[Federal Register Volume 72, Number 37 (Monday, February 26, 2007)]
[Rules and Regulations]
[Pages 8261-8263]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-3231]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM369, Special Conditions No. 25-345-SC]


Special Conditions: Raytheon Aircraft Company Model BAe.125 
Series 800A; High-Intensity Radiated Fields (HIRF)

AGENCY: Federal Aviation Administration (FAA), DOT.

[[Page 8262]]


ACTION: Final special conditions; request for comments.

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SUMMARY: These special conditions are issued for Raytheon Aircraft 
Company Model BAe.125 Series 800A airplanes modified by Duncan Aviation 
Inc. These modified airplanes will have novel or 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 electronic flight and 
engine instrument systems. The applicable airworthiness regulations do 
not contain adequate or appropriate safety standards for protecting 
these systems from the effects of high-intensity radiated fields 
(HIRF). These special conditions contain the additional safety 
standards 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 February 12, 
2007. We must receive your comments by March 28, 2007.

ADDRESSES: You must mail two copies of your comments to: Federal 
Aviation Administration, Transport Airplane Directorate, Attention: 
Rules Docket (ANM-113), Docket No. NM369, 1601 Lind Avenue SW., Renton, 
Washington 98057-3356. You may deliver two copies to the Transport 
Airplane Directorate at the address indicated above. You must mark your 
comments: Docket No. NM369. You can inspect comments 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 98057-3356; 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 
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, we invite interested persons to take part in this 
rulemaking by sending 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. You may inspect the docket 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 by 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 October 27, 2006, Duncan Aviation, Inc., 15745 South Airport 
Road, Battle Creek, Michigan 49015, applied for a supplemental type 
certificate (STC) to modify Raytheon Aircraft Company Model BAe.125 
Series 800A airplanes currently approved under Type Certificate No. 
A3EU. The Model BAe.125 Series 800A airplanes are small transport 
category airplanes. They are powered by two turbojet engines, with 
maximum takeoff weight of 31,000 pounds as modified by Modification No. 
253379A or 26,866 pounds as modified by Modification No. 25B047A. These 
airplanes operate with 2-person crew and can seat up to 15 passengers. 
The proposed modification is to install the Rockwell Collins Pro Line 
21 Integrated Display Systems. The avionics/electronics and electrical 
systems installed in this airplane have the potential to be vulnerable 
to high-intensity radiated fields (HIRF) external to the airplane.

Type Certification Basis

    Under 14 CFR 21.101, Duncan Aviation, Inc. must show the Raytheon 
Aircraft Company Model BAe.125 Series 800A aircraft, as changed, 
continue to meet the applicable provisions of the regulations 
incorporated by reference in Type Certificate No. A3EU. They must also 
continue to meet the applicable regulations in effect on the date of 
application for the change. We commonly refer to the regulations 
incorporated by reference in the type certificate as the ``original 
type certification basis.'' The regulations incorporated by reference 
in Type Certificate No. A3EU include Part 10 of the British Civil 
Airworthiness Requirements. This certification is equivalent to Civil 
Air Regulations (CAR) 4b dated December 1953, as amended by Amendment 
4b-1 through Amendment 4b-11, exclusive of CAR 4b 350(e). It 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 Raytheon Aircraft Company Model 
Bae.125, Series 800A airplanes, because of a novel or unusual design 
feature, special conditions are prescribed under Sec.  21.16.
    Besides the applicable airworthiness regulations and special 
conditions, the Raytheon Aircraft Company Model BAe.125, Series 800A 
airplanes, must comply with the fuel vent exhaust emission requirements 
of 14 CFR part 34 and the noise certification requirements of 14 CFR 
part 36.
    We issue special conditions, as defined in 14 CFR 11.19, under 
Sec.  11.38 and they become part of the type certification basis under 
Sec.  21.101.
    Special conditions are initially applicable to the model for which 
they are issued. Should Duncan Aviation Inc., apply later 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 Sec.  21.101.

Novel or Unusual Design Features

    As noted earlier, the Raytheon Aircraft Company Model BAe.125 
Series 800A aircraft, as modified by Duncan Aviation, Inc., will 
incorporate the Rockwell Collins Pro Line 21 Integrated Display 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

[[Page 8263]]

adverse effects of HIRF. Therefore, we consider this system 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 BAe.125 
Series 800A airplanes modified by Duncan Aviation, Inc. 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 because of 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 BAe.125 Series 800A airplanes modified 
by Duncan Aviation, Inc. Should Duncan Aviation, Inc. apply later 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.

Conclusion

    This action affects only certain novel or unusual design features 
on Raytheon Aircraft Company Model BAe.125 Series 800A airplanes as 
modified by Duncan Aviation, Inc. 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 send views that may 
not have been sent 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.

0
The authority citation for these special conditions is as follows:

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

The Special Conditions

0
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 BAe.125 Series 800A airplanes modified by Duncan Aviation, 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.

    Issued in Renton, Washington, on February 12, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-3231 Filed 2-23-07; 8:45 am]
BILLING CODE 4910-13-P