[Federal Register Volume 69, Number 87 (Wednesday, May 5, 2004)]
[Rules and Regulations]
[Pages 24936-24938]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-10238]


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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.

------------------------------------------------------------------------
                                                       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        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
------------------------------------------------------------------------
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