[Federal Register Volume 59, Number 61 (Wednesday, March 30, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-7456]
[[Page Unknown]]
[Federal Register: March 30, 1994]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM-94; Special Conditions No. 25-ANM-83]
Special Conditions: Modified Canadair Model CL-600-1A11, -2A12,
and -2B16, Series Airplanes; Lightning and High Intensity Radiated
Fields (HIRF)
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final special conditions with request for comments.
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SUMMARY: These special conditions are issued for Canadair Model CL-600-
1A11, -2A12, and -2B16 series airplanes modified by Service Corporation
International, of Houston, Texas. The modification includes the
installation of high-technology digital avionics systems or other
electronic systems that perform critical or essential functions. The
applicable type certification regulations do not contain adequate or
appropriate safety standards for the protection of these systems from
the effects of lighting and high intensity radiated fields (HIRF).
These special conditions provide the additional safety standards that
the Administrator considers necessary to ensure that the critical and
essential functions that these systems perform perform are maintained
when the airplane is exposed to lightning and HIRF.
DATES: The effective date of these special conditions is March 21,
1994. Comments must be received on or before May 13, 1994.
ADDRESSES: Comments on these special conditions may be mailed in
triplicate to: Federal Aviation Administration, Transport Airplane
Directorate (AMN-100), Attn: Docket No. NM-94, 1601 Lind Avenue SW.,
Renton, WA, 98055-4056; or delivered in triplicate to the Transport
Airplane Directorate at the above address. Comments must be marked;
Docket No. NM-94. Comments may be inspected weekdays, except Federal
holidays, between 7:30 a.m. and 4 p.m.
FOR FURTHER INFORMATION CONTACT:William Schroeder, FAA, Standardization
Branch, ANM-113, Transport Airplane Directorate, Aircraft Certification
Service, 1601 Lind Avenue SW., Renton, WA 98055-4056; telephone (206)
227-2148.
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA has determined that good cause exists for making these
special conditions effective upon issuance; however, interested persons
are invited to submit such written data, views, or arguments as they
may desire. Communications should identify the regulatory docket or
special conditions number and be submitted in triplicate to the address
specified above. All communications received on or before the closing
date for comments will be considered by the Administrator. These
special conditions may be changed in light of the comments received.
All comments submitted will be available in the 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.
Persons wishing the FAA to acknowledge receipt of their comments
submitted in response to this request must submit with these comments a
self-addressed, stamped postcard on which the following statement is
made: ``Comments to Docket No. NM-94.'' The postcard will be date
stamped, and returned to the commenter.
Background
On November 16, 1993, Service Corporation International, 7744
Airport Boulevard, Houston, Texas 77061, applied for a supplemental
type certificate to modify Canadair Model CL-600-1A11 series airplanes.
The proposed modification includes the installation of digital
avionics, including an electronic flight instrument system (EFIS) and a
Laseref Inertial Reference System (IRS), which are vulnerable to
lightning and HIRF external to the airplane. Other similar
modifications often installed when updating the digital avionics
include attitude and heading reference systems (AHRS). Because these
are typical modernization modifications for retrofitting state-of-the-
art avionics and electronics to older type certificates, it is expected
that Service Corporation International will apply for installation of
similar modifications on Canadair Model CL-600-1A11, -2A12, and 2B16
series airplanes in the near future. Therefore, Service Corporation
International will need appropriate lightning and HIRF criteria
available for application to those projects.
Canadair Model CL-600-1A11, 2A12, and -2B16 series airplanes are
all listed on Type Certificate A21EA. The airplanes are pressurized,
have a seating capacity of 6 to 12 passengers (depending on the
specific model and airplane configuration), and are corporate transport
type airplanes that have a maximum operating altitude of 51,000 feet.
The airplanes are powered by two aft fuselage-mounted turbojet or
turbofan engines, depending on the specific model and airplane and
configuration.
Supplemental Type Certification Basis
Under the provisions of Sec. 21.101 of the FAR, Service Corporation
International, must show that the modified Canadair Model CL-600-1A11,
-2A12, and -2B16 series airplanes continue to meet the applicable
provisions of the regulations incorporated by reference in Type
Certification No. A21EA, 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 certification No.
A21EA include the following: Part 25 of the FAR, dated February 1,
1965, including Amendments 25-1 through 25-37. In addition, the
certification basis includes certain special conditions and exemptions
that are not relevant to these special conditions. These specifications
will form an additional part of the type certification basis when
critical or essential digital avionics/electronic systems are being
modified or installed by Service Corporation International.
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 Canadair Model CL-600-1A11, -2A12,
and -2B16 series airplanes 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).
Discussion
The existing lightning protection airworthiness certification
requirements are insufficient to provide an acceptable level of safety
with new-technology avionics and electronic systems. There are two
regulations that specifically pertain to lightning protection: One for
the airframe in general (Sec. 25.581), and the other for fuel system
protection (Sec. 25.954). There are, however, no regulations that deal
specifically with protection of electrical and electronic systems from
lightning. The loss of a critical function of these systems due to
lightning would prevent continued safe flight and landing of the
airplane. Although the loss of an essential function would not prevent
continued safe flight and landing, it would significantly impact the
safety level of the airplane.
There is also no specific regulation that addresses protection
requirements for electrical and electronic systems for 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 Canadair Model CL-600-1A11, -2A12, and -
2B16 series airplanes that would require that new technology electrical
and electronic systems, such as electronic flight instrument systems,
and digital avionics systems be designed and installed to preclude
component damage and interruption of function due to both the direct
and indirect effects of lightning and HIRF.
Lightning
To provide a means of compliance with the lightning special
conditions, clarification of the threat definition of lightning is
needed. The following ``threat definition,'' based on FAA Advisory
Circular (AC) 20-136, Protection of Aircraft Electrical/Electronic
Systems Against the Indirect Effects of Lightning, dated March 5, 1990,
is proposed as a basis to use in demonstrating compliance with the
lightning protection special condition, with the exception of the
multiple burst environment which has been changed to agree with the
latest recommendations from the Society of Automotive Engineers (SAE)
AE4L Committee.
The lightning current waveforms (Components A, D, and H) defined
below, along with the voltage waveforms in AC 20-53A, will provide a
consistent and reasonable standard that is acceptable for use in
evaluating the effects of lightning on the airplane. These waveforms
depict threats that are external to the airplane. The effect of these
threats on the airplane and its systems depends upon several factors,
including installation configuration, materials, shielding, airplane
geometry, etc. Therefore, tests (including tests on the completed
airplane or an adequate simulation) and/or verified analyses need to be
conducted in order to obtain the resultant internal threat to the
installed systems. The electronic systems may then be evaluated with
this internal threat in order to determine their susceptibility to
upset and/or malfunction.
To evaluate the induced effects to these systems, three
considerations are required:
1. First Return Stroke: (Severe Strike--Component A, or Restrike--
Component D). This external threat needs to be evaluated to obtain the
resultant internal threat and to verify that the level of the induced
currents and voltages is sufficiently below the equipment ``hardness''
level.
2. Multiple Stroke Flash: (\1/2\ Component D). A lightning strike
is often composed of a number of successive strokes, referred to as
multiple strokes. Although multiple strokes are not necessarily a
salient factor in a damage assessment, they can be the primary factor
in a system upset analysis. Multiple strokes can induce a sequence of
transients over an extended period of time. While a single event upset
of input/output signals may not affect system performance, multiple
signal upsets over an extended period of time (2 seconds) may affect
the systems under consideration. Repetitive pulse testing and/or
analysts need to be carried out in response to the multiple stroke
environment to demonstrate that the system response meets the safety
objective. This external multiple stroke environment consists of 24
pulses and is described as a single Component A followed by 23 randomly
spaced restrikes of \1/2\ magnitude of Component D (peak amplitude of
50,000 amps). The 23 restrikes are distributed over a period of up to 2
seconds according to the following constraints: (1) The minimum time
between subsequent strokes is 10 ms, and (2) the maximum time between
subsequent strokes is 200 ms. An analysis or test needs to be
accomplished in order to obtain the resultant internal threat
environment for the system under evaluation.
3. Multiple Burst: (Component H). In-flight data-gathering projects
have shown bursts of multiple, low amplitude, fast rates of rise, short
duration pulses accompanying the airplane lightning strike process.
While insufficient energy exists in these pulses to cause physical
damage, it is possible that transients resulting from this environment
may cause upset the some digital processing systems.
The representation of this interference environment is a repetition
of low amplitude, high peak rate of rise, double exponential pulses
which represent the multiple bursts of current pulses observed in these
flight data gathering projects. This component is intended for an
analytical (or test) assessment of function upset of the system. Again,
it is necessary that this component be translated into an internal
environmental threat in order to be used. This ``Multiple Burst''
consists of repetitive Component H waveforms in 3 sets of 20 pulses
each. The minimum time between individual Component H pulses within a
burst is 50 microseconds; the maximum is 1000 microseconds. The 3
bursts are distributed according to the following constraints: (1) the
minimum period between bursts is 30ms, and (2) the maximum period
between bursts is 300ms. The individual ``Multiple Burst'' Component H
waveform is defined below.
The following current waveforms constitute the ``Severe Strike''
(Component A), ``Restrike'' (Component D), ``Multiple Stroke'' (\1/2\
Component D), and the ``Multiple Burst'' (Component H).
These components are defined by the following double exponential
equation:
i(t)=Io (e-at-e-bt)
where:
t=time in seconds,
i=current in amperes, and
----------------------------------------------------------------------------------------------------------------
Severe Multiple Multiple
strike Restrike stroke (\1/ burst
(component (component 2\ component (component
A) D) D) H)
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Io, amp............................................ = 218,810 109,405 54,703 10,572
a, sec-1........................................... = 11,354 22,708 22,708 187,191
b, sec-1........................................... = 647,265 1,294,530 1,294,530 19,105,100
This equation produces the following
characteristics:
ipeak.............................................. = 200 KA 100 KA 50 KA 10 KA
and,
(di/dt)max(amp/sec)................................ = 1.4 x 1011 1.4 x 1011 0.7 x 1011 2.0 x 1011
@t=0+sec @t=0+sec @t=0+sec @t=0+sec
(di/dt), (amp/sec)................................. = 1.0 x 1011 1.0 x 1011 0.5 x 1011
@t=.52 sec)......................... = 2.0 x 106 0.25 x 106 0.0625 x 106
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High-Intensity Radiated Fields (HIRF)
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, such as the EFIS, 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 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)
------------------------------------------------------------------------
10 KHz-100 KHz...................................... 50 50
100 KHz-500 KHz..................................... 60 60
500 KHz-2 MHz....................................... 70 70
2 MHz-30 MHz........................................ 200 200
30 MHz-70 MHz....................................... 30 30
70 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-1 GHz....................................... 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 1270
12 GHz-18 GHz....................................... 3,500 360
18 GHz-40 GHz....................................... 2,100 750
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The envelope given in paragraph 2 above is a revision to the
envelope used in previously issued special conditions in other
certification projects. It is based on new data and SAE AE4R
subcommittee recommendations. This revised envelope includes data from
Western Europe and the U.S. It will also be adopted by the European
Joint Aviation Authorities.
Conclusion
This action affects only certain unusual or novel design features
on the Canadair Model CL-600-1A11, -2A12, and -2B16 series airplanes.
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 Canadair Model CL-600-1A11, -2A12 and -2B16 series airplanes.
The substance of the special conditions for these airplanes has
been subjected to the notice and comment procedure 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 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 immediately. Therefore, these special conditions are being
made effective upon issuance. The FAA is requesting comments to allow
interested persons to submit views that may have not been submitted in
response to the prior opportunities for comment described above.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Federal Aviation Administration,
Reporting and recordkeeping requirements.
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. app. 1344, 1348(c), 1352, 1345(a), 1355,
1421 through 1431, 1502, 1651(b)(2), 42 U.S.C. 1857f-10, 4321 et
seq.; E.O. 11514; and 49 U.S.C. 49 U.S.C. 105(g).
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 Canadair Model 600-1A11, -2A12, and -
2B16 series airplanes modified by Service Corporation International of
Houston, Texas.
1. Lightning Protection
a. 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
lightning.
b. Each electrical or electronic system that performs essential
functions must be protected to ensure that the function can be
recovered in a timely manner after the airplane has been exposed to
lightning.
2. 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 external to the airplane.
3. The Following Definitions Apply With Respect To These Special
Conditions
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.
Essential Functions
Functions whose failure would contribute to or cause a failure
condition that would significantly impact the safety of the airplane or
the ability of the flightcrew to cope with adverse operating
conditions.
Issued in Renton, Washington, on March 21, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service, ANM-100.
[FR Doc. 94-7456 FIled 3-29-94; 8:45 am]
BILING CODE 4910-13-M