[Federal Register: May 5, 2004 (Volume 69, Number 87)]
[Rules and Regulations]
[Page 24936-24938]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr05my04-3]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM277, Special Conditions No. 25-261-SC]
Special Conditions: Cessna Models 500, 550 and S550 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 Cessna Models 500, 550
and S550 airplanes modified by Shadin Company, 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 modification incorporates the
installation of the Shadin Company dual ADC-6000 Air Data Computer
(ADC) which will allow for the removal of the existing encoding
altimeters, air data computer, and pneumatic 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 provided by the
existing airworthiness standards.
DATES: The effective date of these special conditions is April 27,
2004. Comments must be received on or before June 4, 2004.
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. NM277, 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. NM277.
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 are 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 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 1, 2004, Shadin Company, Inc. applied for a supplemental
type certificate (STC) to modify Cessna Models 500, 550 and S550
airplanes. Cessna Model 500, 550 and S550 airplanes are currently
approved under Type Certificate A22CE. The modification incorporates
the installation of the Innovative Solutions & Support (IS & S) Duplex
Reduced Vertical Separation Minimum (RVSM) system which will allow for
the removal of the existing altitude alerter, encoding altimeters, air
data computer, and standby altimeter. This system uses two air data
computer ADC-6000s and interfaces to existing BA-141 altimeters. These
ADCs can be susceptible to disruption to both command and response
signals as a result of electrical and magnetic interference. This
disruption of signals could result in the loss of all critical flight
information displays and annunciations or the presentation of
misleading information to the pilot.
Type Certification Basis
Under the provisions of 14 CFR 21.101, Shadin Company, Inc. must
show that Cessna Model 500, 550 and S550 airplanes, as changed,
continue to meet the applicable provisions of the regulations
incorporated by reference in Type Certificate A22CE 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 modified Cessna Models 500, 550 and S550
airplanes includes 14 CFR 25, effective February 1, 1965 as described
in Type Certificate A22CE.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR 25, as amended) do not contain adequate or
appropriate safety standards for the Cessna Model 500, 550 and S550
airplanes because of novel or unusual design features, special
conditions are prescribed under the provisions of Sec. 21.16.
Special conditions, as defined in 14 CFR 11.19, are issued in
accordance with Sec. 11.38 and become part of the type
[[Page 24937]]
certification basis in accordance with Sec. 21.101.
Special conditions are initially applicable to the models for which
they are issued. Should the applicant apply for a supplemental type
certificate to modify any other model included on Type Certificate
A22CE to incorporate the same novel or unusual design feature, the
special conditions would also apply to the other models under the
provisions of Sec. 21.101.
Novel or Unusual Design Features
The modified Cessna Model 500, 550 and S550 airplanes will
incorporate a new altitude display system, the Shadin Company ADC-6000
system, which will perform critical functions. This system may be
vulnerable to high-intensity radiated fields (HIRF) 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 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 Cessna Models 500, 550 and S550 airplanes
modified by the Shadin Company, Inc. These special conditions require
that new electrical and electronic systems that perform critical
functions, such as the ADC-6000, 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 avionic/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 in accordance 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
indicated in the table below for the frequency ranges indicated. Both
peak and average field strength components from the table below 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..................................... 700 700
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 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 Cessna
Model 500, 550 and S550 airplanes modified by Shadin Company, Inc.
Should Shadin Company, Inc. apply at a later date for design change
approval to modify any other model included on the same type
certificate 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 Cessna Model 500, 550 and S550 airplanes modified by Shadin Company,
Inc. It is not a rule of general applicability and affects only the
applicant which applied to the FAA for approval of these features on
these airplanes.
The substance of the special conditions for this airplane 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.
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 Cessna Model 500, 550 and
S550 airplanes modified by the Shadin Company, 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 24938]]
Issued in Renton, Washington, on April 27, 2004.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 04-10238 Filed 5-4-04; 8:45 am]
BILLING CODE 4910-13-P