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  97-2608. Airworthiness Directives; Fokker Model F28 Mark 0100 Series Airplanes  

  • [Federal Register Volume 62, Number 29 (Wednesday, February 12, 1997)]
    [Rules and Regulations]
    [Pages 6459-6461]
    From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
    [FR Doc No: 97-2608]
    
    
    
    [[Page 6459]]
    
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    DEPARTMENT OF TRANSPORTATION
    14 CFR Part 39
    
    [Docket No. 95-NM-02-AD; Amendment 39-9915; AD 97-03-09]
    RIN 2120-AA64
    
    
    Airworthiness Directives; Fokker Model F28 Mark 0100 Series 
    Airplanes
    
    AGENCY: Federal Aviation Administration, DOT.
    
    ACTION: Final rule.
    
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    SUMMARY: This amendment adopts a new airworthiness directive (AD), 
    applicable to certain Fokker Model F28 Mark 0100 series airplanes, that 
    requires repetitive checks to detect backlash in the elevator 
    mechanical control system, and various follow-on actions. This 
    amendment also provides for an optional terminating action for the 
    repetitive check requirements. This amendment is prompted by a report 
    indicating that corrosion was found on the pivot bolts and bushings of 
    the backlash remover lever mechanism on the elevator booster control 
    unit (BCU) of a Model F28 Mark 0100 series airplane. The actions 
    specified by this AD are intended to prevent such corrosion, which 
    could result in backlash in the elevator controls and reduced elevator 
    control authority in the manual mode.
    
    DATES: Effective March 19, 1997.
        The incorporation by reference of certain publications listed in 
    the regulations is approved by the Director of the Federal Register as 
    of March 19, 1997.
    
    ADDRESSES: The service information referenced in this AD may be 
    obtained from Fokker Aircraft USA, Inc., 1199 North Fairfax Street, 
    Alexandria, Virginia 22314. This information may be examined at the 
    Federal Aviation Administration (FAA), Transport Airplane Directorate, 
    Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the 
    Office of the Federal Register, 800 North Capitol Street, NW., Suite 
    700, Washington, DC.
    
    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) 227-1149.
    
    SUPPLEMENTARY INFORMATION: 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 March 17, 
    1995 (60 FR 14395). That action proposed to require repetitive checks 
    to detect backlash in the elevator mechanical control system, and 
    various follow-on actions. That action also proposed an optional 
    terminating action for the repetitive check requirements.
        Interested persons have been afforded an opportunity to participate 
    in the making of this amendment. Due consideration has been given to 
    the comments received.
    
    Request To Defer Release of Final Rule
    
        One commenter requests that the FAA defer the release of the final 
    rule until a bolt replacement program can be developed to 
    satisfactorily address the problems with corrosion. This commenter 
    asserts that the proposed rule goes beyond what is needed to address 
    the stated safety concern. Further, this commenter considers that, 
    since both U.S. operators affected by this proposed rule already have 
    instituted a maintenance program that includes applying corrosion 
    inhibitor to the subject bolts, the FAA's interim safety objectives are 
    being met. The commenter also notes that a similar problem of bolt 
    corrosion occurred on the same system on a Fokker Model F28 series 
    airplane, and the manufacturer simply recommended that a corrosion-
    resistant bolt be installed. The commenter maintains that, if the 
    proposed rule is adopted without change, then the FAA will be mandating 
    a very complex inspection program at operators' ``B''-check intervals, 
    with little thought to actually correcting the unsafe condition. If 
    there is a simple, cost-effective terminating action that could be 
    introduced--other than the replacement of the elevator booster control 
    unit (BCU) with an improved unit--then it should be considered prior to 
    going forward with this AD.
        The FAA does not concur with the commenter's request to delay the 
    issuance of this AD until a ``bolt replacement program'' is developed, 
    because such a ``program'' is already included in the AD as an optional 
    terminating action. This AD provides for two optional actions, either 
    of which could be accomplished in order to terminate the required 
    repetitive inspections:
        1. modification of the affected BCU by replacing the currently 
    installed bolts with improved bolts that are corrosion-resistant; or
        2. replacement of the currently installed BCU with a unit that 
    already has the improved, corrosion-resistant bolts installed.
        The FAA has provided the terminating actions as optional to 
    operators, since the accomplishment of either terminating action is far 
    more complicated and time-consuming than performing the required 
    repetitive operational checks and inspections. For example, because it 
    is physically impossible to replace one of the affected bolts while the 
    BCU is still installed on the airplane, in order to perform either 
    terminating action, the BCU must be removed; this procedure in itself 
    is more labor-intensive that performing the required checks and 
    inspections. However, the FAA maintains that the accomplishment of 
    either action provided for in this AD--repetitive checks/inspections or 
    terminating action--will adequately address the unsafe condition 
    presented by corrosion.
        The FAA cannot concur with the commenter's suggestion that the 
    FAA's ``interim safety objectives are being met'' by operators' current 
    practice of applying a corrosion inhibitor to the suspect bolts. The 
    commenter provided no data to substantiate that the procedure will 
    provide a level of safety equivalent to that provided by the actions 
    required by this AD. However, under the provisions of paragraph (e) of 
    the final rule, the FAA may approve requests for use of alternative 
    methods of compliance if data are submitted to substantiate that such a 
    method would provide an acceptable level of safety.
    
    Request To Add ``Intermediate'' Step in Operational Check
    
        One commenter requests that the proposal be revised to include the 
    ``intermediate'' step of checking the position of the backlash remover 
    lever, which is specified in the referenced Fokker Service Bulletin 
    SBF100-27-052. This commenter notes that proposed paragraph (b), as 
    written, would require an inspection of the elevator BCU backlash 
    remover bolts for freedom of movement and corrosion if any backlash is 
    detected during the operational check required by proposed paragraph 
    (a). However, the referenced Fokker service bulletin specifies an 
    intermediate step to inspect the position of the backlash remover to 
    determine whether the bolt inspection is even necessary, or if 
    troubleshooting for some other cause of the problem is necessary.
        The FAA concurs with the commenter's request. While this 
    ``intermediate'' step was not specified in the proposal, the FAA's 
    intent was to require operators to accomplish all of the check and 
    inspection procedures specified in Fokker Service Bulletin SBF100-27-
    052. The final rule has been revised to indicate that operators are to 
    perform this intermediate step to determine if the bolt inspection is
    
    [[Page 6460]]
    
    necessary, rather than immediately performing the bolt inspection in 
    all cases. Since this addition to the final rule is relieving in nature 
    (i.e., operators may not have to accomplish a more complicated 
    inspection immediately, as was proposed), it will not increase the 
    economic burden on any operator, nor will it increase the scope of the 
    AD.
    
    Request To Allow Deferment of BCU Replacement Requirement
    
        One commenter requests that the proposal be revised to include the 
    option to defer the replacement of the elevator BCU prior to further 
    flight if the backlash remover bolts are found to be frozen or 
    corroded. The commenter states that the backlash remover bolts are 
    neither torqued nor subjected to high shear loads; therefore, operators 
    should not be required to remove the BCU prior to further flight, 
    provided that the bolts can be freed and lubricated, and the backlash 
    operational check is subsequently accomplished successfully. If removal 
    and modification of the BCU (in accordance with Fokker Service Bulletin 
    SBF100-27-061) could be deferred so that operators could schedule it 
    during a regular maintenance interval, the amount of downtime and 
    additional expenses could be minimized.
        The FAA concurs with the commenter's request. If the bolt having 
    part number NAS6204C22D can be freed so that it rotates and slides 
    freely, and is lubricated; and if the backlash operational check is 
    subsequently accomplished and is successful; then the FAA agrees that 
    the replacement of the elevator BCU can be deferred somewhat. The FAA 
    considers an appropriate deferral interval to be 10 days. Paragraph (b) 
    of the final rule has been revised to specify this deferral provision.
        However, for the bolt having part number NAS6204C13D, the FAA has 
    determined that its replacement cannot be deferred if it does not 
    rotate and slide freely, or if there are any signs of corrosion; under 
    those conditions, that bolt must be replaced prior to further flight. 
    The FAA considers this action both appropriate and warranted, since 
    that bolt is readily accessible on the airplane.
    
    Request To Add Optional Repetitive Inspections
    
        One commenter requests that the proposal be revised to include the 
    option to conduct periodic inspections of the backlash remover 
    mechanism and to apply corrosion preventative lubrication on the 
    subject backlash remover bolts at 1,800-flight cycle intervals. The 
    commenter requests that operators be permitted to accomplish these 
    actions in lieu of the proposed operational checks to detect backlash. 
    This commenter does not consider the proposed backlash check from the 
    flight deck to be a good solution to the problem of corroded or frozen 
    backlash remover lever bolts because:
        1. the check is subjective, since it requires a sense of feel that 
    may vary from person to person; and
        2. the check procedures are ill-defined in the referenced Fokker 
    Service Bulletin SBF100-27-052.
        In addition, this commenter states that the Fokker service bulletin 
    does not provide any instructions that will prevent the existing bolts 
    from corroding.
        This commenter, a U.S. operator, indicates that it already has 
    implemented a program that includes periodic inspection and lubrication 
    of the subject bolts at 1,800-flight cycle intervals; the commenter 
    considers its program to be a more proactive approach to addressing the 
    unsafe condition.
        The FAA does not concur with the commenter's request. In 
    consultation with Fokker and the Netherlands airworthiness authority 
    (RLD), the FAA has determined that the operational check is not 
    ``subjective,'' as suggested by the commenter: there will be a clear 
    indication of backlash if the mechanism is stuck, and the referenced 
    Fokker service bulletin provides objective standards of approximately 2 
    inches of freeplay. In addition, the commenter has not provided any 
    technical data to prove that inspection and lubrication of the bolts at 
    1,800-flight cycle intervals will provide at least the same level of 
    safety as that provided by the operational check at 500-flight cycle 
    intervals. While an inspection and lubrication may help to prevent 
    sticking of the mechanism, it may not provide the necessary safety 
    margins. Paragraph (e) of the final rule, however, does provide for the 
    use of alternative methods of compliance with the AD, provided that 
    sufficient justification is presented to the FAA.
        Further, the FAA agrees that Fokker Service Bulletin SBF100-27-052 
    does not provide instructions to prevent corrosion, other than 
    inspection and lubrication of the bolts whenever backlash is detected 
    during the operational check. However, this AD provides for two 
    optional terminating actions for the checks: either modification of the 
    existing BCU by replacing the currently-installed bolts with corrosion-
    resistant bolts (as described in Fokker Service Bulletin SBF100-26-
    061); or by replacement of the affected elevator BCU with a unit that 
    already has corrosion-resistant bolts installed. Such replacement of 
    the bolts positively addresses the problem of galvanic corrosion.
    
    Conclusion
    
        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 changes previously 
    described. The FAA has determined that these changes will neither 
    increase the economic burden on any operator nor increase the scope of 
    the AD.
    
    Cost Impact
    
        The FAA estimates that 112 Fokker Model F28 Mark 0100 series 
    airplanes of U.S. registry will be affected by this AD, that it will 
    take approximately 1 work hour 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 manufacturer at no cost to the operators. 
    Based on these figures, the cost impact of the AD on U.S. operators is 
    estimated to be $6,720, or $60 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.
    
    Regulatory Impact
    
        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
    
    [[Page 6461]]
    
    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. 106(g), 40113, 44701.
    
    
    Sec. 39.13  [Amended]
    
        2. Section 39.13 is amended by adding the following new 
    airworthiness directive:
    
    97-03-09 FOKKER: Amendment 39-9915. Docket 95-NM-02-AD.
    
        Applicability: Model F28 Mark 0100 series airplanes; equipped 
    with Menasco Aerospace Elevator Booster Control Unit (BCU) having 
    part number (P/N) 23400-3 or P/N 23400-5 with serial numbers MC-001 
    through MC-288 inclusive; 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 (e) 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 backlash in the elevator controls and reduced 
    elevator control authority in the manual mode, accomplish the 
    following:
        (a) Within 500 flight cycles or 60 days after the effective date 
    of this AD, whichever occurs first, perform an operational check to 
    detect backlash in the elevator mechanical control system, in 
    accordance with Part 1 of the Accomplishment Instructions of Fokker 
    Service Bulletin SBF100-27-052, Revision 1, dated March 29, 1994. If 
    no backlash is detected, repeat the check thereafter at intervals 
    not to exceed 500 flight cycles or 60 days, whichever occurs first.
        (b) If any backlash of the elevator mechanical control system is 
    detected during any operational check required by paragraph (a) of 
    this AD, prior to further flight, perform an inspection to determine 
    whether the backlash remover lever and pistons are in the proper 
    position, in accordance with Part 2 (paragraph I.) of Fokker Service 
    Bulletin SBF100-27-052, Revision 1, dated March 29, 1994.
        (1) If the backlash remover lever and pistons are in the proper 
    position: Prior to further flight, perform appropriate trouble-
    shooting procedures in accordance with the Airplane Maintenance 
    Manual.
        (2) If the backlash remover lever and pistons are not in the 
    proper position: Prior to further flight, perform an inspection to 
    determine whether the elevator booster control unit (BCU) bolts, 
    having part numbers (P/N) NAS6204C22D and P/N NAS6204C13D, rotate 
    and slide freely; and to detect corrosion on the bolts of the 
    backlash remover lever mechanism; in accordance with Part 2 
    (paragraph J.) of the Accomplishment Instructions of Fokker Service 
    Bulletin SBF100-27-052, Revision 1, dated March 29, 1994.
        (i) If no anomaly is detected, prior to further flight, perform 
    appropriate trouble-shooting procedures in accordance with the 
    Airplane Maintenance Manual.
        (ii) Except as provided by paragraph (b)(2)(iii) of this AD, if 
    any anomaly is detected, prior to further flight, replace the 
    elevator BCU or bolts, as applicable, with serviceable parts, in 
    accordance with the service bulletin.
        (iii) If any anomaly is detected, replacement of the elevator 
    BCU or the bolt having P/N NAS6204C22D, as applicable, may be 
    deferred for a period of 10 days, provided that the three conditions 
    specified below are met:
        (A) The bolt having P/N NAS6204C22D can be freed so that it 
    rotates and slides freely; and
        (B) That bolt is lubricated subsequent to the inspection; and
        (C) An operational check, as specified in paragraph (a) of this 
    AD, is accomplished subsequent to lubrication and is successful.
    
        Note 2: The deferral provision of paragraph (b)(2)(iii) of this 
    AD does not apply to the bolt having P/N NAS6204C13D. Replacement of 
    that part-numbered bolt, when necessary, cannot be deferred.
    
        (c) Terminating action for the repetitive check and inspection 
    requirements of this AD consists of the accomplishment of the 
    actions specified in either paragraph (c)(1) or (c)(2) of this AD:
        (1) Modification of the affected elevator BCU having P/N 23400-3 
    or -5, in accordance with Fokker Service Bulletin SBF100-27-061, 
    dated March 2, 1994; or
        (2) Replacement of any affected elevator BCU having P/N 23400-3 
    or -5 with a unit having a serial number other than MC-001 through 
    MC-288 inclusive, in accordance with the Airplane Maintenance 
    Manual.
        (d) As of the effective date of this AD, no person shall install 
    in any airplane a Menasco Aerospace BCU having P/N 23400-3 or P/N 
    23400-5 with serial numbers MC-001 through MC-288, inclusive.
        (e) 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.
    
        (f) 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.
        (g) The actions shall be done in accordance with Fokker Service 
    Bulletin SBF100-27-052, Revision 1, dated March 29, 1994; and Fokker 
    Service Bulletin SBF100-27-061, dated March 2, 1994. 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.
        (h) This amendment becomes effective on March 19, 1997.
    
        Issued in Renton, Washington, on January 28, 1997.
    Darrell M. Pederson,
    Acting Manager, Transport Airplane Directorate, Aircraft Certification 
    Service.
    [FR Doc. 97-2608 Filed 2-11-97; 8:45 am]
    BILLING CODE 4910-13-U
    
    
    

Document Information

Effective Date:
3/19/1997
Published:
02/12/1997
Department:
Transportation Department
Entry Type:
Rule
Action:
Final rule.
Document Number:
97-2608
Dates:
Effective March 19, 1997.
Pages:
6459-6461 (3 pages)
Docket Numbers:
Docket No. 95-NM-02-AD, Amendment 39-9915, AD 97-03-09
RINs:
2120-AA64: Airworthiness Directives
RIN Links:
https://www.federalregister.gov/regulations/2120-AA64/airworthiness-directives
PDF File:
97-2608.pdf
CFR: (1)
14 CFR 39.13