[Federal Register Volume 66, Number 4 (Friday, January 5, 2001)]
[Proposed Rules]
[Pages 1054-1057]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-341]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-284-AD]
RIN 2120-AA64


Airworthiness Directives; Various Transport Category Airplanes 
Equipped With Certain Air Traffic Control (ATC) Transponders 
Manufactured by Rockwell Collins

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of Proposed Rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to various transport category 
airplanes equipped with certain Mode C air traffic control (ATC) 
transponders manufactured by Rockwell Collins, Inc. This proposal would 
require testing each transponder; replacing certain parts in any 
transponder which fails the initial test and performing additional 
test(s); and making repairs, as necessary so that the transponder 
passes the test. This proposal is prompted by reports that indicate 
that the equipment used to conduct earlier tests of certain 
transponders did not detect certain malfunctions. An airplane equipped 
with such malfunctioning transponders could transmit inaccurate data 
concerning its altitude to a nearby airplane equipped with the traffic 
alert and collision avoidance system (TCAS II), causing the TCAS II to 
issue an erroneous resolution advisory to the pilot. The actions 
specified by the proposed AD are intended to prevent transmission of 
inaccurate data concerning altitude from one airplane to another, which 
could cause the pilot receiving the data to change course, either 
ascending or descending, and possibly lead to a mid-air collision or 
near mid-air collision.

DATES: Comments must be received by February 20, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-284-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the

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Internet using the following address: <a href="/cdn-cgi/l/email-protection#4e77632f202363203e3c232d2123232b203a0e282f2f60292138"><span class="__cf_email__" data-cfemail="b38a9ed2ddde9eddc3c1ded0dcdeded6ddc7f3d5d2d29dd4dcc5">[email protected]</span></a>. 
Comments sent via fax or the Internet must contain ``Docket No. 2000-
NM-284-AD'' in the subject line and need not be submitted in 
triplicate. Comments sent via the Internet as attached electronic files 
must be formatted in Microsoft Word 97 for Windows or ASCII text.
    The service information referenced in the proposed rule may be 
obtained from Rockwell Collins, Inc., 400 Collins Road NE; Cedar 
Rapids, Iowa 52498. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Peter Skaves, Aerospace Engineer, ANM-
111, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056; telephone (425) 227-2795; fax (425) 227-
1320.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this action may be changed in 
light of the comments received.
    Submit comments using the following format:
    <bullet> Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
    <bullet> For each issue, state what specific change to the proposed 
AD is being requested.
    <bullet> Include justification (e.g., reasons or data) for each 
request.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket. 
Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NM-284-AD.'' The postcard will be date stamped 
and returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 2000-NM-284-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Related Rulemaking

AD 99-23-22
    On November 4, 1999, the FAA issued AD 99-23-22, amendment 39-11418 
(64 FR 61493, November 12, 1999), applicable to various transport 
category airplanes equipped with Mode C air traffic control (ATC) 
transponders with single Gillham code altitude input. That action was 
prompted by reports of eleven incidents, each of which involved an 
airplane equipped with Mode C transponders and a second nearby airplane 
equipped with the traffic alert and collision avoidance system (TCAS 
II). In these incidents, the airplane equipped with the Mode C 
transponders transmitted inaccurate data regarding its altitude to the 
other airplane. AD 99-23-22 required repetitive tests to detect 
discrepancies of the transponders and other equipment associated with 
transmission of an airplane's altitude--aincluding the air data 
computer and certain wiring connections. The AD also required repairs, 
if necessary, and reports of the findings (both positive and negative) 
of the initial and the repetitive tests to the FAA. The actions 
required by that AD were intended to prevent an airplane equipped with 
one or two malfunctioning Mode C ATC transponders from transmitting 
such inaccurate altitude data to a nearby airplane equipped with TCAS 
II, causing the TCAS II to issue an erroneous resolution advisory to 
the pilot to ascend or descend to avoid the other airplane. Such an 
incident could result in a decrease of separation between the two 
airplanes, possibly leading to a mid-air collision or a near mid-air 
collision.
AD 99-23-22 R1
    On December 10, 1999, the FAA issued AD 99-23-22 R1, amendment 39-
11473 (64 FR 70181, December 16, 1999), to extend certain compliance 
times and limit the applicability of AD 99-23-22.
AD 99-23-22 R2
    On April 7, 2000, the FAA issued AD 99-23-22 R2, amendment 39-11686 
(65 FR 21133, April 20, 2000), to rescind AD 99-23-22 R1, because test 
data collected since issuance of AD 99-23-22 R1 demonstrated that 
repetitive tests of the transponders, air data computer, and certain 
wiring connections were no longer necessary. Approximately 8 percent of 
the tests indicated that the Mode C transponders were transmitting 
erroneous altitude data. Of the tests that indicated a malfunction, 
over 50 percent were caused by failure of the transponders rather than 
failure of the air data computer or the wiring connections. Many of the 
transponders that failed were of a particular type manufactured by 
Rockwell Collins, Inc. The FAA concluded, on the basis of those 
results, that continued repetitive tests on the subject airplane models 
were unnecessary, since the corrective actions had been accomplished on 
all transport category airplanes identified in AD 99-23-22 and AD 99-
23-22 R1. In addition, the FAA determined that the repetitive tests 
required by AD 99-23-22 R1 could result in increased or accelerated 
component wear, which could contribute to malfunctioning of the Mode C 
ATC transponders, resulting in transmission of additional inaccurate 
data concerning the altitude of an airplane.

Since Issuance of AD 99-23-22 R2

    In the preamble to AD 99-23-22 R2, the FAA indicated that the 
agency was conducting further reviews to determine whether there was a 
systemic failure of the transponders. The FAA added that it might 
consider further rulemaking to address problems with the Mode C ATC 
transponder. Since the issuance of AD 99-23-22 R2, Rockwell Collins, 
Inc., the manufacturer of the transponders, has advised that use of 
more sensitive testing equipment is detecting a higher malfunction rate 
in Mode C transponders than had been detected earlier. This finding 
suggests the need for further testing of certain Rockwell Collins Mode 
C ATC transponders, including those which had been tested previously 
and had apparently been functioning properly.
    On May 25, 2000, Rockwell Collins, Inc. issued Service Information 
Letter (SIL) 00-1, which pertained to the 621A-3 transponder (with part 
number 522-2703-XXX). The document, subtitled ``621A-3 Transponder 
Overhaul Manual Test Equipment Modification Recommendation,'' indicates 
that some operators using ATC ramp tester model number 601 (ATC-

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601) to verify performance of Mode C transponders with single Gillham 
encoded altitude input were experiencing a high reject rate of the 
621A-3 transponders manufactured by Rockwell Collins, Inc. The service 
letter states that the ATC-601 ramp tester is capable of detecting out-
of-tolerance errors in the framing pulse width, whereas the ATC-600 
ramp tester previously used to test the transponders did not detect 
these pulse width errors.

Explanation of Relevant Service Information

    Rockwell Collins, Inc. has issued temporary revisions to the 621A-3 
ATC Transponder Overhaul Manual with Illustrated Parts List to provide 
a more rigorous performance test of the Mode C ATC transponders. The 
revisions are Temporary Revision No. 34-44-00-38, dated April 20, 2000, 
and Temporary Revision No. 34-44-00-39, dated May 23, 2000.
    Rockwell Collins, Inc. SIL 00-1 refers to Rockwell Collins Service 
Bulletin 621A-3-34-21, Revision 1, dated November 14, 1975, which 
provides information on modification of the transponder by replacing 
the transmitter tube and resistor.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of the same type design, the 
proposed AD would require testing each transponder; replacing the 
transmitter tube and the resistor in any transponder which fails the 
initial test and performing additional test(s); and making repairs, as 
necessary, so that the transponder passes the test. Accomplishment of 
the actions specified in the service bulletin is intended to adequately 
address the identified unsafe condition.

Cost Impact

    There are approximately 800 airplanes with transponders with the 
affected part in the worldwide fleet. The FAA estimates that 
approximately 400 airplanes of U.S. registry would be affected by this 
proposed AD, that it would take approximately 4 work hours per airplane 
to accomplish the proposed test, and that the average labor rate is $60 
per work hour. Based on these figures, the cost impact of the proposed 
AD on U.S. operators is estimated to be $96,000, or $240 per airplane.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the proposed requirements of 
this AD action, and that no operator would accomplish those actions in 
the future if this proposed AD were not adopted. The cost impact 
figures discussed in AD rulemaking actions represent only the time 
necessary to perform the specific actions actually required by the AD. 
These figures typically do not include incidental costs, such as the 
time required to gain access and close up, planning time, or time 
necessitated by other administrative actions.

Regulatory Impact

    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.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 draft 
regulatory 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, Safety.

Adoption of the Amendment

    Accordingly, pursuant to 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. Section 39.13 is amended by the following new airworthiness 
directive (AD):

    Transport Category Airplanes: Docket 2000-NM-284-AD.

    Applicability: Transport category airplanes, certificated in any 
category, equipped with Rockwell Collins Mode C 621A-3 Air Traffic 
Control (ATC) transponder(s), part number (P/N) 522-2703-XXX (where 
XXX is any series number).

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, 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 the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent transmission of inaccurate data concerning altitude 
from one airplane to another, which could cause the pilot receiving 
the data to change course, either ascending or descending, and 
possibly lead to a mid-air collision or near mid-air collision, 
accomplish the following:

Testing

    (a) Within 6 months after the effective date of this AD: Perform 
a pulse width test to detect malfunctions of any Mode C 621A-3 ATC 
transponder(s) equipped with P/N 522-2703-XXX, where XXX is any part 
number, in accordance with Rockwell Collins Air Transport Systems 
Overhaul Manual with Illustrated Parts List, Temporary Revision No. 
34-44-00-38, dated April 20, 2000.

Replacement

    (b) If the pulse width test required by paragraph (a) of this AD 
detects malfunction of a transponder: Prior to further flight, 
replace the transmitter tube and resistor, in accordance with 
Rockwell Collins Service Bulletin 621A-3-34-21, Revision 1, dated 
November 14, 1975, and repeat the pulse width test specified in 
paragraph (a) of this AD.

Repair

    (c) If the follow-up pulse width test required by paragraph (b) 
of this AD detects malfunction of a transponder: Prior to further 
flight, repair the transponder, air data computer, or wiring 
connections between them, in accordance with the applicable Mode C 
transponder component maintenance manual and airplane maintenance 
manual. If the repair information is not available in the applicable 
manual, prior to further flight, repair the transponder in 
accordance with a method approved by the Manager, Airplane and 
Flight Crew Interface Branch, ANM-111, FAA, Transport Airplane 
Directorate.

    Note 2: The airplane may be operated in accordance with the 
provisions and limitations specified in the FAA-approved Master 
Minimum Equipment List (MMEL), provided that only one Mode C 
transponder on the airplane is inoperative.


[[Page 1057]]



Reporting Requirements

    (d) Submit a report of the results (both positive and negative) 
of the tests required by paragraph (a) and (b) of this AD to: Peter 
Skaves, Aerospace Engineer, ANM-111, FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; 
fax (425) 227-1320. The report must be submitted within 60 days from 
the time of the transponder test. It must include the part number of 
the Mode ``C'' transponder(s) and whether corrective action was 
required. Information collection requirements contained in this 
regulation have been approved by the Office of Management and Budget 
(OMB) under the provisions of the Paperwork Reduction Act of 1980 
(44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 
2120-0056.

Alternative Methods of Compliance

    (e) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Airplanes and Flight Crew Interface 
Branch, ANM-111. Operators shall submit their requests through an 
appropriate FAA Principal Maintenance or Avionics Inspector, who may 
add comments and then send it to the Manager, Airplane and Flight 
Crew Interface Branch, ANM-111.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Manager, Airplane and Flight Crew Interface 
Branch, ANM-111.

Special Flight Permits

    (f) Special flight permits may be issued in accordance with 
Secs. 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 
21.197 and 21.199) to operate the airplane to a location where the 
requirements of this AD can be accomplished.

    Issued in Renton, Washington, on December 29, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-341 Filed 1-4-01; 8:45 am]
BILLING CODE 4910-13-U


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