[Federal Register Volume 59, Number 3 (Wednesday, January 5, 1994)]
[Rules and Regulations]
[Pages 511-514]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 93-32115]


[[Page Unknown]]

[Federal Register: January 5, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-NM-68-AD; Amendment 39-8786; AD 94-01-04]

 

Airworthiness Directives; Honeywell Traffic Alert and Collision 
Avoidance System II Computer Units, as Installed on Various Transport 
Category Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to all Honeywell Traffic Alert and Collision Avoidance 
System II (TCAS II) computer units installed on various transport 
category airplanes, that requires replacing certain TCAS II computer 
units with new units that incorporate updated collision avoidance 
system (CAS) logic, and modifying the computer surveillance logic. This 
amendment is prompted by the development of candidate enhancements to 
TCAS II logic that will improve its utility and increase its overall 
operational acceptance. The actions specified by this AD are intended 
to prevent collisions or near misses caused by incompatibility between 
the TCAS II processors and the current air traffic control system.

DATES: Effective February 4, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of February 4, 1994.

ADDRESSES: The service information referenced in this AD may be 
obtained from Honeywell Inc., Commercial Flight Systems Group, Air 
Transport Systems Division, P.O. Box 21111, Phoenix, Arizona 85036. 
This information may be examined at the Federal Aviation Administration 
(FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, 
SW., Renton, Washington; at the FAA, Transport Airplane Directorate, 
Los Angeles Aircraft Certification Office, 3229 East Spring Street, 
Long Beach, California; or at the Office of the Federal Register, 800 
North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Abby Malmir, Aerospace Engineer, 
Systems and Equipment Branch, ANM-132L, FAA, Transport Airplane 
Directorate, Los Angeles Aircraft Certification Office, 3229 East 
Spring Street, Long Beach, California 90806-2425; telephone (310) 988-
5351; fax (310) 988-5210.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations to include an airworthiness directive (AD) that is 
applicable to all Honeywell Traffic Alert and Collision Avoidance 
System II (TCAS II) computer units installed on various transport 
category airplanes was published in the Federal Register on September 
9, 1993 (58 FR 47407). That action proposed to require replacing 
certain TCAS II computer units with new units that incorporate updated 
collision avoidance system (CAS) logic, and modifying the computer 
surveillance logic.
    Since the issuance of the notice, an additional change to Version 
6.04A collision avoidance system (CAS) logic was recommended at a 
meeting held to discuss the progress made in implementing logic 
modification 6.04A. Meeting attendees included representatives from the 
FAA and European civil aviation authorities, U.S. and European aviation 
industry, and U.S. operators. The logic change that was recommended 
involves reducing unnecessary crossing resolution advisories (RA). That 
change is included in a new enhanced software package (identified as 
Version 6.04A), specified in Mitre letter F046-L-0069, dated September 
21, 1993.
    Subsequently, Honeywell Inc. has issued Service Bulletin 4066010-
34-SW16, dated December 20, 1993. The service bulletin describes 
procedures for converting certain TCAS II computer units to new units 
(Version 6.04A). The new units incorporate all of the logic changes 
specified in the preamble to the notice, including updating CAS logic, 
modifying the computer surveillance logic to ensure that these units 
accommodate Mode C altitude input of 100-foot increments, and ensuring 
that the system will be tracked and coordinated by intruding aircraft 
when the Mode S transponder CA field is set at CA=7. The conversion is 
onboard-loadable, or it may be accomplished at a field repair shop. The 
first method involves data loading the TCAS II computer unit in the 
aircraft equipment bay using an ARINC 615 or 603 data loader. The 
second method entails performing a final test, and then programming the 
TCAS II computer unit to convert it to the latest enhanced version at a 
field repair shop.
    The notice proposed that operators accomplish the modification 
requirements of this AD in accordance with a method approved by the 
FAA. However, the FAA has reviewed and approved the Honeywell service 
bulletin discussed previously, and has determined that accomplishment 
of this service bulletin is an appropriate method of compliance. 
Consequently, the FAA has revised paragraph (a) of the final rule to 
cite the Honeywell service bulletin as the appropriate source of 
service information, and has removed the language referring to 
accomplishing the actions ``in accordance with a method approved by the 
FAA.'' Even though this language has been deleted from paragraph (a), 
operators may still be permitted to accomplish the actions in 
accordance with an FAA-approved method under the provisions of 
paragraph (c) of the final rule.
    In light of this new data and software developement, the FAA has 
revised the final rule by changing the reference to Mitre letter F046-
L-0056, dated July 20, 1993, which appeared in paragraph (a)(1) of the 
NPRM, to Mitre letter F046-L-0069, dated September 21, 1993, since the 
latter identifies the enhanced software package. Since the original 
Version 6.04A software was never issued, no operator could have 
installed that version. Therefore, no redundant actions would be 
required on the part of any operator as a result of this change.
    Since the enhanced Version 6.04A software introduces a change in 
the operation of the aircraft, the FAA also finds that a revision to 
the Airplane Flight Manual (AFM) is necessary as a conforming change to 
correspond with that new software configuration. The AFM revision is 
advisory only, and will ensure that the flight crew is aware of the 
changes associated with the new software installation. Consequently, 
paragraph (b) has been added to the final rule to reflect this 
informational AFM revision.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received in response to the notice:
    One commenter, Honeywell, objects to the proposed compliance date 
of December 30, 1993, and states that December 31, 1994, represents a 
more realistic compliance timeframe. Honeywell indicates that operators 
vary in their ability to load the updated software due to maintenance 
and aircraft schedules and data-load/test resources. Honeywell states 
that, although it has been working aggressively to implement the latest 
change, that change has resulted in a delay in the date operators will 
be able to implement the latest change.
    Several other commenters also request that the FAA extend the 
proposed compliance date from 3 to 18 months after the date specified 
in the proposal in order to accommodate implementation, verification, 
certification, and incorporation of the proposed software change into 
existing installations. One commenter, the Air Transport Association 
(ATA) of America, supports implementation of the latest enhanced 
Version 6.04A, and requests that the FAA issue a supplemental notice of 
proposed rulemaking (NPRM) to propose that this revised software be 
retrofitted by June 30, 1995. ATA contends that significant differences 
exist between Version 6.04A and the latest enhanced version. Another 
commenter requests that the FAA solicit comments from foreign agencies 
participating in TCAS evaluation and simulations to help ensure that 
the proposed Version 6.04A revision will be compatible and acceptable.
    The FAA concurs partially with these requests to extend the 
compliance time. The FAA has considered the safety implications, the 
time necessary for approval of the enhanced Version 6.04A software, the 
size of the fleet, and normal maintenance schedules for timely 
accomplishment of implementation of the modification. In light of these 
considerations, the FAA has determined that a compliance date of 
December 31, 1994, is appropriate. Paragraph (a) of the final rule has 
been revised to specify the revised compliance date.
    However, in response to the requests that a supplemental NPRM be 
issued and that further public comments be solicited, the FAA submits 
the following. Comments received in response to the proposal reflect 
unanimous support for implementation of the latest enhanced Version 
6.04A software. The FAA considers the logic change (reduction of 
unnecessary crossing RA's) incorporated in the enhanced software to be 
a minor change. The intent of this AD is to require that the addressed 
unsafe condition be corrected by installing modified TCAS II computer 
units that incorporate updated CAS logic. The FAA has determined that a 
requirement to implement Version 6.04A software, including the latest 
enhancement, will meet that intent, will not alter the substance of the 
rule, and will impose no additional burden on any member of the public. 
Additionally, issuance of a supplemental NPRM would necessitate (under 
the provisions of the Administrative Procedure Act) reissuing the 
notice, reopening the period for public comment, considering additional 
comments received, and eventually issuing a final rule; the time 
required for that procedure may be as long as four additional months. 
In light of this, and in consideration of the amount of time that has 
already elapsed since issuance of the original NPRM, the FAA concludes 
that solicitation of further public comment is not necessary and that 
further delay of this final rule action is not appropriate.
    One commenter requests that the FAA require Honeywell TCAS II 
processors that are already installed be operated in the ``traffic 
advisory (TA) only'' mode until the updated software package is 
installed. The commenter indicates that ``possible hidden problems'' 
could exist between the different versions of logic that are installed 
currently in the TCAS II processors.
    The FAA does not concur with the commenter's request. Operation of 
currently installed TCAS II processors in the ``TA only'' mode would 
impair the capability of those processors to alert the flight crew of 
appropriate aircraft maneuvers that must be taken to prevent mid-air 
collisions. Further, the FAA is unaware of any ``possible hidden 
problems'' between the different versions of logic installed currently 
in the TCAS II processors, as suggested by the commenter. Therefore, 
the FAA concludes that currently installed TCAS II processors should 
not be operated in the ``TA only'' mode until the updated software 
packaged is installed.
    One commenter requests clarification of the unsafe condition 
specified in the proposed rule. This commenter points out differences 
in the wording of the unsafe condition between this proposed rule and 
two existing proposals that address the same CAS logic change for 
Rockwell International/Collins Air Transport Division (Collins), and 
Allied Signal Aerospace Company/Air Transport Avionics (Allied Signal), 
TCAS II processors. From this comment, the FAA infers that the 
commenter requests that the proposed statement of unsafe condition more 
closely parallels the statement of unsafe condition in the other two 
proposals addressing the same subject.
    The FAA concurs. The FAA has revised the unsafe condition specified 
in this final rule to coincide with the proposals that address Collins 
and Allied Signal TCAS II processors to more explicitly reference 
safety considerations, as follows: ``* * * to prevent collisions or 
near misses caused by incompatibility between the TCAS II processors 
and the current air traffic control system.''
    One commenter, Falcon Jet Corporation, indicates that Honeywell 
TCAS II processors are installed on Mystere-Falcon Model 50 and 900 
series airplanes, and requests that these airplanes be included in the 
portion of the applicability of the AD that lists airplanes on which 
this TCAS II processor may be installed. The FAA concurs with the 
commenter's request and has revised the final rule accordingly. In 
addition, the FAA has become aware of other airplane models affected by 
this AD and has included those models in that portion of the 
applicability statement of the final rule. The FAA clarifies that, as 
stated in the preamble and the applicability of the proposal, the 
affected Honeywell TCAS II processors are installed on various 
transport category airplanes and are not limited only to those 
airplanes listed in the applicability of this AD.
    Several commenters request that the FAA revise the economic impact 
information specified in the proposal to reflect costs borne by 
suppliers, installers, and airline operators associated with 
development, testing, and certification of the modified processor.
    The FAA does not concur with the commenters' request to revise the 
economic impact information contained in this AD. The appropriate 
number of hours required to accomplish the required actions, specified 
as 3 in the economic impact information, below, was provided to the FAA 
by the processor manufacturer based on the best data available to date. 
This number represents the time required to gain access, remove the 
existing processor, install a diskette containing the revised software, 
and close up. The cost analysis in AD rulemaking actions typically does 
not include costs associated with development, testing, and 
certification of a modified processor, as suggested by the commenter.
    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.
    There are approximately 2,700 transport category airplanes in the 
worldwide fleet on which the Honeywell TCAS II computer units may be 
installed. The FAA estimates that 1,150 airplanes of U.S. registry will 
be affected by this AD, that it will take approximately 3 work hours 
per airplane to accomplish the required actions, and that the average 
labor rate is $55 per work hour. Required parts will be supplied by the 
manufacturer at no cost to operators. Based on these figures, the total 
cost impact of the AD on U.S. operators is estimated to be $189,750, or 
$165 per airplane. This total cost figure assumes that no operator has 
yet accomplished the requirements of this AD.
    The regulations adopted herein will not have substantial direct 
effects 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, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from 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, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 14 CFR part 
39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES

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

    Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

94-01-04  Honeywell: Amendment 39-8786. Docket 93-NM-68-AD.

    Applicability: Traffic Alert and Collision Avoidance System 
(TCAS) II computer units; part numbers 4066010-901, -902, and -903; 
as installed on, but not limited to, the following airplanes, 
certificated in any category:

Airbus Industrie Model A300-600, A310-200, A310-300, A320-200, and 
A340 series airplanes;
Boeing Model 727-100 and -200; 737-100, -200, -300, and -400; 747-
100, -200, -300, -400 and 747SP; 757-200 and -500; and 767-200 and -
300 series airplanes;
Cessna Citation Model C550 and C560 series airplanes, and Cessna 
Citation III and VII series airplanes;
Canadair Challenger Model CL-600-2B16 and -2A12 series airplanes;
British Aerospace Model 125-800A;
Gulfstream Model GII, GIIB, GIII, and GIV series airplanes;
Lockheed Model L-1011 series airplanes;
McDonnell Douglas Model DC-9-10, -20, -30-, -40, and -50; DC-10-10, 
-15, -30, and -40; MD-11; and DC-9-80 series airplanes; and Model 
MD-88 airplanes;
Dassault Aviation Model Mystere-Falcon 50 and 900 series airplanes;
Short Brothers Model SD3-60 series airplanes;
de Havilland Model DHC-8-100 and DHC-7 series airplanes;
Fokker Model F27 series airplanes; and
Corporate Jets Limited Model BAe 125-800A and BAe 125-1000A series 
airplanes.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent collisions or near misses caused by incompatibility 
between the TCAS II processors and the current air traffic control 
system, accomplish the following:
    (a) Before December 31, 1994, accomplish the requirements of 
paragraphs (a)(1) and (a)(2) of this AD in accordance with Honeywell 
Service Bulletin 4066010-34-SW16, dated December 20, 1993.
    (1) Remove existing Honeywell TCAS II computer units, part 
numbers 4066010-901, -902, and -903, and replace those units with 
new units that incorporate updated collision avoidance system (CAS) 
logic, identified as Version 6.04A in Mitre letter F046-L-0069, 
dated September 21, 1993.
    (2) Modify the computer surveillance logic on Honeywell TCAS II 
computer units, part numbers 4066010-901, -902, and -903, to ensure 
that these units accommodate Mode C altitude input of 100-foot 
increments and that the system will be tracked and coordinated by 
intruding aircraft when the Mode S transponder CA field is set at 
CA=7.
    (b) Prior to further flight after accomplishing the requirements 
of paragraph (a) of this AD, revise the Airplane Flight Manual (AFM) 
or AFM Supplement by accomplishing either paragraph (b)(1) or (b)(2) 
of this AD.
    (1) Revise the Normal Procedures Section of the AFM to include 
the appropriate TCAS operating characteristic relative to the 
modifications required by paragraph (a) of this AD, in accordance 
with a method approved by the Manager, Los Angeles Aircraft 
Certification Office (ACO), FAA, Transport Airplane Directorate; or
    (2) Revise the Normal Procedures Section of the AFM to include 
the following TCAS operating characteristic relative to the 
modification required by paragraph (a) of this AD. This may be 
accomplished by inserting a copy of this AD in the AFM or AFM 
Supplement.
    ``All Resolution Advisory (RA) and Traffic Advisory (TA) aural 
messages are inhibited at a radio altitude of less than 1,100 feet 
above ground level (AGL) climbing, and less than 900 feel AGL 
descending.''
    (c) 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, Los Angeles Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. Operators shall 
submit their requests through an appropriate FAA Principal Avionics 
Inspector, who may add comments and then send it to the Manager, Los 
Angeles ACO.

    Note: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.

    (d) Special flight permits may be issued in accordance with FAR 
21.197 and 21.199 to operate the airplane to a location where the 
requirements of this AD can be accomplished.
    (e) The replacement and modification shall be done in accordance 
with Honeywell Service Bulletin 4066010-34-SW16, dated December 20, 
1993. This incorporation by reference was approved by the Director 
of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR 
part 51. Copies may be obtained from Honeywell Inc., Commercial 
Flight Systems Group, Air Transport Systems Division, P.O. Box 
21111, Phoenix, Arizona 85036. Copies may be inspected at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; at the FAA, Transport Airplane Directorate, Los Angeles 
Aircraft Certification Office, 3229 East Spring Street, Long Beach, 
California; or at the Office of the Federal Register, 800 North 
Capitol Street, NW., suite 700, Washington, DC.
    (f) This amendment becomes effective on February 4, 1994.

    Issued in Renton, Washington, on December 29, 1993.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 93-32115 Filed 12-30-93; 8:45 am]
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