AD 96-24-10

Effective December 24, 1996, to all persons except those persons to whom it was made immediately effective by emergency AD 96-24-10, issued on November 19, 1996, which contained the requirements of this amendment.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of December 24, 1996.

Comments for inclusion in the Rules Docket must be received on or before February 18, 1997.

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 96-NM-268-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

The applicable service information may be obtained from Fokker Aircraft USA, Inc., 1199 North Fairfax Street, Alexandria, Virginia 22314. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Tim Dulin, Aerospace Engineer, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2141; fax (206) 227-1149.

On November 8, 1996, the FAA issued AD 96-23-16, amendment 39-9825 (61 FR 5887, November 20, 1996), applicable to all Fokker Model F28 Mark 0070 and 0100 series airplanes. That AD:

1. Requires a revision to the Airplane Flight Manual (AFM) to include information that will enable the flightcrew to determine if the thrust reversers are properly stowed and locked prior to take-off;

2. Provides for dispatch of the airplane with both autothrottle channels inoperative, provided that both thrust reversers are deactivated and secured in the stowed position, and no operations are conducted that are predicated on thrust reverser operation; and

3. Requires revising the maintenance program to provide instructions to correct malfunctions of the thrust reverser system.

The requirements of that AD were intended to prevent an unannunciated failure of the secondary lock relay 1 of the thrust reversers, which could result in reduced protection against inadvertent deployment of the thrust reversers during flight.

Since the issuance of AD 96-23-16, the Rijksluchtvaartdienst (RLD), which is the airworthiness authority for the Netherlands, advises that Fokker has conducted an additional review and safety assessment of the thrust reverser control and indication system. The results of this review indicate that a potential latent failure of the secondary lock switch 1 in the open position may occur; this is in addition to the potential failure of the secondary lock relay 1 in the energized position, which was addressed by AD 96-23-16.

Failure of the secondary lock switch 1 in the open position could prevent or block the automatic signal to command the thrust reversers to the stow position when an uncommanded movement of the secondary lock actuator occurs.

Fokker has issued All Operator Message TS96.67591, dated November 14, 1996, including Appendix 1 and Appendix 2. Among other things, the All Operator Message describes procedures for performing a daily check to detect a latent failure of the secondary lock switch 1. Accomplishment of these actions will prevent a latent failure of the secondary lock switch 1. The RLD classified the All Operator Message as mandatory and issued Netherlands airworthiness directive (BLA) 1996-138/2 (A), dated November 15, 1996, in order to assure the continued airworthiness of these airplanes in the Netherlands.

These airplanes model are manufactured in the Netherlands and are type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the RLD has kept the FAA informed of the situation described above. The FAA has examined the findings of the RLD, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Since the unsafe condition described is likely to exist or develop on other airplanes of the same type design registered in the United States, the FAA issued emergency AD 96-24-10 to prevent failure of the secondary lock relay 1 of the thrust reversers in the energized position and secondary lock switch 1 in the open position, which could result in reduced protection against inadvertent deployment of the thrust reversers during flight. The new AD supersedes AD 96-23-16, but continues to require a revision to the Limitations Section of the FAA-approved AFM to enable the flightcrew to determine if the thrust reversers are properly stowed and locked prior to take-off by monitoring proper engagement of the autothrottle system (ATS). This new AD allows dispatch of the airplane with both thrust reversers inoperative, provided they are deactivated and secured in the stowed position, and no operations are conducted that are predicated on thrust reverser operation. In addition, the new AD requires a new revision to the FAA-approved maintenance program to incorporate instructions to correct malfunctions of the secondary lock relay 1 of the thrust reversers found during the operational tests; to perform a daily check to detect latent failure of the secondary lock switch 1; and to take corrective actions, if necessary. The revision to the maintenance program is required to be accomplished in accordance with Appendix 2 of the All Operator Message previously described.

Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual notices issued on November 19, 1996, to all known U.S. owners and operators of Fokker Model F28 Mark 0070 and 0100 series airplanes. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective as to all persons.

This AD is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking.

This AD differs from the Netherlands airworthiness directive (BLA) 1996-138/2 (A), in the following respects:

1. This AD allows dispatch with both thrust reversers inoperative, provided they are deactivated and stowed, and no operations are conducted that are predicated on thrust reverser operation; whereas, the Dutch airworthiness directive does not address this issue. The FAA-approved Master Minimum Equipment List (MMEL) only allows one thrust reverser to be inoperative; whereas, the Dutch MMEL allows both thrust reversers to be inoperative. Therefore, the FAA finds that the AD must include provisions for dispatch of the airplane with both thrust reversers deactivated and stowed.

2. The AD does not allow both autothrottle channels to be inoperative; whereas, the Dutch airworthiness directive does permit this option, albeit with certain restrictions. The FAA-approved MMEL allows only one autothrottle to be inoperative. The FAA finds no safety-related reason to change this requirement.

3. The AD does not allow dispatch of the airplane with an inoperative thrust reverser indication and alerting system, which is consistent with the FAA-approved MMEL. The Dutch airworthiness directive removes this provision from the Dutch MMEL.

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 96-NM-268-AD.'' The postcard will be date stamped and returned to the commenter.

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.

The FAA has determined that this regulation is an emergency regulation 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.

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

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:

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

Authority: 49 U.S.C. 106(g), 40113, 44701.