AD 94-08-13

This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F-28 Mark 0100 series airplanes, that requires the installation of modified Flight Warning Computers and Flight Augmentation Computers. This amendment is prompted by reports of nuisance yaw-damper fault warnings and undetected horizontal trim motion, and the development of improved computers that eliminate these problems. The actions specified by this AD are intended to prevent nuisance warnings in the cockpit and undetected trim motion, both of which could compromise the safe takeoff of the airplane.

Final rule

94-08-13 FOKKER: Amendment 39-8885. Docket 93-NM-165-AD.
Applicability: Model F-28 Mark 0100 series airplanes; serial numbers 11244 through 11348, inclusive; equipped with Flight Warning Computer, P/N 80-0610-2-( ); or equipped with Fight Augmentation Computer, part number (P/N) 622-7478-321 or P/N 622-7478-401; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent nuisance yaw-damper fault warnings and undetected trim motion, accomplish the following:

(a) For airplanes having serial numbers 11244 through 11321 inclusive, 11323 through 11329 inclusive, 11331, and 11333; and equipped with Flight Warning Computer (FWC) P/N 80-0610-2-( ): Within one year after the effective date of this AD, remove the currently installed FWC, modify the airplane, and install FWC P/N 80-0610-3-30, in accordance with Fokker Service Bulletin SBF100-31-020, Revision 1, dated June 12, 1993.

NOTE 1: Installation accomplishedprior to the effective date of this AD in accordance with Fokker Service Bulletin SBF100-31-020, dated May 24, 1991, is considered to be in compliance with this paragraph.

NOTE 2: Installation of FWC P/N 80-0610-3-31, in accordance with Fokker Service Bulletin SBF100-31-031, dated June 23, 1993, is considered an acceptable alternative method of compliance with this paragraph.

(b) For airplanes having serial numbers 11244 through 11339 inclusive, 11341, and 11342; and equipped with Flight Augmentation Computer (FAC) P/N 622-7478-321: At the same time as, or prior to further flight after, accomplishing the requirements of paragraph (a) of this AD, remove the currently installed FAC and replace it with either of the following:

(1) FAC P/N 622-7478-401MOD11, in accordance with Fokker Service Bulletin SBF100-22-032, dated September 2, 1991; or
(2) FAC P/N 622-7478-411, in accordance with Fokker Service Bulletin SBF100-22-037, dated
May 31, 1993. Equipment combinations listed in that service bulletin must be adhered to.

(c) For airplanes having serial numbers 11244 through 11348 inclusive, and equipped with FAC P/N 622-7478-401: Within one year after the effective date of this AD, remove the currently installed FAC and replace it with either of the following:

(1) FAC P/N 622-7478-401MOD11, in accordance with Fokker Service Bulletin SBF100-22-032, dated September 2, 1991; or

(2) FAC P/N 622-7478-411, in accordance with Fokker Service Bulletin SBF100-22-037, dated May 31, 1993. Equipment combinations listed in that service bulletin must be adhered to.

(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 3: 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 Federal Aviation Regulations (FAR) 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.

(f) The installations shall be done in accordance with Fokker Service Bulletin SBF100-22-032, dated September 2, 1991; Fokker Service Bulletin SBF100-22-037, dated May 31, 1993, and Fokker Service Bulletin SBF100-31-020, Revision 1, dated June 12, 1993, which contains the following list of effective pages:

Page Number
Revision Level
Shown on Page
Date
Shown on Page
1, 2, 5-12,
17, 19A, 19B,
22-24, 32, 34,
36
1
June 12, 1993
3, 4, 13-16,
18, 19, 20, 21,
25-31, 33, 35
Original
May 24, 1991

This incorporation by reference wasapproved 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 May 20, 1994.

A proposal to amend part 39 of the Federal Aviation Regulations to include an airworthiness directive (AD) that is applicable to certain Fokker Model F-28 Mark 0100 series airplanes was published in the Federal Register on November 12, 1993 (58 FR 59968). That action proposed to require the installation of modified Flight Warning Computers (FWC) and Flight Augmentation Computers (FAC).

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

One commenter supports the proposed rule.

Another commenter requests that the proposed rule be revised to include an additional part-numbered FWC as an acceptable alternative part for compliance. This commenter states that it has installed FWC's having part number 80-0610-3-31, in accordance with Fokker Service Bulletin SBF100-31-033, dated June 23, 1993, on its fleet of affected airplanes. The FAA hasreviewed this data and finds that FWC's having part number 80-0610-3-31 are acceptable alternatives to those called out in the proposal. The FAA has revised the final rule to indicate that this.

This same commenter requests that the proposed rule be revised to include the words "or subsequent" for all part numbers, so that future designs of the components would be permitted to be installed as alternatives to the specific part numbered components called out in the AD. The FAA does not concur, since there would be no way to establish that the inclusion of these words would prevent the installation of incompatible components. For example, the "Material Information" portion of the referenced Fokker Service Bulletin SBF100-22-037, concerning the replacement of FAC's, indicates that specific equipment combinations (those having similar part numbers in the component series) may not be compatible. For this reason, the FAA considers it inappropriate to permit the indiscriminate installation of any future component designs.

This same commenter requests that the proposed rule not require accomplishment of the actions specifically in accordance with the service bulletins; the service bulletins should be for reference only. Although the commenter does not specify a particular reason for this request, the FAA infers that (1) the commenter would like to install improved or modified equipment versions of the same basic part number series that may or may not be called out in a service bulletin; or (2) the commenter would prefer that the rule permit installation of the subject components in accordance with an operator's own methods. The FAA does not concur. As for the first inference, the FAA has addressed this in the previous paragraph. As for the second inference, the FAA points out that the referenced service bulletins contain specific wiring procedures necessary for installation of the components; the FAA has determined that these procedures must be followed in order to ensure proper installation.

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 with the change previously described. The FAA has determined that this change will neither increase the economic burden on any operator nor increase the scope of the AD.

The FAA estimates that 27 airplanes of U.S. registry will be affected by this AD.

Installation of the new FWC will require approximately 46 work hours to accomplish, at an average labor charge of $55 per work hour. Required parts will cost approximately $450 per airplane. Based on these figures, the total cost impact of the FWC installation on U.S. operators is estimated to be $2,980 per airplane.

The requirement to replace the FAC will vary, depending upon the configuration of the FAC installed. Additionally, operators have a choice of two different FAC's to use as replacement installations:

Should an operator elect to install an FAC having part number 622-7478-401MOD11, it will require approximately 1 work hour to accomplish, at an average labor charge of $55 per work hour. Required parts will be provided at no cost to the operator. Based on these figures, the total cost impact of this specific installation requirement on U.S. operators would be $55 per airplane.

Should an operator elect to install an FAC having part number 622-7478-411, it will require approximately 52 work hours to accomplish, at an average labor charge of $55 per work hour. Required parts will cost approximately $2,515 per airplane. Based on these figures, the total cost impact of this specific FAC installation requirement on U.S. operators is estimated to be $5,375 per airplane.

Based on the figures discussed above, the total cost impact of this proposed AD on U.S. operators would be between $3,005 and $8,355 per airplane, or between $81,135 and $225,585 for the entire U.S. fleet.The total cost impact figures discussed above are 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. However, the FAA has been advised that at least one U.S. operator affected by the AD has previously accomplished the required installations on most of its fleet of airplanes. In light of this, the total future cost impact of the rule is expected to be less than the figures indicated above.

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 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.

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