Discussion
What Events Have Caused This AD?
The FAA has received reports of erroneous Mode C and Mode S random transponder transmissions from aircraft equipped with Gillham encoded altitude sources and certain Rockwell Collins CTL-92 transponder control panels. Rockwell Collins introduced new A6 circuit cards for these transponder control panels in September 2000.
These circuit cards exhibit reduced ground integrity in the area of the Gillham input processing. This results in noise generation within the CTL-92 transponder control panels that the transponder can interpret and transmit as a random altitude. Air traffic control (ATC) and traffic alert and collision avoidance system (TCAS)-equipped aircraft can then interpret these erroneous random altitudes as valid altitudes.
The following Rockwell Collins CTL-92 control unit part numbers are affected: 622-6523-204, 622-6523-205,
622-6523-206, 622-6523-207, and 622-6523-208.
TheseRockwell Collins CTL-92 transponder control panels could be installed on, but not limited to, the following aircraft:
--Aerospatiale ATR42 and ATR72 series airplanes;
--Saab Aircraft Models 340B and SF340A airplanes;
--Embraer EMB-120 series airplanes;
--deHavilland DHC-8 series airplanes; and
--Raytheon Models C90A, B200, 350, and 1900D airplanes.
What Are the Consequences if the Condition Is Not Corrected?
Such erroneous altitude interpretations could result in reduced vertical separation or unsafe TCAS resolution advisories.
Is There Service Information That Applies to This Subject?
Rockwell Collins has issued Service Bulletin 33 (CTL-92-34-33), dated April 5, 2001. This service bulletin includes:
--Procedures for how to modify the altitude encoder inputs of these transponder control panels; and
--A list of part numbers and serial numbers of the affected CTL-92 transponder control panels.
The FAA's Determination and an Explanation of the Provisions of this AD What Has FAA Decided?
The FAA has reviewed all available information, including the service information referenced above, and determined that:
--The unsafe condition referenced in this document exists or could develop on type design aircraft that incorporate these Rockwell Collins CTL-92 transponder control panels;
--The actions specified in the previously-referenced service information should be accomplished on the affected Rockwell Collins CTL-92 transponder control panels; and
--AD action should be taken in order to correct this unsafe condition.
What Does This AD Require?
This AD requires you to modify the altitude encoder inputs of the CTL-92 transponder control panels. Rockwell Collins Service Bulletin 33 (CTL-92-34-33), dated April 5, 2001, specifies the exact part numbers and serial numbers that are affected and includes procedures on how to modify these transponder control panels.
Will I Have the Opportunity To Comment Prior tothe Issuance of the Rule?
Because the unsafe condition described in this document could result in reduced vertical separation or unsafe TCAS resolution advisories, FAA finds that notice and opportunity for public prior comment are impracticable. Therefore, good cause exists for making this amendment effective in less than 30 days.
Comments Invited
How Do I Comment on This AD?
Although this action is in the form of a final rule and was not preceded by notice and opportunity for public comment, we invite your comments on the rule. You may submit whatever written data, views, or arguments you choose. You need to include the rule's docket number and submit your comments in triplicate to the address specified under the caption ADDRESSES. We will consider all comments received on or before the closing date specified above. We may amend this rule in light of comments received. Factual information that supports your ideas and suggestions is extremely helpful in evaluating theeffectiveness of the AD action and determining whether we need to take additional rulemaking action.
Are There Any Specific Portions of the AD I Should Pay Attention to?
The FAA specifically invites comments on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. You may examine all comments we receive before and after the closing date of the rule in the Rules Docket. We will file a report in the Rules Docket that summarizes each FAA contact with the public that concerns the substantive parts of this AD.
We are reviewing the writing style we currently use in regulatory documents, in response to the Presidential memorandum of June 1, 1998. That memorandum requires federal agencies to communicate more clearly with the public. We are interested in your comments on whether the style of this document is clear, and any other suggestions you might have to improve the clarity of FAA communications that affect you. You can get more information about the Presidential memorandum and the plain language initiative at http://frwebgate.access.gpo.gov/
cgi-bin/leaving.cgi?from=leavingFR.html&log=linklog&to=http://www.plainlanguage.gov.
How Can I Be Sure FAA Receives My Comment?
If you want us to acknowledge the receipt of your comments, you must include a self-addressed, stamped postcard. On the postcard, write "Comments to Docket No. 2001-CE-22-AD." We will date stamp and mail the postcard back to you.
Regulatory Impact
Does This AD Impact Various Entities?
These regulations 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, FAA has determined that this final rule does not have federalism implications under Executive Order 13132.
Does This AD Involve a Significant Rule or Regulatory Action?The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and 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 (otherwise, an evaluation is not required). A copy of it, if filed, may be obtained from the Rules Docket.
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 airworthiness directive (AD) to read as follows: