AD 94-09-04

This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F28 Mark 0100 series airplanes, that requires replacement of the flight control computers (FCC) with new, improved FCC's; and removal of certain limitations from the Airplane Flight Manual (AFM), if necessary. This amendment is prompted by reports indicating that, during a level change descent with auto throttles engaged and manual flight, airplanes inadvertently have approached near minimum speeds. The actions specified by this AD are intended to prevent inadvertent loss of airspeed during a level change descent.

Final rule

94-09-04 FOKKER: Amendment 39-8892. Docket 93-NM-147-AD.
Applicability: Model F28 Mark 0100 series airplanes, serial numbers 11244 through 11364, inclusive, certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent inadvertent loss of airspeed during a level change descent, accomplish the following:

(a) Within 60 days after the effective date of this AD, replace any flight control computer (FCC) having part number (P/N) 622-7476-321, P/N 622-7476-331, or P/N 622-7476- 401, with either of the following improved FCC's:

(1) P/N 622-7476-402, in accordance with Fokker Service Bulletin SBF100- 22-029, dated January 6, 1992; or

(2) P/N 622-7476-411, in accordance with Fokker Service Bulletin SBF100- 22-037, dated May 31, 1993.

NOTE 1: Each service bulletin referenced in this paragraph lists equipment configurations under paragraph 1.C. ("Description") and paragraph 3. ("Material Information") that must be adhered to in order to ensure proper operation of the FCC's.

(b) Prior to further flight after accomplishment of paragraph (a) of this AD, the following limitations, if present, must be removed from the Limitations Section of the FAA- approved Airplane Flight Manual (AFM), Section 2.08.01.

"FLIGHT DIRECTOR
Manual Flight with Flight Director ON.
For accurate speed control and
adequate speed protection the FD pitch commands must be followed when
flying manually.
In case the FD commands are not followed, switch both FD's to FPV or
OFF.
Non-precision Approach
Do not use LVLCH descent mode below 2000 ft. AGL. With PROF
engaged, do not lower the FMP altitude below the initial approach or
missed approach altitude."

(c) As of the effective date of this AD, no person shall install any FCC having P/N 622-7476-321, P/N 622-7476-331, or P/N 622-7476-401 on any airplane.

(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 installation shall be done in accordance with Fokker Service Bulletin SBF100- 22-029, dated January 6, 1992; or Fokker Service Bulletin SBF100-22-037, dated May 31, 1993. The incorporation by reference of thefirst service bulletin listed was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. The incorporation by reference of the latter service bulletin was approved previously by the Director of the Federal Register as of August 2, 1993 (58 FR 38283, July 16, 1993). 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 F28 Mark 0100 series airplanes was published in the Federal Register on November 12, 1993 (58 FR 59970). That action proposed to require replacement of the flight control computers (FCC) with new, improved FCC's; and removal of two related limitations from the Limitations Section of the FAA-approved Airplane Flight Manual (AFM), if those limitations are currently present in the AFM.

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 FCC as an acceptable alternative component for compliance. This commenter states that it has installed an FCC havingpart number 622-7476-411, in accordance with Fokker Service Bulletin SBF100-22-037, dated May 31, 1993, on its affected airplanes. The commenter installed this particular FCC when complying with an optional terminating action provided in AD 93-14-02 (58 FR 38283, July 16, 1993). The FAA has reviewed this data and finds that an FCC having part number 622-7476-411 is an acceptable alternative to that called out in the proposal. The FAA has revised the final rule to indicate this.

This same commenter requests that the proposed rule be revised to include the words "or subsequent" for the part number, so that future designs of the FCC would be permitted to be installed as alternatives to the specific part numbered component 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 Fokker service bulletins cited in the AD indicates that only specific equipment combinations are compatible (implying that similar part numbers in the component series that are not listed may not be compatible). For this reason, the FAA considers it inappropriate to permit the indiscriminate installation of any future FCC designs. A Note has been added to the final rule to make operators aware of the equipment combination limitations described in the service bulletins.

This same commenter requests that the proposed rule not require accomplishment of the actions specifically in accordance with the cited 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 the service bulletins; or (2) the commenter would prefer that the rule permit installation of the FCC 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 FCC and contain equipment configuration limitations; the FAA has determined that these procedures must be followed in order to ensure proper installation and operation. Paragraph (d) of the final rule does provide for the use of alternative methods of compliance with this rule, provided that data is submitted to the FAA to justify the use of such a method.

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 39 airplanes of U.S. registry will be affected by this AD, that it will take approximately 16 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 $460 per airplane. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $52,260, or $1,340 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 ExecutiveOrder 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: