00-25153. Airworthiness Directives; Rockwell Collins, Inc. ADC-85, ADC-85A, ADC-850C, and ADC-850F Air Data Computers

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes to adopt a new airworthiness directive (AD) that would apply to certain Rockwell Collins, Inc. (Rockwell) ADC-85, ADC-85A, ADC-850C, and ADC-850F air data computers that are installed on airplanes. The proposed AD would require you to replace any air data computer (ADC) with one that has reprogrammed and tested central processing unit (CPU) circuit card and circuit card assemblies. The proposed AD is the result of a flight test that showed that these ADC's could display an unwarranted ADC flag in response to the airplane's “Normal/Alternate Air” static source selection capability. The actions specified by the proposed AD are intended to prevent the ADC from displaying an unwarranted ADC flag when switching static air sources. This could cause the flight crew to deselect a valid alternate static air source during the time the unwarranted ADC flag is displayed and possibly result in the display of misleading information during critical operating situations.

DATES:

The Federal Aviation Administration (FAA) must receive any comments on this proposed rule by November 6, 2000.

ADDRESSES:

Send comments in triplicate to FAA, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 2000-CE-14-AD, 901 Locust, Room 506, Kansas City, Missouri 64106. You may inspect comments at this location between 8 a.m. and 4 p.m., Monday through Friday, except holidays.

You may get the service information referenced in the proposed AD from Rockwell Collins, Business and Regional Systems, 400 Collins Road Northeast, Cedar Rapids, Iowa 52498. You may read this information at the Rules Docket at the address above.

FOR FURTHER INFORMATION CONTACT:

Roger A. Souter, FAA, Wichita Aircraft Certification Office (ACO), 1801 Airport Road, Rm 100, Wichita, Kansas 67209; telephone: [phone]; facsimile: [phone]. E-mail address: [e-mail].

SUPPLEMENTARY INFORMATION:

Comments Invited

How do I comment on this AD? We invite your comments on the proposed rule. You may send whatever written data, views, or arguments you choose. You need to include the rule's docket number and send your comments in triplicate to the address specified under the caption ADDRESSES. We will consider all comments received by the closing date specified above, before acting on the proposed rule. We may change the proposals contained in this notice because of the comments received.

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 proposed rule that might call for a need to change the proposed rule. You may read all comments we receive. We will file a report in the Rules Docket that summarizes each FAA contact with the public that concerns the substantive parts of this proposal.

The FAA is 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 the ease of understanding this document, 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://www.faa.gov/​language/​.

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. 2000-CE-14-AD.” We will date stamp and mail the postcard back to you.

Discussion

What events have caused this proposed AD? The air data computer (ADC), as part of its monitoring process, tests for errant sensor behavior, such as unreasonable jumps in altitude and unreasonably high vertical speed. When the ADC detects an errant sensor behavior, the ADC displays a flag for 5.5 seconds plus the time it takes for the sensor to settle within the limits for another 5.5-second period. This results in a minimum ADC flag display of 11 seconds.

Testing of certain Rockwell Collins ADC's reveals the ADC could display unwarranted flags on aircraft where you can select the “Normal/Alternate Air” static source. When there is a significant difference between normal and alternate/revisionary static air sources, you can exceed the ADC monitor thresholds and the ADC would display flags.

If the flight crew used the undesirable ADC flag displays to deselect the alternate static air source before the initial 11-second display period, a valid air source may have been deselected. Confusion could result when the previously unflagged normal static air source is reselected. This may also result in the ADC displaying a flag for the first 11 seconds. The affected ADC's include:

Unit	Part No.	Applicable to serial No.	Production installed serial No.
ADC-85	622-8051-002, 622-8051-003	All units	None.
ADC-85A	822-0370-113, 822-0370-123, 822-0370-139, 822-0370-404, 822-0370-408	All units	None.
ADC-850C	822-0374-121, 822-0374-135, 822-0374-407, 822-0374-410	1FWH and below, except 1B16 through 1P6C	1B16 through 1P6C, 1LT6 and above.
ADC-850F	822-1036-406, 822-1036-418	All Units	None.

What are the consequences if the condition is not corrected? If these situations were to occur while the flight crew were making critical flight decisions, this unwarranted ADC flag could distract the crew and the lack of attention to the critical actions could result in an unsafe operating condition.

Relevant Service Information

What service information applies to this subject? Rockwell has issued Service Bulletin No. 62 (ADC-85/85A/850C/850F-34-62), dated October 25, 1999.

What are the provisions of this service bulletin? The service bulletin contains procedures for replacing or reprogramming applicable parts or Circuit Card Assemblies on CPU Circuit Cards in the ADC and testing the modified ADC.

The FAA's Determination and an Explanation of the Provisions of the Proposed AD

What has FAA decided? After examining the circumstances and reviewing all available information related to the incidents described above, we have determined that:

—The unsafe condition referenced in this document exists or could develop on airplanes equipped with either a Rockwell ADC-85, ADC-85A, ADC-850C, or ADC-850F ADC's;

—Any airplane with one of these ADC units should have the actions specified in the above service bulletin incorporated; and

—The FAA should take AD action to correct this unsafe condition.

What does this proposed AD require? This proposed AD would require you to:

—Remove the ADC from the airplane,

—Replace or reprogram applicable parts or Circuit Card Assemblies on the CPU Circuit Card,

—Test the modified ADC, and

—Install the modified ADC in the airplane.

Cost Impact

How many airplanes does this proposed AD impact? We estimate the proposed AD would affect 245 airplanes in the U.S. registry.

What is the cost impact of the proposed action for the affected airplanes on the U.S. Register? We estimate that it would take about 1 workhour per airplane to remove the ADC. We estimate that it would take about 1 workhour to install the ADC in the airplane.

We estimate that it would take about 1 workhour per airplane to do the proposed installation and reprogramming and about 3 workhours per airplane to do the proposed testing at an average labor rate of $60 an hour. Parts to do this action cost up to $680. Based on the figures presented above, we estimate the total cost impact of the proposed action on U.S. operators is $254,800, or $1,040 per airplane.

For units that are still under warranty, Rockwell will provide the parts and labor at no charge.

Regulatory Impact

Does this proposed AD impact relations between Federal and State governments? The proposed regulations would 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. It is determined that this proposed rule would not have federalism implications under Executive Order 13132.

Does this proposed AD involve a significant rule or regulatory action? For the reasons discussed above, I certify that this proposed action (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under Department of Transportation Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if put into effect 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. We have placed a copy of the draft regulatory evaluation prepared for this action in the Rules Docket. You may get a copy of it 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

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the Federal Aviation Administration (FAA) proposes to amend 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.

§ 39.13

[Amended]

2. FAA amends Section 39.13 by adding a new airworthiness directive (AD) to read as follows:

Rockwell Collins, Inc.: Docket No. 2000-CE-14-AD.

(a) What airplanes are affected by this AD? The following Rockwell Collins air data computers (ADC) that are installed in, but not limited to the airplanes that are listed below:

(1) Affected ADC's:

Unit	Part No.	Applicable to serial No.	Production installed serial No.
ADC-85	622-8051-002, 622-8051-003	All Units	None.
ADC-85A	822-0370-113, 822-0370-123, 822-0370-139, 822-0370-404, 822-0370-408	All Units	None.
ADC-850C	822-0374-121, 822-0374-135, 822-0374-407, 822-0374-410	1FWH and below, except 1B16 through 1P6C	1B16 through 1P6C, 1LT6 and above.
ADC-850F	822-1036-406, 822-1036-418	All Units	None.

(2) List of airplanes where the affected ADC could be installed. This is not a comprehensive list and airplanes not on this list that have the ADC installed through field approval or other methods are still affected by this AD:

Unit	Airplane model
ADC-85/ADC-85A	Astra AIA, Chinese Y7 and Y8, Czech LET-610, DC-8, Falcon 20F, Piaggio P-180, Raytheon King 250, 350, and 1900, Saab 340.
ADC-850D	Lear 60.
ADC-850F	Falcon 20, 50, and 50EX.

(b) Who must comply with this AD? Anyone who wishes to operate any airplane on the U.S. Register that uses one of the above referenced Rockwell air data computers must comply with this AD.

(c) What problem does this AD address? The actions specified by this AD are intended to prevent an unwarranted display of the ADC flag when switching static air sources. This could cause the flight crew to react to this incorrect flight information and possibly result in an unsafe operating condition.

(d) What must I do to address this problem? To address this problem, you must accomplish the following actions:

Actions	Compliance times	Procedures
(1) Remove any affected ADC from the airplane	Within 1 year after the effective date of this AD	Do these actions in accordance with Rockwell Collins Service Bulletin No. 62 (ADC-85/85A/850C/850F-34-62), dated October 25, 1999, the applicable Collins Computer Component Maintenance Manual, and Collins Avionics Standard Shop Practices Instruction Manual.
(2) As applicable, replace or reprogram parts or Circuit Card assemblies on Central Processing Unit Circuit Cards
(3) Test the ADC
(4) Install the modified ADC in the airplane
(5) Do not install on any airplane one of the affected ADC's unless the modification and test required by paragraphs (d)(2) and (d)(3) of this AD are accomplished	As of the effective date of this AD	Use the procedures in the referenced service information.

(e) Can I comply with this AD in any other way? You may use an alternative method of compliance or adjust the compliance time if:

(1) Your alternative method of compliance provides an equivalent level of safety; and

(2) The Manager, Wichita Aircraft Certification Office (ACO, 1801 Airport Road, Rm 100, Wichita, Kansas 67209, approves your alternative. Send your request through an FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Wichita ACO.

Note:

This AD applies to each airplane with a Rockwell air data computer identified in paragraph (a) of this AD, 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. You should include in the request an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if you have not eliminated the unsafe condition, specific actions you propose to address it.

(f) Where can I get information about any already-approved alternative methods of compliance? You can contact Roger A. Souter, FAA, Wichita Aircraft Certification Office (ACO), 1801 Airport Road, Rm 100, Wichita, Kansas 67209; telephone: [phone]; facsimile: [phone], E-mail: [e-mail].

(g) What if I need to fly the airplane to another location to comply with this AD? The FAA can issue a special flight permit under sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate your airplane to a location where you can accomplish the requirements of this AD.

(h) How do I get copies of the documents referenced in this AD? You may obtain copies of the documents referenced in this AD from Rockwell Collins, Business and Regional Systems, 400 Collins Road Northeast, Cedar Rapids, Iowa 52498; or may read this document at FAA, Central Region, Office of the Regional Counsel, 901 Locust, Room 506, Kansas City, Missouri 64106.

Issued in Kansas City, Missouri, on September 26, 2000.

Michael K. Dahl,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.