Airworthiness Directives; Various Transport Category Airplanes Equipped With Mode ``C'' Transponder(s) With Single Gillham Code Altitude Input

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-328-AD; Amendment 39-11473; AD 99-23-22 R1]

RIN 2120-AA64

Airworthiness Directives; Various Transport Category Airplanes

Equipped With Mode ``C'' Transponder(s) With Single Gillham Code

Altitude Input

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment revises an existing airworthiness directive

(AD), applicable to various transport category airplanes equipped with

certain Mode ``C'' transponder(s) with single Gillham code altitude

input. That AD currently requires repetitive tests to detect

discrepancies of the Mode ``C'' transponder(s), air data computer, and

certain wiring connections; and corrective actions, if necessary. The

existing AD is prompted by reports that, during level flight, the

Traffic Alert Collision Avoidance System (TCAS II) issued false

advisories that directed the flightcrew to change course and either

climb or descend. The actions specified by that AD are intended to

prevent such false advisories due to inaccurate airplane altitude

reporting, which could result in the flightcrew deviating the airplane

from its assigned flight path and a possible mid-air collision. This

new action revises certain compliance times and limits the

applicability of the existing AD.

DATES: Effective November 29, 1999.

Comments for inclusion in the Rules Docket must be received on or

before February 14, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-114,

Attention: Rules Docket No. 99-NM-328-AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056.

Information pertaining to this amendment may be obtained from or

examined at the FAA, Transport Airplane Directorate, 1601 Lind Ave,

SW., Renton, Washington 98055-4056.

FOR FURTHER INFORMATION CONTACT: Peter Skaves, Aerospace Engineer,

Airplane and Flight Crew Interface Branch, ANM-111, FAA, Transport

Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington

[[Page 70182]]

98055-4056; telephone (425) 227-2795; fax (425) 227-1320.

SUPPLEMENTARY INFORMATION: 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 certain Mode

``C'' transponder(s) with single Gillham code altitude input. That AD

requires repetitive tests to detect discrepancies of the Mode ``C''

transponder(s), air data computer, and certain wiring connections; and

corrective actions, if necessary. That action was prompted by reports

that, during level flight, the Traffic Alert Collision Avoidance System

(TCAS II) issued false advisories that directed the flightcrew to

change course and either climb or descend. The actions required by that

AD are intended to prevent such false advisories due to inaccurate

airplane altitude reporting, which could result in the flightcrew

deviating the airplane from its assigned flight path and a possible

mid-air collision.

Actions Since Issuance of Previous Rule

Since the issuance of AD 99-23-22, the FAA has determined that the

existing AD should be revised as follows:

1. The applicability section of the existing AD has been revised to

identify only airplane models used in the same type of operations as

those involved in the reported incidents of reduced airplane

separation. Specifically, the applicable airplane models have been

limited to only those transport category airplanes that can be operated

for extended periods in level flight cruise at altitudes greater than

24,000 feet and that are equipped with Mode ``C'' transponder(s) with

single Gillham code altitude input. As the FAA has not yet determined

the precise cause of the erroneous Mode ``C'' altitude reporting,

investigations into the cause of the unsafe condition are continuing.

The FAA has determined that the applicability of the existing AD should

be limited to airplanes with more exposure to the potential risks of

incorrect altitude reporting. Based on the review of the data received

from these airplane inspections, the FAA may consider future rulemaking

to expand the applicability of this AD.

2. A note has been added to the existing AD to clarify that the

requirements of that AD DO NOT supersede the current airplane Master

Minimum Equipment List (MMEL) requirements for deferral of repair of

malfunctioning systems. The existing AD states that any malfunctioning

Mode ``C'' altitude reporting system is to be repaired prior to further

flight. Note 3 of this revised AD explains that Mode ``C'' transponder

altitude reporting systems that have been determined to be

malfunctioning must be turned off and placarded as inoperative, as

specified in the MMEL. The airplane may then be operated in accordance

with the MMEL.

3. The compliance time for accomplishment of the initial and

repetitive tests required by paragraph (a) of the existing AD has been

extended from 45 days to 90 days after the effective date of the

existing AD. Test results received to date indicate that a substantial

number of airplanes have already been tested without failures. Based on

these test results and on the increased awareness of operators using

Mode ``C'' altitude reporting, the FAA has determined that the risk of

exposure to incorrect altitude reporting has been sufficiently reduced

to allow extension of the compliance time for accomplishment of the

initial and repetitive testing. Extended test intervals also will

provide additional time for operators required to schedule and execute

the tests. In addition, the reporting requirement specified in

paragraph (c) of the existing AD has been extended from 10 days to 20

days after accomplishment of the initial and repetitive tests required

by paragraph (a) of the existing AD.

4. The alternative method of compliance paragraph of the existing

AD has been revised to identify the Manager, Airplane and Flight Crew

Interface Branch, Transport Airplane Directorate, as the point of

contact in lieu of the Manager, Seattle Aircraft Certification Office.

Explanation of Requirements of Rule

Since an unsafe condition has been identified that is likely to

exist or develop on other airplanes of this same type design, this AD

revises AD 99-23-22 to continue to require repetitive tests to detect

discrepancies of the Mode ``C'' transponder(s), air data computer, and

certain wiring connections; and corrective actions, if necessary. This

action revises certain compliance times and limits the applicability of

the existing AD. This AD also includes a note which describes

provisions for continued operation of the airplane in accordance with

the provisions and limitations specified in the operator's FAA-approved

Master Minimum Equipment List (MMEL).

Interim Action

This is considered to be interim action until final action is

identified, at which time the FAA may consider further rulemaking.

Determination of Rule's Effective Date

Since a situation exists that requires the immediate adoption of

this regulation, it is found that notice and opportunity for prior

public comment hereon are impracticable, and that good cause exists for

making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves

requirements affecting flight safety and, thus, was not preceded by

notice and an opportunity for public comment, comments are invited on

this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All

communications received on or before the closing date for comments will

be considered, and this rule may be amended in light of the comments

received. Factual information that supports the commenter's ideas and

suggestions is extremely helpful in evaluating the effectiveness of the

AD action and determining whether additional rulemaking action would be

needed.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the rule that might

suggest a need to modify the 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 that

summarizes each FAA-public contact concerned with the substance of this

AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments

submitted in response to this rule must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket Number 99-NM-328-AD.'' The postcard will be date stamped and

returned to the commenter.

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.

The FAA has determined that this regulation is an emergency

regulation

[[Page 70183]]

that must be issued immediately to correct an unsafe condition in

aircraft, and that it is not a ``significant regulatory action'' under

Executive Order 12866. It has been determined further that this action

involves an emergency regulation under DOT Regulatory Policies and

Procedures (44 FR 11034, February 26, 1979). If it is determined that

this emergency regulation otherwise would be significant under DOT

Regulatory Policies and Procedures, a final regulatory evaluation will

be prepared and placed in the Rules Docket. A copy of it, if filed, 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, 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 removing amendment 39-11418 (64 FR

61493, November 12, 1999), and by adding a new airworthiness directive

(AD), amendment 39-11473, to read as follows:

099-23-22 R1 Transport Category Airplanes: Amendment 39-11473.

Docket 99-NM-328-AD. Revises AD 99-23-22, Amendment 39-11418.

Applicability: Transport category airplanes, as listed below,

certificated in any category, equipped with any Mode ``C''

transponder with single Gillham code altitude input, including, but

not limited to, the transponder part numbers listed below. Whether a

Mode ``C'' transponder has a single Gillham code altitude input may

be determined by reviewing the transponder installation

instructions.

Airplane Models

Airbus Industrie

A300

A310

British Aerospace

BAe Avro 146-RJ

BAe ATP

Fokker

F28 Mark 0070

F28 Mark 0100

F28 Mark 1000-4000

Lockheed

L-1011 TriStar

L-188 Electra

CASA

CN-235

Dassault Aviation

Mystere Falcon 50

Mystere Falcon 900

Mystere Falcon 200

Fan Jet Falcon Series G

Boeing (MDC)

DC-10-30

DC-10-40

DC-9

DC-9-81

DC-9-82

DC-9-83

DC-9-87

Boeing 707

Boeing 727

Boeing 737

Boeing 747

Bombardier

CL-215-1A10

CL-215-6B11

CL-600-1A11

CL-600-2A12

CL-600-2B16

Gulfstream

G1159 (G-II)

G-1159A (G-III)

G-IV

Mode ``C'' Transponder Part Numbers:

Rockwell Collins

622-2224-001

622-2224-003

522-2703-001

522-2703-011

787-6211-001

787-6211-002

Bendix

066-1056-00

066-1056-01

066-1123-00

2041599-6508

Wilcox

97637-201

97637-301

IFF

APX-100

APX-101

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 (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 as indicated, unless accomplished

previously.

To prevent false Traffic Alert Collision Avoidance System (TCAS

II) advisories due to inaccurate airplane altitude reporting, which

could result in the flightcrew deviating the airplane from its

assigned flight path and a possible mid-air collision, accomplish

the following:

Repetitive Tests

(a) Within 90 days after November 29, 1999 (the effective date

of AD 99-23-22, amendment 39-11418): Perform the test procedures

specified in paragraphs (a)(1) through (a)(9) of this AD to detect

any discrepancies of the Mode ``C'' transponder(s), air data

computer (ADC), or Gillham wiring connections, in accordance with

the applicable ADC and Mode ``C'' transponder component maintenance

manuals and airplane maintenance manual. Repeat the test procedures

thereafter at intervals not to exceed 90 days.

(1) Connect an air data test set to the Captain's (No. 1) Pitot/

Static system.

(2) In the airplane flight deck, select Mode ``C'' transponder

(1), or left Mode ``C'' transponder, depending on airplane flight

deck configuration, and select ADC source (1).

(3) Select the air data test set to the following altitude

reporting values:

1,000 feet;

4,100 feet;

15,700 feet; and

31,000 feet.

(4) For each selected altitude, verify that the Mode ``C''

altitude reporting is within tolerance (+/-125 feet), and record the

altitude output as follows:

1,000 feet (+/-125 feet);

4,100 feet (+/-125 feet);

15,700 (+/-125 feet); and

31,000 feet (+/-125 feet).

(5) In the airplane flight deck, select ADC source (2) and

repeat paragraphs (a)(3) and (a)(4) of this AD.

(6) In the airplane flight deck, select Mode ``C'' transponder

(2), or the right Mode ``C'' transponder, depending on airplane

flight deck configuration, select ADC source (1), and repeat

paragraphs (a)(3) and (a)(4) of this AD.

(7) In the airplane flight deck, select ADC source (2) and

repeat paragraphs (a)(3) and (a)(4) of this AD.

(8) Connect an air data test set to the Captain's (No. 2) Pitot/

Static system.

(9) Repeat paragraphs (a)(2) through (a)(7) of this AD.

Note 2: The tests required by paragraph (a) of this AD examine

the three primary sources of inaccurate airplane altitude reporting.

These three sources are: ADC's, Mode ``C'' transponders, and the

Gillham wiring connections between the ADC and Mode ``C''

transponder.

Corrective Actions

(b) Except as permitted by the Master Minimum Equipment List

(MMEL): If any discrepancy is detected during any test required by

paragraph (a) of this AD: Prior to further flight, repair in

accordance with the applicable ADC and Mode ``C'' transponder

component maintenance manual and airplane maintenance manual. If the

repair information is not available in the applicable manual, except

as permitted by the MMEL, prior to further flight, repair in

accordance with a method approved by the Manager, Seattle Aircraft

Certification Office (ACO), FAA, Transport Airplane Directorate.

Note 3: The airplane may be operated in accordance with the

provisions and

[[Page 70184]]

limitations specified in the FAA-approved MMEL, provided that only

one Mode ``C'' transponder on the airplane is inoperative.

Reporting Requirement

(c) Within 20 days after accomplishing the initial and

repetitive tests required by paragraph (a) of this AD, submit a

report of the inspection and test results (both positive and

negative findings) to: Peter Skaves, Aerospace Engineer, Airplane

and Flight Crew Interface Branch, ANM-111, FAA, Transport Airplane

Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056;

fax (425) 227-1320. The test results must include the Mode ``C''

transponder(s) and ADC part number(s), and must specify if any

discrepancies of the Gillham wiring connections were detected, and

if 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

(d) 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, Airplane and Flight Crew Interface

Branch, ANM-111, FAA, Transport Airplane Directorate. 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, ANM-111.

Note 4: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Manager, ANM-111.

Special Flight Permits

(e) Special flight permits may be issued in accordance with

sections 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.

(f) The effective date of this amendment remains November 29,

1999.

Issued in Renton, Washington, on December 10, 1999.

D.L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-32584 Filed 12-15-99; 8:45 am]

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