[Federal Register Volume 61, Number 213 (Friday, November 1, 1996)]
[Rules and Regulations]
[Pages 56408-56409]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-28107]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM-128; Special Conditions No. 25-ANM-121]
Special Conditions: deHavilland DHC-8-400 Airplane; High-
Intensity Radiated Fields
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final special conditions.
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SUMMARY: These special conditions are issued to the de Havilland
Aircraft Company of Canada for the de Havilland DHC-8-400 airplane.
This airplane will utilize new avionics/electronic systems that provide
critical data to the flightcrew. The applicable regulations do not
contain adequate or appropriate safety standards for the protection of
these systems from the effects of high-intensity radiated fields. 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.
EFFECTIVE DATE: December 2, 1996.
FOR FURTHER INFORMATION CONTACT:
Tim Backman, FAA, Standardization Branch, ANM-113, Transport Airplane
Directorate, Aircraft Certification Service, 1601 Lind Avenue SW.,
Renton, Washington, 98055-4056, telephone (206) 227-2797 or facsimile
(206) 227-1149.
SUPPLEMENTARY INFORMATION:
Background
On January 31, 1995, the de Havilland Aircraft Company of Canada,
Garratt Boulevard, Downsview, Ontario M3K1Y5, applied for an amendment
to their Type Certificate No. A13NM to include their new model Dash 8
Series 400 (DHC-8-400), Model 401/402 airplane, which is a derivative
of the DHC-8-300. The DHC-8-400 is a high wing, T-tail, twin engine,
turbopropeller powered regional transport. Each engine will be capable
of delivering 4830 shaft horsepower. The flight controls are manual,
except for the tandem rudder which will be hydraulically powered. The
airplane has a seating capacity of up to 78, and a maximum takeoff
weight of 62,500 pounds.
Type Certification Basis
Under the provisions of 14 CFR Sec. 21.101, deHavilland must show
that the DHC-8-400 meets the applicable provisions of the regulations
incorporated by reference in Type Certificate No. A13NM, or the
applicable regulations in effect on the date of application for the
change of the Model 300. 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. A13NM include part 25, as amended by Amendments
25-1 through 25-51, and certain other later amended sections of part 25
that are not relevant to these special conditions. In addition,
deHavilland has chosen to comply with the applicable regulations in
effect on March 6, 1995; specifically part 25 as amended by Amendments
25-1 through 25-83. In addition to the applicable airworthiness
regulations and special conditions, the DHC-8-400 must comply with the
fuel vent and exhaust emission requirements of part 34, effective
September 10, 1990, plus any amendments in effect at the time of
certification; and the noise certification requirements of part 36,
effective December 1, 1969, as amended by Amendment 36-1 through the
amendment in effect at the time of certification. No exemptions are
anticipated. These special conditions will form an additional part of
the type certification basis.
If the Administrator finds that the applicable airworthiness
regulations (i.e., part 25, as amended) do not contain adequate or
appropriate safety standards for the DHC-8-400 because of a novel or
unusual design feature, special conditions are prescribed under the
provisions of Sec. 21.16 to establish a level of safety equivalent to
that established in the regulations.
Special conditions, as appropriate, are issued in accordance with
Sec. 11.49 of the FAR after public notice, as required by Secs. 11.28
and 11.29(b), and become part of the type certification basis in
accordance with Sec. 21.101(b)(2).
Special conditions are initially applicable to the model for which
they are issued. Should the type certificate for that model be amended
later to include any other model that incorporates the same novel or
unusual design feature, or should any other model already included on
the same type certificate be modified to incorporate the same novel or
unusual design feature, the special conditions would also apply to the
other model under the provisions of Sec. 21.101(a)(1).
Novel or Unusual Design Features
The DHC-8-400 airplane avionics enhancement will utilize electronic
systems that perform critical functions,
[[Page 56409]]
including a digital Electronic Flight Instrument System (EFIS),
attitude and heading reference systems (AHRS), and air data systems
(ADS). These systems may be vulnerable to high-intensity radiated
fields (HIRF) external to the airplane.
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 electrical and electronic 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 DHC-8-400, which require that new
technology electrical and electronic systems, such as the EFIS, AHRS
and ADS, 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
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 digital avionics 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, and adequate level of
protection exists when compliance with the HIRF protection special
condition is shown with either paragraphs 1 or 2 below:
1. A minimum threat of 100 volts per meter peak 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 following field
strengths for the frequency ranges indicated.
------------------------------------------------------------------------
Peak (V/ Average
Frequency M) (V/M)
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10 KHz-100 KHz.................................... 50 50
110 KHz-500 KHz................................... 60 60
500 KHz-2000 KHz.................................. 70 70
2 MHz-30 MHz...................................... 200 200
30 MHz-100 MHz.................................... 30 30
100 MHz-200 MHz................................... 150 33
200 MHz-400 MHz................................... 70 70
400 MHz-700 MHz................................... 4,020 935
700 MHz-1000 MHz.................................. 1,700 170
1 GHz-2 GHz....................................... 5,000 990
2 GHz-4 GHz....................................... 6,680 840
4 GHz-6 GHz....................................... 6,850 310
6 GHz-8 GHz....................................... 3,600 670
8 GHz-12 GHz...................................... 3,500 1,270
12 GHz-18 GHz..................................... 3,500 360
18 GHz-40 GHz..................................... 2,100 750
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As discussed above, these special conditions are applicable
initially to the DHC-8-400 airplane. Should de Havilland apply at a
later date for a change to the type certificate to include another
model incorporating the same novel or unusual design feature, the
special conditions would apply to that model as well, under the
provisions of Sec. 21.101(a)(1).
Discussion of Comments
Notice of proposed special conditions No. SC-96-3-NM was published
in the Federal Register on July 22, 1996 (61 FR 37844). No comments
were received.
Conclusion
This action affects certain design features only on the DHC-8-400
airplane. It is not a rule of general applicability and affects only
the manufacturer who applied to the FAA for approval of these features
on the airplane.
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 type certification basis for the deHavilland DHC-8-400 series
airplanes.
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 this special condition, 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 October 15, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service, ANM-100.
[FR Doc. 96-28107 Filed 10-31-96; 8:45 am]
BILLING CODE 4910-13-M
