[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)     
----------------------------------------------------------------------------------------------------------------
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              
                                                                                                                
----------------------------------------------------------------------------------------------------------------

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
------------------------------------------------------------------------

    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