[Federal Register Volume 71, Number 86 (Thursday, May 4, 2006)]
[Rules and Regulations]
[Pages 26189-26191]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-4187]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM345, Special Conditions No. 25-317-SC]


Special Conditions: Sabreliner Model NA-265-60; 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 Sabreliner Model NA-
265-60 airplanes. These 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 dual Honeywell Model AM-
250 digital altimeters. 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 14, 
2006. We must receive your comments by June 5, 2006.

ADDRESSES: You must mail two copies of your comments to: Federal 
Aviation Administration, Transport Airplane Directorate, Attn: Rules 
Docket (ANM-113), Docket No. NM345, 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. NM345. 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 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, 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 4:00 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

[[Page 26190]]

postcard on which the docket number appears. We will stamp the date on 
the postcard and mail it back to you.

Background

    On May 17, 2005, Flight Test Associates of Mojave, California, 
applied to the FAA, Los Angeles Aircraft Certification Office, for a 
supplemental type certificate (STC) to modify Sabreliner Model NA-265-
60 airplanes. This model, currently approved under Type Certificate No. 
A2WE, is powered by two Pratt and Whitney Turbo Wasp JT12A-8 engines 
and carries up to ten passengers. The modification incorporates 
installation of dual Honeywell Model AM-250 digital altimeters that 
perform critical functions. These digital altimeters have the potential 
to be vulnerable to high-intensity radiated fields external to the 
airplanes.

Type Certification Basis

    Under 14 CFR 21.101, Flight Test Associates must show that the 
Sabreliner Model NA-265-60 airplanes, as modified, continue to meet the 
applicable provisions of the regulations incorporated by reference in 
Type Certificate No. A2WE, 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 incorporated by 
reference in Type Certificate No. A2WE include Civil Air Regulations 
4b, as amended by Amendments 4b-1 through 4b-9.
    If the Administrator finds that the applicable airworthiness 
regulations do not contain adequate or appropriate safety standards for 
the modified Sabreliner Model NA-265-60 airplanes because of a novel or 
unusual design feature, special conditions are prescribed under the 
provisions of Sec.  21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the Sabreliner Model NA265-60 airplanes 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 Flight Test Associates apply at a later date 
for an STC to modify any other model included on Type Certificate No. 
A2WE 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, the Sabreliner Model NA-265-60 airplanes modified 
by Flight Test Associates will incorporate dual primary altimeters that 
perform critical functions. These systems may be vulnerable to HIRF 
external to the airplane. The current airworthiness standards 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 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 reference, special 
conditions are needed for the Sabreliner Model NA-265-60 airplanes 
modified by Flight Test Associates. These special conditions require 
that new primary altimeters 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 digital 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 following table for the frequency ranges indicated. 
Both peak and average field strength components from the table 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 
Sabreliner Model NA-265-60 airplanes modified by Flight Test 
Associates. Should Flight Test Associates apply at a later date for an 
STC to modify any other model included on Type Certificate No. A2WE to 
incorporate the same or similar novel or unusual design feature, these 
special conditions would apply to that model as well as under Sec.  
21.101.

Conclusion

    This action affects only certain novel or unusual design features 
on the Sabreliner Model NA-265-60 airplanes. It is not a rule of 
general applicability and affects only the applicant which applied to 
the FAA for approval of these features on the airplane.

[[Page 26191]]

    The substance of the special conditions for these airplanes has 
undergone 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 Sabreliner Model NA-
265-60 airplanes modified by Flight Test Associates.
    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 14, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 06-4187 Filed 5-3-06; 8:45 am]
BILLING CODE 4910-13-P