holidays, between the hours of 7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT:
J. Lowell Foster, Standards Office, Small Airplane Directorate, 
Aircraft Certification Service, Federal Aviation Administration, 601 
East 12th Street, Kansas City, Missouri 64106; telephone (816) 426-
5688.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule 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 in this 
notice are also invited. Substantive comments should be accompanied by 
cost estimates. Comments should identify the regulatory docket or 
notice number and should be submitted in triplicate to the Rules Docket 
address specified above. All comments received on or before the closing 
date for comments specified 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 received will be available, both before and after the 
closing date for comments, in the Rules Docket for examination by 
interested persons. A report summarizing each substantive public 
contact with Federal Aviation Administration (FAA) personnel concerned 
with this rulemaking will be filed in the docket. Commenters wishing 
the FAA to acknowledge receipt of their comments submitted in response 
to this notice must include a preaddressed, stamped postcard on which 
the following statement is made: ``Comments to Docket No. 28011.'' The 
postcard will be date stamped and mailed 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 Inquiry Center, APA-200, 800 Independence Avenue, 
SW., Washington, DC 20591, or by calling (202) 267-3484. Communications 
must identify the notice number of this NPRM.
    Persons interested in being placed on the mailing list for future 
NPRMs should request, from the above office, a copy of Advisory 
Circular No. 11-2A, Notice of Proposed Rulemaking Distribution System, 
which describes the application procedure.

Background

Statement of the Problem

    The FAA proposes to amend Title 14 of the Code of Federal 
Regulations (CFR), Sec. 23.1305(b)(4), which currently requires a fuel 
pressure indicator for each pump fed engine. The pressure indicator 
gives continuous fuel pressure readings to the pilot. This information 
provides an advance warning of engine failure only when a pilot notices 
that the pressure reading has deviated from the norm, and the pilot can 
diagnose what those deviations mean in terms of potential engine 
failure. This proposal would allow the options of a fuel pressure 
indicator, a fuel flow indicator, or a means that continuously monitors 
the fuel system and warns the pilot of any engine trend that could 
cause engine failure. A fuel flow indicator would give continuous fuel 
flow readings to the pilot; fuel flow information can be more 
meaningful to the pilot during critical phases of flight. The proposed 
continuous fuel system monitoring would alert the pilot to any trend 
that could lead to engine failure.

History

    The first requirement for a fuel pressure indicator was found in 
Civil Air Regulation (CAR) 4b, the predecessor to part 25 of Title 14 
for transport airplanes. That requirement applied to all reciprocating 
engine airplanes. CAR 3, applicable to small airplanes, followed CAR 4b 
and was the predecessor to part 23 of Title 14. Amendment 1 to CAR 3, 
adopted December 15, 1946, required fuel pressure indicators on 
airplanes with pump-fed engines. Many small airplanes of that era used 
gravity-fed fuel systems, which made a fuel pressure indication 
unnecessary. Also, a fuel pressure indication was not required if the 
fuel pump was certificated as part of the engine. Since early fuel 
pumps were less reliable, the intent of the CAR requirements was to 
provide the pilot with advance warning of a fuel pump failure. This 
allowed the pilot to diagnose the problem and prevent engine failure or 
determine the cause after the engine quit.
    Engines of the CAR 3 era were designed with carburetors. 
Carburetors were replaced by fuel injection. At the same time, radial 
engines were being replaced with horizontally opposed engines, the 
configurations currently used in the majority of light airplanes.
    As horizontally opposed engines gained popularity and grew in 
displacement, two different types of fuel injection systems emerged. 
One consisted of a fuel injector or fuel metering unit that relied on a 
separate constant pressure pump to supply fuel to the injector. Since 
the metering (regulating) was done at the injector, the fuel pressure 
required was not critical as long as the pump could provide a specific 
range of pressures. For example, if the injector had a 20 psi 
requirement, 23-30 psi pump pressure was acceptable because the fuel 
pressure on the outlet side of the injector was 20 psi. But, if the 
pressure out of the pump fell below 20 psi, the injector would fail to 
provide adequate fuel to the engine.
    The second type of fuel injection system used a fuel pump in which 
pressure was proportional to engine RPM. This pump is still referred to 
as a speed-sensing integral fuel pump. Any change in pump pressure 
resulted in a change in engine operation.
    Regulatory interpretation resulted in confusion over what was 
acceptable for fuel pressure monitoring, including the requirements for 
the content of indicated information and the pressure pick-up location. 
Some installations utilizing the constant pressure pump were required 
to have a pressure indicator measuring unmetered fuel pressure at the 
fuel pump output. On the other hand, installations using the speed-
sensing integral pump system were approved with a fuel pressure 
indicator measuring metered fuel pressure at the fuel distribution 
valve. Airplanes utilizing this system have a fuel pressure indicator 
labeled in fuel used per hour or fuel flow. Agency policy, briefing 
paper from Central Region dated October 7, 1981, accepted these fuel 
pressure indicators as an equivalent means of compliance if the engine 
was certificated with an integral speed-sensing pressure pump.
    The Aircraft Owners and Pilots Association (AOPA) petitioned the 
FAA for new standards that would allow, on all pump-fed engines, a fuel 
flow system employing a differential pressure transducer to be accepted 
as an equivalent means of compliance to the current fuel pressure 
indicator requirements (55 FR 39299; September 26, 1990). The AOPA 
believes that adopting its petition would open the door for the 
development of new and valuable engine monitoring equipment, while 
potentially reducing the instrument panel clutter.
    In its petition, the AOPA states that one of the reasons for 
current Sec. 23.1305(b)(4) is to give the pilots sufficient warning of 
any decreasing trend that could lead to partial or total engine 
failure. The AOPA also states that differential pressure indicators 
should be accepted as a means of compliance with Sec. 23.1305(b)(4), 
not that direct sensing systems should be removed from part 23.
    Following receipt of the AOPA's petition for rulemaking, the FAA 
requested that the Aviation Rulemaking Advisory Committee (ARAC) review 
the petition and recommended a course of action to the FAA. The ARAC 
was chartered in February 1991, under the Federal Advisory Committee 
Act, to provide recommendations to the FAA Administrator on FAA 
rulemaking activity relating to aviation safety issues.
    In January 1992, the Fuel Indicators Working Group of the ARAC on 
General Aviation and Business Airplane Issues began review of the 
AOPA's petition. Subsequently, the ARAC, recommended that the FAA 
revise the certification standards for fuel pressure indicators. The 
ARAC agreed with the AOPA's petition to allow a pressure-based fuel 
flow system, but felt that there may be other options in the future, 
and that the AOPA's language regarding a differential pressure 
transducer would be too restrictive. Technical advances in the 
automobile industry with engine systems and controls may offer 
improvements over the current warning systems. The ARAC did not want 
the proposed rule to be limited to a fuel pressure or pressure-based 
fuel flow gauge.

General Discussion of the Proposals

Section 23.1305

    The intent of the fuel pressure indicator requirement for pump-fed 
engines is to advise the pilot of a fuel pressure deficiency before 
total engine failure. The term ``indicator'' in Sec. 23.1305(b)(4) 
implies that the fuel pressure be constantly displayed.
    This proposal would change the current requirements in that a fuel 
pressure indicator or a fuel flow indicator would be acceptable. The 
fuel flow indicator would constantly display information that the pilot 
could use to evaluate engine power, fuel mixture, and other engine 
performance factors. Furthermore, it is technologically possible to 
have a microprocessor that monitors engine operation and triggers a 
warning if the fuel system operation does not match the other monitored 
engine trends. Therefore, this proposal would also change the rule to 
accept a means that monitors the fuel system and warns the pilot of any 
trend that could lead to engine failure.
    Accordingly, this proposal would adopt a performance standard, 
instead of a requirement for specific equipment. In this way, the 
designer could show compliance with paragraph (b) of the proposal by 
developing any design that monitors the fuel system and warns the pilot 
of any trend that could lead to engine failure. The ARAC did not 
believe this would reduce the level of safety originally intended by 
the requirement. A warning light system could possibly alert the pilot 
sooner than if the pilot relied on an instrument panel scan to notice a 
trend in the fuel pressure indication.
    Microprocessing units that monitor engine operation and warn of 
fuel system problems have already been incorporated in transport 
aircraft and automobiles. Furthermore, pilots are not monitoring gauges 
like they use to; instead, they are increasingly relying on warnings to 
alert them. Late model automobiles, computers and other equipment are 
designed to protect the operators from mistakes by using built-in 
warnings. It is important to note that this NPRM does not propose to 
allow ``idiot lights'' to replace fuel pressure gauges. A light that 
comes on at the same time that the engine quits is useless. A warning 
light system that would comply with this proposal would be 
sophisticated enough to read transients and trends, and would give a 
useful warning to the pilot. The FAA expects this proposal to result in 
fuel systems that provide the pilot with useful engine operating 
information; thereby, it would offer more value to the operator.
    Today, fuel pumps are more reliable than those built in the 1940's 
and 50's. Consequently, airplane operators are more concerned about 
reducing engine operating costs than they are about the probability of 
a fuel pump failure.
    A fuel flow indicator offers additional value compared to a fuel 
pressure indicator. It enables the operator to monitor the engine's 
fuel consumption and compare it to fuel consumption listed in the 
airplane flight manual. If a fuel monitoring system is installed that 
automatically controls the engine or helps the pilot to properly lean 
the fuel mixture, then engine operation would be optimized and the 
direct operating costs would go down through reduced fuel consumption. 
Reciprocating engines run better if the fuel to air mixture is leaned 
out according to the optimum (manufacturer's) specified setting. 
Furthermore, fuel flow also relates to power, and pilots can use fuel 
flow readings to quickly assess the health of their engine during 
critical phases of flight, such as takeoff.
    Comprehensive engine monitors and redesigned electronic engine 
instrument displays are also being used in experimental aircraft. The 
FAA should encourage airplane manufacturers to utilize new technology 
to improve operation and reduce operating costs. New engine monitoring 
systems may improve reliability and engine life, resulting in increased 
safety.
    The proposal would achieve the same safety objective as the current 
rule; the crew would have sufficient warning of any negative trend that 
could lead to partial or total engine failure. However, the proposal 
recognizes that this objective can be achieved by measuring fuel 
pressure, fuel flow, or with a ``smart'' fuel monitoring system.

International Compatibility

    The agency has reviewed corresponding International Civil Aviation 
Organization international standards and recommended practices and 
Joint Aviation Authorities requirements for compatibility.

Paperwork Reduction Act

    In accordance with the Paperwork Reduction Act of 1990 (44 U.S.C. 
3501 et seq.), there are no reporting or recordkeeping requirements 
associated with this proposed rule.

Regulatory Evaluation Summary

    Proposed changes to federal regulations must undergo several 
economic analyses. First, Executive Order 12866 directs Federal 
agencies to promulgate new regulations or modify existing regulations 
only if the potential benefits to society outweigh the potential costs. 
Second, the Regulatory Flexibility Act of 1980 requires agencies to 
analyze the economic impact of regulatory change son small entities. 
Finally, the Office of Management and Budget directs agencies to assess 
the effects of regulatory change son international trade. In conducting 
these analyses, the FAA has determined that this rule: (1) Would 
generate benefits exceeding its costs and is not significant as defined 
in Executive Order 12866; (2) is not significant as defined in DOT's 
Policies and Procedures; (3) would not have a significant economic 
impact on small entities; and (4) would not affect international trade. 
These analyses, available in the docket, are summarized below.

Cost-Benefit Analysis

    Since the proposed rule would permit but not require alternative 
means of warning pilots of fuel system problems, it is inherently cost-
beneficial. To the extent that it would encourage the development and 
utilization of comprehensive engine control, monitoring and diagnostic 
systems in the future, it would contribute benefits in the form of 
enhanced safety, improved fuel efficiency, power output, and engine 
life.

Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (RFA) was enacted by 
Congress to ensure that small entities are not unnecessarily and 
disproportionately burdened by government regulations. The RFA requires 
a Regulatory Flexibility Analysis if a rule would have a significant 
economic impact, either detrimental or beneficial, on a substantial 
number of small entities. Based on criteria in FAA Order 2100.14A, 
Regulatory Flexibility Criteria and guidance, the FAA has determined 
that the proposed rule would not have a significant economic impact on 
a substantial number of small manufacturers or operators.

International Trade Impact Assessment

    The proposed rule would not constitute a barrier to international 
trade, including the export of U.S. airplanes to foreign markets or the 
import of foreign airplanes into the United States.

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 12866, it is determined that this 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.

Conclusion

    The FAA proposes to amend the airworthiness standards to allow 
airplane manufacturers to utilize new technology for fuel system 
monitoring to improve the operation and economy of part 23 airplanes 
powered by pump-fed engines. The current requirements provide for a 
fuel pressure indication; it, thus, limits the means of compliance. The 
advances in automobile engine monitoring systems and electronics offer 
technology that should be utilized by the aviation community. By 
broadening this airworthiness standard, fuel flow indicators or new 
fuel system monitors may be utilized that will provide more useful 
information to the pilot.
    For the reasons discussed in the preamble, and based on the 
findings in the Regulatory Flexibility Determination and the 
International Trade Impact Analysis, the FAA has determined that this 
proposed regulation is not significant under Executive Order 12866. In 
addition, the FAA certifies that this proposal, if adopted, will not 
have a significant economic impact, positive or negative, on a 
substantial number of small entities under the criteria of the 
Regulatory Flexibility Act. This proposal is not considered significant 
under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 
1979). An initial regulatory evaluation of the proposal, including a 
Regulatory Flexibility Determination and Trade Impact Analysis, has 
been placed in the docket. A copy may be obtained by contacting the 
person identified under FOR FURTHER INFORMATION CONTACT.

List of Subjects in 14 CFR Part 23

    Aircraft, Air transportation, Aviation safety, Safety.

The Proposed Amendment

    In consideration of the foregoing, the Federal Aviation 
Administration proposes to amend part 23 of the Federal Aviation 
Regulations (14 CFR part 23) as follows:

PART 23--AIRWORTHINESS STANDARDS; NORMAL, UTILITY, ACROBATIC, AND 
COMMUTER CATEGORY AIRPLANES

    1. The authority citation for part 23 continues to read as follows:

    Authority: 49 U.S.C. 1344, 1354(a), 1355, 1421, 1423, 1425, 
1428, 1429, 1430; 49 U.S.C. 106(g).

    2. Section 23.1305 is amended by revising paragraph (b)(4) to read 
as follows:


Sec. 23.1305  Powerplant instruments.

* * * * *
    (b) * * *
    (4) For each pump-fed engine, a means:
    (i) That continuously indicates, to the pilot, the fuel pressure or 
fuel flow; or
    (ii) That continuously monitors the fuel system and warns the pilot 
of any trend that could lead to engine failure.
* * * * *
    Issued in Washington D.C. on December 21, 1994.
Elizabeth Yoest,
Acting Director, Aircraft Certification Service.
[FR Doc. 94-31913 Filed 12-27-94; 8:45 am]
BILLING CODE 4910-13-M