[Federal Register Volume 64, Number 232 (Friday, December 3, 1999)]
[Proposed Rules]
[Pages 67804-67806]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-31397]


 ========================================================================
 Proposed Rules
                                                 Federal Register
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
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 

  Federal Register / Vol. 64, No. 232 / Friday, December 3, 1999 / 
Proposed Rules  

[[Page 67804]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM165, Notice No. 25-99-09-SC]


Special Conditions: McDonnell Douglas DC-9-30 Series Airplanes; 
High Intensity Radiated Fields (HIRF)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This notice proposes special conditions for the McDonnell 
Douglas DC-9-30 series airplanes modified by Lockheed Martin Aircraft 
Center. These airplanes will have novel and unusual design features 
when compared to the state of technology envisioned in the 
airworthiness standards for transport category airplanes. The 
applicable type certification regulations do not contain adequate or 
appropriate safety standards for the protection of this system from the 
effects of high-intensity radiated fields (HIRF). These proposed 
special conditions contain the additional safety standards that the 
Administrator considers necessary to establish a level of safety 
equivalent to that provided by the existing airworthiness standards.

DATES: Comments must be received on or before January 18, 2000.

ADDRESSES: Comments on this proposal may be mailed in duplicate to: 
Federal Aviation Administration, Transport Airplane Directorate, Attn: 
Rules Docket (ANM-114), Docket No. NM165, 1601 Lind Avenue SW., Renton, 
Washington, 98055-4056; or delivered in duplicate to the Transport 
Airplane Directorate at the above address. Comments must be marked: 
Docket No. NM165. Comments may be inspected in the Rules Docket 
weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT: Connie Beane, FAA, Standardization 
Branch, ANM-113, Transport Airplane Directorate, Aircraft Certification 
Service, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; 
telephone (425) 227-2796; facsimile (425) 227-1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of 
these proposed special conditions by submitting such written data, 
views, or arguments, as they may desire. Communications should identify 
the regulatory docket or notice number and be submitted in duplicate to 
the address specified above. All communications received on or before 
the closing date for comments will be considered by the Administrator 
before further rulemaking action on this proposal is taken. The 
proposals contained in this notice may be changed in light of the 
comments received. All comments received will be available by the Rules 
Docket for examination by interested persons, both before and after the 
closing date for comments. 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 submitted in response to this notice must include a self-
addressed, stamped postcard on which the following statement is made: 
``Comments to Docket No. NM165.'' The postcard will be date stamped and 
returned to the commenter.

Background

    On April 20, 1998, Lockheed Martin Aircraft Center, Inc. (LMAC), 
244 Terminal Road, Greenville, NC 29605, applied for a supplemental 
type certificate (STC) to modify McDonnell Douglas DC-9-30 series 
airplanes listed on Type Certificate A6WE. The modification 
incorporates the installation of a Rockwell-Collins FDS-255 Electronic 
Flight Instrument System, consisting of an electronic attitude display, 
an electronic horizontal situation indicator, and a display controller 
for each pilot. This advanced system uses electronics to a far greater 
extent than the original mechanical attitude displays and may be more 
susceptible to electrical and magnetic interference. This disruption of 
signals could result in loss of attitude display or present misleading 
attitude information to the pilot.
    In addition, on August 18, 1998, LMAC applied for an additional STC 
to modify McDonnell Douglas DC-9-30 series airplanes listed on Type 
Certificate A6WE. The modification incorporates the installation of an 
Innovative Solution & Support electronic air data instrument system, 
which consists of an electronic airspeed display, an electronic 
altimeter, and a digital air data computer for each pilot. This 
advanced system uses electronics to a far greater extent than the 
original pneumatic pitot-static instruments and may be more susceptible 
to electrical and magnetic interference. This disruption of signals 
could result in loss of air data display or present misleading air data 
information to the pilot.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, LMAC must show that the 
McDonnell Douglas DC-9-30 series airplanes, as changed, continue to 
meet the applicable provisions of the regulations incorporated by 
reference in Type Certificate No. A6WE, or the applicable regulations 
in effect on the date of application for the change. The regulations 
incorporated by reference in the type certificate are commonly referred 
to as the ``original type certification basis.'' The certification 
basis for the modified the McDonnell Douglas DC-9-30 series airplanes 
include CAR 4b, dated December 31, 1953, with Amendments 4b-1 through 
4b-16, as amended by Type Certificate Data Sheet (TCDS) A6WE.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., CAR 4b, as amended) do not contain adequate or 
appropriate safety standards for the McDonnell Douglas DC-9-30 series 
airplanes because of novel or unusual design features, special 
conditions are prescribed under the provisions of Sec. 21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the Model DC-9-30 must comply with the fuel vent and 
exhaust emission requirements of 14 CFR part 34 and the noise 
certification requirements of 14 CFR part 36.
    Special conditions, as appropriate, are issued in accordance with 
14 CFR 11.49, as required by Secs. 11.28 and 11.29, and become part of 
the type certification basis in accordance with Sec. 21.101(b)(2).

[[Page 67805]]

    Special conditions are initially applicable to the model for which 
they are issued. Should LMAC apply at a later date for design change 
approval to modify any other model already included on the same type 
certificate to incorporate the same novel or unusual design feature, 
this special conditions would also apply to the other model under the 
provisions of Sec. 21.101(a)(1).

Novel or Unusual Design Features

    The modified McDonnell Douglas DC-9-30 series airplanes will 
incorporate an electronic attitude display system and an electronic air 
data system, which were not available at the time of certification of 
these airplanes, both of which perform critical functions. These 
systems may be vulnerable to HIRF external to the airplane.

Discussion

    There is no specific regulation that addresses protection 
requirements for electrical and electronic systems from HIRF. Increased 
power levels from ground-based radio transmitters and the growing use 
of sensitive electrical and electronic systems to command and control 
airplanes have made it necessary to provide adequate protection.
    To ensure that a level of safety is achieved equivalent to that 
intended by the regulations incorporated by reference, special 
conditions are needed for the McDonnell Douglas DC-9-30 series 
airplanes. These special conditions require that new electrical and 
electronic systems, such as the electronic attitude and air data 
display systems that perform critical functions, be designed and 
installed to preclude component damage and interruption of function due 
to both the direct and indirect effects of HIRF.

High-Intensity Radiated Fields (HIRF)

    With the trend toward increased power levels from ground-based 
transmitters, plus the advent of space and satellite communications, 
coupled with electronic command and control of the airplane, the 
immunity of critical digital avionics systems to HIRF must be 
established.
    It is not possible to precisely define the HIRF to which the 
airplane will be exposed in service. There is also uncertainty 
concerning the effectiveness of airframe shielding for HIRF. 
Furthermore, coupling of electromagnetic energy to cockpit-installed 
equipment through the cockpit window apertures is undefined. Based on 
surveys and analysis of existing HIRF emitters, an adequate level of 
protection exists when compliance with the HIRF protection special 
condition is shown with either paragraph 1, or 2 below:
    1. A minimum threat of 100 volts rms per meter electric field 
strength from 10 KHz to 18 GHz.
    a. The threat must be applied to the system elements and their 
associated wiring harnesses without the benefit of airframe shielding.
    b. Demonstration of this level of protection is established through 
system tests and analysis.
    2. A threat external to the airframe of the following field 
strengths for the frequency ranges indicated.

------------------------------------------------------------------------
                                                       Field Strength
                                                      (volts per meter)
                     Frequency                     ---------------------
                                                       Peak     Average
------------------------------------------------------------------------
10 kHz--100 kHz...................................         50         50
100 kHz--500 kHz..................................         50         50
500 kHz--2 MHz....................................         50         50
2 MHz--30 MHz.....................................        100        100
30 MHz--70 MHz....................................         50         50
70 MHz--100 MHz...................................         50         50
100 MHz--200 MHz..................................        100        100
200 MHz--400 MHz..................................        100        100
400 MHz--700 MHz..................................        700         50
700 MHz--1 GHz....................................        700        100
1 GHz--2 GHz......................................       2000        200
2 GHz--4 GHz......................................       3000        200
4 GHz--6 GHz......................................       3000        200
6 GHz--8 GHz......................................       1000        200
8 GHz--12 GHz.....................................       3000        300
12 GHz--18 GHz....................................       2000        200
18 GHz--40 GHz....................................        600       200
------------------------------------------------------------------------
The field strengths are expressed in terms of peak root-mean-square
  (rms) values.

    The threat levels identified above are the result of an FAA review 
of existing studies on the subject of HIRF in light of the ongoing work 
of the Electromagnetic Effects Harmonization Working Group of the 
Aviation Rulemaking Advisory Committee.

Applicability

    As discussed above, these special conditions would be applicable 
initially to the McDonnell Douglas DC-9-30 series airplanes modified by 
LMAC. Should LMAC apply at a later date for a supplemental type 
certificate to modify any other model included on the same type 
certificate to incorporate the same novel or unusual design feature, 
these special conditions would apply to that model as well under the 
provisions of Sec. 21.101(a)(1).

Conclusion

    This action affects only certain novel or unusual design features 
on the McDonnell Douglas DC-9-30 series airplanes modified by LMAC. It 
is not a rule of general applicability and affects only the applicant 
who applied to the FAA for approval of these features on the airplane.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.
    The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration proposes the 
following special conditions as part of the type certification basis 
for McDonnell Douglas DC-9-30 series airplanes modified by Lockheed 
Martin Aircraft Center.

[[Page 67806]]

    1. Protection from Unwanted Effects of High-Intensity Radiated 
Fields (HIRF). Each electrical and electronic system that performs 
critical functions must be designed and installed to ensure that the 
operation and operational capability of these systems to perform 
critical functions are not adversely affected when the airplane is 
exposed to high intensity radiated fields.
    2. For the purpose of these special conditions, the following 
definition applies:
    Critical Functions. Functions whose failure would contribute to or 
cause a failure condition that would prevent the continued safe flight 
and landing of the airplane.

    Issued in Renton, Washington, on November 17, 1999.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 99-31397 Filed 12-2-99; 8:45 am]
BILLING CODE 4910-13-P