[Federal Register Volume 68, Number 11 (Thursday, January 16, 2003)]
[Rules and Regulations]
[Pages 2183-2185]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-1010]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 21 and 29

[Docket No. SW012; Special Condition No. 29-012-SC]


Special Conditions: ST 2017RC-R, Installation of Pratt & Whitney 
Canada PT6-67D on Global Helicopter Technology, Inc. (GHTI), Restricted 
Category Model UH-1H, TC R00002RC, With Full Authority Digital Engine 
Control (FADEC)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special condition; request for comments.

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SUMMARY: This special condition is issued for Supplemental Type 
Certificate (STC), Project  ST2017RC-R, the installation of a 
Pratt and Whitney PT6-67D Turbine Engine on Global Helicopter 
Technology Inc. (GHTI), Restricted Category, U.S. Army military surplus 
helicopter, Model UH-1H, type certificated under TC R00002RC. The 
installation of the PT6-67D on the Restricted Category UH-1H will have 
a novel or unusual design feature associated with the installation of 
the Full Authority Digital Engine Control (FADEC). The applicable 
airworthiness regulations do not contain adequate or appropriate safety 
standards to protect systems that perform critical functions from the 
effects of a high-intensity radiated field (HIRF). This special 
condition contains the additional safety standards that the 
Administrator considers necessary to ensure that critical functions of 
systems will be maintained when exposed to HIRF.

DATES: The effective date of this special condition is January 8, 2003. 
Comments must be received on or before March 17, 2003.

ADDRESSES: Comments on this special condition may be mailed in 
duplicate to: Federal Aviation Administration (FAA), Office of the 
Regional Counsel, Attention: Rules Docket No. SW012, Fort Worth, Texas 
76193-0007, or delivered in duplicate to the Office of the Regional 
Counsel at 2601 Meacham Blvd., Fort Worth, Texas 76137. Comments must 
be marked: Docket No. SW012. Comments may be inspected in the Rules 
Docket weekdays, except Federal holidays, between 8:30 a.m. and 4 p.m. 
The Rules Docket for special conditions is maintained at the Federal 
Aviation Administration, Rotorcraft Directorate, 2601 Meacham Blvd., 
Room 448, Fort Worth, Texas 76137.

FOR FURTHER INFORMATION CONTACT: Bob McCallister, FAA, Rotorcraft 
Directorate, Rotorcraft Standards Staff, Fort Worth, Texas 76193-0110; 
telephone 817-222-5121, fax 817-222-5961.

SUPPLEMENTARY INFORMATION: The FAA has determined that notice and 
opportunity for prior public comment hereon are impracticable because 
these procedures would significantly delay issuance of the approval 
design and thus delivery of the affected aircraft. In addition, the 
substance of this special condition 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 
this special condition effective upon issuance.

Comments Invited

    The FAA invites interested persons to participate in this 
rulemaking by submitting written comments, views, or data. 
Communications should identify the regulatory docket or special 
condition number and be submitted in duplicate to the address specified 
above. We will consider all comments we receive on or before the 
closing date for comments. We may change this special condition in 
light of the comments we receive. 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. If you want the 
FAA to acknowledge receipt of your mailed comments on this special 
condition, include a self-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 November 29, 2000, Global Helicopter Technology, Inc. (GHTI) 
applied for an STC for the installation of a Pratt & Whitney PT6-67D 
Turbine Engine on the GHTI, U.S. Army UH-1H, Restricted Category 
Helicopter, type certificated under Type Certificate R00002RC. The UH-
1H Restricted Category helicopter is a utility/heavy lift helicopter 
with a two-bladed teetering main rotor system. It is to be powered by a 
single Pratt and Whitney PT6-67D engine that incorporates a full 
authority digital engine control (FADEC). The maximum gross weight of 
the aircraft is 9,500 pounds.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, GHTI must show that the 
Engine Installation meets the applicable provisions of the regulations 
as listed below:
    [sbull] 14 CFR part 29 as amended through and including Amendment 
29-1, effective August 12, 1965.
    [sbull] 14 CFR 29.1529, Instructions for Continued Airworthiness, 
Amendment Number 20, effective September 11, 1980.
    In accordance with 14 CFR 36.1(a)(4), compliance with the noise 
requirements was not shown for the aircraft. Therefore, the engine 
installations under this supplemental type certificate are only 
eligible for external load operations excepted by 14 CFR 36.1(a)(4) and 
defined under section 133.1(b). Any alteration to the aircraft for 
Special Purpose not identified above will require further FAA approval 
and in addition, may require noise and/or flight testing.
    In addition, the certification basis includes certain equivalent 
safety findings that are not relevant to this special condition.
    If the Administrator finds that the applicable airworthiness 
regulations do not contain adequate or appropriate safety standards for 
this STC because of a novel or unusual design feature, special 
conditions are prescribed under the provisions of Sec.  21.16.
    Special conditions, as appropriate, are defined in Sec.  11.19 and 
issued in accordance with Sec.  11.38 and become part of the STC 
certification basis in accordance with Sec.  21.17(a)(2).
    Special conditions are initially applicable to the model and/or 
modification for which they are issued. Should the type certificate or 
supplemental type certificate (STC) for that model or installation 
respectively, be amended later to include any other model that 
incorporates the same novel or unusual design feature, the special 
conditions would also apply to the other model or modification under 
the provisions of Sec.  21.101(a)(1).

Novel or Unusual Design Features

    The GHTI UH-1H Restricted Category Helicopter with a Pratt & 
Whitney PT6-67D engine installed will incorporate the following novel 
or unusual design features: Electrical, electronic, or a combination of 
electrical electronic (electrical/electronic) systems such as FADEC 
that will be performing functions critical to the continued safe flight 
and landing of the helicopter. FADEC is an electronic device that 
performs the functions of engine control during flight operations.

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Discussion

    The GHTI installation of the PT-6-67D in the UH-1H helicopter, at 
the time of application, was identified as incorporating one and 
possibly more electrical/electronic systems, such as a FADEC. After the 
design is finalized, GHTI will provide the FAA with a preliminary 
hazard analysis that will identify any other critical functions that 
are performed by the electrical/electronic systems required for safe 
flight and landing.
    Recent advances in technology have given rise to the application in 
aircraft designs of advanced electrical/electronic systems that perform 
critical functions. These advanced systems respond to the transient 
effects of induced electrical current and voltage caused by HIRF 
incidents on the external surface of the helicopter. These induced 
transient currents and voltages can degrade the performance of the 
electrical/electronic systems by damaging the components or by 
upsetting the systems' functions.
    Furthermore, the electromagnetic environment has undergone a 
transformation not envisioned by the current application of Sec.  
29.1309(a). Higher energy levels radiate from operational transmitters 
currently used for radar, radio, and television. Also, the number of 
transmitters has increased significantly.
    Existing aircraft or alteration certification requirements are 
inappropriate in view of these technological advances. In addition, the 
FAA has received reports of some significant safety incidents and 
accidents involving military aircraft equipped with advanced 
electrical/electronic systems when they were exposed to electromagnetic 
radiation.
    The combined effects of the technological advances in helicopter 
design and the changing environment have resulted in an increased level 
of vulnerability of the electrical/electronic systems required for the 
continued safe flight and landing of the helicopter. Effective measures 
to protect these helicopters against the adverse effects of exposure to 
HIRF will be provided by the design and installation of these systems. 
The following primary factors contributed to the current conditions: 
(1) Increased use of sensitive electronics that perform critical 
functions; (2) reduced electromagnetic shielding afforded helicopter 
systems by advanced technology airframe materials; (3) adverse service 
experience of military aircraft using these technologies; and (4) an 
increase in the number and power of radio frequency emitters and the 
expected increase in the future.
    The FAA recognizes the need for aircraft certification standards to 
keep pace with the developments in technology and environment and, in 
1986, initiated a high priority program to (1) determine and define 
electromagnetic energy levels; (2) develop and describe guidance 
material for design, test, and analysis; and (3) prescribe and 
promulgate regulatory standards.
    The FAA participated with industry and airworthiness authorities of 
other countries to develop internationally recognized standards for 
certification.
    The FAA and airworthiness authorities of other countries have 
identified a level of HIRF environment that a helicopter could be 
exposed to during visual flight rules (VFR) operations. While the HIRF 
rulemaking requirements are being finalized, the FAA is adopting a 
special condition for the certification of aircraft that employ 
electrical/electronic systems that perform critical functions. The 
accepted maximum energy levels that civilian helicopter system 
installations must withstand for safe operation are based on surveys 
and analysis of existing radio frequency emitters. This special 
condition will require the engine installation's electrical/electronic 
systems and associated wiring to be protected from these energy levels. 
These external threat levels are believed to represent the worst-case 
exposure for a helicopter operating under VFR conditions.
    These special conditions will require the systems that perform 
critical functions, as installed in the aircraft, meet certain 
standards based on either a defined HIRF environment or a fixed value 
using laboratory tests.
    The applicant may demonstrate that the operation and operational 
capabilities of the installed electrical/electronic systems that 
perform critical functions are not adversely affected when the aircraft 
is exposed to the defined HIRF test environment. The FAA has determined 
that the test environment defined in Table 1 is acceptable for critical 
functions in helicopters.
    The applicant may also demonstrate by a laboratory test that the 
electrical/electronic systems that perform critical functions can 
withstand a peak electromagnetic field strength in a frequency range of 
10 KHz to 18 GHz. If a laboratory test is used to 
show compliance with the defined HIRF environment, no credit will be 
given for signal attenuation due to installation. A level of 100 volts 
per meter (v/m) and other considerations, such as alternate or backup 
technology that is immune to HIRF, are appropriate for critical 
functions during instrument flight rules (IFR) operations. A level of 
200 v/m is more appropriate for critical functions during VFR 
operations. Laboratory test levels are defined according to RTCA/DO-
160D Section 20 Category W (100 v/m and 150 mA) and Category Y (200 v/m 
and 300 mA). As defined in DO-160D Section 20, the test levels are 
defined as the peak of the root means squared (rms) envelope. As a 
minimum, the modulations required for RTCA/DO-160D Section 20 
Categories W and Y will be used. Other modulations should be selected 
as the signal most likely to disrupt the operation of the system under 
test, based on its design characteristics. For example, flight control 
systems may be susceptible to 3 Hz square wave modulation 
while the video signals for electronic display systems may be 
susceptible to 400 Hz sinusoidal modulation. If the worst-
case modulation is unknown or cannot be determined, default modulations 
may be used. Suggested default values are a 1 KHz sine wave 
with 80 percent depth of modulation in the frequency range from 10 
KHz to 400 MHz and 1 KHz square wave 
with greater than 90 percent depth of modulation from 400 
MHz to 18 GHz. For frequencies where the 
unmodulated signal would cause deviations from normal operation, 
several different modulating signals with various waveforms and 
frequencies should be applied.
    Applicants must perform a preliminary hazard analysis to identify 
electrical/electronic systems that perform critical functions. The term 
``critical'' means those functions whose failure would contribute to or 
cause an unsafe condition that would prevent the continued safe flight 
and landing of the helicopter. The systems identified by the hazard 
analysis as performing critical functions are required to have HIRF 
protection.
    A system may perform both critical and noncritical functions. 
Primary electronic flight display systems and their associated 
components perform critical functions such as attitude, altitude, and 
airspeed indications. HIRF requirements would apply only to the systems 
that perform critical functions.
    Compliance with HIRF requirements will be demonstrated by tests, 
analysis models, similarity with existing systems, or a combination of 
these methods. The two basic options of either testing the rotorcraft 
to the defined environment or laboratory testing may not be combined. 
The laboratory test allows some frequency

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areas to be under tested and requires other areas to have some safety 
margin when compared to the defined environment. The areas required to 
have some safety margin are those shown, by past testing, to exhibit 
greater susceptibility to adverse effects from HIRF; and laboratory 
tests, in general, do not accurately represent the aircraft 
installation. Service experience alone will not be acceptable since 
such experience in normal flight operations may not include an exposure 
to HIRF. Reliance on a system with similar design features for 
redundancy, as a means of protection against the effects of external 
HIRF, is generally insufficient because all elements of a redundant 
system are likely to be concurrently exposed to the radiated fields.
    The modulation that represents the signal most likely to disrupt 
the operation of the system under test, based on its design 
characteristics should be selected. For example, flight control systems 
may be susceptible to 3 Hz square wave modulation. If the worst-case 
modulation is unknown or cannot be determined, default modulations may 
be used. Suggested default values are a 1 KHz sine wave with 80 percent 
depth of modulation in the frequency range from 10 KHz to 400 MHz, and 
1 KHz square wave with greater than 90 percent depth of modulation from 
400 MHz to 18 GHz. For frequencies where the unmodulated signal would 
cause deviations from normal operation, several different modulating 
signals with various waveforms and frequencies should be applied.
    Acceptable system performance would be attained by demonstrating 
that the critical function components of the system under consideration 
continue to perform their intended function during and after exposure 
to required electromagnetic fields. Deviations from system 
specifications may be acceptable but must be independently assessed by 
the FAA on a case-by-case basis.

                  Table 1.--Field Strength Volts/Meter
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                     Frequency                         Peak     Average
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10-100 KHz........................................        150        150
100-500...........................................        200        200
500-2000..........................................        200        200
2-30 MHz..........................................        200        200
30-100............................................        200        200
100-200...........................................        200        200
200-400...........................................        200        200
400-700...........................................        730        200
700-1000..........................................       1400        240
1-2 GHz...........................................       5000        250
2-4...............................................       6000        490
4-6...............................................       7200        400
6-8...............................................       1100        170
8-12..............................................       5000        330
12-18.............................................       2000        330
18-40.............................................       1000        420
------------------------------------------------------------------------

Applicability

    As discussed above, this special condition is applicable to 
Supplemental Type Certificate (STC) Project Number ST2017RC-R, for the 
installation of a Pratt & Whitney PT6-67D turbine engine in GHTI UH-1H 
military surplus helicopters type certificated under TC R00002RC. 
Should GHTI apply at a later date for a change to the STC to include 
another model incorporating the same novel or unusual design feature, 
the special condition would apply to that STC modification as well 
under the provisions of Sec.  21.101(a)(1).

Conclusion

    This action affects only certain novel or unusual design features 
associated with the STC project listed above. 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 helicopter.
    The substance of this special condition 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 helicopter 
modification which is imminent, the FAA has determined that prior 
public notice and comment are unnecessary and impracticable, and good 
cause exists for adopting this special condition 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 Parts 21 and 29

    Aircraft, Air transportation, Aviation safety, Rotorcraft, Safety.

    The authority citation for this special condition is as follows:

    Authority: 42 U.S.C. 7572; 49 U.S.C. 106(g), 40105, 40113, 
44701-44702, 44704, 44709, 44711, 44713, 44715, 45303.

The Special Condition

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special condition is issued as part of the 
type certification basis for STC Project ST2017RC-R, installation of 
PT6-67D on Global Helicopter Technology, Inc (GHTI), Model UH-1H, 
Restricted Category Helicopters, type certificated under TC R00002RC.

Protection for Electrical and Electronic Systems From High Intensity 
Radiated Fields

    Each system that performs critical functions must be designed and 
installed to ensure that the operation and operational capabilities of 
these critical functions are not adversely affected when the helicopter 
is exposed to high intensity radiated fields external to the 
helicopter.

    Issued in Fort Worth, Texas, on January 8, 2003.
Eric Bries,
Acting Manager, Aircraft Certification Service, Rotorcraft Directorate.
[FR Doc. 03-1010 Filed 1-15-03; 8:45 am]
BILLING CODE 4910-13-P