[Federal Register Volume 61, Number 215 (Tuesday, November 5, 1996)]
[Proposed Rules]
[Pages 56925-56927]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-28323]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-94-AD]


Airworthiness Directives; Fokker Model F28 Mark 0100 and Mark 
0070 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 certain Fokker Model F28 Mark 0100 
and Mark 0070 series airplanes. This proposal would require 
modification of the hook and latch engagement assemblies of the engine 
cowl doors, measurement of the aerodynamic mismatch between the fixed 
cowl and lower cowl door, and repair, if necessary. This proposal is 
prompted by reports of operational experience that indicate that an 
aerodynamic mismatch may exist between the fixed engine cowl and the 
lower cowl door, and may be the result of one or more hooks of the 
engagement assemblies not engaging adequately. This condition may cause 
the other hooks to carry loads higher than they were originally 
designed to carry, and could result in the failure of those hooks that 
are engaged. The actions specified by the proposed AD are intended to 
prevent possible separation of the lower cowling from the airplane due 
to failure of the hooks of the engagement assemblies.

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

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-94-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: 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:

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 95-NM-94-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. 95-NM-94-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 certain Fokker Model F28 Mark 0100 and Mark 0070 
series airplanes. The RLD has received reports indicating that 
operational experience has shown that an aerodynamic mismatch (gap) may 
exist between the fixed engine cowl and the lower cowl door. The lower 
cowl

[[Page 56926]]

door is engaged in the ``closed'' position by two latches and three 
hooks. An excessive aerodynamic mismatch (or gap) in this assembly 
indicates that one or more hooks are not engaged properly. If this is 
the case, the aerodynamic mismatch could cause the hooks that are 
engaged to carry loads higher than they were originally designed to 
carry; in the event of a burst engine bypass duct, this situation could 
result in failure of the hooks that are engaged. Failure of these hooks 
could result in the lower engine cowling separating from the airplane 
and subsequently causing damage to other airplane structure or posing a 
hazard to persons on the ground.

Explanation of Relevant Service Information

    Fokker has issued Service Bulletin SBF100-71-019, dated March 21, 
1996, which describes procedures for:
    1. modifying the hook and latch engagement assemblies of the left 
and right engine lower cowl door; and
    2. measuring the aerodynamic mismatch between the fixed cowl and 
lower cowl.
    If the measurement of the aerodynamic mismatch is beyond the limits 
specified in the service bulletin, the service bulletin also provides 
procedures to measure the mis-engagement between the left and right 
engine hooks of the fixed cowl door and the clevis fittings of the 
lower cowl door. The service bulletin also describes modification 
procedures for the mid-clevis fitting on the right and left engine 
lower cowl door if the mis-engagement is beyond the limits specified in 
the service bulletin.
    The RLD classified this service bulletin as mandatory and issued 
Netherlands airworthiness directive BLA 1989-049/3 (A), dated June 28, 
1996, 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 registered 
in the United States, the proposed AD would require modification of the 
hook and latch engagement assemblies of the left and right engine lower 
cowl door. It would also require measurement of the aerodynamic 
mismatch between the fixed cowl and lower cowl, and various follow-on 
actions, dependent upon whether the measurement of the aerodynamic 
mismatch is beyond certain limits. These actions would be required to 
be accomplished in accordance with the service bulletin described 
previously.

Cost Impact

    The FAA estimates that 124 Fokker Model F28 Model 0100 and 0070 
series airplanes of U.S. registry would be affected by this proposed 
AD, that it would take approximately 3 work hours per airplane to 
accomplish the initial inspection and modification, and that the 
average labor rate is $60 per work hour. Based on these figures, the 
total cost impact of the proposed AD on U.S. operators is estimated to 
be $22,320, or $180 per airplane.
    The total cost impact figure discussed above is 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Fokker: Docket 95-NM-94-AD.

    Applicability: Model F28 Mark 0100 and Mark 0070 series 
airplanes as listed in Fokker Service Bulletin SBF100-71-019, dated 
March 21, 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 (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 separation of the lower cowling from the airplane due 
to failure of the hook and latch engagement assembly of the cowl 
door, accomplish the following:
    (a) Accomplish the requirements of paragraph (b) of this AD at 
the later of the times indicated in paragraph (a)(1), (a)(2), or 
(a)(3) of this AD:
    (1) prior to the accumulation of 2,500 total flight cycles; or
    (2) within 2,500 flight cycles since the last inspection 
performed in accordance with Fokker Service Bulletin SBF100-71-003, 
dated April 14, 1989; Revision 1, dated August 8, 1989, or Revision 
2, dated November 21, 1994; or
    (3) within 30 days after the effective date of this AD.

[[Page 56927]]

    (b) At the time specified in paragraph (a) of this AD, 
accomplish the actions specified in either paragraph (b)(1) or 
(b)(2) of this AD, as applicable:
    (1) For airplanes specified in Part 1 of Fokker Service Bulletin 
SBF100-71-019, dated March 21, 1996: Modify the hook and latch 
engagement assemblies of the left and right engine cowl doors, and 
inspect to determine the aerodynamic mismatch between the fixed cowl 
and lower cowl door; in accordance with Part 1 of the Accomplishment 
Instructions of Fokker Service Bulletin SBF100-71-019, dated March 
21, 1996.

    Note 2: Accomplishment of the modification of the hook and latch 
engagement assemblies of the left and right engine cowl doors, in 
accordance with Part 1 of the Accomplishment Instructions of Fokker 
Service Bulletin SBF100-71-003, dated April 14, 1989; Revision 1, 
dated August 8, 1989; or Revision 2, dated November 21, 1994; is 
considered acceptable for compliance with the applicable 
modification specified in paragraph (b)(1) of this amendment.

    (2) For airplanes specified in Part 2 of Fokker Service Bulletin 
SBF100-71-019, dated March 21, 1996, excluding those airplanes 
subject to paragraph (b)(1) of this AD: Perform a one-time 
inspection to determine the aerodynamic mismatch between the fixed 
cowl and the lower cowl door, in accordance with Part 2 of the 
Accomplishment Instructions of Fokker Service Bulletin SBF100-71-
019, dated March 21, 1996.
    (c) If the aerodynamic mismatch measured between the fixed cowl 
and lower cowl door is less than or equal to 4.5 mm, no further 
action is required by this AD.
    (d) If the aerodynamic mismatch measured between the fixed cowl 
and lower cowl door is greater than 4.5 mm, prior to further flight, 
perform a one-time inspection to measure the mis-engagement between 
the left and right engine hooks of the fixed cowl door and the 
clevis fittings of the lower cowl door; in accordance with Part 2 of 
the Accomplishment Instructions of Fokker Service Bulletin SBF100-
71-019, dated March 21, 1996.
    (1) If the mis-engagement is less than or equal to 6.5 mm, no 
further action is required by this AD.
    (2) If the mis-engagement is greater than 6.5 mm: Within 1 year 
after measuring the mis-engagement required by this paragraph, 
modify the mid-clevis fitting on the right and left engine lower 
cowl door; in accordance with Part 3 of the Accomplishment 
Instructions of Fokker Service Bulletin SBF100-71-019, dated March 
21, 1996. After accomplishment of this modification, no further 
action is required by 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 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.

    Issued in Renton, Washington, on October 29, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-28323 Filed 11-4-96; 8:45 am]
BILLING CODE 4910-13-P