# Airworthiness Directives; Fokker Model F28 Mark 0100 Series Airplanes > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A94-11353 ## Record - **Collection:** Federal Register - **Document type:** Uncategorized Document - **Published:** May 11, 1994 ## Text DEPARTMENT OF TRANSPORTATION 14 CFR Part 39 [Docket No. 94-NM-38-AD] Airworthiness Directives; Fokker Model F28 Mark 0100 Series Airplanes AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Fokker Model F28 Mark 0100 series airplanes. This proposal would require replacement of the autopilot disconnect switches with modified units. This proposal is prompted by several incidents in which the flight crew did not depress both halves of the autopilot disconnect switch during the LAND 2 or LAND 3 approach and, as a result, one autopilot remained engaged. This condition resulted in unanticipated movements of the stabilizer trim and higher than anticipated control forces of the flight controls. The actions specified by the proposed AD are intended to prevent the flight crew from inadvertently disconnecting only one autopilot when both autopilots are engaged, which could result in unanticipated control surface movements. DATES: Comments must be received by June 20, 1994. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 94-NM-38-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. The service information referenced in the proposed rule 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. FOR FURTHER INFORMATION CONTACT: 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) 227-1320. SUPPLEMENTARY INFORMATION: Comments Invited Interested persons are invited to participate in the making of the proposed 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 above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket. Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 94-NM-38-AD.'' The postcard will be date stamped and returned to the commenter Availability of NPRMs Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 94-NM-38-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Discussion The Rijksluchtvaartdienst (RLD), which is the airworthiness authority for the Netherlands, recently notified the FAA that an unsafe condition may exist on certain Fokker Model F28 Mark 0100 series airplanes. The RLD advises that operators have reported several incidents in which the flight crew did not depress both halves of the autopilot disconnect switch during the LAND 2 or LAND 3 approach and, as a result, one autopilot remained engaged. Although certain aural warnings sounded and visual indicators illuminated in these situations, the flight crew still believed that both autopilots had been disconnected. Consequently, unanticipated movements of the stabilizer trim and higher than anticipated control forces of the flight controls occurred. Inadvertent disconnection of only one autopilot when both autopilots are engaged could result in unanticipated control surface movements. Fokker has issued Service Bulletin SBF100-22-020, dated September 25, 1990, that describes procedures for replacement of the autopilot disconnect switches with modified units. Installation of the modified units will ensure that if one-half of the autopilot disconnect switch is depressed, both autopilots will disengage; in addition, the system will remain separated. The RLD classified this service bulletin as mandatory and issued Netherlands Airworthiness Directive 90-112(A), dated October 15, 1990, in order to assure the continued airworthiness of these airplanes in the Netherlands. This airplane model is manufactured in the Netherlands and is type certificated for operation in the United States under the provisions of Sec. 21.29 of the Federal Aviation Regulations 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 an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, the proposed AD would require replacement of the autopilot disconnect switches with modified units. The actions would be required to be accomplished in accordance with the service bulletin described previously. The FAA estimates that 19 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 8 work hours per airplane to accomplish the proposed actions, and that the average labor rate is $55 per work hour. Required parts would cost approximately $2,500 per airplane. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $55,860, or $2,940 per airplane. The total cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The regulations proposed herein 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. Therefore, in accordance with Executive Order 12612, it is determined that this proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. For the reasons discussed above, I certify that this proposed regulation (1) is not a ``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 draft regulatory 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, Safety. The Proposed Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 14 CFR part 39 of the Federal Aviation Regulations as follows: PART 39--AIRWORTHINESS DIRECTIVES- 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding the following new airworthiness directive: Fokker: Docket 94-NM-38-AD. Applicability: Model F28 Mark 0100 series airplanes; serial numbers 11244 through 11286 inclusive, 11289 through 11293 inclusive, 11295 through 11297 inclusive, 11300, 11303, 11306, 11308, 11310, 11312, and 11313; certificated in any category. Compliance: Required as indicated, unless accomplished previously. To prevent the flight crew from inadvertently disconnecting only one autopilot when both autopilots are engaged, which could result in unanticipated control surface movements, accomplish the following: (a) Within 6 months after the effective date of this AD, replace the autopilot disconnect switches with modified units, in accordance with Fokker Service Bulletin SBF100-22-020, dated September 25, 1990. (b) As of 6 months after the effective date of this AD, no person shall install an autopilot disconnect switch, part number A47007-401 or A47007-403, on any airplane. (c) 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, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Standardization Branch, ANM-113. Note: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch, ANM-113. (d) Special flight permits may be issued in accordance with Federal Aviation Regulations (FAR) Sec. 21.197 and Sec. 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished. Issued in Renton, Washington, on May 5, 1994. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certificate Service. [FR Doc. 94-11353 Filed 5-10-94; 8:45 am] BILLING CODE 4910-13-U --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A94-11353. Public record. Not legal advice.