[Federal Register Volume 68, Number 96 (Monday, May 19, 2003)]
[Rules and Regulations]
[Pages 26991-26993]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-12376]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM253, Special Conditions No. 25-235-SC]


Special Conditions: Raytheon Aircraft Company Model HS 125 Series 
700A and 700B Airplanes; High Intensity Radiated Fields (HIRF)

AGENCY: Federal Aviation Administration (FAA) DOT.

ACTION: Final special conditions; request for comments.

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SUMMARY: These special conditions are issued for the Raytheon Aircraft 
Company Model HS 125 Series 700A and 700B airplanes modified by 
Raytheon Aircraft Services, Inc. These modified 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 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 provided by the existing 
airworthiness standards.

DATES: The effective date of these special conditions is April 18, 
2002. Comments must be received on or before July 3, 2003.

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. NM253, 1601 Lind 
Avenue SW., Renton, Washington, 98055-4056; or delivered in duplicate 
to the Transport Airplane Directorate at the above address. All 
comments must be marked: Docket No. NM253.

FOR FURTHER INFORMATION CONTACT: Connie Beane, FAA, Standardization 
Branch, ANM-113, Transport Airplane Directorate, Aircraft Certification 
Service, 1601 Lind Avenue SW.,

[[Page 26992]]

Renton, Washington, 98055-4056; telephone (425) 227-2796; facsimile 
(425) 227-1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA has determined that notice and opportunity for prior public 
comment is impracticable because these procedures would significantly 
delay certification of the airplane and thus delivery of the affected 
aircraft. In addition, 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, the FAA invites 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 based on 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 December 31, 2002, Raytheon Aircraft Services Inc., applied to 
the FAA, Fort Worth Special Certification Office, for a supplemental 
type certificate (STC) to modify certain Raytheon Aircraft Company 
Model HS 125 Series 700A and 700B airplanes. These airplanes are two 
flightcrew, two-engine airplanes, each with a maximum takeoff weight of 
up to 25,500 lbs. The proposed modification incorporates the 
installation of an Electronic Flight Instrument System (EFIS). The 
equipment originally installed in these airplanes presented the 
required information in the form of analog displays. The information 
presented is flight critical. The EFIS as a digital system is 
vulnerable to HIRF external to the airplane. The avionics/electronics 
and electrical systems installed in this airplane have the potential to 
be vulnerable to HIRF external to the airplane.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, Amendment 21-69, effective 
September 16, 1991, Raytheon Aircraft Services, Inc. must show that the 
modified Raytheon Aircraft Company Model HS 125 Series 700A and 700B 
airplanes, as changed, continue to meet the applicable provisions of 
the regulations incorporated by reference in Type Certificate No. A3EU, 
or the applicable regulations in effect on the date of application for 
the change. Subsequent changes have been made to 14 CFR 21.101 as part 
of Amendment 21-77, but those changes do not become effective until 
June 10, 2003. 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. 
A3EU include Part 10 of the Civil Air Regulations (CAR). This 
certification is equivalent to CAR 4b dated December 1953, as amended 
by Amendment 4b-1 through Amendment 4b-11, exclusive of CAR 4b 350(e), 
and includes Special Regulation SR 422B. In addition, the certification 
basis includes certain later amendments to 14 CFR part 25 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 Raytheon Aircraft Company 
Model HS 125 Series 700A and 700B airplanes modified by Raytheon 
Aircraft Services Inc. because of a novel or unusual design feature, 
special conditions are prescribed under the provisions of Sec.  21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the Model HS 125 Series 700A and 700B 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(b)(2), Amendment 21-69, effective 
September 16, 1991.
    Special conditions are initially applicable to the model for which 
they are issued. Should Raytheon Aircraft Services Inc. 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 also 
apply to the other model under the provisions of Sec.  21.101(a)(1), 
Amendment 21-69, effective September 16, 1991.

Novel or Unusual Design Features

    The modified Raytheon Aircraft Company Model HS 125 Series 700A and 
700B airplanes will incorporate brand new avionics/electronics and 
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/electronics and electrical 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 Raytheon Aircraft Company Model HS 125 
Series 700A and 700B 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, and 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

[[Page 26993]]

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 (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 
identified 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
                       Frequency                             meter)
                                                       -----------------
                                                          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-2GHz............................................     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 
Raytheon Aircraft Company Model HS 125 Series 700A and 700B airplanes. 
Should Raytheon Aircraft Services 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 as under the provisions of 14 CFR 
21.101(a)(1), Amendment 21-60, effective September 16, 1991.

Conclusion

    This action affects only certain novel and unusual design features 
on the Raytheon Aircraft Company Model HS 125 Series 700A and 700B 
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 airplane.
    The substance of the special conditions 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 upon issuance. 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 record keeping 
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 the modified Raytheon 
Aircraft Company Model HS 125 Series 700A and 700B 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 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 April 18, 2003.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-12376 Filed 5-16-03; 8:45 am]
BILLING CODE 4910-13-P