[Federal Register Volume 61, Number 57 (Friday, March 22, 1996)]
[Rules and Regulations]
[Pages 11728-11730]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-7000]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM-122; Special Conditions No. 25-ANM-111]


Special Conditions: McDonnell Douglas Model DC9-10, -20, -30, -
40, -50, High-Intensity Radiated Fields

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final special conditions; request for comments.

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SUMMARY: These special conditions are issued for the McDonnell Douglas 
DC9-10, -20, -30, -40, -50 airplane. This airplane will utilize new 
avionics/electronic systems that provide critical data to the 
flightcrew. The applicable regulations do not contain adequate or 
appropriate safety standards for the protection of these systems from 
the effects of high-intensity radiated fields. These special conditions 
contain the additional safety standards that the Administrator 
considers necessary to establish a level of safety equivalent to that 
established by the existing airworthiness standards.

DATES: The effective date of these special conditions is March 14, 
1996. Comments must be received on or before April 6, 1996.

ADDRESSES: Comments on these final special conditions, request for 
comments, may be mailed in duplicate to: Federal Aviation 
Administration, Office of the Assistant Chief Counsel, Attn: Rules 
Docket (ANM-7), Docket No. NM-122, 1601 Lind Avenue SW., Renton, 
Washington 98055-4056; or delivered in duplicate to the Office of the 
Assistant Chief Counsel at the above address. Comments must be marked: 
Docket No. NM-122. Comments may be inspected in the Rules Docket 
weekdays, except Federal holidays, between 7:30 a.m. and 4:00 p.m.

FOR FURTHER INFORMATION CONTACT:
Gerald Lakin, FAA, Standardization Branch, ANM-113, Transport Airplane

[[Page 11729]]
Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., 
Renton, Washington, 98055-4056, (206) 227-1187.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    The FAA has determined that good cause exits for making these 
special conditions effective upon issuance; however, interested persons 
are invited to submit such written data, views, or arguments as they 
may desire. Communications should identify the regulatory docket and 
special conditions 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. These 
special conditions may be changed in light of comments received. All 
comments submitted will be available in 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. Persons wishing the FAA to acknowledge receipt of their 
comments submitted in response to this request must be submitted with 
those comments a self-addressed, stamped postcard on which the 
following statement is made: ``Comments to Docket No. NM-122.'' The 
postcard will be date stamped and returned to the commenter.

Background

    On June 25, 1995, JanzAir Consulting Services, Suite 202, Lee 
Wagener Blvd., Fort Lauderdale, Florida 33315-3570, applied for a 
supplemental type certificate in the transport airplane category for 
the McDonnell Douglas Model DC9-10, -20, -30, -40, -50 airplane. The 
DC9-10, -20, -30, -40, -50 is a low swept wing, commercial jet airplane 
powered by two Pratt & Whitney JT8D turbofan engines mounted on pylons 
extending from the aft fuselage. The airplane has a seating capacity of 
80 to 125 passengers, and a maximum takeoff weight of 85,700 to 121,000 
pounds. The flight controls will be powered and capable of manual 
reversion.

Type Certification Basis

    Under the provisions of Sec. 21.101 of the FAR, JanzAir must show, 
except as provided in Sec. 25.2, that the modified DC9-10, -20, -30, -
40, -50 meets the applicable provisions of part 25, effective February 
1, 1965, as amended by Amendments 25-1 through 25-83. In addition, the 
proposed certification basis for the modified DC9-10, -20, -30, -40, -
50 includes part 34, effective September 10, 1990, plus any amendments 
in effect at the time of certification; and part 36, effective December 
1, 1969, as amended by Amendment 36-1 through the amendment in effect 
at the time of certification. No exemptions are anticipated. The 
special conditions incorporated herein form an additional part of the 
type certification basis. In addition, the certification basis may 
include other special conditions that are not relevant to these special 
conditions.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., part 25, as amended) do not contain adequate or 
appropriate safety standards for the modified DC9-10, -20, -30, -40, -
50 because of a novel or unusual design feature, special conditions are 
prescribed under the provisions of Sec. 21.16 to establish a level of 
safety equivalent to that established in the regulations.
    Special conditions, as appropriate, are issued in accordance with 
Sec. 11.49 of the FAR after public notice, 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).
    Special conditions are initially applicable to the model for which 
they are issued. Should the type certificate for that model be amended 
later to include any other model that incorporates the same novel or 
unusual design feature, or should any other model already included on 
the same type certificate be modified to incorporate the same novel or 
unusual design feature, the special conditions would also apply to the 
other model under the provisions of Sec. 21.101(a)(1).

Novel or Unusual Design Features

    The McDonnell Douglas Model DC9-10, -20, -30, -40, -50 airplane 
avionics enhancement will utilize electronic systems that perform 
critical functions, including a digital Electronic Flight Instrument 
System (EFIS), attitude and heading reference systems (AHRS), and air 
data systems (ADS). These systems may be vulnerable to high-intensity 
radiated fields (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 issued for the modified McDonnell Douglas DC9 which 
require that new technology electrical and electronic systems, such as 
the EFIS, AHRS and ADS, 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

    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 paragraphs 1 or 2 below.
    1. A minimum threat of 100 volts per meter peak 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.

------------------------------------------------------------------------
                                                        Peak (V/ Average
                       Frequency                           M)     (V/M) 
------------------------------------------------------------------------
10 KHz-100 KHz........................................       50       50
100 KHz-500 KHz.......................................       60       60
500 KHz-2000 KHz......................................       70       70
2 MHz-30 MHz..........................................      200      200
30 MHz-100 MHz........................................       30       30
100 MHz-200 MHz.......................................      150       33
200 MHz-400 MHz.......................................       70       70
400 MHz-700 MHz.......................................    4,020      935
700 MHz-1000 MHz......................................    1,700      170
1 GHz-2 GHz...........................................    5,000      990
2 GHz-4 GHz...........................................    6,680      840
4 GHz-6 GHz...........................................    6,850      310
6 GHz-8 GHz...........................................    3,600      670
8 GHz-12 GHz..........................................    3,500    1,270
12 GHz-18 GHz.........................................    3,500      360
18 GHz-40 GHz.........................................    2,100      750
------------------------------------------------------------------------


[[Page 11730]]

    As discussed above, these special conditions would be applicable 
initially to the modified Model DC9-10, -20, -30, -40, -50. Should 
JanzAir apply at a later date for a supplemental type certificate to 
include another model incorporating 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).
    Under standard practice, the effective date of final special 
conditions would be 30 days after the date of publication in the 
Federal Register. However, as issuance of the supplemental type 
certificate for the JanzAir modified DC9 airplane is planned for March 
22, 1996, the FAA finds that good cause exists for making these special 
conditions effective upon issuance.

Conclusion

    This action affects certain design features only on the modified 
DC9-10, -20, -30, -40, -50 airplane. It is not a rule of general 
applicability and affects only the manufacturer who applied to the FAA 
for approval of these features on the airplane.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Federal Aviation Administration, 
Reporting and record keeping requirements.

    The authority citation for these proposed special conditions is as 
follows:

    Authority: 49 U.S.C. app. 1344, 1348(c), 1352, 1354(a), 1355, 
1421 through 1431, 1502, 1651(b)(2), 42 U.S.C. 1857f-10, 4321 et 
seq., E.O. 11514; and 49 U.S.C. 106(g).

The Special Conditions

    Accordingly, the following special conditions are issued as part of 
the type certification basis for the JanzAir modified DC9-10, -20, -30, 
-40, -50 airplanes.
    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 this 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 March 14, 1996.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 96-7000 Filed 3-21-96; 8:45 am]
BILLING CODE 4910-13-M