[Federal Register Volume 70, Number 132 (Tuesday, July 12, 2005)]
[Rules and Regulations]
[Pages 39908-39910]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-13662]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM311; Special Conditions No. 25-291-SC]


Special Conditions: Raytheon Model BH.125 Series 400A, DH.125 
Series 400A, and HS.125 Series 400B 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 Raytheon Model BH.125 
series 400A, DH.125 series 400A, and HS.125 series 400B airplanes 
modified by Envoy Aerospace. These modified airplanes will have a novel 
or unusual design feature when compared to the state of technology 
envisioned in the airworthiness standards for transport category 
airplanes. The modification incorporates digital air data computers and 
displays that perform critical functions. 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 July 1, 2005. 
Comments must be received on or before August 11, 2005.

ADDRESSES: Comments on these special conditions may be mailed in 
duplicate to: Federal Aviation Administration, Transport Airplane 
Directorate, Attention: Rules Docket (ANM-113), Docket No. NM311, 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. NM311.

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-
1320.

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 
airplanes. 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, 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 based on the comments we receive.
    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 28, 2005, Envoy Aerospace, 5027 Switch Grass Lane, 
Naperville, Illinois 60564-5368, applied for a supplemental type 
certificate (STC) to modify Raytheon Model BH.125 series 400A, DH.125 
series 400A, and HS.125 series 400B airplanes. Raytheon Model BH.125 
series 400A, DH.125 series 400A, and HS.125 series 400B airplanes are 
currently approved under Type Certificate No. A3EU. The Raytheon Model 
BH.125 series 400A, DH.125 series 400A, and HS.125 series 400B 
airplanes are transport category airplanes powered by two turbofan 
engines, with maximum takeoff weights of up to 23,600 pounds. These 
airplanes operate with a 2-pilot crew and can seat up to 8 passengers. 
The proposed modification includes the incorporation of dual Innovative 
Solutions and Support Air Data Systems. The avionics installed in 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, Envoy Aerospace must show 
that the Raytheon Aircraft Company Model BH.125 series 400A, DH.125 
series 400A, and HS.125 series 400B 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. The regulations 
incorporated by reference in the type certificate are commonly referred 
to as the ``original type certification basis.'' The certification 
basis for the Raytheon Aircraft Company Model BH.125 series 400A, 
DH.125 series 400A, and HS.125 series 400B airplanes includes CAR.4b 
dated December 1953, Amendment 4b-1 through 4b-11, exclusive of CAR 
4b.350(e), and includes Special Regulation SR.422B. In addition, the 
certification basis includes later amended sections of 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 Raytheon Aircraft Company Model 
BH.125 series 400A, DH.125 series 400A, and HS.125 series 400B 
airplanes, 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 Raytheon Aircraft Company Model BH.125 series 400A, 
DH.125 series 400A, and HS.125 series 400B 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.

[[Page 39909]]

    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 Envoy Aerospace apply at a later date for a 
supplemental type certificate to modify any other model included on 
Type Certificate No. A3EU to incorporate the same or similar 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

    As noted earlier, the Raytheon Aircraft Company Model BH.125 series 
400A, DH.125 series 400A, and HS.125 series 400B airplanes modified by 
Envoy Aerospace will incorporate dual Innovative Solutions and Support 
Air Data Systems that will perform critical functions. These systems 
may be vulnerable to high-intensity radiated fields external to the 
airplane. The current airworthiness standards of part 25 do not contain 
adequate or appropriate safety standards for the protection of this 
equipment from the adverse effects of HIRF. Accordingly, this system is 
considered to be a novel or unusual design feature.

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 BH.125 
series 400A, DH.125 series 400A, and HS.125 series 400B airplanes 
modified by Envoy Aerospace. 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 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 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 table below 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 
Raytheon Aircraft Company Model BH.125 series 400A, DH.125 series 400A, 
and HS.125 series 400B airplanes modified by Envoy Aerospace. Should 
Envoy Aerospace apply at a later date for a supplemental type 
certificate to modify any other model included on Type Certificate No. 
A3EU, to incorporate the same or similar novel or unusual design 
feature, these special conditions would apply to that model as well 
under the provisions of Sec.  21.101.

Conclusion

    This action affects only certain novel or unusual design features 
on Raytheon Aircraft Company Model BH.125 series 400A, DH.125 series 
400A, and HS.125 series 400B airplanes modified by Envoy Aerospace. 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 these 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 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 the Raytheon Aircraft 
Company Model BH.125 series 400A, DH.125 series 400A, and HS.125 series 
400B airplanes modified by Envoy Aerospace.
    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

[[Page 39910]]

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 July 1, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-13662 Filed 7-11-05; 8:45 am]
BILLING CODE 4910-13-P