AD 96-07-02

This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F28 Mark 0100 series airplanes, that requires inspections to verify the correct operation of the main landing gear (MLG) downlock actuators, and replacement of any discrepant unit with a serviceable unit. This amendment also will require eventual replacement of the MLG downlock actuators with improved units. This amendment is prompted by reports of improper operation of the MLG downlock actuator due to jamming. The actions specified by this AD are intended to prevent such jamming of the downlock actuator, which could result in failure of the MLG downlock system, and a potential gear-up landing.

Final rule

96-07-02 FOKKER: Amendment 39-9551. Docket 95-NM-99-AD.
Applicability: Model F28 Mark 0100 series airplanes equipped with Dowty Aerospace Hydraulics main landing gear (MLG) downlock actuators having part number (P/N) 201218001, 201218002, 201218003, or 201218004, all serial numbers; certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, 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 (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent jamming of the MLG downlock actuator and a potential gear-up landing, accomplish the following:

(a) Within 2 months after the effective date of this AD, and thereafter at intervals not to exceed 1,250 landings: Perform an inspection to verify correct operation of the MLG downlock actuator having P/N 201218001, 201218002, 201218003, or 201218004, all serial numbers, in accordance with Fokker Service Bulletin SBF100-32-072, dated March 30, 1993, and Dowty Aerospace Hydraulics Service Bulletin F100-32-505, Revision 1, dated April 16, 1993.

(1) If the MLG downlock actuator operates as specified in the inspection procedure contained in the Accomplishment Instructions of Dowty Aerospace Hydraulics Service Bulletin F100-32-505, Revision 1, dated April 16, 1993, prior to further flight, record the accomplishment of the inspection onthe unit nameplate in accordance with the Dowty Aerospace Hydraulics service bulletin. Following accomplishment of each subsequent inspection required by this AD, record the accomplishment of the inspection in accordance with the requirement of this paragraph.

(2) If any MLG downlock actuator does not operate as specified in the inspection procedure contained in the Accomplishment Instructions of Dowty Aerospace Hydraulics Service Bulletin F100-32-505, Revision 1, dated April 16, 1993, prior to further flight, replace the downlock actuator with a serviceable unit, in accordance with Chapter 32-32-05 of the Aircraft Maintenance Manual. Thereafter, perform repetitive inspections of the replacement unit in accordance with paragraph (a) of this AD until the replacement required by paragraph (b) of this AD is accomplished.

(b) Within 9 months after the effective date of this AD, replace any MLG downlock actuator having P/N 201218001, 201218002, 201218003, or 201218004, any serial number, with an improved unit having P/N 201218005, 201218006, 201218007, or 201218008, respectively; in accordance with Fokker Service Bulletin SBF100-32-074, dated July 21, 1993, and Dowty Aerospace Hydraulics Service Bulletin F100-32-506, dated June 9, 1993. Accomplishment of this replacement constitutes terminating action for the repetitive inspections required by paragraph (a) of this AD.

(c) As of the effective date of this AD, no person shall install on any airplane a MLG downlock actuator having P/N 201218001, 201218002, 201218003, or 201218004, any serial number.

(d) 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 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch, ANM-113.

(e) 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.

(f) The actions shall be done in accordance with Fokker Service Bulletin SBF100-32-072, dated March 30, 1993; Fokker Service Bulletin SBF100-32-074, dated July 21, 1993; Dowty Aerospace Hydraulics Service Bulletin F100-32-505, Revision 1, dated April 16, 1993; or Dowty Aerospace Hydraulics Service Bulletin F100-32-506, dated June 9, 1993, as applicable. This incorporation by reference was approved by the Director of 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.

(g) This amendment becomes effective on April 25, 1996.

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 December 11, 1995 (60 FR 63468). That action proposed to require repetitive inspections to verify the correct operation of the MLG downlock actuators; and replacement of any discrepant unit with a serviceable unit. For airplanes on which no discrepant unit is found, the AD also will require recording the accomplishment of each inspection on the unit nameplate. In addition, the AD will require eventual replacement of the MLG downlock actuators with improved units.

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

The commenter supports the proposed rule.

After careful review of the available data, including the comment 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 119 airplanes of U.S. registry will be affected by this AD, that it will take approximately 21 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will be supplied by the vendor at no cost to operators. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $149,940, or $1,260 per airplane.

The 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 USC 106(g), 40113, 44701.

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