[Federal Register Volume 66, Number 75 (Wednesday, April 18, 2001)]
[Rules and Regulations]
[Pages 19847-19850]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-9531]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM188; Special Conditions No. 25-177-SC]


Special Conditions: Cessna Aircraft Company Model 500, 550, S550, 
and 560 Series 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 Aircraft 
Company Model 500, 550, S550, and 560 series airplanes modified by 
ElectroSonics. These modified airplanes will have a novel or unusual 
design feature associated with the installation of new 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.

DATES: The effective date of these special conditions is April 10, 
2001. Comments must be received on or before May 18, 2001.

ADDRESSES: Comments on these special conditions may be mailed in 
duplicate to: Federal Aviation Administration, Transport Airplane 
Directorate, Attention: Rules Docket (ANM-114), Docket No. NM188, 1601 
Lind Avenue SW., Renton, Washington 98055-4056; or delivered in 
duplicate to the Transport Airplane Directorate at that address. All 
comments must be marked: Docket No. NM188. Comments may be inspected in 
the Rules Docket weekdays, except Federal holidays, between 7:30 a.m. 
and 4:00 p.m.

FOR FURTHER INFORMATION CONTACT: For information concerning the 
certification program for Cessna Model 500, 550, S550, and 560 
airplanes, contact: Meghan Gordon, Federal Aviation Administration, 
Standardization Branch, ANM-113, Transport Airplane Directorate, 
Aircraft Certification Service, 1601 Lind Avenue SW., Renton, 
Washington 98055-4056; telephone (425) 227-2138; fax (425) 227-1149.
    For information on the general subject of HIRF, contact: Stephen 
Slotte, Federal Aviation Administration, Transport airplane 
Directorate, Airplane and Flight Crew Interface Branch, ANM-111, 1601 
Lind Avenue SW., Renton, Washington 98055-4056; telephone (425) 227-
2315; fax (425) 227-1320.

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA has determined that good cause exists for making these 
special conditions effective upon issuance; however, interested persons 
are invited to submit such written data, views, or

[[Page 19848]]

arguments, as they may desire. Communications should identify the 
regulatory docket number and be submitted in duplicate to the address 
specified in the ADDRESSES section, above. All communications received 
on or before the closing date for comments will be considered by the 
Administrator. These special conditions may be changed in light of the 
comments received. All comments received will be available in the Rules 
Docket for examination by interested persons, both before and after the 
closing date for comments. A report summarizing each substantive public 
contact with FAA personnel concerning this rulemaking will be filed in 
the docket. Commenters wishing the FAA to acknowledge receipt of their 
comments submitted in response to these special conditions must include 
a self-addressed, stamped postcard on which the following statement is 
made: ``Comments to Docket No. NM188.'' The postcard will be date 
stamped and returned to the commenter.

Background

    On August 10, 2000, ElectroSonics, 4391 International Gateway, 
Columbus, Ohio, applied for a Supplemental Type Certificate (STC) to 
modify Cessna Aircraft Company Model 500, 550, S550, and 560 airplanes. 
These models are certificated under 14 CFR part 25 as (small) transport 
category airplanes.
     The Cessna Model 500 airplane is powered by two Pratt & 
Whitney JT15D-1(A/B) turbofans with a maximum takeoff weight of 11,850 
pounds. This airplane operates with a two-pilot crew and can hold up to 
7 passengers.
     The Cessna Model 550 airplane is powered by two Pratt & 
Whitney JT15D-4 turbofans with a maximum takeoff weight of 14,100 
pounds. This airplane operates with a two-pilot crew and can hold up to 
11 passengers.
     The Cessna Model S550 airplane is powered by two Pratt & 
Whitney JT15D-4B turbofans with a maximum takeoff weight of 15,100 
pounds. This airplane operates with a two-pilot crew and can hold up to 
11 passengers.
     The Cessna Model 560 airplane is powered by two Pratt & 
Whitney JT15D-5A/D turbofans with a maximum takeoff weight of 16,300 
pounds. This airplane operates with a two-pilot crew and can hold up to 
11 passengers.
    The modification that is the subject of these special conditions 
incorporates the installation of Innovative Solutions & Support air 
data display units (ADDU). The ADDU is a replacement for the existing 
analog flight instrumentation, and provides additional functional 
capability and redundancy in the system. The avionics/electronics and 
electrical systems installed in the subject Cessna airplanes have the 
potential to be vulnerable to HIRF external to the airplane.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, ElectroSonics must show that 
the Cessna Model 500, 550, S550, and 560 airplanes, as changed, 
continue to meet the applicable provisions of the regulations 
incorporated by reference in Type Certificate No. 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 regulations included in the certification 
basis for theses airplanes are as follows:

1. For the Cessna Model 500 Airplane

     14 CFR part 25, effective February 1, 1965, as amended by 
Amendments 25-1 through 25-17; Secs. 25.934 and 25.1091(d)(2) as 
amended by Amendments 25-1 through 25-23;
     Sec. 25.1387 as amended by Amendments 25-1 through 25-30;
     Secs. 25.1385 and 25.1303(a)(2) as amended by Amendments 
25-1 through 25-38;
     Special Conditions 25-25-CE-4; and
     additional requirements listed in the type certificate 
data sheet that are not relevant to these special conditions.

2. For the Cessna Model 550 Airplane

     14 CFR part 25 effective February 1, 1965, as amended by 
Amendments 25-1 through 25-17;
     Secs. 25.934 and 25.1091(d)(2) as amended by Amendments 
25-1 through 25-23;
     Sec. 25.1401 as amended by Amendments 25-1 through 25-27;
     Sec. 25.1387 as amended by Amendments 25-1 through 25-30;
     Secs. 25.1303(a)(2) and 25.1385(c) as amended by 
Amendments 25-1 through 25-38;
     Special Conditions 25-25-CE-4; and
     additional requirements listed in the type certificate 
data sheet that are not relevant to these special conditions.

3. For the Cessna Model S550 Airplane

     14 CFR part 25 effective February 1, 1965, as amended by 
Amendments 25-1 through 25-17;
     Secs. 25.251(e), 25.934, and 25.1091(d)(2) as amended by 
Amendments 25-1 through 25-23;
     Sec. 25.1401 as amended by Amendments 25-1 through 25-27;
     Sec. 25.1387 as amended by Amendments 25-1 through 25-30;
     Secs. 25.787, 25.789, 25.791, 25.853, 25.855, 25.857, and 
25.1359 as amended by Amendments 25-1 through 25-32;
     Secs. 25.1303(a)(2) and 25.1385(c) as amended by 
Amendments 25-1 through 25-38;
     Special Conditions 25-25-CE-4; and
     additional requirements listed in the type certificate 
data sheet that are not relevant to these special conditions.

4. For the Cessna Model 560 Airplane, Serial Numbers 560-0001 through 
560-0259

     14 CFR part 25 effective February 1, 1965, as amended by 
Amendments 25-1 through 25-17;
     Secs. 25.251(e), 25.934, and 25.1091(d)(2) as amended by 
Amendments 25-1 through 25-23;
     Sec. 25.1401 as amended by Amendments 25-1 through 25-27;
     Sec. 25.1387 as amended by Amendments 25-1 through 25-30;
     Secs. 25.787, 25.789, 25.791, 25.853, 25.855, 25.857, and 
25.1359 as amended by Amendments 25-1 through 25-32;
     Secs. 25.1303(a)(2) and 25.1385(c) as amended by 
Amendments 25-1 through 25-38;
     Special Conditions 25-25-CE-4; and
     additional requirements listed in the type certificate 
data sheet that are not relevant to these special conditions.

5. For the Cessna Model 560 Airplane, Serial Numbers 560-0260 Through 
560-0538

     14 CFR part 25 effective February 1, 1965, as amended by 
Amendments 25-1 through 25-17;
     Secs. 25.251(e), 25.934, and 25.1091(d)(2) as amended by 
Amendments 25-1 through 25-23;
     Sec. 25.1401 as amended by Amendments 25-1 through 25-27;
     Sec. 25.1387 as amended by Amendments 25-1 through 25-30;
     Secs. 25.787, 25.789, 25.791, 25.853, 25.855, 25.857, and 
25.1359 as amended by Amendments 25-1 through 25-32;
     Secs. 25.1303(a)(2) and 25.1385(c) as amended by 
Amendments 25-1 through 25-38;
     Sec. 25.305 as amended by Amendments 25-1 through 25-54; 
and
     Sec. 25.1001 as amended by Amendments 25-1 through 25-57.
    In addition to the applicable airworthiness regulations and special 
conditions, these Cessna Model 500, 550, S550, and 560 airplanes must 
comply with the fuel vent and exhaust emission requirements of part 34 
and the noise certification requirements of part 36.

[[Page 19849]]

The Effect of Special Conditions on the Type Certification Basis

    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 25, as amended) do not contain adequate 
or appropriate safety standards for the Cessna Model 500, 550, S550, 
and 560 airplanes modified by ElectroSonics because of a novel or 
unusual design feature, special conditions are prescribed under the 
provisions of Sec. 21.16.
    Special conditions, as defined in Sec. 11.19, are issued in 
accordance with Sec. 11.38. In accordance with Sec. 21.101(b)(2), the 
special conditions approved in this document will form an additional 
part of the type certification basis for these airplanes.
    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 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 500, 550, S550, and 560 
airplanes modified by ElectroSonics will incorporate a dual electronic 
primary flight display system that will perform critical functions. 
This system may be vulnerable to 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 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 500, 550, S550, and 560 
airplanes modified by ElectroSonics. 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, alternatively, 
paragraph 2., below:
    1. A minimum threat of 100 volts rms 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.

or

    2. A threat external to the airframe for both of the following 
field strengths for the frequency ranges indicated. Both peak and 
average field strength components from Table 1 are to be demonstrated.

                                 Table 1
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                                                         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 in Table 1 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 500, 550, S550, and 560 airplanes modified by 
ElectroSonics. Should ElectroSonics apply at a later date for a 
supplemental type certificate to modify any other model included on 
Type Certificate A22CE to incorporate the same novel or unusual design 
feature, these special conditions would apply to that model as well 
under the provisions of Sec. 21.101(a)(1).

Conclusion

    This action affects only certain novel or unusual design features 
on the Cessna Model 500, 550, S550, and 560 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 these special conditions has been subjected to the 
notice and comment period in several prior instances and has been 
derived without substantive change from those previously issued. It is 
unlikely that prior public comment would result in a significant change 
from the substance contained herein. For this reason, and 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.

[[Page 19850]]


    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 Model 500, 550, S550, and 560 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.
    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 10, 2001.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-9531 Filed 4-17-01; 8:45 am]
BILLING CODE 4910-13-U