[Federal Register Volume 63, Number 126 (Wednesday, July 1, 1998)]
[Rules and Regulations]
[Pages 35787-35790]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-17301]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-CE-30-AD; Amendment 39-10637; AD 98-14-03]
RIN 2120-AA64


Airworthiness Directives; AlliedSignal Inc. KT 76A Air Traffic 
Control (ATC) 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 AlliedSignal Inc. (AlliedSignal) KT 76A ATC 
transponders that are installed on aircraft. This AD requires 
incorporating a modification on the affected transponders that consists 
of replacing two resistor network modules with glass-coated modules. 
This AD is the result of reports of these ATC transponders transmitting 
misleading encoding altimeter information to ground-based ATC radar 
sites and nearby Traffic Alert and Collision Avoidance System (TCAS)-
equipped aircraft. The actions specified by this AD are intended to 
prevent the transmission of misleading encoding altimeter information 
between affected aircraft caused by the inability of these ATC 
transponders to coordinate with ground-based ATC radar sites and nearby 
TCAS-equipped aircraft.

DATES: Effective August 16, 1998.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of August 16, 1998.

ADDRESSES: Service information that applies to this AD may be obtained 
from AlliedSignal Inc., General Aviation Avionics, 400 N. Rogers Road, 
Olathe, Kansas 66062-1212. This information may also be examined at the 
Federal Aviation Administration (FAA), Central Region, Office of the 
Regional Counsel, Attention: Rules Docket No. 97-CE-30-AD, Room 1558, 
601 E. 12th Street, Kansas City, Missouri 64106; or at the Office of 
the Federal Register, 800 North Capitol Street, NW, suite 700, 
Washington, DC.


[[Page 35788]]


FOR FURTHER INFORMATION CONTACT: Mr. Roger A. Souter, Aerospace 
Engineer, Wichita Aircraft Certification Office, FAA, 1801 Airport 
Road, Mid-Continent Airport, Wichita, Kansas 67209; telephone: (316) 
946-4134; facsimile: (316) 946-4407.

SUPPLEMENTARY INFORMATION:

Events Leading to the Issuance of This AD

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to include an AD that would apply to certain AlliedSignal 
KT 76A ATC transponders that are installed on aircraft was published in 
the Federal Register as a notice of proposed rulemaking (NPRM) on 
February 4, 1998 (63 FR 5763). The NPRM proposed to require replacing 
two resistor network modules, RM401 and RM402, with new glass-coated 
parts. Accomplishment of the proposed action as specified in the NPRM 
would be in accordance with AlliedSignal Service Bulletin SB KT 76A-7, 
dated July 1996.
    The NPRM was the result of reports of these ATC transponders 
transmitting misleading encoding altimeter information to ground-based 
ATC radar sites and nearby Traffic Alert and Collision Avoidance System 
(TCAS)-equipped aircraft.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Comment Issue: The Compliance Time Should Be Extended

    Three commenters believe that the proposed compliance time of 6 
calendar months is unrealistic. These comments are detailed as follows:
    1. One commenter states that, in order to accomplish the work, 
Allied Signal would have to supply 38 repairmen who would work 8 hours 
per day for 6 months. The commenter questions whether this commitment 
will be made.
    2. Another commenter agrees with the FAA's decision to state the 
compliance in calendar time, but believes that a more appropriate and 
more convenient time would be to require the work at the next annual 
inspection or transponder system inspection. This would reduce the 
down-time for the affected aircraft by allowing the work to be 
accomplished during regularly scheduled maintenance.
    3. The third commenter states that many of the affected 
transponders will be part of a complete pitot-static system that 
requires biennial calibration in accordance with Sec. 91.413 of the 
Federal Aviation Regulations (14 CFR 91.413). The commenter proposes 
that since the unit will already be at the avionics shop for this 
calibration, then the FAA should write the compliance time to coincide 
with the biennial pitot-static system calibration.
    The FAA partially concurs with the above comments, as follows:
    1. After re-evaluating all information related to this subject, the 
FAA concurs that 6 calendar months is an unrealistic time period to 
have the work accomplished on all of the affected transponders. The FAA 
believes that a large number of the affected aircraft already have the 
proposed modification incorporated on the transponder. Based on all 
information, the FAA believes that a 12 calendar month compliance time 
is more realistic. The final rule will reflect this change.
    2. The 12 calendar month compliance time will allow the 
modification to be incorporated during the airplane's next annual 
inspection, as requested by the commenter.
    3. Because the silver migration process is affected by 
environmental factors as well as occurring over time, the FAA cannot 
predict when a particular transponder could fail. A transponder could 
work well one day and then fail the next day. With this in mind, the 
FAA does not concur that the compliance time should be written to 
coincide with the next pitot-static system biennial calibration in 
accordance with Sec. 91.413 of the Federal Aviation Regulations (14 CFR 
91.413). This could allow the condition defined in this AD to go 
undetected for up to 24 months.

Comment Issue: Problem Occurs Only on Aircraft Operating Above 
10,000 Feet and the AD Should Be Limited to Only Those Aircraft 
Operating in Instrument Flight Rule (IFR) Conditions

    Two commenters believe that the condition specified in the NPRM is 
associated with ``at altitude'' operations over time. The commenters 
state that one could imply that:

``aircraft in the high altitude structure may be more likely to 
experience this problem than one operating below 10,000 feet and 
using the Allied Signal KT 76A ATC transponder simply because the 
aircraft operates within Class B or C airspace or within a 30 
nautical miles ``veil'' for a class B airport. The problem with an 
erroneous altitude report from a high speed aircraft operating in 
the IFR airspace system is significantly different than a small 
airplane flying in visual flight rules (VFR) conditions.''

    Both commenters recommend different actions than are already 
proposed based on the above information and both believe that the 
private operator (who is mostly a Sunday pilot) would remove the 
equipment from the aircraft since aircraft in VFR operation outside of 
the B and C airspace do not need to have a transponder unit. Both 
believe that removing the transponder would reduce safety. These 
recommendations are as follows:
    1. One commenter suggests that those operating in only VFR 
conditions fabricate and install a placard with the words ``For VFR Use 
Only''. If or when these aircraft's transponders no longer comply with 
the 125-foot error requirement of part 43, Appendix E, of the Federal 
Aviation Regulations (14 CFR part 43, Appendix E), then the commenter 
proposes that the AD require immediate replacement or modification of 
the transponder equipment. The commenter feels that this would allow 
thousands of small aircraft to fly legally and safely within the 30 
nautical mile veils associated with Class B airports, without incurring 
an additional expense to their flying activities.
    2. The other commenter recommends that the FAA not issue the 
proposed AD as a final rule, or if issued, limit the Applicability of 
the AD to only turbine-powered or ``10-or-more seats'' aircraft. This 
commenter feels that replacing equipment that meets performance 
standards because of a ``maybe'' malfunction (which will simply cause 
an error in altitude reporting) is wrong when it comes to private 
aircraft (used mostly for pleasure). The commenter also suggests a 
possible mandatory replacement or modification of the equipment if a 
certain error is detected.
    The FAA does not concur with the proposed alternatives presented by 
the commenters. The altitude at which an aircraft equipped with one of 
the affected transponders is flown and the amount of time flown at this 
altitude do not affect the probability of the unit failing. The 
``silver migration'' process occurs regardless of the altitude or the 
time ``at altitude''. This ``silver migration'' process is slow and is 
affected by environmental factors as well. The FAA cannot assure that 
any given unit would not be affected by this condition during any given 
2 year period. A unit could pass on one day and then fail the next day. 
Aircraft that are operated in VFR conditions are interrogated by TCAS-
equipped aircraft in the areas. The ATC system and misleading aircraft 
altitude information could represent a hazard to the aircraft in VFR 
conditions. The FAA has determined that safety would be compromised if 
the AD allowed, for aircraft operating in VFR conditions, the

[[Page 35789]]

system to fail before mandating replacement or modification.

Comment Issue: Limit the AD to Only Those Aircraft Exhibiting 
Problems

    In addition to the comments above proposing replacement or 
modification of the Allied Signal KT 76A ATC transponder upon condition 
for aircraft operating in VFR conditions, one commenter proposes that 
the AD only apply to those transponders that exhibit problems during 
the 24 calendar month pitot-static system calibration in accordance 
with Sec. 91.413 of the Federal Aviation Regulations (14 CFR 91.413). 
This would be for all transponders regardless of the type of operation 
in which the aircraft is involved. The commenter believes that this 
would accomplish the intent of the AD without burdening operators 
already in good working order.
    The FAA does not concur. As discussed earlier, the FAA cannot 
predict when a particular transponder could fail. A transponder could 
work well one day and then fail the next day. The FAA has determined 
that safety would be compromised if the AD allowed the system to fail 
before mandating replacement or modification.

Comment Issue: Wait for Results of Technical Field Study on 
Transponders

    One commenter agrees with the FAA that the KT 76A ATC transponders 
have a demonstrated history of inaccurate or misleading data 
transmission and that corrective action is necessary to address this 
issue. This commenter goes on to state that the FAA Technical Center in 
Atlantic City conducted a full-scale field study of transponder 
performance in general aviation aircraft and determined that a variety 
of deficiencies exist in a broad range of transponders, including the 
KT 76A ATC transponders. This commenter suggests that the FAA withhold 
issuance of this AD until the full scope of the transponder issues can 
be addressed, including the problems associated with ``silver 
migration'' in the KT 76A ATC transponders.
    The FAA concurs that the information from the Technical Center 
Study is very important. However, correspondence received from the 
Technical Center indicates that resolution of these issues may take a 
considerable amount of time. As stated earlier, the FAA cannot predict 
when a particular transponder could fail. A transponder could work well 
one day and then fail the next day. The FAA has determined that safety 
would be compromised if the AD was not issued awaiting a resolution 
from the FAA Technical Center in Atlantic City, regarding the full 
scope of the transponder issues.

Comment Issue: Certain Aspects Not Covered in the Cost Impact

    Four commenters propose changes to the section that describes the 
cost impact upon the public. These include:

--It will take 2.5 workhours to accomplish the action instead of 2 
workhours as presented in the NPRM;
--In addition to providing parts at no charge, Allied Signal is 
providing warranty credit for up to 2.5 workhours to accomplish the 
action;
--The cost impact should include the costs of a recalibration of the 
pitot-static system; and
--The cost impact does not take into account the costs the affected 
aircraft operators will incur while their aircraft is out-of-service.

    The FAA concurs that it will take 2.5 workhours to accomplish the 
action and that Allied Signal will provide warranty credit for up to 
2.5 workhours to accomplish the action. The final rule will incorporate 
this information.
    The FAA does not concur that the cost impact section should account 
for recalibration costs because the inputs affected by the silver 
migration are encoding altimeter inputs and are not directly connected 
to the pitot static system. Therefore, there are no costs associated 
with pitot static system when complying with this AD.
    The FAA believes that the change in the compliance time from 6 
calendar months to 12 calendar months will take into account the cost 
impact of aircraft ``out-of-service.'' This will allow the operator to 
schedule the replacement and modification to coincide with a regularly 
schedule maintenance event, thus, the AD will not necessitate any 
additional downtime. Even if additional downtime is necessary for some 
airplanes, the FAA does not possess sufficient information to evaluate 
the number of airplanes that may be so affected or the amount of 
additional downtime that may be required.

Comment Issue: Include Statistical Data Concerning the Problem in 
the AD

    One commenter states that including statistical data that more 
fully discusses the origin of the ``silver migration'' problem would be 
helpful.
    The FAA, in working with the manufacturer, saw a three-fold 
increase in the usage of spare parts of the Allied Signal KT76A ATC 
transponders. Between the last quarter of 1995 and the first quarter of 
1996, quarterly usage of spare parts increased from approximately 40 
parts per quarter to approximately 120 parts for that quarter. This 
indicates a significant trend and failure analysis of these 
transponders. Information submitted to the FAA revealed that this 
increase in spare parts usage was due to the ``silver migration'' 
problem. Within a 3-month period, over 150 of these transponder units 
were in the repair shops to have ``silver migration'' problems 
remedied.

Comment Issue: Concur With the Action

    One commenter agrees with the proposal as written and states that 
accomplishing ``this relatively inexpensive and simple repair action 
will eliminate the potential hazard and enhance general flying safety 
in the National Airspace System.''

The FAA's Determination

    After careful review of all available information related to the 
subject presented above, the FAA has determined that air safety and the 
public interest require the adoption of the rule as proposed except for 
the change in the compliance time and minor editorial corrections. The 
FAA has determined that this change and minor corrections will not 
change the meaning of the AD and will not add any additional burden 
upon the public than was already proposed.

Cost Impact

    The FAA estimates that 20,000 transponder units could be affected 
by this AD if all were installed in aircraft of U.S. registry. 
Approximately 2.5 workhours will be needed to accomplish this action, 
at an average labor rate of $60 an hour. However, Allied Signal will 
provide warranty credit for up to 2.5 workhours to accomplish the 
action, as well as providing all necessary parts at no cost to the 
owners/operators of airplanes with the affected transponder units 
installed. Based on these figures and Allied Signal's warranty program, 
this AD will impose no cost impact on U.S. operators of the affected 
aircraft.

Regulatory Impact

    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.

[[Page 35790]]

    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, 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 adding a new airworthiness directive 
(AD) to read as follows:

98-14-03  AlliedSignal Inc.: Amendment 39-10637; Docket No. 97-CE-
30-AD.

    Applicability: AlliedSignal KT 76A Air Traffic Control (ATC) 
transponders; part number (P/N) 066-1062-00/10/02; serial numbers 
93,000 through 109,999, as installed on, but not limited to the 
following airplanes (all serial numbers), certificated in any 
category:

Cessna Aircraft Company: 172, 182, R182, T182, 06, P206, U206, 
TP206, 210, T210, P210, 310, 310, T310, and 421 series airplanes.
Twin Commander Aircraft Company: 500, 520, 560, 680, 681, 685, 690, 
695, and 720 series airplanes.
The New Piper Aircraft Corporation: PA-31, PA-32, and PA-34 series 
airplanes.
Raytheon Aircraft Company: E33, F33, G33, 35, J35, K35, L35, K35, 
M35, P35, S35, V35, 36, A26, B36, D55, E55, 56, A56, 58, 58A, 95, 
B95, D95, and E95 series airplanes.
Mooney Aircraft Corporation: M20 series airplanes.
McDonnell Douglas Helicopter Company: Model 500N rotorcraft.

    Note 1: This AD applies to each aircraft equipped with a 
transponder that is 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 
aircraft 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 (d) 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 within the next 12 calendar months after 
the effective date of this AD, unless already accomplished.
    To prevent the transmission of misleading encoding altimeter 
information between affected aircraft caused by the inability of the 
affected ATC transponders to coordinate with ground-based air 
traffic control (ATC) radar sites and nearby Traffic Alert and 
Collision Avoidance System (TCAS)-equipped aircraft, accomplish the 
following:
    (a) Replace the two resistor network modules, M401 and RM402, 
with new glass-coated parts in accordance with the MODIFICATION 
PROCEDURE section of AlliedSignal Service Bulletin SB KT 76A-7, 
dated July 1996. When accomplished, this replacement is referred to 
as Mod 7.
    (b) As of the effective date of this AD, no person may install 
an AlliedSignal KT 76A ATC transponder; part number (P/N) 066-1062-
00/10/02; serial numbers 93,000 through 109,999, in an aircraft 
without first incorporating Mod 7 as specified in paragraph (a) of 
this AD.
    (c) 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.
    (d) An alternative method of compliance or adjustment of the 
compliance time that provides an equivalent level of safety may be 
approved by the Manager, Wichita Aircraft Certification Office 
(ACO), 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, 
Kansas 67209. The request shall be forwarded through an appropriate 
FAA Maintenance Inspector, who may add comments and then send it to 
the Manager, Wichita ACO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Wichita ACO.

    (e) The replacement required by this AD shall be done in 
accordance with AlliedSignal Service Bulletin SB KT 76A-7, dated 
July 1996. 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 AlliedSignal Inc., 
General Aviation Avionics, 400 N. Rogers Road, Olathe, Kansas 66062-
1212. Copies may be inspected at the FAA, Central Region, Office of 
the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, 
Missouri, or at the Office of the Federal Register, 800 North 
Capitol Street, NW, suite 700, Washington, DC.
    (f) This amendment becomes effective on August 16, 1998.

    Issued in Kansas City, Missouri, on June 23, 1998.
Marvin R. Nuss,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-17301 Filed 6-30-98; 8:45 am]
BILLING CODE 4910-13-U