[Federal Register Volume 62, Number 124 (Friday, June 27, 1997)]
[Rules and Regulations]
[Pages 34617-34619]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-16103]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-154-AD; Amendment 39-10051; AD 97-13-05]
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 loosening certain nuts on the horizontal stabilizer control 
unit (HSCU) to reduce stress on bolts; a one-time inspection of certain 
bolts on the HSCU to detect cracking, and replacement, if necessary; 
application of corrosion protection to these bolts; and reassembly and 
reidentification of the modified HSCU. This amendment is prompted by 
reports indicating that stress corrosion, resulting from overtightening 
of nuts on these bolts, has caused some of these bolts to crack and 
fail. The actions specified by this AD are intended to prevent failure 
of these bolts because of stress corrosion cracking which, if not 
corrected, could lead to loss of control of the horizontal stabilizer 
and reduced controllability of the airplane.

DATES: Effective August 1, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of August 1, 1997.

ADDRESSES: The service information referenced in this AD may be 
obtained from Fokker Services B.V., Technical Support Department, P.O. 
Box 75047, 1117 ZN Schiphol Airport, The Netherlands. 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,

[[Page 34618]]

Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2141; fax (425) 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 0100 
series airplanes was published in the Federal Register on November 8, 
1996 (61 FR 57832). That action proposed to require loosening of nuts 
on lower bolts that join the dog-links to the pistons of the horizontal 
stabilizer control unit (HSCU); a one-time inspection of these bolts to 
detect cracking, and replacement of discrepant bolts with serviceable 
bolts; application of corrosion protection to these bolts; and 
reassembly and reidentification of the HSCU that has been modified. 
(Some airplanes were modified on the production line, but the HSCU was 
not reidentified. That action proposes to require that the HSCU on 
those airplanes also be reidentified.)
    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 proposal and remarks, ``However, we seek 
the FAA to ensure that the change in stress loading of the certain 
bolts does not result in a change to the integrity of the HSCU that 
could cause it to become jammed or fail in some manner that could be 
hazardous if it happened in flight.'' The FAA has determined that the 
change does not affect the structural integrity of the HSCU, since the 
bolts are loaded in shear not tension. No change to the final rule is 
required.

Conclusion

    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.

Cost Impact

    The FAA estimates that 125 Fokker Model F28 Mark 0100 series 
airplanes of U.S. registry will be affected by this AD, that it will 
take approximately 5 work hours per airplane to accomplish the required 
loosening of nuts, and that the average labor rate is $60 per work 
hour. Based on these figures, the cost impact of the loosening of nuts 
on U.S. operators is estimated to be $37,500, or $300 per airplane.
    The FAA also estimates that it will take approximately 6 work hours 
per airplane to accomplish the required inspection, apply corrosion 
protection to the bolts, and reassemble and reidentify the HSCU. The 
average labor rate is $60 per work hour. Based on these figures, the 
cost impact of these actions on U.S. operators is estimated to be 
$45,000, or $360 per airplane.
    There currently are no known airplanes of U.S. registry that will 
be required to accomplish the required reidentification of the HSCU 
because the HSCU was modified on the production line and not 
reidentified.
    The 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.

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 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:

97-13-05  Fokker: Amendment 39-10051. Docket 96-NM-154-AD.

    Applicability: Model F28 Mark 0100 series airplanes, as listed 
in Fokker Service Bulletin SBF100-27-069, dated January 1, 1996; 
certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 failure of the lower bolts that join the dog-links to 
the piston of the horizontal stabilizer control unit (HSCU) because 
of stress corrosion cracking, which could result in loss of control 
of the horizontal stabilizer and reduced controllability of the 
airplane, accomplish the following:
    (a) Within 3 months after the effective date of this AD, loosen 
the nut [part number (P/N) MS17825-10] on each lower bolt (P/N 
23233-1) that joins the dog-links to the piston of the HSCU, in 
accordance with Part 1 of the Accomplishment Instructions of Fokker 
Service Bulletin SBF100-27-069, dated January 1, 1996, as revised by 
Part 1 of Fokker Service Bulletin Change Notification SBF100-27-069/
01, dated January 8, 1996; and Part A of the Accomplishment 
Instructions of Menasco Aerospace Ltd. Service Bulletin 23100-27-19, 
dated November 10, 1995.
    (b) Within 6 months after the effective date of this AD, inspect 
each lower bolt (P/N 23233-1) that joins the dog-links to the 
pistons of the HSCU to detect cracking and failure, in accordance 
with Part 2 of the Accomplishment Instructions of Fokker Service 
Bulletin SBF100-27-069, dated January 1, 1996, as revised by Part 2 
of Fokker Service Bulletin Change Notification SBF100-27-069/01, 
dated January 8, 1996; and Part B of the Accomplishment Instructions 
of Menasco Aerospace Ltd. Service Bulletin 23100-27-19, dated 
November 10, 1995.
    (1) If no cracking or failure is detected, prior to further 
flight, apply corrosion protection to each bolt, and reassemble and 
reidentify the HSCU, in accordance with Part 2 of the Accomplishment 
Instructions of Fokker Service Bulletin SBF100-27-069, dated January 
1, 1996, as revised by Part 2

[[Page 34619]]

of Fokker Service Bulletin Change Notification SBF100-27-069/01, 
dated January 8, 1996; and Part B of the Accomplishment Instructions 
of Menasco Aerospace Ltd. Service Bulletin 23100-27-19, dated 
November 10, 1995.
    (2) If any cracking or failure is detected, prior to further 
flight, replace the discrepant bolt with a serviceable bolt, apply 
corrosion protection to each serviceable bolt, and reassemble and 
identify the HSCU, in accordance with Part 2 of the Accomplishment 
Instructions of Fokker Service Bulletin SBF100-27-069, dated January 
1, 1996, as revised by Part 2 of Fokker Service Bulletin Change 
Notification SBF100-27-069/01, dated January 8, 1996; and Part B of 
the Accomplishment Instructions of Menasco Aerospace Ltd. Service 
Bulletin 23100-27-19, dated November 10, 1995.
    (c) For airplanes having serial numbers 11500, 11505, and 11511: 
Within 6 months after the effective date of this AD, reidentify the 
HSCU in accordance with Part 3 of the Accomplishment Instructions of 
Fokker Service Bulletin SBF100-27-069, dated January 1, 1996.
    (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 SBF100-27-069, dated January 1, 1996, as revised by Fokker 
Service Bulletin Change Notification SBF100-27-069/01, dated January 
8, 1996; and Menasco Aerospace Ltd. Service Bulletin 23100-27-19, 
dated November 10, 1995. This incorporation by reference was 
approved by the Director of the Federal Register n accordance with 5 
U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Fokker 
Services B.V., Technical Support Department, P.O. Box 75047, 1117 ZN 
Schiphol Airport, The Netherlands. 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 August 1, 1997.

    Issued in Renton, Washington, on June 13, 1997.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-16103 Filed 6-26-97; 8:45 am]
BILLING CODE 4910-13-U