FR Doc E6-19205

[Federal Register: November 15, 2006 (Volume 71, Number 220)]
[Proposed Rules]
[Page 66633-66642]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr15no06-21]

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Part III

Department of Transportation

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Federal Aviation Administration

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14 CFR Parts 121, 125, and 135

Filtered Flight Data; Proposed Rule

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 121, 125, and 135

[Docket No. FAA-2006-26135; Notice No. 06-16]
RIN 2120-AI79

Filtered Flight Data

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to amend the digital flight data recorder
(DFDR) regulations by prohibiting the filtering of some original
parameter sensor signals. This proposed rule is based on
recommendations issued by the National Transportation Safety Board, and
is intended to improve the accuracy and quality of the data recorded on
DFDRs and used during accident and incident investigations.

DATES: Send your comments on or before February 13, 2007.

ADDRESSES: You may send comments [identified by Docket Number FAA-2006-
26135] using any of the following methods:
DOT Docket Web site: Go to http://dms.dot.gov and follow

the instructions for sending your comments electronically.
Government-wide rulemaking Web site: Go to http://www.regulations.gov
and follow the instructions for sending your

comments electronically.
Mail: Docket Management Facility; U.S. Department of
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401,
Washington, DC 20590-001.
Fax: 1-202-493-2251.
Hand Delivery: Room PL-401 on the plaza level of the
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
For more information on the rulemaking process, see the
SUPPLEMENTARY INFORMATION section of this document.
Privacy: We will post all comments we receive, without change, to
http://dms.dot.gov, including any personal information you provide. For

more information, see the Privacy Act discussion in the SUPPLEMENTARY
INFORMATION section of this document.
Docket: To read background documents or comments received, go to
http://dms.dot.gov at any time or to Room PL-401 on the plaza level of

the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: For technical questions: Timothy W.
Shaver, Avionics Systems Branch, Aircraft Certification Service, AIR-
130, Federal Aviation Administration, 800 Independence Avenue, SW.,
Washington, DC 20591; telephone (202) 385-4686; facsimile (202) 385-
4651; e-mail tim.shaver@faa.gov. For legal questions: Karen L.
Petronis, Regulations Division, Office of Chief Council, AGC-200,
Federal Aviation Administration, 800 Independence Avenue, SW.,
Washington, DC 20591; telephone (202) 267-3073; facsimile (202) 267-
7971; e-mail karen.petronis@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites interested persons to participate in this
rulemaking by submitting written comments, data, or views. We also
invite comments relating to the economic, environmental, energy, or
federalism impacts that might result from adopting the proposals in
this document. The most helpful comments reference a specific portion
of the proposal, explain the reason for any recommended change, and
include supporting data. We ask that you send us two copies of written
comments.
We will file in the docket all comments we receive, as well as a
report summarizing each substantive public contact with FAA personnel
concerning this proposed rulemaking. The docket is available for public
inspection 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 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays. You may also review the docket using the
Internet at the Web address in the ADDRESSES section.
Privacy Act: Using the search function of our docket Web site,
anyone can find and read the comments received into any of our dockets,
including the name of the individual sending the comment (or signing
the comment on behalf of an association, business, labor union, etc.).
You may review DOT's complete Privacy Act Statement in the Federal
Register published on April 11, 2000 (65 FR 19477-78) or you may visit
http://dms.dot.gov.

Before acting on this proposal, we will consider all comments we
receive on or before the closing date for comments. We will consider
comments filed late if it is possible to do so without incurring
expense or delay. We may change this proposal in light of the comments
we receive.
If you want the FAA to acknowledge receipt of your comments on this
proposal, include with your comments a pre-addressed, stamped postcard
on which the docket number appears. We will stamp the date on the
postcard and mail it to you.

Proprietary or Confidential Business Information

Do not file in the docket information that you consider to be
proprietary or confidential business information. Send or deliver this
information directly to the person identified in the FOR FURTHER
INFORMATION CONTACT section of this document. You must mark the
information that you consider proprietary or confidential. If you send
the information on a disk or CD ROM, mark the outside of the disk or CD
ROM and also identify electronically within the disk or CD ROM the
specific information that is proprietary or confidential.
Under 14 CFR 11.35(b), when we are aware of proprietary information
filed with a comment, we do not place it in the docket. We hold it in a
separate file to which the public does not have access, and place a
note in the docket that we have received it. If we receive a request to
examine or copy this information, we treat it as any other request
under the Freedom of Information Act (5 U.S.C. 552). We process such
requests under the DOT procedures found in 49 CFR part 7.

Availability of Rulemaking Documents

You can get an electronic copy using the Internet by:
(1) Searching the Department of Transportation's electronic Docket
Management System (DMS) Web page (http://dms.dot.gov/search); (2) Visiting the Office of Rulemaking's Web page at http://

http://www.faa.gov/regulations_policies/; or

(3) Accessing the Government Printing Office's Web page at http://www.gpoaccess.gov/fr/index.html
.

You can also get a copy by sending a request to the Federal
Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence
Avenue SW., Washington, DC 20591, or by calling (202) 267-9680. Make
sure to identify the docket number, notice number, or amendment number
of this rulemaking.

Authority for This Rulemaking

The FAA's authority to issue rules regarding aviation safety is
found in Title 49 of the United States Code.

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Subtitle I, section 106 describes the authority of the FAA
Administrator. Subtitle VII, Aviation Programs, describes in more
detail the scope of the agency's authority.
This rulemaking is promulgated under the authority described in
subtitle VII, part A, subpart III, section 44701. Under that section,
the FAA is charged with prescribing regulations providing minimum
standards for other practices, methods and procedures necessary for
safety in air commerce. This regulation is within the scope of that
authority since flight data recorders are the only means available to
account for aircraft movement and flight crew actions critical to
finding the probable cause of incidents or accidents, including data
that could prevent future incidents or accidents.

Background

Statement of the Problem

During several aircraft accident investigations, the National
Transportation Safety Board (NTSB or Board) found that some flight data
recorder (FDR) systems were filtering flight recorder parameter signals
before they were recorded. As a result, the data being recorded did not
accurately reflect the aircraft's performance or the movements of the
flight control systems prior to and during the accident/incident being
investigated. This signal filtering both hampered and delayed the
investigations. In addition, the NTSB expended significant resources
and time attempting to recreate the performance and movements of the
flight control systems of the affected aircraft.
Designers of the information sources that provide input to the DFDR
system have their own reasons for filtering data, such as making it
more aesthetically appealing for display in the cockpit. During the
design of DFDR systems, it appears that convenience and a desire to
reduce cost and complexity by eliminating multiple data paths have led
to the DFDR recording filtered data rather than raw data from the
sensors. The FAA understands that, in some cases, it may have been an
error in the choice of data selection sources that resulted in filtered
data being recorded. We have no reason to believe that filtering is
being used to disguise data that are central to accident/incident
investigations.
After its most recent experience with signal filtering, the NTSB
issued three recommendations (NTSB Recommendations A-03-48/A-03-49/A-
03-50, November 6, 2003). The NTSB recommended that the FAA require all
aircraft have installed a DFDR system ``capable of recording values
that meet the accuracy requirements through the full dynamic range of
each parameter at a frequency sufficient to determine a complete,
accurate, and unambiguous time history of parameter activity, with
emphasis on capturing each parameter's dynamic motion at the maximum
rate possible, including reversals of direction at the maximum rate
possible.''
The FAA agrees with these NTSB recommendations and is proposing to
prohibit signal filtering for specified recorded parameters.

History

First Encounter With Filtered Data
The NTSB's first encounter with filtered data that impeded an
investigation occurred during its investigation of three similar Boeing
767 accidents. Two of these accidents occurred in 1992 and one in 1993
when, during landing, the nose gear contacted the runway with excessive
force after normal touchdown on the main landing gear. In each case,
the airplane fuselage structure and nose wheel wells were damaged, but
there were no injuries or fatalities. During its investigation, the
NTSB found that the Engine Instrument Crew Alert System (EICAS) was
filtering flight control position data before it was sent to and
recorded by the DFDR. A low sample rate (once per second) rendered the
filtered data even less usable, making it impossible for the NTSB to
determine the pilots' actions with precision.
At the same time the NTSB was investigating these three accidents,
it was also investigating several alleged uncommanded rudder movements
on Boeing 767s. In these cases, the NTSB found that the EICAS was also
filtering rudder position data before being recorded by the DFDRs. An
investigation disclosed that the discrepancy between the recorded
rudder position and the actual rudder position could be greater than 20
degrees in some dynamic situations.
As a result of these findings, in June 1994 the NTSB recommended
that the FAA:
(1) Require design modification to the Boeing 757 \1\ and 767
models so that flight control position data sent to the DFDR is
accurate and not filtered by the EICAS (NTSB Recommendation A-94-120);
and
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\1\ The Boeing 757 was included in the recommendation because it
carried the same EICAS system as the 767. The filtering issue was
resolved by modifications to the EICAS that were mandated in a
rulemaking unrelated to data filtering.
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(2) Review other airplane designs to ensure that flight control
position data to the DFDR are accurately recorded and that flight
control position data filtered by systems such as EICAS are not
substituted for accurate data (NTSB Recommendation A-94-121).
FAA Action: Recommendation A-94-120
The FAA addressed NTSB Recommendation A-94-120 in two ways. First,
in 1997, the FAA revised the DFDR regulations to require that certain
aircraft be equipped to accommodate additional DFDR parameters
(Revisions to Digital Flight Data Recorder Rules; Final Rule (62 FR
38362, July 17, 1997)). The revised DFDR regulations prescribe that up
to 88 data parameters be recorded on DFDRs, with the exact number of
parameters determined by the date of airplane manufacture. The number
of parameters that must be recorded range from 18 for a transport
category airplane manufactured on or before October 11, 1991, to 88 for
airplanes manufactured after August 19, 2002. The revised rule applies
to certain turbine-engine-powered airplanes and rotorcraft having 10 or
more passenger seats.
The purpose of the 1997 revision was to provide additional
information to enable the investigative authority--the NTSB in the
United States--to conduct more thorough investigations of accidents and
incidents. Although the 1997 rule language did not specifically
prohibit filtering, we believed that the technical accuracy required by
the specifications in Appendix M of part 121 would preclude filtering
as a design option. In addition, the preamble to the final rule
included our reply to an NTSB comment in which we stated that including
the ``dynamic condition'' language in Appendix M reflected our position
that filtered data was not acceptable.
The FAA further addressed NTSB Recommendation A-94-120 by issuing
Advisory Circular (AC) 20-141, Airworthiness and Operational Approval
of Flight Data Recorder Systems, on August 4, 1998. This AC provided
detailed guidance on recording filtered data. Section 7 of AC 20-141,
titled ``Type Certification,'' states:

``(1) The applicant must identify any parameters that are
filtered before they are recorded. For these parameters, the
applicant must show, by test, that there is no significant
difference between the recorded parameter data under both static and
dynamic conditions.''

Based on the FAA's actions in response to NTSB Recommendation A-

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94-120, the NTSB classified NTSB Recommendation A-94-120 ``Closed-
Acceptable Action'' on May 11, 2000.
FAA Action: Recommendation A-94-121
In response to NTSB Recommendation A-94-121, the FAA first reviewed
the flight control position data sent to the FDR on the McDonnell
Douglas MD-80/90 and MD-11 model airplanes. In an August 29, 1994
letter to the NTSB, we indicated that the flight control positions were
recorded in accordance with the regulations in effect at the time.
We next reviewed the flight control position data sent to the FDR
for aircraft manufactured by Aerospatiale, CASA, Cessna, Grumann,
Gulfstream, Israel Aircraft Industries, Lockheed and SAAB. In a
November 1996 letter to the NTSB, we indicated that we had concluded
that the flight control position data being recorded was accurate. We
also indicated our intent to conduct similar reviews for aircraft
manufactured by several specified manufacturers.
In May 1997, the NTSB indicated that the language of then-proposed
Appendix M to part 121 ``appear(s) to preclude the use of data
filters,'' and agreed that ``EICAS-filtered data parameters, would not
meet this proposed requirement * * *. The Board supports the FAA's
proposal to eliminate filtered FDR data * * *.''
In February 1998, following the issuance of the 1997 regulatory
revisions and the publication of AC 20-141, we informed the NTSB that
we believed no further reviews of aircraft systems were necessary
because the rule would ensure that accurate data were being recorded.
The Board left its recommendation classified ``open-acceptable''
pending notification from the FAA on the reviews of other airplane
designs.
In April 2000, we informed the NTSB that our review of Embraer and
Dassualt (Falcon) aircraft indicated that the data were recorded
accurately on these aircraft and representative of control surface
positions. We stated that we considered our response to the
recommendation complete and that no further action was planned.
In August 2000, the NTSB expressed disappointment that the FAA did
not complete a review of all aircraft designs, but stated that it was
pleased overall with the FAA's response to NTSB Recommendation A-94-
121, and classified it as ``Closed-Acceptable Action.'' \2\
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\2\ In 2002, the FAA did an informal survey of several
manufacturers regarding data filtering, but it did not yield any
meaningful results.
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American Airlines Flight 587
On November 12, 2001, American Airlines Flight 587, an Airbus A300-
600, crashed shortly after takeoff from John F. Kennedy Airport,
Jamaica, New York. Flight 587 experienced an in-flight separation of
the vertical fin and rudder assembly. During its investigation, the
NTSB discovered a discrepancy between the recorded inputs to the rudder
pedal position and the recorded rudder surface movement. The Board
sought Airbus's input to explain the apparent discrepancies. Following
further analysis, Airbus explained that the system data analog
converter (SDAC), which supplies the flight control surface position
data, digitized and then filtered the analog signals from the flight
control surface position sensors before outputting the signals to the
FDR system. Subsequent aircraft performance evaluations conducted
independently by the NTSB and Airbus confirmed that the filtered data
recorded by the FDR did not reflect an accurate flight control surface
position time history during the critical final seconds of Flight 587.
As a result of this discovery, NTSB investigators had to evaluate
and validate the filtered flight control surface position data from the
Flight 587 FDR against other A300 FDR and flight simulator data before
they could analyze the critical performance parameters central to the
investigation of the Flight 587 accident. The lack of unfiltered data
delayed the analysis of the flight recorder data needed to determine
the probable cause of the accident and to quickly identify necessary
corrective actions.
NTSB Recommendations A-03-48/49/50
Following its investigation of Flight 587, on November 6, 2003, the
NTSB recommended that the FAA:
(1) Require that all newly manufactured transport-category aircraft
that are required to carry a flight data recorder be fitted with a
flight data recorder system capable of recording values that meet the
accuracy requirements through the full dynamic range of each parameter
at a frequency sufficient to determine a complete, accurate, and
unambiguous time history of parameter activity, with emphasis on
capturing each parameter's dynamic motion at the maximum rate possible,
including reversals of direction at the maximum rate possible. (NTSB
Recommendation A-03-48).
(2) Require that all existing transport aircraft that are required
to carry a flight data recorder be retrofitted with a flight data
recorder system capable of recording values that meet the accuracy
requirements through the full dynamic range of each parameter at a
frequency sufficient to determine a complete, accurate, and unambiguous
time history of parameter activity, with emphasis on capturing each
parameter's dynamic motion at the maximum rate possible, including
reversals of direction at the maximum rate expected. (NTSB
Recommendation A-03-49).
(3) Require that, within 2 years, all Airbus A300-600/A310 and
Boeing 747-400 \3\ airplanes and any other aircraft that may be
identified as recording filtered data be retrofitted with a flight data
recorder system capable of recording values that meet the accuracy
requirements through the full dynamic range of each parameter at a
frequency sufficient to determine a complete, accurate, and unambiguous
time history of parameter activity, with emphasis on capturing each
parameter's dynamic motion at the maximum rate possible, including
reversals of direction at the maximum rate possible. (NTSB
Recommendation A-03-50).
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\3\ The Boeing 747-400 was included based on early data from
Boeing that the airplane was filtering flight data.
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Public Meeting
On July 7, 2004, the FAA hosted a public meeting to discuss NTSB
Safety Recommendation A-03-50 and the issue of filtering flight data
before it is recorded. The meeting was intended to gather information
from industry about current practices of processing data before they
are recorded. We specifically sought answers to the following:
What if any data gets filtered before they are recorded,
and how is the filtering accomplished?
How do individual manufacturers comply with the required
``method for readily retrieving'' the recorded data?
What equipment and procedures would need to be changed,
and the costs involved, if the FAA were to adopt the NTSB
recommendation (A-03-50) as written?
Representatives from the NTSB, Airbus, Boeing, the Allied Pilots
Association, and the Air Line Pilots Association each made a
presentation at the public meeting. During this meeting, Airbus
confirmed that data filtering was also occurring on the rudder
parameter

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for the A320 model airplane. In its presentation, Boeing noted that its
original assessment was incorrect, as subsequent investigation revealed
that no flight control parameter data were being filtered before being
recorded on Boeing 747-400 aircraft.
Based on information received during the meeting, the FAA
determined that the language of the existing regulations governing
DFDRs needed to specifically address flight data filtering. While we
recognize that some types of filtering are necessary (e.g., dampening
noise to obtain a clear signal), data filtering that may obscure raw
data to the extent it hampers an NTSB investigation has always been
considered unacceptable. Accordingly, we are proposing this rule to
amend the DFDR regulations by defining filtering in the regulation and
prohibiting signal filtering for certain specified recorded parameters.

Alternatives Considered

Before deciding to promulgate this proposed rule, the FAA
considered the following alternatives concerning data filtering:
(1) Take no action: In its recommendations following the Boeing 767
and Flight 587 accidents, and again at the 2004 public meeting, the
NTSB described in great detail how its investigations were hampered by
filtered data. When it finds filtered data, the NTSB must analyze it in
an effort to approximate the actual control surface movement (in
essence, unfilter the data), such as in the investigation of Flight
587. This processing requires detailed analysis and testing, which are
time-consuming, costly, and for which techniques are not always readily
available. Even after processing, the results retain a degree of
uncertainty, as evidenced in the findings from Flight 587. As a result,
the NTSB may be unable to determine the performance or flight control
surface movements of an aircraft precisely enough to determine the
probable cause of an incident or accident.
If the FAA decided to take no action on this issue, the NTSB would
likely continue to encounter filtered data and have difficulty
analyzing airplane incident and accident data. Thus, questions would
remain over the industry's interpretation of regulatory requirements,
thereby allowing filtering to continue or even increase as those
interpretations expand. Our conclusion that the recording of unfiltered
data is necessary for aircraft incident and accident investigations
leads to our rejecting this option.
(2) Address newly manufactured aircraft only: A regulatory
alternative that is limited to future-manufactured aircraft is always
less costly. It would fail, however, to address all of the aircraft in
the U.S. airline fleet, and would allow filtering to continue on these
airplanes or even increase as a result of future system modifications.
Information we have gathered thus far indicates that flight data are
being filtered on two models of Airbus aircraft currently in use.
Filtering, as it is defined here, may be occurring on other aircraft in
the fleet as well, despite the 1997 regulatory revisions. Experience
with the Boeing 767 and the Airbus A300 has already demonstrated that
filtering has occurred in the existing fleet, causing problems during
investigations. Failing to address this problem on in-service aircraft
is not an acceptable alternative.
(3) Enforce the current regulation on operators of individual
aircraft that we know filter data before it is recorded: This option
places the burden on the FAA to identify the specific aircraft affected
with a problem we presumed was resolved by regulation in 1997, and take
action through enforcement channels. It would bring into question each
cited operator's interpretation of compliance with the regulation, and
do nothing to resolve the issue for all manufacturers and operators. It
could lead to selective, inconsistent enforcement and result in
inconsistent regulatory compliance. We do not consider this an
effective solution to a continuing issue.

Need for Regulatory Action

Our experience with Flight 587 and the NTSB's investigation of the
accident all but demand that a more detailed regulatory solution be
implemented. Following the loss of Flight 587, the FAA was intent on
determining, as quickly as possible, whether there was anything wrong
with the airplane that could be prevented from happening on other
aircraft of that type. We expected that information needed to make that
decision would be immediately available from the flight data recorder.
The initial analysis of Flight 587 DFDR data indicated that the
airplane experienced an in-flight separation of the vertical stabilizer
and rudder assembly. The first analysis of the recorded rudder motion
indicated that the failure may have occurred at 1.24 times the
prescribed limit load, well below the certification requirement that it
be able to withstand 1.50 times the prescribed limit load (Sec.
25.303). If we had presumed the initial flight recorder information to
be correct, we most likely would have taken more dramatic action to
ensure the safety of the other A300s still operating, including
grounding the rest of the fleet while an investigation into its
airworthiness took place.
Once the NTSB discovered the inconsistent data, and learned that
the rudder position signal had been filtered for display in the
cockpit, however, NTSB staff began work to discern the actual motion of
the rudder. The Board compared Flight 587 data with the data recorded
by other A300 airplanes, and data from the A300 simulator. The NTSB's
eventual conclusion was that Flight 587's vertical stabilizer separated
at almost 2 times the prescribed limit load. Although several analyses
were performed, including an ``inverse filtering'' exercise with the
manufacturer, and the FAA was satisfied with the underlying
airworthiness of the A300-600 airplane, the NTSB has never been able to
produce conclusive evidence of the actual motion and failure of the
airplane's vertical stabilizer and rudder. This is exactly the kind of
information we had intended be available under the 1997 requirements
for digital flight data recorders.
When the FAA promulgated the 1997 regulatory revision, we had every
expectation that the upgrades to the equipment and the more significant
requirements for data sampling and accuracy would result in more
reliable, usable data. What we have discovered is that some flight data
systems are recording data that we know is inaccurate, and therefore
not meeting the intent of the 1997 regulations. For these reasons, we
have concluded that we must take action to clarify the regulations,
specifically that filtering must be addressed as a defined term with a
specific prohibition for certain critical parameters of flight data.

General Discussion of the Proposal

Proposed Rule Language

This section describes the rule language that would appear in part
121 and Appendix M. The same language is being proposed for parts 125
and 135 and the associated appendices, though the discussion has been
abbreviated to reference only part 121 and Appendix M. We note that the
language in part 135 has a more limited scope based on the
applicability of portions of Sec. 135.152. We also note that operators
of aircraft subject to Sec. 91.1045 may be affected by the changes to
the other sections that are referenced in that operating rule.

Section 121.344(n)

Proposed new Sec. 121.344(n) has four parts. Paragraph (n)
prohibits filtering of all parameters except those listed in

[[Page 66638]]

paragraph (2). Paragraph (n)(1) defines filtering, including what does
not constitute filtering. Paragraph (n)(2) lists those parameters that
may be filtered. Paragraph (n)(3) presents the compliance times.
Proposed paragraph (n) states that no flight data sensor signal
that is required to be recorded may be filtered, except for those
parameters listed in proposed paragraph (n)(2). This regulation is
designed to be prohibitive for all parameters unless specifically
excepted in the regulation.
Proposed paragraph (n)(1) defines a filtered signal as one that is
changed in any way, except that filtering does not include analog to
digital conversion, reformatting for compatibility with a DFDR format,
or elimination of a high frequency component that is outside the
bandwidth of the sensor. All signals may, as necessary, receive any of
these treatments and not be considered filtered.
Proposed paragraph (n)(2) contains the list of parameters that may
be filtered beyond the limits of paragraph (n), as long as the recorded
signal still complies with the specifications of the applicable
appendix.
Proposed paragraph (n)(3) presents the proposed compliance times.
Aircraft that are manufactured up to 18 months after the effective date
of the rule have 4 years from the date of the rule to comply. For
aircraft manufactured on or after 18 months after the effective date of
the rule, compliance is required at manufacture.
This compliance period is designed to permit operators to
accomplish any required modifications during a regularly scheduled
heavy maintenance visit, reducing potential impact on scheduled
operations or additional out-of-service time. The four year compliance
time is consistent with FAA actions in previous flight recorder
regulations and has been supported by the industry as an adequate time
for retrofit and for introducing new system design into aircraft being
manufactured.
Our review of the 88 parameters listed in Sec. 121.344(a) resulted
in a determination that some parameters are too critical to allow any
filtering beyond the allowable stated signal conditioning. Those
parameters include flight control surface position, control column
position, control forces, and others that reflect sensitive system
information.
We are also including discretes in the list of parameters that are
not to be filtered. By definition, discretes show something is on or
off; we know of no need for these data to be filtered.
The parameters listed in proposed Sec. 121.344(n)(2), the ones
that may be filtered, are those from which a loss of raw information
would not be critical. We do not, however, encourage the filtering of
any original sensor signal, and the recorded signals for the parameters
listed in proposed paragraph (n)(2) must continue to meet the range,
resolution, rate, and accuracy requirements of the applicable
appendices under all conditions. If a parameter proposed for inclusion
in proposed paragraph (n)(2) is later found to be inappropriate for
filtering because it impedes an investigation, it will be removed from
that paragraph.
We request specific comment on the propriety of the items included
in proposed paragraph (n)(2). As previously stated, the FAA
acknowledges that some conditioning of data is necessary (e.g.,
dampening noise) and that recognized signal conditioning does not
alter, change or manipulate the data in such a way as to affect the
accuracy of the data recorded. We request specific comment on any
parameter for which commenters have reason to include or exclude from
the filtering prohibition.

Additional Language on Dynamic Condition

At the beginning of current Appendix M, the following language
appears:

``The recorded values must meet the designated range,
resolution, and accuracy requirements during dynamic and static
conditions. All data recorded must be correlated in time to one
second.''

When we proposed this language in 1996, the NTSB commented that it
thought the FAA needed to include more explanation of what the testing
language entailed. We responded that further explanation would appear
in the Advisory Circular that was being developed in conjunction with
the rule.
More notably, we also included the following in the final rule
preamble, in response to the NTSB:

``The FAA added the requirement for a dynamic test condition to
ensure accurate dynamic recording of aircraft performance. This
requirement was necessary to preclude the presumption that
information * * * may be obtained from filtered or modified
signals.''

(62 FR 38371, July 17, 1997, emphasis added)

We maintain that this language should have been sufficient to stop
the recording of filtered flight data, even before the advisory
circular material was published. Since we are aware of at least one
instance in which the meaning of ``dynamic and static conditions'' was
not recognized, we are proposing an addition to that language in this
rulemaking to further clarify what has been required.
``Static condition'' is generally understood to mean the part being
tested is at rest or in a balanced, steady state. The term ``dynamic
condition'' causes more debate, however, concerning the rate of change
that is required for the test. In the case of control surfaces, for
example, we mean the limits of motion and at what rate the surface must
be traveling while meeting the operational performance requirements and
accuracy required by Appendix M.
While most operators have interpreted the dynamic condition phrase
as we do, Flight 587 served as notice that the understanding is not
universal. While it appeared that the rudder surface parameter on
Flight 587 was recorded correctly and reflected the airplane's
movements within operational performance requirements, the final NTSB
accident report revealed that the estimated actual surface movement was
greater than the recorded movement (from filtered SDAC data) by more
than 5 degrees. This margin of difference between actual and recorded
rudder movement does not meet the requirement in Appendix M.
To further clarify the regulation regarding test conditions, we are
proposing to add a phrase to the Appendix M language to include maximum
rate of change. We are also expanding the discussion of dynamic testing
in the next version of the advisory circular.

Effect of the Proposed Regulation

There are currently only two known aircraft models in the U.S.
fleet that have flight data systems that filter data before they are
recorded--the Airbus A300 and A310 series airplanes, and the Airbus
A320 ``family'' of airplanes that includes the A318, A319, A320, and
A321.
We asked Airbus for proposed solutions for each series of airplanes
that would eliminate the filtering of flight data before the data are
recorded.
The modification proposed by Airbus for the A300 and A310 airplanes
includes a modification of the System Digital Analog Converter (SDAC)
and the Symbol Generator Unit (SGU). Simply stated, the modification
would change what the digitized signals would be named by the SGU,
allowing one set of signals to reach the recorder in an unfiltered
state. The modification can be made regardless of how many other
changes may have been made to the DFDR systems on these airplanes
because it does not include modification of the flight data acquisition
unit or the

[[Page 66639]]

recorder itself, the equipment most often affected by changes to
regulatory requirements or general system upgrades. The FAA's initial
reaction to the proposed modification is that it is simple and
effective. Our analysis indicates that the modification would cost
approximately $16,025 per airplane.
The modification proposed by Airbus for the A320 family of
airplanes, however, is neither straightforward nor inexpensive. Instead
of a simple change to the SDAC and the SGU, Airbus is incorporating the
change for filtering in the Electronic Instrument System (known as
EIS2) master change modification. The EIS2 modification is an extensive
system modification that includes new software in the SDAC and a
complete replacement of the flight deck indication systems, including
an upgrade from cathode ray tubes to liquid crystal displays and
associated rewiring. This modification is designed to correct a variety
of other issues with the existing flight deck instrumentation system on
the A320 family of airplanes. Airbus's addition to the existing EIS2
modification will eliminate rudder data filtering by leaving the output
data the same and changing the indication system that recognizes it.
This differs from the A300/A310 solution, which captures the data
before it is filtered and creates a new name for it when it is
recorded.
In response to our inquiries why the rudder data filtering issue
cannot be addressed alone in a manner similar to the A300/A310, Airbus
indicated it would not provide another solution. In addition, Airbus
did not break out the cost of the filtering solution from the rest of
the EIS2 modification.
The proposed comprehensive EIS2 solution for the A320 family is far
more expensive--$800,000 per airplane according to the Airbus service
bulletin--than the A300/A310 solution. The FAA does not accept the
implication that the only means of correcting the rudder filtering
problem on the A320 family is the costly EIS2 modification, and we do
not accept the EIS2 modification cost estimate in estimating costs to
correct the problem.
In fact, we believe that this rule does not propose any known
modification costs for which we have not accounted previously. When we
wrote and analyzed the 1997 regulatory changes for flight recorders, we
included the cost of equipment needed to meet the requirements of
Appendix M (and its equivalent in other operating parts). As stated
previously, we understood that compliance with Appendix M essentially
eliminated filtering as an option, since filtered data would not meet
the considerable technical specifications of the Appendix nor the
requirement for dynamic testing. We replied to the NTSB's comment
indicating that the inclusion of the dynamic testing requirement was
meant to preclude the use of filtered data.
To argue that filtered data is somehow acceptable under Appendix M
is to argue that the FAA spent three years and imposed high costs in
order to allow inaccurate (and unusable) data to be recorded. While we
understand that the language of the 1997 regulation does not
specifically define and prohibit filtering, we also know that the
regulation had that intent, as was expressed in the preamble, and was
written to be as performance-based as possible. We stated the data
requirements in Appendix M but did not specify any exact equipment
requirements as long as the qualitative data goals were met. We will
not now accept an argument that we intended the regulation to permit
the recordation of inaccurate or incomplete data, as Flight 587
demonstrated, when the sole purpose of flight recorder data is to
collect accurate data to assist investigations of accidents and
incidents. The experience of the NTSB and FAA during the investigation
of Flight 587 has shown that the regulation needs clarification. But
the regulatory goal of the 1997 revision remains unchanged--the
recordation of accurate, usable flight data, described in Appendix M,
and accounted for in the economic evaluation of the 1997 final rule.
Data that do not accurately reflect the movement of an aircraft cannot
be said to meet Appendix M or the goal of the flight recorder
regulations overall. To the extent work is required to modify aircraft
DFDR systems to provide accurate data, the costs of modifications or
design changes were already accounted for in the 1997 final rule, even
though they may have yet to be accomplished.
There are costs associated with this rule, but they are limited to
operators confirming that the DFDR systems on their aircraft do not
filter any parameter on the prohibited list. We are not aware of any
aircraft that filters the prohibited parameters other than the Airbus
airplanes already discussed. The estimated costs for confirming
compliance are related to engineering evaluation of the systems
installed on various models of airplanes, and are discussed in the
regulatory evaluation for this rulemaking. The regulatory evaluation
also includes a detailed estimate of the costs to retrofit the Airbus
airplanes that we know are filtering the rudder movement data. As
stated, we do not consider those to be a cost of this rule, but of
ultimate compliance with the 1997 regulations.

Paperwork Reduction Act

The Paperwork Reduction Act of 1995 (44 U.S.C. 3507(d)) requires
that the FAA consider the impact of paperwork and other information
collection burdens imposed on the public. We have determined that there
are no new information collection requirements associated with this
proposed rule.

International Compatibility

In keeping with U.S. obligations under the Convention on
International Civil Aviation, it is FAA policy to comply with
International Civil Aviation Organization (ICAO) Standards and
Recommended Practices to the maximum extent practicable. The FAA has
determined that there are no ICAO Standards and Recommended Practices
that correspond to these proposed regulations.

Regulatory Evaluation, Regulatory Flexibility Determination,
International Trade Impact Assessment, and Unfunded Mandates Assessment

Changes to Federal regulations must undergo several economic
analyses. First, Executive Order 12866 directs that each Federal agency
shall propose or adopt a regulation only upon a reasoned determination
that the benefits of the intended regulation justify its costs. Second,
the Regulatory Flexibility Act of 1980 (Pub. L. 96-354) requires
agencies to analyze the economic impact of regulatory changes on small
entities. Third, the Trade Agreements Act (Pub. L. 96-39) prohibits
agencies from setting standards that create unnecessary obstacles to
the foreign commerce of the United States. In developing U.S.
standards, this Trade Act requires agencies to consider international
standards and, where appropriate, that they be the basis of U.S.
standards. Fourth, the Unfunded Mandates Reform Act of 1995 (Pub. L.
104-4) requires agencies to prepare a written assessment of the costs,
benefits, and other effects of proposed or final rules that include a
Federal mandate likely to result in the expenditure by State, local, or
tribal governments, in the aggregate, or by the private sector, of
$128.1 million or more annually (adjusted for inflation with base year
of 1995). This portion of the preamble summarizes the FAA's analysis of
the economic impacts of this proposed rule. We suggest readers seeking
greater detail read the full regulatory

[[Page 66640]]

evaluation, a copy of which we have placed in the docket for this
rulemaking.
In conducting these analyses, FAA has determined this proposed rule
has benefits that justify its costs, and is not a ``significant
regulatory action'' as defined in section 3(f) of Executive Order
12866. The rulemaking is also not ``significant'' as defined in DOT's
Regulatory Policies and Procedures. The proposed rule, if adopted, will
not have a significant economic impact on a substantial number of small
entities, will not create unnecessary obstacles to international trade
and will not impose an unfunded mandate on state, local, or tribal
governments, or on the private sector. These analyses, available in the
draft regulatory evaluation supporting this NPRM, are summarized below.

Total Costs and Benefits of This Rule

The estimated cost of this proposed rule would be $675,000
($571,592 in present value terms). This proposed rule would clarify the
regulations to define and prohibit data filtering, which would ensure
more accurate data for accident investigations. More detailed benefits
and cost information will be provided below. The FAA seeks comments on
these estimates.

Who Is Potentially Affected by This Rule

This proposed rule would affect all part 121 and part 125 aircraft,
and would also affect those part 135 aircraft having 10-30 passenger
seats that are manufactured after August 2000 (in accordance with 14
CFR 135.152 (i) and (j)). Operators subject to Sec. 91.1045 may be
affected if their aircraft are subject to one of the listed
requirements.

Assumptions

Discount rate--7%. Sensitivity analysis was performed on
3% and 7%.
Period of Analysis--2007 through 2010.
Burdened labor rate for engineers and quality
professionals--$75/hour.
Final rule will become effective 4 years after
publication.

Benefits of This Rule

In 1994, the National Transportation Safety Board (NTSB)
recommended a review of airplane designs to ensure flight control data
to the DFDR are accurate and that filtered data are not substituted for
accurate data. Beginning in 1994, the FAA conducted a review of several
different aircraft and did not discover any filtered data being sent to
the DFDR. In 1997, the Revisions to Digital Flight Data Recorder
Regulations was published. Based on these FAA actions, NTSB classified
that recommendation as ``Closed--Acceptable Action.'' Although the 1997
revision did not specifically define and prohibit filtering, the
regulation had that intent as was expressed in the final rule preamble.
The American Airlines Flight 587 accident involving an Airbus A300-600
demonstrated that this problem of filtered data still existed, and
hampered the investigation. Filtered data has slowed and reduced the
certainty of the Airbus A300-600 accident investigation. Unfortunately,
some data filtering continues and has obscured key causal factors of an
accident. (The FAA intends with this rule to specifically define and
prohibit filtered data for NTSB accident investigations.)

Costs of This Rule

The costs of the proposed rule from 2007 through 2010 would be
$571,592 in present value terms. Refer to the tables below for a more
detailed breakdown of the costs. The FAA requests comments on the
costs.

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

Relevant US fleet category Aircraft Cost
------------------------------------------------------------------------
Part 121...................................... 6,573 $492,975
Part 125...................................... 628 47,100
Part 135 (overestimate)....................... 1,799 134,925
Total affected aircraft (overestimate).... 9,000 675,000
------------------------------------------------------------------------
Sources: ACAS database by Flight, Federal Aviation Administration.

Total Costs
(Undiscounted and Discounted)
----------------------------------------------------------------------------------------------------------------
2007 2008 2009 2010 Total
----------------------------------------------------------------------------------------------------------------
Number of Planes......................................... 2,250 2,250 2,250 2,250 9,000
Undiscounted Costs....................................... 168,750 168,750 168,750 168,750 675,000
Costs Discounted at 7%................................... 157,710 147,393 137,750 128,739 571,592
Costs Discounted at 3%................................... 163,835 159,063 154,430 149,932 627,260
----------------------------------------------------------------------------------------------------------------

Regulatory Flexibility Determination

The Regulatory Flexibility Act of 1980 (Pub. L. 96-354) (RFA)
establishes ``as a principle of regulatory issuance that agencies shall
endeavor, consistent with the objective of the rule and of applicable
statutes, to fit regulatory and informational requirements to the scale
of the business, organizations, and governmental jurisdictions subject
to regulation.'' To achieve that principle, the RFA requires agencies
to consider flexible regulatory proposals, to explain the rationale for
their actions, and to solicit comments. The RFA covers a wide-range of
small entities, including small businesses, not-for-profit
organizations and small governmental jurisdictions.
Agencies must perform a review to determine whether a rule will
have a significant economic impact on a substantial number of small
entities. If the agency determines that it will, the agency must
prepare a regulatory flexibility analysis as described in the RFA.
However, if an agency determines that a proposed rule is not
expected to have a significant economic impact on a substantial number
of small entities, section 605(b) of the RFA provides that the head of
the agency may so certify and a regulatory flexibility analysis is not
required. The certification must include a statement providing the
factual basis for this determination, and the reasoning should be
clear.
The FAA believes that this proposal would not have a significant
impact on a substantial number of entities for the following reason:
the individual airplane cost of $75 would not represent a significant
economic burden on airplane operators. Therefore, the FAA certifies
that this proposal would not have a significant economic impact on a
substantial number of small entities. The FAA solicits comments
regarding this finding.

[[Page 66641]]

International Trade Impact Assessment

The Trade Agreements Act of 1979 (Pub. L. 96-39) prohibits Federal
agencies from establishing any standards or engaging in related
activities that create unnecessary obstacles to the foreign commerce of
the United States. Legitimate domestic objectives, such as safety, are
not considered unnecessary obstacles. The statute also requires
consideration of international standards and, where appropriate, that
they be the basis for U.S. standards. The FAA has assessed the
potential effect of this proposed rule and determined that it would
respond to a domestic safety objective and would not be considered an
unnecessary barrier to trade.

Unfunded Mandates Assessment

Title II of the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-
4) requires each Federal agency to prepare a written statement
assessing the effects of any Federal mandate in a proposed or final
agency rule that may result in an expenditure of $100 million or more
(adjusted annually for inflation with the base year 1995) in any one
year by State, local, and tribal governments, in the aggregate, or by
the private sector; such a mandate is deemed to be a ``significant
regulatory action.'' The FAA currently uses an inflation-adjusted value
of $128.1 million in lieu of $100 million.
This proposed rule does not contain such a mandate. The
requirements of Title II do not apply.

Executive Order 13132, Federalism

The FAA has analyzed this proposed rule under the principles and
criteria of Executive Order 13132, Federalism. We determined that this
action would not have a substantial direct effect on the States, on the
relationship between the national Government and the States, or on the
distribution of power and responsibilities among the various levels of
government, and therefore would not have federalism implications.

Environmental Analysis

FAA Order 1050.1E identifies FAA actions that are categorically
excluded from preparation of an environmental assessment or
environmental impact statement under the National Environmental Policy
Act in the absence of extraordinary circumstances. The FAA has
determined this proposed rulemaking action qualifies for the
categorical exclusion identified in Chapter 3, paragraph 312f, and
involves no extraordinary circumstances.

Regulations that Significantly Affect Energy Supply, Distribution, or
Use

The FAA has analyzed this NPRM under Executive Order 13211, Actions
Concerning Regulations that Significantly Affect Energy Supply,
Distribution, or Use (May 18, 2001). We have determined that it is not
a ``significant energy action'' under the executive order because it is
not a ``significant regulatory action'' under Executive Order 12866,
and it is not likely to have a significant adverse effect on the
supply, distribution, or use of energy.

List of Subjects in 14 CFR Parts 121, 125, and 135

Air carriers, Aircraft, Aviation safety, Safety, Transportation.

The Proposed Amendment

In consideration of the foregoing, the Federal Aviation
Administration proposes to amend part 121 of Chapter I of Title 14,
Code of Federal Regulations as follows:

PART 121--OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL
OPERATIONS

1. The authority citation for part 121 continues to read as
follows:

Authority: 49 U.S.C. 106(g), 40113, 40119, 44101, 44701-44702,
44705, 44709-44711, 44713, 44716-44717, 44722, 44901, 44903-44904,
44912, 46105.
2. Amend Sec. 121.344 by adding a new paragraph (n) to read as
follows:

Sec. 121.344 Digital flight data recorders for transport category
airplanes.

* * * * *
(n) For any parameter required by this section to be recorded, no
flight data sensor signal may be filtered, except as provided in
paragraph (n)(2) of this section.
(1) A signal is filtered when an original sensor signal has been
changed in any way, other than changes necessary to:
(i) Accomplish analog to digital conversion of the signal;
(ii) reformat a digital signal into a DFDR-compatible format; or
(iii) eliminate a high frequency component of a signal that is
outside the operational bandwidth of the sensor.
(2) The original sensor signals for the following parameters
described in paragraph (a) of this section may be filtered, provided
that each recorded signal continues to meet the requirements of
Appendix M of this part: 1-7, 9, 11, 18, 20, 21, 24, 26-28, 32, 34, 37-
39, 43, 45-54, 58, 59, 68, 70, 73, 77, and 82-85.
(3) Compliance with this paragraph is required as follows:
(i) For aircraft manufactured before [date 18 months from effective
date of the final rule], compliance is required by [date 4 years from
effective date of the final rule].
(ii) For aircraft manufactured on and after [date 18 months from
effective date of the final rule], compliance is required at
manufacture.
3. Amend Sec. 121.344a by adding a new paragraph (g) to read as
follows:

Sec. 121.344a Digital flight data recorders for 10-19 seat airplanes.

* * * * *
(g) Compliance with the requirements of Sec. 121.344(n) of this
part is required for all airplanes covered by this section.
4. Amend appendix M to part 121 by revising the introductory text
immediately following the appendix title to read as follows:

Appendix M to Part 121--Airplane Flight Recorder Specifications

The recorded values must meet the designated range, resolution
and accuracy requirements during static and dynamic conditions.
Dynamic condition means the parameter is experiencing change at the
maximum rate available, including the maximum rate of reversal. All
data recorded must be correlated in time to within one second.
* * * * *

PART 125--CERTIFICATION AND OPERATIONS: AIRPLANES HAVING A SEATING
CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF
6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH
AIRCRAFT

5. The authority citation for part 125 continues to read as
follows:

Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44705, 44710-
44711, 44713, 44716-44717, 44722.

6. Amend Sec. 125.226 to add a new paragraph (m) to read as
follows:

Sec. 125.226 Digital flight data recorders.

* * * * *
(m) For any parameter required by this section to be recorded, no
flight data sensor signal may be filtered, except as provided in
paragraph (m)(2) of this section.
(1) A signal is filtered when an original sensor signal has been
changed in any way, other than changes necessary to:
(i) Accomplish analog to digital conversion of the signal;
(ii) reformat a digital signal into a DFDR-compatible format; or

[[Page 66642]]

(iii) eliminate a high frequency component of a signal that is
outside the operational bandwidth of the sensor.
(2) The original sensor signals for the following parameters
described in paragraph (a) of this section may be filtered, provided
that each recorded signal continues to meet the requirements of
Appendix E of this part: 1-7, 9, 11, 18, 20, 21, 24, 26-28, 32, 34, 37-
39, 43, 45-54, 58, 59, 68, 70, 73, 77, and 82-85.
(3) Compliance with this paragraph is required as follows:
(i) For aircraft manufactured before [date 18 months from effective
date of the final rule], compliance is required by [date 4 years from
effective date of the final rule].
(ii) For aircraft manufactured on and after [date 18 months from
effective date of the final rule], compliance is required at
manufacture.
7. Amend appendix E to part 125 by revising the introductory text
immediately following the appendix title to read as follows:

Appendix E to Part 125--Airplane Flight Recorder Specifications

PART 135--OPERATING REQUIREMENTS: COMMUTER AND ON DEMAND OPERATIONS
AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT

8. The authority citation for part 135 continues to read as
follows:

Authority: 49 U.S.C. 106(g), 41706, 44113, 44701-44702, 44705,
44709, 44711-44713, 44715-44717, 44722.

9. Amend Sec. 135.152 by adding a new paragraph (l) to read as
follows:

Sec. 135.152 Flight recorders.

* * * * *
(l) For aircraft subject to paragraph (i) or (j) of this section:
(1) For any parameter required by this section to be recorded, no
flight data sensor signal may be filtered, except as provided by
paragraph (l)(3) of this section.
(2) A signal is filtered when an original sensor signal has been
changed in any way, other than changes necessary to:
(i) Accomplish analog to digital conversion of the signal;
(ii) reformat a digital signal into a DFDR-compatible format; or
(iii) eliminate a high frequency component of a signal that is
outside the operational bandwidth of the sensor.
(3) The following original sensor signals for the parameters
described in paragraph (h) of this section may be filtered, provided
that each recorded signal continues to meet the requirements of
Appendix F of this part: 1-7, 9, 11, 18, 20, 21, 24, 26-28, 32, 34, 37-
39, 43, 45-54, 58, 59, 68, 70, 73, 77, and 82-85.
(4) Compliance with this section is required as follows:
(i) For aircraft manufactured before [date 18 months from effective
date of the final rule], compliance is required by [date 4 years from
effective date of the final rule].
(ii) For aircraft manufactured on and after [date 18 months from
effective], compliance is required at manufacture.
10. Amend appendix F to part 135 by revising the introductory text
immediately following the appendix title to read as follows:

Appendix F to Part 135--Airplane Flight Recorder Specifications

Issued in Washington, DC, on November 1, 2006.
Dorenda D. Baker,
Acting Director, Aircraft Certification Service.
[FR Doc. E6-19205 Filed 11-14-06; 8:45 am]

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