[Federal Register Volume 69, Number 197 (Wednesday, October 13, 2004)]
[Rules and Regulations]
[Pages 60795-60797]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-22947]



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  Federal Register / Vol. 69, No. 197 / Wednesday, October 13, 2004 / 
Rules and Regulations  

[[Page 60795]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM290; Special Conditions No. 25-274-SC]


Special Conditions: Raytheon Aircraft MU-300 Airplanes; High 
Intensity Radiated Fields (HIRF)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

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

SUMMARY: These special conditions are issued for Raytheon Aircraft 
Company Model MU-300 airplanes modified by ARINC, Inc. 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 modification incorporates the installation of a 
Thommen AD32 Air Data Display Unit (ADDU) which incorporates a Digital 
Air Data Computer and Altimeter. The applicable airworthiness 
regulations do not contain adequate or appropriate safety standards for 
the protection of these systems from the effects of high-intensity-
radiated fields (HIRF). 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 October 1, 
2004. Comments must be received on or before November 12, 2004.

ADDRESSES: Comments on these special conditions may be mailed in 
duplicate to: Federal Aviation Administration, Transport Airplane 
Directorate, Attn: Rules Docket (ANM-113), Docket No. NM290, 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. NM290. 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: Greg Dunn, FAA, Airplane and Flight 
Crew Interface Branch, ANM-111, Transport Airplane Directorate, 
Aircraft Certification Service, 1601 Lind Avenue SW., Renton, 
Washington, 98055-4056; telephone (425) 227-2799; facsimile (425) 227-
1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA has determined that notice and opportunity for prior public 
comment hereon is unnecessary as the substance of these special 
conditions has been subject to the public comment process in several 
prior instances with no substantive comments received. The FAA, 
therefore, finds that good cause exists for making these special 
conditions effective upon issuance; however, we invite interested 
persons to participate in this rulemaking by submitting written 
comments, data, or views. The most helpful comments reference a 
specific portion of the special conditions, explain the reason for any 
recommended change, and include supporting data. We ask that you send 
us two copies of written comments.
    We will file in the docket all comments we receive, as well as a 
report summarizing each substantive public contact with FAA personnel 
concerning these special conditions. The docket is available for public 
inspection before and after the comment closing date. If you wish to 
review the docket in person, go to the address in the ADDRESSES section 
of this preamble between 7:30 a.m. and 4 p.m. Monday through Friday, 
except Federal holidays.
    We will consider all comments we receive on or before the closing 
date for comments. We will consider comments filed late if it is 
possible to do so without incurring expense or delay. We may change 
these special conditions in light of the comments received.
    If you want the FAA to acknowledge receipt of your comments on 
these special conditions, include with your comments a pre-addressed, 
stamped postcard on which the docket number appears. We will stamp the 
date on the postcard and mail it back to you.

Background

    On March 1, 2004, ARINC Inc., 1632 South Murray Blvd. Colorado 
Springs, CO 80916 applied for a supplemental type certificate (STC) to 
modify Raytheon Aircraft Company Models MU-300 (Diamond I and IA) 
airplanes. The Raytheon MU-300 airplanes are small transport category 
airplanes powered by two turbojet engines, with maximum takeoff weights 
of up to 14,630 pounds. These airplanes operate with a 2-pilot crew and 
can seat up to 9 passengers. The proposed modification incorporates the 
installation of a Dual Thommen AD-32 Air Data Display Units. The 
information this equipment presents is flight critical. The avionics/
electronics and electrical systems to be installed on these airplanes 
have the potential to be vulnerable to high-intensity radiated fields 
(HIRF) external to the airplane.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, ARINC Inc. must show that 
the Raytheon Aircraft Company Model MU-300 airplanes, as changed, 
continue to meet the applicable provisions of the regulations 
incorporated by reference in Type Certificate No. A14SW, 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 regulations incorporated by reference in Type Certificate No. 
A14SW include 14 CFR part 25, as amended by Amendments 25-1 through 25-
40; Sec. Sec.  25.1351(d), 25.1353(c)(5), and 25.1450, as amended by 
Amendment 25-41; Sec. Sec.  25.1353(c)(6), and 25.255, as amended by 
Amendment 25-42; Sec.  25.361(b) as amended by Amendment 25-46; and 14 
CFR part 36 as amended by Amendment 36-1 through 36-12.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., part 25, as amended) do not contain adequate or 
appropriate safety standards for modified Model MU-300 airplanes, 
because of a novel or unusual design feature, special conditions are 
prescribed under the provisions of Sec.  21.16.

[[Page 60796]]

    In addition to the applicable airworthiness regulations and special 
conditions, the Raytheon Model MU-300 airplanes 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 defined in 14 CFR 11.19, are issued in 
accordance with Sec.  11.38, and become part of the type certification 
basis in accordance with Sec.  21.101.
    Special conditions are initially applicable to the model for which 
they are issued. Should ARINC Inc. apply at a later date for 
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 also apply to the other model 
under the provisions of Sec.  21.101.

Novel or Unusual Design Features

    The modified Model MU-300 airplanes will incorporate avionics/
electrical systems that will 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 avionics/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 Model MU-300 airplanes. These special 
conditions require that new avionics/electronics and electrical 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/electronics and electrical 
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 is shown with either HIRF protection 
special condition paragraph 1 or 2 below:
    1. A minimum threat of 100 volts rms (root-mean-square) 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 field strengths 
indicated in the following table for the frequency ranges indicated. 
Both peak and average field strength components from the table are to 
be demonstrated.

------------------------------------------------------------------------
                                                        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 of the root-mean-
  square (rms) over the complete modulation period.

    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 are applicable to the 
Raytheon Aircraft Company Model MU-300 airplanes. Should ARINC, Inc. 
apply at a later date for a change to the 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 14 CFR 21.101.

Conclusion

    This action affects only certain novel or unusual design features 
on the Raytheon Aircraft Company Model MU-300 airplanes. 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 airplanes.
    The substance of the special conditions for these airplanes has 
been subjected to the notice and comment procedure in several prior 
instances and has been derived without substantive change from those 
previously issued. Because a delay would significantly affect the 
certification of the airplane, which is imminent, the FAA has 
determined that prior public notice and comment are unnecessary and 
impracticable, and good cause exists for adopting these special 
conditions immediately. The FAA is requesting comments to allow 
interested persons to submit views that may not have been submitted in 
response to the prior opportunities for comment described above.

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 Special Conditions

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the supplemental type certification basis for Raytheon Aircraft Company 
Model MU-300 airplanes modified ARINC Inc.
    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.


[[Page 60797]]


    Issued in Renton, Washington, on October 1, 2004.
Kalene C. Yanamura,
Acting Manager, , Transport Airplane Directorate, Aircraft 
Certification Service.
[FR Doc. 04-22947 Filed 10-12-04; 8:45 am]
BILLING CODE 4910-13-P