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18 November 2007
[Federal Register: November 16, 2007 (Volume 72, Number 221)]
[Rules and Regulations]
[Page 64529-64532]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr16no07-3]
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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
[[Page 64532]]
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