[Federal Register Volume 63, Number 27 (Tuesday, February 10, 1998)]
[Proposed Rules]
[Pages 6826-6827]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-3344]



[[Page 6825]]

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Part VI





Department of Transportation





_______________________________________________________________________



Federal Aviation Administration



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14 CFR Part 135



Commercial Passenger-Carrying Operations in Single-Engine Aircraft 
Under Instrument Flight Rules; Proposed Rule

  Federal Register / Vol. 63, No. 27 / Tuesday, February 10, 1998 / 
Proposed Rules  

[[Page 6826]]



DEPARTMENT OF TRANSPORTATION

 Federal Aviation Administration

14 CFR Part 135

[Docket No. 28743; Notice No. 98-11]
RIN 2120-AG55


Commercial Passenger-Carrying Operations in Single-Engine 
Aircraft Under Instrument Flight Rules

AGENCY: Federal Aviation Administration, DOT.

AGENCY: Notice of proposed rulemaking.

-----------------------------------------------------------------------

SUMMARY: The Federal Aviation Administration (FAA) is proposing to 
revise and clarify certain conditions and limitations in Part 135 for 
instrument flight rule (IFR), passenger-carrying operations in single-
engine aircraft. The clarification is necessary to resolve ambiguity in 
the current rule over the requirement for redundant power for 
gyroscopic instrumentation. The intended effect of this action is to 
remove any ambiguity concerning the required power sources for the 
gyroscopic instruments required for flight under IFR for single engine 
aircraft involved in commercial, passenger carrying operations.

DATES: Comments must be received by March 12, 1998.

ADDRESSES: Comments on this notice should be submitted in triplicate 
to: Federal Aviation Administration, Office of the Chief Counsel, Attn: 
Rules Docket (AGC-200), Room 915-G, Docket No. 28743, 800 Independence 
Ave., SW, Washington, DC 20591.
    Comments must be marked Docket No. 28743. Comments also may be 
submitted electronically to the following Internet address: 9-nprm-
[email protected]. Comments may be examined in room 915G weekdays 
between 8:30 a.m. and 5 p.m. except on Federal holidays.

FOR FURTHER INFORMATION CONTACT: Mr. Dan Meier, Flight Standards 
Service, Federal Aviation Administration, 800 Independence Ave., SW, 
Washington, DC, 20591 (202) 267-8166.

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, 
federal, or economic impact that might result from adopting the 
proposals in this notice are also invited. Substantive comments should 
be accompanied by cost estimates, if appropriate. 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 specified 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 received will be available, 
both before and after the closing dates for comments, in the Rules 
Docket for examination by interested persons. A report summarizing each 
substantive contact with 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 pre-addressed, stamped postcard on which the following 
statement is made: ``Comments to Docket No. 28743.'' The postcard will 
be date stamped and returned to the commenter.

Availability of NPRMs

    An electronic copy of this document may be downloaded, using a 
modem and suitable communications software, from the FAA regulations 
section of the Fedworld electronic bulletin board service (703) 321-
3339), the Federal Register's electronic bulletin board service ((202) 
512-1661), or the FAA's Aviation Rulemaking Advisory Committee Bulletin 
Board service ((800) 322-2722 or (202) 267-5948).
    Internet users may reach the FAA's web page at http://www.faa.gov 
or the Federal Register web page at http://www.access.gpo.gov/su__ docs for access to recently published rulemaking documents.
    Any person may obtain a copy of this NPRM by submitting a request 
to the Federal Aviation Administration, Office of Rulemaking, ARM-1, 
800 Independence Ave, SW, Washington, DC 20591, or by calling (202) 
267-9677. Communications must identify the notice number or docket 
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

    On August 6, 1997, the FAA published Amendment 135-70 (62 FR 42364) 
that allowed commercial, passenger-carrying operations under IFR in 
single-engine aircraft under certain conditions and limitations, and 
eliminates the limited IFR provision of the current rule. The effective 
date for the new rule is May 4, 1998 (62 FR 45014) to allow operators 
to obtain the necessary parts and approvals, to modify their operations 
manuals and specifications, and to retrofit their aircraft. The FAA 
also established Special Federal Aviation Regulations (SFAR) 81 to 
accommodate those operators who may be ready to meet the requirements 
of the rule sooner than the effective date.

Discussion of the Proposed Rule

    Current SFAR 81, paragraph 2(b) and 14 CFR 135.163(h) require 
single-engine, passenger-carrying aircraft flying IFR to have two 
independent sources of energy (with means of selecting either), of 
which at least one is an engine-driven pump or generator, each of which 
is able to drive all gyroscopic instruments and installed so that 
failure of one instrument or source does not interfere with the energy 
supply to the remaining instruments or the other energy source.
    A question was raised as to whether this requirement would allow 
the use of a ``split panel,'' in which gyroscopic instruments could be 
driven by different energy sources, including vacuum, bleed air, or 
electrical sources. This question was also raised when the original 
requirement for dual sources of energy for gyroscopic instruments was 
promulgated. In the October 10, 1978 (43 FR 46769) preamble discussion 
regarding Sec. 135.163(h), the Agency stated that:

    Other commenters state that Sec. 135.163 prohibits ``splitting'' 
gyro instruments between electrical and vacuum sources and that 
defeats safety. For instrument panels with both electric and vacuum 
instruments, a pump or generator is unable to drive all gyroscopic 
instruments. The pilot must be able to select an energy source which 
will drive all gyros if the other source fails. Anything less under 
IFR conditions would derogate safety. Where a split panel is 
desired, each engine must have both a generator and a vacuum pump. 
(emphasis added)

    Thus, in October 1978, the Agency clearly contemplated that split 
panels would be used and that failure of one energy source must not 
impact the operation of the gyroscopic instruments. This requirement 
can readily be met by multi-engine aircraft because 14 CFR parts 23 and 
135 require each independent source of energy to be on separate engines 
and that the means of selecting the energy source be either automatic 
or manual. For single-engine aircraft, however, the issue centers on

[[Page 6827]]

whether one energy source must be able to drive all gyroscopic 
instruments. While a single engine airplane does not provide engine 
redundancy, system redundancy is still required for each gyroscopic 
instrument.
    Therefore, the FAA has determined that a ``split panel,'' i.e., 
instruments driven by separate and independent sources, is an 
acceptable configuration for single-engine aircraft provided that each 
required gyroscopic instrument has a redundant energy source. This 
means that if any one energy source fails, all gyroscopic instruments 
must remain operable. This does not mean, however, that each source 
must drive all of the instruments, but rather that the failure of any 
one source would not result in the loss of energy to any gyroscopic 
instrument powered by that energy source.
    For example, an acceptable configuration would be a gyroscopic 
direction indicator powered by redundant electrical sources, and a 
gyroscopic pitch and bank indicator (with artificial horizon) powered 
by bleed air and vacuum sources. Failure of any one energy source would 
not affect operation of all of the gyroscopic instruments. Thus, in 
this example, if one electrical source fails there is a redundant 
electrical system to power the direction indicator, and the artificial 
horizon indicator continues to be powered by the vacuum or bleed air 
system.
    Therefore, to clarify that although each independent source of 
energy need not drive all gyroscopic instruments, and that each 
gyroscopic instrument must be powered by redundant sources, the Agency 
has deleted the phrase ``all gyroscopic instruments,'' and has replaced 
it with the phrase ``all gyroscopic instruments powered by, or to be 
powered by, that particular source.''
    The FAA also wishes to clarify that where single-engine, passenger-
carrying IFR operations are flown with a single pilot and an autopilot, 
only the gyroscopic instruments on the pilot's panel need be operable 
and powered by redundant energy sources. However, where such operation 
is to be flown with both a pilot and a co-pilot, the gyroscopic 
instruments on both panels must be operable and powered by redundant 
energy sources.
    Another question was raised as to the meaning of the phrase ``means 
of selecting either,'' as it pertains to energy source redundancy. As 
discussed above, Sec. 23.1331(c) requires that the means of selecting 
energy sources be either automatic or manual. In the example cited 
above, Sec. 23.1331 would be met because when the direction indicator 
failed, the redundant electrical source powering that instrument 
automatically allowed for its continued operation.

Regulatory Analyses

    The FAA is proposing this change because some commenters to the 
final rule on Commercial Passenger-Carrying Operations in Single-Engine 
Aircraft under Instrument Flight Rules had questions on the redundant 
sources of power to the gyroscopic flight instruments. This propose 
change will alleviate any ambiguity and clarify the regulatory 
requirements. Therefore, the FAA has determined that this regulation 
imposes no additional burden on any entity. Accordingly, it has been 
determined that the action (1) is not significant under Executive Order 
12866 and (2) is not a significant rule under the Department of 
Transportation Regulatory Policies and Procedures (44 FR 11034; 
February 26, 1979). Also, because this proposed amendment is editorial 
in nature, no impact is expected to result and a full regulatory 
evaluation is not required. In addition, the FAA certifies that this 
proposal will not have a significant economic impact, either positive 
or negative, on a substantial number of small entities under the 
criteria of the Regulatory Flexibility Act.

International Trade Impact

    The proposed amendment would not impose any costs on either U.S. or 
foreign operators. Therefore, a competitive trade disadvantage would 
not be incurred by either U.S. operators abroad or foreign operators in 
the United States.

Paperwork Reduction Act

    This proposed rule contains no information collection requests 
requiring approval of the Office of Management and Budget pursuant to 
the Paperwork Reduction Act (44 U.S.C. 3507 et seq.).

List of Subjects in 14 CFR Part 135

    Air taxis, Aircraft, Aviation safety, Safety, Single-engine 
aircraft.

    For the reasons set out in the preamble, 14 CFR part 135 is 
proposed to be amended as set forth below:

PART 135--OPERATING REQUIREMENTS: COMMUTER AND ON-DEMAND OPERATIONS

    1. The authority citation for part 135 continues to read as 
follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44705, 44709, 
44711-44713, 44715-44717, 44722.


SFAR No. 81  [Amended]

    2. Paragraph 2(b) of Special Federal Aviation Regulation No. 81 is 
revised to read as follows:

SFAR No. 81--Passenger-Carrying Single-Engine IFR Operations

    2. * * *
    (a) * * *
    (b) Two independent sources of energy (with means of selecting 
either) of which at least one is an engine-driven pump or generator, 
each of which is able to drive all gyroscopic instruments powered by, 
or to be powered by, that particular source and installed so that 
failure of one instrument or source does not interfere with the energy 
supply to the remaining instruments or the other energy source, unless, 
for single-engine aircraft in all cargo operations only, the rate of 
turn indicator has a source of energy separate from the bank and pitch 
and direction indicators. For the purpose of this paragraph, for multi-
engine aircraft, each engine-driven source of energy must be on a 
different engine.
* * * * *
    3. Section 135.163 is amended by revising paragraph (h) to read as 
follows:


Sec. 135.163  Equipment requirements: Aircraft carrying passengers 
under IFR.

* * * * *
    (h) Two independent sources of energy (with means of selecting 
either) of which at least one is an engine-driven pump or generator, 
each of which is able to drive all gyroscopic instruments powered by, 
or to be powered by, that particular source and installed so that 
failure of one instrument or source, does not interfere with the energy 
supply to the remaining instruments or the other energy source unless, 
for single-engine aircraft in all cargo operations only, the rate of 
turn indicator has a source of energy separate from the bank and pitch 
and direction indicators. For the purpose of this paragraph, for multi-
engine aircraft, each engine-driven source of energy must be on a 
different engine.
* * * * *
    Issued in Washington, D.C. on February 4, 1998.
Thomas E. Stuckey,
Director, Flight Standards Service.
[FR Doc. 98-3344 Filed 2-9-98; 8:45 am]
BILLING CODE 4910-13-M