[Federal Register Volume 71, Number 220 (Wednesday, November 15, 2006)]
[Proposed Rules]
[Pages 66634-66642]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-19205]



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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

  Federal Register / Vol. 71, No. 220 / Wednesday, November 15, 2006 / 
Proposed Rules  

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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 [email protected]. 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 [email protected].

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://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

    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 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

    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.
* * * * *

    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]
BILLING CODE 4910-13-P