[Federal Register Volume 67, Number 57 (Monday, March 25, 2002)]
[Rules and Regulations]
[Pages 13564-13566]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-6625]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-CE-32-AD; Amendment 39-12683; AD 2002-06-06]
RIN 2120-AA64


Airworthiness Directives; Rockwell Collins, Inc. TDR-94 and TDR-
94D Mode S Transponders

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
applies to certain Rockwell Collins TDR-94 and TDR-94D Mode S 
transponders that derive altitude information from a Gillham (gray 
code) encoded pressure altitude source and are installed on airplanes. 
This AD requires you to have the unit modified to prevent erroneous 
altitude reporting. This AD is the result of reports that erroneous 
altitude resolutions could occur when the affected transponders are 
utilized in areas with other airplanes equipped with certain aircraft 
collision avoidance system (ACAS) or traffic alert and collision 
avoidance system (TCAS) configurations. The actions specified by this 
AD are intended to prevent these erroneous altitude resolutions from 
causing a reduction in the intended ACAS or TCAS Change 7 separation 
margins. Such a condition could result in air traffic control or the 
pilot making flight decisions that put the airplane in unsafe flight 
conditions.

DATES: This AD becomes effective on May 3, 2002.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in the regulations as of May 
3, 2002.

ADDRESSES: You may get the service information referenced in this AD 
from Rockwell Collins Inc., Business and Regional Systems, 400 Collins 
Road Northeast, Cedar Rapids, Iowa 52498. You may view this information 
at the Federal Aviation Administration (FAA), Central Region, Office of 
the Regional Counsel, Attention: Rules Docket No. 2000-CE-32-AD, 901 
Locust, Room 506, Kansas City, Missouri 64106; or at the Office of the 
Federal Register, 800 North Capitol Street, NW., suite 700, Washington, 
DC.

FOR FURTHER INFORMATION CONTACT: Roger A. Souter, FAA, Wichita Aircraft 
Certification Office (ACO), 1801 Airport Road, Room 100, Wichita, 
Kansas 67209; telephone: (316) 946-4134; facsimile: (316) 946-4407; e-
mail: [email protected].

SUPPLEMENTARY INFORMATION:

Discussion

What Events Have Caused This AD?

    The FAA has received information that erroneous altitude 
resolutions could occur on certain Rockwell Collins TDR-94 and TDR-94D 
Mode S transponders installed in airplanes with Gillham (gray code) 
encoded sources. This information indicates that these transponders are 
utilized in areas with other airplanes equipped with certain aircraft 
collision avoidance system (ACAS) or traffic alert and collision 
avoidance system (TCAS) configurations. In these situations, the 
transponders could receive incorrect TCAS resolution advisories. This 
could result in a reduction in the intended ACAS or TCAS Change 7 
minimum separation margins.
    Gillham altitude sources have a 100-foot resolution. The affected 
transponder will set the altitude resolution status to indicate a 25-
foot resolution when connected to a Gillham altitude source. For those 
units that have digital sources of altitude information, the altitude 
resolution status is set correctly.
    These Rockwell Collins TDR-94 and TDR-94D Mode S transponders could 
be installed on, but not limited to, the following airplanes:

--Aerospatiale ATR42 series airplanes;
--deHavilland DHC-7 and DHC-8 series airplanes; and
--Short Brothers Models SD3-60 and SD3-60 SHERPA airplanes.

What Is the Potential Impact if FAA Took No Action?

    As described above, such erroneous altitude resolutions could cause 
a reduction in the intended ACAS or TCAS Change 7 separation margins 
and result in air traffic control or the pilot making flight decisions 
that put the airplane in unsafe flight conditions.

Has FAA Taken Any Action to This Point?

    We issued a proposal to amend part 39 of the Federal Aviation 
Regulations (14 CFR part 39) to include an AD that would apply to 
certain Rockwell Collins TDR-94 and TDR-94D Mode S transponders that 
derive altitude information from a Gillham (gray code) encoded pressure 
altitude source and are installed on airplanes. This proposal was 
published in the Federal Register as a notice of proposed rulemaking 
(NPRM) on November 5, 2001 (66 FR 55898). The NPRM proposed to require 
you to have the actions of Rockwell Collins Service Bulletin No. 17 
(TDR-94/94D-34-17), dated February 8, 1999, incorporated on any 
affected Mode S transponder that is installed on a type-certificated 
airplane where Gillham pressure altitude encoding sources are used.

Was the Public Invited To Comment?

    The FAA encouraged interested persons to participate in the making 
of this amendment. The following presents the comments received on the 
proposal and FAA's response to each comment:

Comment Issue No. 1: Add Revision 1 of Service Bulletin 17 as an 
Acceptable Method of Compliance

What Is the Commenter's Concern?

    A commenter states that Rockwell Collins Service Bulletin No. 17 
(TDR-94/94D-34-17), Revision No. 1, dated May 15, 2000, should be 
included as an acceptable method of compliance. The commenter states 
that the only change revision 1 makes to the original service bulletin 
is in the Material Information.

What Is FAA's Response to the Concern?

    The FAA concurs that Revision 1 of the service bulletin should be 
included as an acceptable method of compliance with this AD. We will 
incorporate this bulletin into the AD.

Comment Issue No. 2: Add Another Service Bulletin as an Acceptable 
Method of Compliance

What Is the Commenter's Concern?

    The commenter states that Rockwell Collins Service Bulletin 20 
(TDR-94/94D-34-20), Revision 1, dated May 2, 2001, should also be 
included as an acceptable method of compliance with this AD. Service 
Bulletin 20 allows modification of TDR-94 and TDR-94D Mode S 
Transponders from the -004 or -005 status to the -006 status. Service 
Bulletin 20 includes all -005 status functionality required in Service 
Bulletin 17.

What Is FAA's Response to the Concern?

    The FAA concurs that Rockwell Collins Service Bulletin 20 (TDR-94/
94D-34-20), Revision 1, dated May 2,

[[Page 13565]]

2001, should be included as an acceptable method of compliance with 
this AD. We will incorporate this bulletin into the AD.

FAA's Determination

What Is FAA's Final Determination on This Issue?

    After careful review of all available information related to the 
subject presented above, we have determined that air safety and the 
public interest require the adoption of the rule as proposed except for 
the addition of the referenced service information and minor editorial 
corrections. We have determined that these additions and minor 
corrections:

--Provide the intent that was proposed in the NPRM for correcting the 
unsafe condition; and
--Do not add any additional burden upon the public than was already 
proposed in the NPRM.

Cost Impact

How Many Airplanes Does This AD Impact?

    We estimate that 1,400 affected Rockwell Collins TDR-94 and TDR-94D 
Mode S transponders could be installed on airplanes in the U.S. 
registry.

What Is the Cost Impact of This AD on Owners/Operators of the Affected 
Airplanes?

    We estimate the following costs to accomplish the modification:

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                                                                                 Total cost per   Total cost on
                          Labor cost                              Parts cost        airplane      U.S. operators
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3 workhours  x  $60 per hour = $180..........................             $295             $475         $665,000
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    The manufacturer will provide warranty credit for parts and labor 
for work done in accordance with Rockwell Collins Service Bulletin No. 
17, dated February 8, 1999, Service Bulletin 17, Revision No. 1, dated 
May 15, 2000, and to the extent noted in Service Bulletin 20, Revision 
No. 1, dated May 2, 2001.

Compliance Time of This AD

Why Is the Compliance Time of This AD Presented in Calendar Time 
Instead of Hours Time-In-Service (TIS)?

    The compliance of this AD is presented in calendar time instead of 
hours TIS because the condition exists regardless of airplane 
operation. The erroneous altitude indications could occur regardless of 
the number of times and hours the airplane was operated or the age of 
the Mode S transponder. For these reasons, FAA has determined that a 
compliance based on calendar time should be utilized in this AD in 
order to ensure that the unsafe condition is addressed in a reasonable 
time period on all airplanes that have an affected Rockwell Collins 
TDR-94 and TDR-94D Mode S transponder installed, and where Gillham 
pressure altitude encoding sources are used.

Regulatory Impact

Does This AD Impact Various Entities?

    The regulations adopted herein will 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. Therefore, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.

Does This AD Involve a Significant Rule or Regulatory Action?

    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a 
significant economic impact, positive or negative, on a substantial 
number of small entities under the criteria of the Regulatory 
Flexibility Act. A copy of the final evaluation prepared for this 
action is contained in the Rules Docket. A copy of it may be obtained 
by contacting the Rules Docket at the location provided under the 
caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. FAA amends Sec. 39.13 by adding a new AD to read as follows:

2002-06-06  Rockwell Collins, Inc.: Amendment 39-12683; Docket No. 
2000-CE-32-AD.

    (a) What airplanes are affected by this AD? This AD applies to 
TDR-94 Mode S transponders (Collins part number (CPN) 622-9352-004) 
and TDR-94D Mode S transponders (CPN 622-9210-004) that derive 
altitude information from a Gillham (gray code) encoded pressure 
altitude source and are installed on, but not limited to, the 
following airplanes that are certificated in any category:
    (1) Aerospatiale ATR42 series airplanes;
    (2) deHavilland DHC-7 and DHC-8 series airplanes; and
    (3) Short Brothers Models SD3-60 and SD3-60 SHERPA airplanes.
    (b) Who must comply with this AD? Anyone who wishes to operate 
any airplane with one of the affected TDR-94 or TDR-94D Mode S 
Transponder units installed must comply with this AD.
    (c) What problem does this AD address? The actions specified by 
this AD are intended to prevent erroneous altitude resolutions from 
causing a reduction in the intended aircraft collision avoidance 
system (ACAS) or traffic alert and collision avoidance system (TCAS) 
Change 7 minimum separation margins. Such a condition could result 
in air traffic control or the pilot making flight decisions that put 
the airplane in unsafe flight conditions.
    (d) What actions must I accomplish to address this problem? To 
address this problem, you must accomplish the following:

[[Page 13566]]



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                 Actions                           Compliance                          Procedures
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(1) Determine whether the altitude         Within the next 3 months    As specified in Rockwell Collins Service
 information from any TDR-94 Mode S         after May 3, 2002 (the      Bulletin No. 17 (TDR-94/94D-34-17),
 transponder (CPN 622-9352-004) or TDR-     effective date of this      dated February 8, 1999, Service Bulletin
 94D Mode S transponder (CPN 622-9120-      AD).                        17, Revision No. 1, dated May 15, 2000,
 004) is derived from a digital air data                                or Service Bulletin 20 (TDR-94/94D-34-
 source or a Gillham (gray code) encoded                                20), Revision No. 1, dated May 2, 2001.
 source.                                                                Collins Product Information Letter No.
                                                                        71, dated January 1999, references
                                                                        Service Bulletin 17, dated February 8,
                                                                        1999
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(2) If the altitude information is         At the next transponder     In accordance with Rockwell Collins
 derived from a Gillham (gray code)         check required by 14 CFR    Service Bulletin No. 17 (TDR-94/94D-34-
 encoded source, have the unit modified     91.413 and occurs 3         17), dated February 8, 1999, Service
 to prevent erroneous altitude reporting.   months after May 3, 2002    Bulletin 17, Revision No. 1, dated May
 The modification encompasses converting    (the effective date of      15, 2000, or Service Bulletin 20 (TDR-94/
 the TDR-94 transponder from Collins part   this AD) or within the      94D-34-20), Revision No. 1, dated May 2,
 number (CPN) 622-9352-004 to CPN 622-      next 9 months after May     2001. Collin Product Information Letter
 9352-005 or converting CPN 622-9352-004/   3, 2002 (the effective      No. 71, dated January 1999, references
 005 to CPN 622-9352-006; and converting    date of this AD),           Service Bulletin 17, dated February 8,
 the TDR 94D transponder from CPN 622-      whichever occurs first.     1999.
 9210-004 to CPN 622-9210-005 or
 converting CPN 622-9210-004/005 to CPN
 622-9210-006.
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(3) If the altitude information from all   Not applicable............  Not applicable.
 affected transponders is derived from a
 digital air data source, no modification
 action is required by this AD.
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(4) Do not install any TDR-94 Mode S       As of May 6, 2002 (the      Accomplish the modification in accordance
 transponder (CPN 622-9352-004) or TDR-     effective date of this      with Rockwell Collins Service Bulletin
 94D Mode S transponder (CPN 622-9210-      AD).                        No. 17 (TDR-94/94D-34-17), dated
 004) on any airplane if the altitude                                   February 8, 1999, Service Bulletin 17,
 information is derived from a Gillham                                  Revision No. 1, dated May 15, 2000, or
 (gray code) encoded source, unless the                                 Service Bulletin 20 (TDR-94/94D-34-20),
 modification required by paragraph                                     Revision No. 1, dated May 2, 2001.
 (d)(2) of this Ad is incorporated.                                     Collins Product Information Letter No.
                                                                        71, dated January 1999, references
                                                                        Service Bulletin 17, dated February 8,
                                                                        1999.
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    (e) Can I comply with this AD in any other way? You may use an 
alternative method of compliance or adjust the compliance time if:
    (1) Your alternative method of compliance provides an equivalent 
level of safety; and
    (2) The Manager, Wichita Aircraft Certification Office (ACO), 
approves your alternative. Submit your request through an FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, Wichita ACO.

    Note: This AD applies to each airplane identified in paragraph 
(a) of this AD, regardless of whether it has been modified, altered, 
or repaired in the area subject to the requirements of this AD. For 
airplanes that have been modified, altered, or repaired so that the 
performance of the requirements of this AD is affected, the owner/
operator must request approval for an alternative method of 
compliance in accordance with paragraph (e) of this AD. The request 
should include an assessment of the effect of the modification, 
alteration, or repair on the unsafe condition addressed by this AD; 
and, if you have not eliminated the unsafe condition, specific 
actions you propose to address it.

    (f) Where can I get information about any already-approved 
alternative methods of compliance? You can contact Roger A. Souter, 
FAA, Wichita Aircraft Certification Office (ACO), 1801 Airport Road, 
Room 100, Wichita, Kansas 67209; telephone: (316) 946-4134; 
facsimile: (316) 946-4407; e-mail: [email protected].
    (g) What if I need to fly the airplane to another location to 
comply with this AD? The FAA can issue a special flight permit under 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate your airplane to a location where 
you can accomplish the requirements of this AD.
    (h) Are any service bulletins incorporated into this AD by 
reference? Actions required by this AD must be done in accordance 
with Rockwell Collins Service Bulletin No. 17 (TDR-94/94D-34-17), 
dated February 8, 1999, Rockwell Collins Service Bulletin Service 
Bulletin 17 (TDR-94/94D-34-17), Revision No. 1, dated May 15, 2000, 
or Service Bulletin 20 (TDR-94/94D-34-20), Revision No. 1, dated May 
2, 2001. The Director of the Federal Register approved this 
incorporation by reference under 5 U.S.C. 552(a) and 1 CFR part 51. 
You can get copies from Rockwell Collins Inc., Business and Regional 
Systems, 400 Collins Road Northeast, Cedar Rapids, Iowa 52498. You 
can look at copies at the FAA, Central Region, Office of the 
Regional Counsel, 901 Locust, Room 506, Kansas City, Missouri, or at 
the Office of the Federal Register, 800 North Capitol Street, NW, 
suite 700, Washington, DC.
    (i) When does this amendment become effective? This amendment 
becomes effective on May 3, 2002.

    Issued in Kansas City, Missouri, on March 12, 2002.
Dorenda D. Baker,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-6625 Filed 3-22-02; 8:45 am]
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