[Federal Register Volume 61, Number 152 (Tuesday, August 6, 1996)]
[Proposed Rules]
[Pages 40760-40762]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-19892]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-142-AD]
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: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to all Fokker Model F27 Mark 100, 
200, 300, 400, 500, 600, and 700 series airplanes. This proposal would 
require 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. The proposed AD also would require modification of the 
stringers of the lower skin of the wings, which would terminate the 
repetitive inspections. This proposal is prompted by reports of fatigue 
cracking found in stringers 4 through 7 of the lower skin of the wings. 
The actions specified by the proposed AD are intended to prevent such 
fatigue cracking, which could result in reduced structural integrity of 
the wings.

DATES: Comments must be received by September 16, 1996.


[[Page 40761]]


ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-142-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays.
    The service information referenced in the proposed rule may be 
obtained from Fokker Aircraft USA, Inc., 1199 North Fairfax Street, 
Alexandria, Virginia 22314. This information may be examined at the 
FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

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:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 96-NM-142-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules 
Docket No. 96-NM-142-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The Rijksluchtvaartdienst (RLD), which is the airworthiness 
authority for the Netherlands, recently notified the FAA that an unsafe 
condition may exist on all Fokker Model F27 Mark 100, 200, 300, 400, 
500, 600, and 700 series airplanes. The RLD advises that it has 
received reports indicating that, during modification of the upper wing 
skin at stringers 4 through 7 (required by AD 94-26-08, amendment 39-
9103 (60 FR 332, January 4, 1995)), cracking was found in certain 
stringers of the lower skin of the wing. Investigation revealed that 
such cracking, which started at the rivet holes of the rib-to-stringer 
connections, was caused by fatigue-related stress. This condition, if 
not detected and corrected in a timely manner, could result in reduced 
structural integrity of the wings.

Explanation of Relevant Service Information

    Fokker has issued Service Bulletin F27/57-70, dated May 17, 1993, 
which describes the following procedures:
    1. Performing repetitive x-ray inspections to detect cracks in 
stringers 4 through 7, inclusive, at certain wing stations of the lower 
skin of the wings;
    2. Modifying stringers 4 through 7, inclusive, at certain wing 
stations of the lower skin of the wings, which eliminates the need for 
the repetitive inspections; this modification will minimize the 
possibility of cracks developing in the subject area of the stringers 
of the lower skin of the wings;
    3. Temporarily repairing the cracked stringer until the 
modification is accomplished.
    In addition, the service bulletin permits further flight, under 
certain conditions, with stringers that are cracked within certain 
limits.
    The RLD classified this service bulletin as mandatory and issued 
Dutch airworthiness directive BLA 93-094 (A), dated July 16, 1993, in 
order to assure the continued airworthiness of these airplanes in the 
Netherlands.

FAA's Conclusions

    This airplane model is manufactured in the Netherlands and is type 
certificated for operation in the United States under the provisions of 
section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and 
the applicable bilateral airworthiness agreement. Pursuant to this 
bilateral airworthiness agreement, the RLD has kept the FAA informed of 
the situation described above. The FAA has examined the findings of the 
RLD, reviewed all available information, and determined that AD action 
is necessary for products of this type design that are certificated for 
operation in the United States.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design, the 
proposed AD would 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. The 
proposed AD also would require modification of certain stringers of the 
lower skin of the wings, which would constitute terminating action for 
the repetitive inspection requirements. The actions would be required 
to be accomplished in accordance with the service bulletin described 
previously.

Differences Between the Proposed Rule and the Relevant Service 
Information

    Operators should note that, unlike the procedures described in the 
referenced service bulletin, this proposed AD would not permit further 
flight with cracking detected in the stringers. The FAA has determined 
that, due to the safety implications and consequences associated with 
such cracking, the subject stringers that are found to be cracked must 
be repaired, and these stringers connections eventually must be 
modified. This repair and modification (in accordance with Fokker 
Service Bulletin F27/57-70, dated May 17, 1993) will ensure the 
structural integrity of the subject are of the wing.

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 would be affected 
by this proposed AD.
    It would take approximately 16 work hours per airplane to 
accomplish the proposed inspection, at an average labor rate of $60 per 
work hour. Based on these figures, the cost impact of the inspection 
proposed by this AD on U.S. operators is estimated to be $32,640, or 
$960 per airplane, per inspection cycle.
    It would take approximately 400 work hours per airplane to 
accomplish the proposed modification, at an average labor rate of $60 
per work hour. Required parts would cost approximately $1,365 per 
airplane.

[[Page 40762]]

Based on these figures, the cost impact of the modification proposed by 
this AD on U.S. operators is estimated to be $862,410, or $25,365 per 
airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the proposed 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 proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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:

Fokker: 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 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 
Secs. 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.

    Issued in Renton, Washington, on July 30, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-19892 Filed 8-5-96; 8:45 am]
BILLING CODE 4910-13-U