AD 94-19-03

This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F28 Mark 0100 series airplanes, that requires replacement of the autopilot disconnect switches with modified units. This amendment 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 this 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.

Final rule

94-19-03 FOKKER: Amendment 39-9025. 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 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.

(e) The replacement shall be done in accordance with Fokker Service Bulletin SBF100-22-020, dated September 25, 1990. This incorporation by reference was approved by the Directorof the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Fokker Aircraft USA, Inc., 1199 North Fairfax Street, Alexandria, Virginia 22314. Copies may be inspected 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.

(f) This amendment becomes effective on October 21, 1994.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Fokker Model F28 Mark 0100 series airplanes was published in the Federal Register on May 11, 1994 (59 FR 24383). That action proposed to require replacement of the autopilot disconnect switches with modified units.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Both commenters support the proposed rule.

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

The FAA estimates that 19 airplanes of U.S. registry will be affected by this AD, that it will take approximately 8 work hours per airplane to accomplish the required actions, and that the average labor rate is $55 per work hour. Required parts will cost approximately $2,500 per airplane. Based on these figures, the total cost impact of the 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 requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.

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.

For the reasons discussed above, I certify that this action (1) is not a"significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it 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, Incorporation by reference, 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.

39.13 - [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: