[Federal Register: December 19, 2005 (Volume 70, Number 242)]
[Rules and Regulations]
[Page 75002-75004]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr19de05-5]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM337; Special Conditions No. 25-310-SC]
Special Conditions: Raytheon Aircraft Company Model HS.125
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 a Raytheon Aircraft
Company Model HS.125 airplane modified by AeroMech Incorporated. This
modified airplane 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 the installation of Innovative Solutions and Support air
data display units (ADDU). These systems 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
[[Page 75003]]
that established by the existing airworthiness standards.
DATES: The effective date of these special conditions is December 9,
2005. Comments must be received on or before January 18, 2006.
ADDRESSES: You must mail two copies of your comments to: Federal
Aviation Administration, Transport Airplane Directorate, Attention:
Rules Docket (ANM-113), Docket No. NM337, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056. You may deliver two copies to the
Transport Airplane Directorate at the above address. You must mark your
comments: Docket No. NM337. 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 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
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 people 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 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 June 6, 2005, AeroMech Incorporated, 1616 Hewitt Avenue, Suite
312, Everett, Washington 98201, applied for a supplemental type
certificate (STC) to modify a Raytheon Aircraft Company Model HS.125
Series 400A airplane. This model is currently approved under Type
Certificate No. A3EU. The Raytheon Model HS.125 airplane is a small
transport category airplane powered by two turbine engines. It operates
with a 2-pilot crew and can seat up to 15 passengers. The modification
incorporates the installation of Innovative Solutions and Support air
data display units. 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 the provisions of 14 CFR 21.101, AeroMech Incorporated must
show that Raytheon Aircraft Company Model HS.125 Series 400A airplane,
as changed, continues 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 HS.125 Series 400A airplane includes Civil Air
Regulations (CAR) 10, British Civil Airworthiness Requirements, and
Special Conditions. This certification is equivalent to CAR 4b dated
December 1953, Amendment 4b-1 through Amendment 4b-11, exclusive of CAR
4b.350(e), and includes Special Regulations SR.422B. Type Certificate
No. A3EU was amended to include HS.125 Series 400A on November 15,
1968. Compliance over and above certification basis requirements has
been met with CAR Amendment 4B-12 and Amendment 4B-14. Compliance has
been established with the special retroactive requirements of 14 CFR
25.2 as amended by Amendment 25-1 through Amendment 25-20, 14 CFR 21 at
Amendment 21-27, and 14 CFR 36(1)(c)(2).
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 Model HS.125 Series 400A
airplane because of a novel or unusual design feature, special
conditions are prescribed under Sec. 21.16.
In addition to the applicable airworthiness regulations and special
conditions, Raytheon Aircraft Company Model HS.125 Series 400A airplane
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 under
Sec. 11.38 and 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 AeroMech Incorporated 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 Sec. 21.101.
Novel or Unusual Design Features
As noted earlier, Raytheon Model HS.125 airplane modified by
AeroMech Incorporated will incorporate Innovative Solutions and Support
air data display units 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
[[Page 75004]]
reference, special conditions are needed for Raytheon Aircraft Company
Model HS.125 Series 400A airplane modified by AeroMech Incorporated.
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.
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Field strength
(volts per meter)
Frequency -------------------
Peak Average
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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
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The field strengths are expressed in terms of peak 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 a
Raytheon Aircraft Company Model HS.125 Series 400A airplane modified by
AeroMech Incorporated. Should AeroMech Incorporated 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 Sec. 21.101.
Conclusion
This action affects only certain novel or unusual design features
on a Raytheon Aircraft Company Model HS.125 Series 400A airplane
modified by AeroMech Incorporated. 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 HS.125 Series 400A airplane modified by AeroMech
Incorporated.
1. Protection from Unwanted Effects of 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 December 9, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 05-24158 Filed 12-16-05; 8:45 am]
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