[Federal Register Volume 72, Number 221 (Friday, November 16, 2007)]
[Rules and Regulations]
[Pages 64529-64532]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 07-5698]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 21 and 29

[Docket No. SW015; Special Condition No. 29-015-SC]


Special Conditions: DynCorp International, Supplemental Type 
Certificate (STC), Project Number ST2902RC-R, Installation of Pratt & 
Whitney Canada PT6-67D Engine With Full Authority Digital Engine 
Control (FADEC) on Global Helicopter Technology, Inc. (GHTI), 
Restricted Category Model UH-1H Helicopters, Type Certificate (TC) 
Number R00002RC

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 Number ST2902RC-R, for the installation of a 
Pratt and Whitney PT6-67D Turbine Engine on Global Helicopter 
Technology Inc. (GHTI), Restricted Category, U.S. Army military surplus 
helicopters, Model UH-1H, type certificated under type certificate (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 
control 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 
control functions of systems will be maintained when exposed to HIRF.

DATES: The effective date of this special condition is November 7, 
2007. We must receive your comments by January 15, 2008.

ADDRESSES: You must mail two copies of your comments to: Federal 
Aviation Administration (FAA), Rotorcraft Directorate, Attention: Rules 
Docket (ASW-111), Docket No. SW015, Fort

[[Page 64530]]

Worth, Texas 76193-0111. You may deliver two copies to the Rotorcraft 
Directorate at the above address. You must mark your comments: Docket 
No. SW015. You can inspect comments 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: Tyrone D. Millard, FAA, Rotorcraft 
Directorate, Rotorcraft Standards Staff, Fort Worth, Texas 76193-0110; 
telephone 817-222-5439, fax 817-222-5961.

SUPPLEMENTARY INFORMATION: The FAA has determined that notice and 
opportunity for prior public comment hereon are unnecessary because the 
substance of this special condition has been subject to the public 
comment process in several prior instances with no substantive comments 
received. We are satisfied that new comments are unlikely. The FAA 
therefore finds that good cause exists for making this special 
condition effective upon issuance.

Comments Invited

    We invite interested people to take part in this rulemaking by 
sending written comments, views, or data. The most helpful comments 
reference a specific portion of the special condition, explain the 
reason for any recommended change, and include supporting data.
    We will file in the docket all comments we receive, as well as a 
report summarizing each substantive public contact with FAA personnel 
about this special condition. You can 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 8:30 a.m. and 4 p.m., Monday through Friday, except Federal 
holidays. We will consider all comments we receive by the closing date 
for comments. We will consider comments filed late if it is possible to 
do so without incurring additional expense or delay. We may change this 
special condition based on the comments we receive.
    If you want us to let you know we received your comments on this 
special condition, send us 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 January 9, 2007, DynCorp International 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. This 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.

Supplemental Type Certification Basis

    Under the provisions of 14 CFR 21.101, DynCorp International must 
show that the Engine Installation meets the applicable provisions of 
the regulations as listed below:
     14 CFR part 29 as amended through and including Amendment 
29-1, effective August 12, 1965.
     14 CFR part 29.1529, Instructions for Continued 
Airworthiness, Amendment Number 20, effective September 11, 1980.
    In accordance with 14 CFR part 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 Sec.  36.1(a)(4) and 
defined under Sec.  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 testing, flight testing, or a 
combination of noise and flight testing.
    In addition, the certification basis includes an equivalent safety 
finding pertaining to a limitation associated with repetitive high 
torque cycle events that is 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.
    The FAA issues special conditions as defined in Sec.  11.19, and 
issued in accordance with Sec.  11.38, and they become part of the STC 
certification basis under Sec.  21.17(a)(2).
    Special conditions are initially applicable to the model, the 
modification, or a combination of the model and the modification for 
which they are issued. Should this STC be revised to include any other 
model that incorporates the same novel or unusual design feature, this 
special condition would also apply to the other model under the 
provisions of Sec.  21.101.

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 and electronic (electrical/electronic) systems, specifically 
a FADEC, that will be performing critical control functions for the 
continued safe flight and landing of the helicopter. A FADEC is an 
electronic device that performs the critical functions of engine 
control during flight operations.

Discussion

    The DynCorp International installation of the PT6-67D in the UH-1H 
helicopter, at the time of application, was identified as incorporating 
an electronic FADEC system. After the design is finalized, DynCorp 
International will provide the FAA with a preliminary hazard analysis. 
This analysis will identify the critical control functions that are 
required for safe flight and landing that are performed by the FADEC 
system.
    Recent advances in technology have given rise to the application in 
aircraft designs of advanced electrical/electronic systems that perform 
critical control 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

[[Page 64531]]

vulnerability of the electrical/electronic systems required for the 
continued safe flight and landing of the helicopter. The design and 
installation of these systems will provide effective measures to 
protect this engine installation on this helicopter against the adverse 
effects of exposure to HIRF. The following primary factors contributed 
to the current conditions: (1) Increased use of sensitive electronics 
that perform critical control 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.
    On July 30, 2007, we issued a final HIRF rule (72 FR 44016, August 
6, 2007). This rule provides standards to protect aircraft electrical 
and electronic systems from HIRFs. It was effective September 5, 2007. 
However, that rule included provisions that provide relief from the new 
testing requirements for equipment previously certificated under HIRF 
special conditions issued in accordance with 14 CFR Sec.  21.16. To 
obtain this relief, the applicant must be able to--
    (1) Provide evidence that the system was the subject of HIRF 
special conditions issued before December 1, 2007;
    (2) Show that there have been no system design changes that would 
invalidate the HIRF immunity characteristics originally demonstrated 
under the previously issued HIRF special conditions; and
    (3) Provide the data used to demonstrate compliance with the HIRF 
special conditions under which the system was previously approved.
    DynCorp's FADEC installation is eligible for this relief provided 
in 14 CFR Sec.  29.1317(d) of the final HIRF rule. However, to meet 
their HIRF requirements, they must comply with this Special Condition, 
which is based on similar, historical HIRF protections requirements.
    These special conditions will require the systems that perform 
critical control functions, as installed in the aircraft, to 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 control 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 control functions in helicopters.
    The applicant may also demonstrate by a laboratory test that the 
electrical/electronic systems that perform critical control 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 200 volts per 
meter (v/m) is more appropriate for critical functions during VFR 
operations. Laboratory test levels are defined according to RTCA/DO-
160D Section 20 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 Category 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 control functions. 
The term ``critical control'' 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 FADEC system 
identified by the hazard analysis as performing critical control 
functions is required to have HIRF protection.
    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 FADEC system 
to the defined environment or laboratory testing may not be combined. 
The laboratory test allows some frequency areas to be undertested 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 control 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 KHz.......................................        200        200
500-2000 KHz......................................        200        200
2-30 MHz..........................................        200        200
30-100 MHz........................................        200        200
100-200 MHz.......................................        200        200
200-400 MHz.......................................        200        200
400-700 MHz.......................................        730        200
700-1000 MHz......................................       1400        240

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1-2 GHz...........................................       5000        250
2-4 GHz...........................................       6000        490
4-6 GHz...........................................       7200        400
6-8 GHz...........................................       1100        170
8-12 GHz..........................................       5000        330
12-18 GHz.........................................       2000        330
18-40 GHz.........................................       1000        420
------------------------------------------------------------------------

Applicability

    As discussed previously, this special condition is applicable to 
Supplemental Type Certificate (STC) Project Number ST2902RC-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 DynCorp International 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.

Conclusion

    This action affects only certain novel or unusual design features 
associated with this STC project. 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 a 
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, the FAA has 
determined that prior public notice and comment are unnecessary, 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.

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 
supplemental type certification basis for STC Project ST2902RC-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.
    1. Each system that performs critical control functions must be 
designed and installed to ensure that the operation and operational 
capabilities of these critical control functions are not adversely 
affected when the helicopter is exposed to high intensity radiated 
fields external to the helicopter.
    2. For the purpose of this special condition, critical control 
functions are defined as those functions, whose failure would 
contribute to, or cause, an unsafe condition that would prevent the 
continued safe flight and landing of the aircraft.

    Issued in Fort Worth, Texas, on November 7, 2007.
Mark R. Schilling,
Acting Manager, Aircraft Certification Service, Rotorcraft Directorate.
[FR Doc. 07-5698 Filed 11-15-07; 8:45 am]
BILLING CODE 4910-13-P