[Federal Register Volume 67, Number 82 (Monday, April 29, 2002)]
[Rules and Regulations]
[Pages 20887-20890]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-9943]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM216; Special Conditions No. 25-199-SC]


Special Conditions: Cessna Model 501 and 551 Series Airplanes; 
High-Intensity Radiated Fields (HIRF)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

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

SUMMARY: These special conditions are issued for Cessna Aircraft 
Company Cessna Model 501 and 551 series airplanes modified by 
ElectroSonics. 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 the installation of dual air data display 
unit systems 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.

[[Page 20888]]


DATES: The effective date of these special conditions is April 17, 
2002. Comments must be received on or before May 29, 2002.

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. NM216, 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. NM216. Comments may be 
inspected 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-
1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA has determined that notice and opportunity for prior public 
comment hereon are impracticable because these procedures would 
significantly delay certification 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, 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 in light of the comments we receive.
    If you want the FAA to acknowledge receipt of your comments on this 
proposal, 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 20, 2002, ElectroSonics, 4391 International Gateway, 
Columbus, Ohio, applied for a Supplemental Type Certificate (STC) to 
modify Cessna Model 501 and 551 series airplanes. The Cessna Model 501 
and 551 series airplanes are normal category turbine powered airplanes. 
The Cessna Model 501 series airplanes are powered by two Pratt & 
Whitney JT15D-1(A/B) turbofan engines and have a maximum takeoff weight 
of 11,850 pounds. These airplanes operate with either a 1-pilot or 2-
pilot crew and can hold up to 8 passengers. The Cessna Model 551 series 
airplanes are powered by two Pratt & Whitney JT15D-4 turbofan engines 
and have a maximum takeoff weight of 12,500 pounds. These airplanes 
operate with either a 1-pilot or 2-pilot crew and can hold up to 10 
passengers. The modification incorporates the installation of 
Innovative Solutions & Support Air Data Display Units (ADDU). The ADDU 
is a replacement for the existing analog flight instrumentation, while 
also providing additional functional capability and redundancy in the 
system. 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, ElectroSonics must show that 
the Cessna Model 501 and 551 series airplanes, as modified to include 
the new air data display units, continue to meet the applicable 
provisions of the regulations incorporated by reference in Type 
Certificate No. A27CE, 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 regulations included in the 
certification basis for the Cessna 501 airplanes include part 23 of the 
Federal Aviation Regulations effective February 1, 1965, as amended by 
Amendments 23-1 through 23-16, with certain exceptions, and section 
23.1385 as amended through Amendment 23-20; part 25, effective February 
1, 1965, as amended by Amendments 25-1 through 25-37, with certain 
exceptions; part 36, effective December 1, 1969, as amended by 
Amendments 36-1 through 36-5; SFAR 27, Fuel Venting (replaced by part 
34, effective September 10, 1990); plus additional requirements listed 
in the type certificate data sheet that are not relevant to these 
special conditions.
    The regulations included in the certification basis for the Cessna 
Model 551 series airplanes include part 23 of the Federal Aviation 
Regulations effective February 1, 1965, as amended by Amendments 23-1 
through 23-16, with certain exceptions, sections 23.1143(e) and 
23.1385(c) as amended through Amendments 23-18, and sections 23.1301 
and 23.1335 as amended by Amendments through 23-20; part 25 effective 
February 1, 1965, as amended by Amendments 25-1 through 25-37 with 
certain exceptions, and sections 25.901(c), 25.903(e)(3), and 
25.1351(d) as amended through Amendments 25-41; part 36, effective 
December 1, 1969, as amended by Amendments 36-1 through 36-6; SFAR 27, 
as amended by Amendments 27-1 through 27-3, Fuel Venting (replaced by 
part 34, effective September 10, 1990). For the Bendix EFS-10, Sperry 
EDZ-600, Sperry EDZ-601, and Sperry EDZ-603 electronic flight 
instrument systems only, compliance has been shown with the following 
regulations: sections 25.1301, 25.1303(b), and 25.1322 as amended 
through Amendment 25-38; sections 25.1309, 25.1321(a), (b), (d), and 
(e), 25.1331, 25.1333, and 25.1335 as amended through Amendments 25-41; 
plus additional requirements listed in the type certificate data sheet 
that are not relevant to these special conditions.
    If the Administrator finds that the applicable airworthiness 
regulations (that is, 14 CRF part 25, as amended) do not contain 
adequate or appropriate safety standards for the Cessna Model 501 and 
551 series airplanes modified by ElectroSonics because of a novel or 
unusual design feature, special conditions are prescribed under the 
provisions of Sec. 21.16.

    Note: Although 14 CFR part 25 is referenced in these special 
conditions, the Cessna Model 501 and 551 series airplanes are 
certified under both part 25 and part 23. The applicable 
airworthiness regulations under part 23, as they relate to HIRF, are 
the same as those under part 25.

    In addition to the applicable airworthiness regulations and special 
conditions, these Cessna Model 501 and 551 series airplanes must comply 
with the fuel vent and exhaust emission requirements of 14 CFR part 34 
and the

[[Page 20889]]

noise certification requirements of part 36.
    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(b)(2).
    Special conditions are initially applicable to the model for which 
they are issued. Should ElectroSonics apply at a later date for a 
supplemental type certificate to modify any other model already 
included on the same type certificate to incorporate the same novel or 
unusual design feature, these special conditions would also apply to 
the other model under the provisions of Sec. 21.101(a)(1).

Novel or Unusual Design Features

    As noted earlier, the Cessna Model 501and 551 series airplanes 
modified by ElectroSonics will incorporate dual air data display unit 
systems that will perform critical functions. These systems may be 
vulnerable to high-intensity radiated fields (HIRF) external to the 
airplane. The current airworthiness standards of (14 CFR part 25) do 
not contain adequate or appropriate safety standards that address 
protecting 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 that is equivalent to 
that intended by the regulations incorporated by reference, special 
conditions are needed for the Cessna Model 501 and 551 series airplanes 
modified by ElectroSonics to include the dual air data display unit 
systems. 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, plus 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 
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       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 
Cessna Model 501 and 551 series airplanes modified by ElectroSonics to 
include Innovative Solutions & Support Air Data Display Units. Should 
ElectroSonics apply at a later date for a supplemental type certificate 
to modify any other model included on the same type certificate to 
incorporate the same novel or unusual design feature, these special 
conditions would apply to that model as well under the provisions of 14 
CFR 21.101(a)(1).

Conclusion

    This action affects only certain novel or unusual design features 
on the Cessna Model 501 and 551 series airplanes modified by 
ElectroSonics. 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 the special conditions for these airplanes has 
been subjected to notice and comment period 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 airplanes, 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 Cessna Aircraft 
Company Cessna Model 501 and 551 series airplanes modified by 
ElectroSonics.
    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.

[[Page 20890]]

    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 April 17, 2002.
Lirio Liu-Nelson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 02-9943 Filed 4-26-02; 8:45 am]
BILLING CODE 4910-13-P