Airworthiness Directives; Fokker Model F27 Mark 050 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-235-AD; Amendment 39-11484; AD 99-27-03]

RIN 2120-AA64

Airworthiness Directives; Fokker Model F27 Mark 050 Series

Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD),

applicable to certain Fokker Model F27 Mark 050 series airplanes. This

action requires repetitive inspections of the connections between

certain ribs and stringers of the wing skins to detect loose or missing

rivets or gaps, and corrective actions, if necessary. This action also

requires eventual modification of the rib-stringer connection, which

terminates the repetitive inspections. This amendment is prompted by

issuance of mandatory continuing airworthiness information by a foreign

civil airworthiness authority. The actions specified in this AD are

intended to prevent fatigue cracking in the skin and stringers, which

could result in reduced structural integrity of the wings.

DATES: Effective January 13, 2000.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of January 13, 2000.

Comments for inclusion in the Rules Docket must be received on or

before January 28, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-114,

Attention: Rules Docket No. 99-NM-235-AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056.

The service information referenced in this AD may be obtained from

Fokker Services B.V., P.O. Box 231, 2150 AE

[[Page 72914]]

Nieuw-Vennep, The Netherlands. This information may be examined 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.

FOR FURTHER INFORMATION CONTACT: Norman B. Martenson, Manager,

International Branch, ANM-116, FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425)

227-2110; fax (425) 227-1149.

SUPPLEMENTARY INFORMATION: The Rijksluchtvaartdienst (RLD), which is

the airworthiness authority for the Netherlands, notified the FAA that

an unsafe condition may exist on certain Fokker Model F27 Mark 050

series airplanes. The RLD advises that rivet heads were missing at the

rib-to-stringer connections of both the upper and lower wing skin.

Investigation revealed that understrength rivets were used in the

affected connections. Such deficient connections reduce the static

buckling strength of the wing skin and may cause fretting of the

stringer. This condition, if not corrected, could result in fatigue

cracking in the skin and stringers, which could result in reduced

structural integrity of the wings.

Explanation of Relevant Service Information

Fokker has issued Service Bulletin SB50-57-019, dated February 27,

1998, which describes procedures for repetitive detailed visual

inspections of the connections between ribs 11260, 11860, 12660, and

13460, and stringers 4, 5, 6, and 7 of the top and bottom wing skins to

detect loose or missing rivets or gaps. The service bulletin also

describes procedures for modification of the rib-stringer connection.

The modification involves reaming the original rivet holes of the rib-

stringer connections, performing a rotating probe eddy current

inspection to detect cracks of these rivet holes, performing corrective

actions for cases where cracking is detected, and installing connecting

angles between the stringers and ribs. The corrective actions include

reaming the diameter of the rivet hole, performing a surface probe eddy

current inspection to detect cracks of the surrounding of each rivet

hole, drilling out rivets, removing connecting angles, and repairing

angles, as applicable. Accomplishment of the modification eliminates

the need for the repetitive inspections.

For cases where cracking is detected during the visual inspection,

the service bulletin describes procedures for accomplishing either of

the following temporary repairs and eventual modification of the rib-

stringer connection (described previously):

Performing a surface probe eddy current inspection to

detect cracks in the surrounding of the rib-stringer connection in the

area of the gap and/or loose or missing rivets; and installing a shim

between the rib-girder and the stringer and new blind rivets, and

repairing the crack; as applicable.

Performing a surface probe eddy current inspection to

detect cracks in the surrounding of the rib-stringer connection in the

area of the gap and/or loose or missing rivet; and installing

connecting angles and repairing the crack; as applicable.

Accomplishment of the actions specified in the service bulletin is

intended to adequately address the identified unsafe condition. The RLD

classified this service bulletin as mandatory and issued Dutch

airworthiness directive BLA 1998-023/2, dated October 30, 1998, 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 21.19) 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 the 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, this AD requires accomplishment of the actions

specified in the service bulletin described previously, except as

discussed below.

Differences Between Proposed Rule and Service Bulletin

Operators should note that, although the service bulletin specifies

that the manufacturer may be contacted for disposition of certain

repair conditions, this AD requires the repair of those conditions to

be accomplished in accordance with a method approved by the FAA, or the

RLD (or its delegated agent). In light of the type of repair required

to address the identified unsafe condition, and in consonance with

existing bilateral airworthiness agreements, the FAA has determined

that, for this AD, a repair approved by either the FAA or the RLD is

acceptable for compliance with this AD.

Cost Impact

None of the airplanes affected by this action are on the U.S.

Register. All airplanes included in the applicability of this rule

currently are operated by non-U.S. operators under foreign registry;

therefore, they are not directly affected by this AD action. However,

the FAA considers that this rule is necessary to ensure that the unsafe

condition is addressed in the event that any of these subject airplanes

are imported and placed on the U.S. Register in the future.

Should an affected airplane be imported and placed on the U.S.

Register in the future, it would require approximately 11 work hours to

accomplish the required visual inspection, at an average labor rate of

$60 per work hour. Based on these figures, the cost impact of the

visual inspection required by this AD would be $660 per airplane, per

inspection cycle.

Should an affected airplane be imported and placed on the U.S.

Register in the future, it would require approximately between 80 and

116 work hours to accomplish the required modification, at an average

labor rate of $60 per work hour. Required parts would cost

approximately $11,850 per airplane. Based on these figures, the cost

impact of the modification required by this AD would be between $16,650

and $18,810 per airplane.

Determination of Rule's Effective Date

Since this AD action does not affect any airplane that is currently

on the U.S. register, it has no adverse economic impact and imposes no

additional burden on any person. Therefore, prior notice and public

procedures hereon are unnecessary and the amendment may be made

effective in less than 30 days after publication in the Federal

Register.

Comments Invited

Although this action is in the form of a final rule and was not

preceded by notice and opportunity for public comment, comments are

invited on this rule. Interested persons are invited to comment on this

rule by submitting such written data, views, or arguments as they may

desire. Communications shall identify the Rules Docket number

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and be submitted in triplicate to the address specified under the

caption ADDRESSES. All communications received on or before the closing

date for comments will be considered, and this rule may be amended in

light of the comments received. Factual information that supports the

commenter's ideas and suggestions is extremely helpful in evaluating

the effectiveness of the AD action and determining whether additional

rulemaking action would be needed.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the rule that might

suggest a need to modify the 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 that

summarizes each FAA-public contact concerned with the substance of this

AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments

submitted in response to this rule must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket Number 99-NM-235-AD.'' The postcard will be date stamped and

returned to the commenter.

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:

99-27-03 Fokker: Amendment 39-11484. Docket 99-NM-235-AD.

Applicability: Model F27 Mark 050 series airplanes, serial

numbers 20103 through 20298 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 fatigue cracking in the skin and stringers, which

could result in reduced structural integrity of the wings,

accomplish the following:

(a) Perform a detailed visual inspection of the connections

between ribs 11260, 11860, 12660, and 13460, and stringers 4, 5, 6,

and 7 of the top and bottom wing skins to detect loose or missing

rivets or gaps, in accordance with Part 1 of Fokker Service Bulletin

SBF50-57-019, dated February 27, 1998; at the time specified in

paragraph (a)(1), (a)(2), (a)(3), or (a)(4) of this AD, as

applicable. Repeat the inspection thereafter at intervals not to

exceed 2,500 flight cycles.

(1) For airplanes that have accumulated less than 15,000 total

flight cycles as of the effective date of this AD: Inspect prior to

the accumulation of 15,000 total flight cycles, or within 12 months

after the effective date of this AD, whichever occurs later.

(2) For airplanes that have accumulated 15,000 total flight

cycles or more but less than 20,000 total flight cycles as of the

effective date of this AD: Inspect within 12 months after the

effective date of this AD.

(3) For airplanes that have accumulated 20,000 total flight

cycles or more but less than 25,000 total flight cycles as of the

effective date of this AD: Inspect within 6 months after the

effective date of this AD.

(4) For airplanes that have accumulated 25,000 total flight

cycles or more as of the effective date of this AD: Inspect within 3

months after the effective date of this AD.

Note 2: For the purposes of this AD, a detailed visual

inspection is defined as: ``An intensive visual examination of a

specific structural area, system, installation, or assembly to

detect damage, failure, or irregularity. Available lighting is

normally supplemented with a direct source of good lighting at

intensity deemed appropriate by the inspector. Inspection aids such

as mirror, magnifying lenses, etc. may be used. Surface cleaning and

elaborate access procedures may be required.''

(b) Except as provided by paragraph (d) of this AD, if no loose

or missing fastener, or no gap is found during any inspection

required by paragraph (a) of this AD, prior to the accumulation of

40,000 total flight cycles, or within 18 months after the effective

date of this AD, whichever occurs later, modify the rib-stringer

connections (i.e., reaming of rivet holes, rotating probe eddy

current inspections, corrective actions, and installation of

connecting angles) in accordance with Part 2 of the Accomplishment

Instructions of Fokker Service Bulletin SBF50-57-019, dated February

27, 1998. Accomplishment of the actions required by this paragraph

constitutes terminating action for the repetitive inspection

requirements of paragraph (a) of this AD.

(c) If any loose or missing fastener, or any gap is found during

any inspection required by paragraph (a) of this AD, prior to

further flight, accomplish the actions specified in paragraph

(c)(1), (c)(2), or (c)(3) of this AD in accordance with Fokker

Service Bulletin SBF50-57-019, dated February 27, 1998.

(1) Accomplish the modification specified in paragraph (b) of

this AD.

(2) Except as provided by paragraph (d) of this AD, accomplish

the temporary repair (i.e., surface probe eddy current inspection,

repair, and installation of a shim and new blind rivets) in

accordance with Part 3 of the Accomplishment Instructions of the

service bulletin. Within 500 flight cycles after accomplishment of

this temporary repair, accomplish the modification specified in

paragraph (b) of this AD.

(3) Except as provided by paragraph (d) of this AD, accomplish

the temporary repair (i.e., surface probe eddy current inspection,

repair, and installation of connecting angles) in accordance with

Part 4 of the Accomplishment Instructions of the service bulletin.

Within 2,500 flight cycles after accomplishment of this temporary

repair, accomplish the modification specified in paragraph (b) of

this AD.

(d) If any discrepancy is found during any inspection required

by paragraph (a), (b), or (c) of this AD; and Fokker Service

Bulletin SBF50-57-019, dated February 27, 1998, specifies to contact

Fokker for appropriate

[[Page 72916]]

action: Prior to further flight, repair in accordance with either a

method approved by the Manager, International Branch, ANM-116, FAA,

Transport Airplane Directorate, or the Rijksluchtvaartdienst (RLD)

(or its delegated agent). For a repair method to be approved by the

Manager, International Branch, ANM-116, as required by this

paragraph, the Manager's approval letter must specifically reference

this AD.

Alternative Methods of Compliance

(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, International Branch, ANM-116.

Operators shall submit their requests through an appropriate FAA

Principal Maintenance Inspector, who may add comments and then send

it to the Manager, International Branch, ANM-116.

Note 3: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the International Branch, ANM-116.

Special Flight Permits

(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.

Incorporation by Reference

(g) Except as provided by paragraph (d) of this AD, the actions

shall be done in accordance with Fokker Service Bulletin SBF50-57-

019, dated February 27, 1998. 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 Services B.V., P.O. Box 231, 2150 AE Nieuw-Vennep, 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.

Note 4: The subject of this AD is addressed in Dutch

airworthiness directive 1998-023/2, dated October 30, 1998.

(h) This amendment becomes effective on January 13, 2000.

Issued in Renton, Washington, on December 21, 1999.

D. L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-33567 Filed 12-28-99; 8:45 am]

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