[Federal Register Volume 62, Number 36 (Monday, February 24, 1997)]
[Rules and Regulations]
[Pages 8159-8161]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-4199]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-142-AD; Amendment 39-9943; AD 97-04-18]
RIN 2120-AA64


Airworthiness Directives; Fokker Model F27 Mark 100, 200, 300, 
400, 500, 600, and 700 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 all Fokker Model F27 Mark 100, 200, 300, 400, 500, 600, 
and 700 series airplanes, that requires repetitive x-ray inspections to 
detect cracks in stringers 4 through 7 of the lower skin of the wings, 
and modification or repair, if necessary. This amendment also requires 
modification of the stringers of the lower skin of the wings, which 
terminates the repetitive inspections. This amendment is prompted by 
reports of fatigue cracking found in stringers 4 through 7 of the lower 
skin of the wings. The actions specified by this AD are intended to 
prevent such fatigue cracking, which could result in reduced structural 
integrity of the wings.

DATES: Effective March 31, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 31, 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: Ruth Harder, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-1721; 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 Fokker Model F27 Mark 100, 200, 
300, 400, 500, 600, and 700 series airplanes was published in the 
Federal Register on August 6, 1996 (61 FR 40760). That action proposed 
to require repetitive x-ray inspections to detect cracks of stringers 4 
through 7, inclusive, at certain wing stations of the lower skin of the 
wings; and modification or repair, if necessary. That action also 
proposed to require modification of certain stringers of the lower skin 
of the wings, which, when accomplished, would constitute terminating 
action for the repetitive inspection 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.

Support for the Proposal

    One commenter supports the proposed AD.

Request to Extend Proposed Compliance Time

    One commenter requests that the proposal be revised to extend the 
compliance time for the initial x-ray inspection (Part 2 of the Fokker 
Service Bulletin F27/57-70)) and the terminating modification (Part 1 
of the Fokker service bulletin) to the next regularly scheduled ``C'' 
check. This commenter states that the 12-month compliance time for the 
inspection creates unnecessary burdens both economically and 
operationally. However, since the downtime for accomplishing the 
terminating action

[[Page 8160]]

would be a minimum of 6 days (dictated by the number of maintenance 
personnel who can work on this area at one time), the commenter 
considers that it would be more feasible to allow both the inspection 
and terminating action to be accomplished during that one time. A 
convenient time for this to take place would be during a ``C'' check 
inspection or equivalent.
    The FAA acknowledges this commenter's request, but finds that 
clarification of the intent of the compliance time is necessary, based 
on the commenter's apparent misinterpretation of it.
    Paragraph (a) of the AD is meant to require that the initial 
inspection be performed at the later of either:
    --paragraph (a)(1)--prior to the accumulation of 30,000 total 
flight cycles; or
    --paragraph (a)(2)--within 2,000 flight cycles or 12 months after 
the effective date of the AD, whichever is earlier.
    The 2,000-cycle/12-month compliance time provided by paragraph 
(a)(2) is meant to serve as a ``grace period'' if an affected airplane 
has already accumulated nearly or more than 30,000 total flight cycles. 
This grace period provision eliminates the situation where an airplane 
having over 30,000 flight cycles would be in immediate non-compliance 
with the AD. For those airplanes then, the inspection must be 
accomplished either within 2,000 flight cycles after the effective date 
of the AD or within 12-months after the effective date, whichever 
occurs first.
    As for the terminating modification, paragraph (d) requires that it 
be installed on all airplanes prior to the accumulation of 30,000 total 
flight cycles, or within 30 months after the effective date of this AD, 
whichever occurs later. Again, this paragraph provides a grace period 
of 30 months for airplanes that are nearly approaching or have exceeded 
30,000 total flight cycles.
    In looking at the AD as a whole, operators should note that the 
inspection specified in paragraph (a) actually is meant to be an 
``optional'' interim action that can be accomplished on higher-time 
airplanes prior to accomplishing the terminating modification, if time 
and schedules dictate. For example, a higher time airplane meeting the 
utilization criteria relevant to paragraph (a)(2) could be initially 
inspected within 12 months and, if no cracking was found during any 
inspection, need not be modified in accordance with paragraph (d) for 
another 18 months (totaling 30 months after the effective date of the 
AD). On the other hand, that airplane instead could be modified prior 
to the 12-month period and, therefore, need not be inspected in 
accordance with paragraph (a) at all.
    For very low-time airplanes, as long as the terminating 
modification is accomplished prior to the accumulation of 30,000 flight 
cycles, the inspection specified in paragraph (a) need not be 
performed.
    In light of this explanation, the FAA does not consider that any 
change to the compliance times, based on the commenters request, is 
necessary.
    Further, the FAA does not concur with the commenter's suggestion to 
state compliance times in terms of maintenance checks (i.e., ``C'' 
checks), since the intervals for those checks may vary greatly from 
operator to operator. Based on the data available concerning fatigue 
cracking in the subject areas, the FAA finds that the compliance time 
intervals, as proposed, are appropriate. Under the provisions of 
paragraph (e) of this final rule, however, operators may request 
approval of adjustments of the compliance time, provided that 
sufficient data are presented to the FAA to justify the request.

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 as proposed.

Cost Impact

    The FAA estimates that 34 Fokker Model F27 Mark 100, 200, 300, 400, 
500, 600, and 700 series airplanes of U.S. registry will be affected by 
this AD.
    It will take approximately 16 work hours per airplane to accomplish 
the required inspection, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the inspection required by 
this AD on U.S. operators is estimated to be $32,640, or $960 per 
airplane, per inspection cycle.
    It will take approximately 400 work hours per airplane to 
accomplish the required modification, at an average labor rate of $60 
per work hour. Required parts will cost approximately $1,365 per 
airplane. Based on these figures, the cost impact of the modification 
required by this AD on U.S. operators is estimated to be $862,410, or 
$25,365 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 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:

97-04-18 Fokker: Amendment 39-9943. Docket 96-NM-142-AD.

    Applicability: All Model F27 Mark 100, 200, 300, 400, 500, 600, 
and 700 series airplanes; 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

[[Page 8161]]

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 fatigue-related cracking of stringers of the lower 
skin of the wings, which could result in reduced structural 
integrity of the wing, accomplish the following:
    (a) Perform an x-ray inspection to detect cracks in stringers 4 
through 7, inclusive, at wing stations 11260, 11860, 12660, and 
13460 of the lower skin of the wings, in accordance with Part 2 of 
the Accomplishment Instructions of Fokker Service Bulletin F27/57-
70, May 17 ,1993, at the later of the times specified in paragraphs 
(a)(1) and (a)(2) of this AD.
    (1) Prior to the accumulation of 30,000 total flight cycles; or
    (2) Within the next 2,000 flight cycles, or within 12 months 
after the effective date of this AD, whichever occurs first.
    (b) If no crack is detected during any inspection required by 
paragraph (a) of this AD, repeat the inspection thereafter at 
intervals not to exceed 4,000 flight cycles.
    (c) If any crack is detected during any inspection required by 
this AD, prior to further flight, accomplish either paragraph (c)(1) 
or (c)(2) of this AD.
    (1) Modify the stringers 4 through 7, inclusive, at wing 
stations 11260, 11860, 12660, and 13460 of the lower skin of the 
wings, in accordance with Part 1 of the Accomplishment Instructions 
of Fokker Service Bulletin F27/57-70, dated May 17, 1993. After 
accomplishment of the modification, no further action is required by 
this AD.
    (2) Repair the crack in accordance with Part 3 of the 
Accomplishment Instructions of Fokker Service Bulletin F27/57-70, 
dated May 17, 1993. Within the next 2,000 flight cycles or 1 year 
following accomplishment of the repair, whichever occurs first, 
modify the stringers 4 through 7, inclusive, at wing stations 11260, 
11860, 12660, and 13460 of the lower skin of the wings, in 
accordance with Part 1 of the Accomplishment Instructions of the 
service bulletin. After accomplishment of the modification, no 
further action is required by this AD.
    (d) Prior to the accumulation of 30,000 flight cycles, or within 
30 months after the effective date of this AD, whichever occurs 
later, modify the stringers 4 through 7, inclusive, at wing stations 
11260, 11860, 12660, and 13460 of the lower skin of the wings, in 
accordance with Part 1 of the Accomplishment Instructions of Fokker 
Service Bulletin F27/57-70, dated May 17, 1993. Accomplishment of 
the modification constitutes terminating action for the requirements 
of this AD.
    (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 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.

    (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 F27/57-70, dated May 17, 1993. 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 31, 1997.

    Issued in Renton, Washington, on February 13, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-4199 Filed 2-21-97; 8:45 am]
BILLING CODE 4910-13-U