AD 96-11-16

This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F28 Mark 0100 series airplanes, that requires a one-time measurement during refueling to determine the pressure in each collector tank; for certain airplanes, non-destructive test (NDT) inspections to detect cracking or deformations of the collector tank ribs on each wing, and repair, if necessary; and modification of top-hat stringers in each outer wing tank. This amendment is prompted by a report of damage to the ribs of the wing collector tank caused by over-pressure in the collector tank during refueling. The actions specified by this AD are intended to prevent cracking and deformation of the wing collector tanks due to over-pressure, which could result in reduced structural integrity of the wing.

Final rule

96-11-16 FOKKER: Amendment 39-9640. Docket 95-NM-172-AD.
Applicability: Model F28 Mark 0100 airplanes, serial numbers 11244 through 11277 inclusive, 11279, 11281 through 11287 inclusive, and 11289 through 11400 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 (g) 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 over-pressurization and/or damage to the wing collector tanks, which could result in reduced structural integrity of the wings, accomplish the following:

(a) Within 45 days after the effective date of this AD, perform a one-time measurement during refueling to determine the pressure in each collector tank in accordance with Part 1 of the Accomplishment Instructions of Fokker Service Bulletin SBF100-57-030, dated December 17, 1994.

NOTE 2: Pressure Limits Categories are defined in Table 2 of Fokker Service Bulletin SBF100-57-030, dated December 17, 1994.

(b) For Pressure Limits Category 1: Within 2 years after the effective date of this AD, modify the four affected top-hat stringers (2.32, 2.33, 2.34, and 2.35) in each outer wing tank area by removing the restriction blocks, in accordance with the Accomplishment Instructions of Fokker Service Bulletin SBF100-57-029, Revision 1, dated March 23, 1995.

(c) For Pressure Limits Categories 2 through 5: Except as provided by paragraph (d) of this AD, prior to the number of accumulated total flight cycles or within the time specified in Table 1 of Fokker Service Bulletin SBF100-57-030, dated December 17, 1994, whichever occurs earlier, accomplish the requirements of paragraphs (c)(1) and (c)(2) of this AD.

(1) Perform the Non-Destructive Test (NDT) inspections specified in Part 2 of the Accomplishment Instructions of Fokker Service Bulletin SBF100-57-030, dated December 17, 1994, to detect cracking or deformations of the collector tank ribs on each wing at wing stations 1825, 2230, and 2635. These inspections are to be performed in accordance with Fokker Service Bulletin SBF100-57-030, dated December 17, 1994.

(2) Modify the four affected top-hat stringers (2.32, 2.33, 2.34, and 2.35) in each outer wing tank area by removing the restriction blocks, in accordance with the Accomplishment Instructions ofFokker Service Bulletin SBF100-57-029, Revision 1, dated March 23, 1995.

(d) For Pressure Limits Category 6, and for airplanes having pressure limits within the limits specified in Categories 3 through 5 and that have exceeded the number of accumulated total flight cycles specified in Table 1: Within 100 flight cycles, accomplish the requirements of paragraphs (d)(1) and (d)(2) of this AD.

(1) Perform the NDT inspections in accordance with the procedures of Part 2 of the Accomplishment Instructions of Fokker Service Bulletin SBF100-57-030, dated December 17, 1994. The fueling pressure must not exceed 25 pounds per square inch (PSI) during refueling.

(2) Modify the four affected top-hat stringers (2.32, 2.33, 2.34, and 2.35) in each outer wing tank area by removing the restriction blocks, in accordance with the Accomplishment Instructions of Fokker Service Bulletin SBF100-57-029, Revision 1, dated March 23, 1995.

(e) For Pressure Limits Category 7: Prior to further flight following the measurement required by paragraph (a) of this AD, accomplish the requirements of paragraphs (e)(1) and (e)(2) of this AD.

(1) Perform the NDT inspections in accordance with the procedures of Part 2 of the Accomplishment Instructions of Fokker Service Bulletin SBF100-57-030, dated December 17, 1994.

(2) Modify the four affected top-hat stringers (2.32, 2.33, 2.34, and 2.35) in each outer wing tank area by removing the restriction blocks, in accordance with the Accomplishment Instructions of Fokker Service Bulletin SBF100-57-029, Revision 1, dated March 23, 1995.

(f) If any cracking or deformation is detected during any inspection required by this AD, prior to further flight, repair in accordance with a method approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate.

(g) 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. 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.

(h) 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.

(i) The measurement and inspections shall be done in accordance with Fokker Service Bulletin SBF100-57-030, dated December 17, 1994. The modification shall be done in accordance with Fokker Service Bulletin SBF100-57-029, Revision 1, dated March 23, 1995. 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.

(j) This amendment becomes effective on July 9, 1996.

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 Mark 0100 series airplanes was published in the Federal Register on December 19, 1995 (60 FR 65256). That action proposed to require:

1. a one-time measurement during refueling to determine the pressure in each collector tank;

2. for certain airplanes, non-destructive test (NDT) inspections to detect cracking or deformations of the collector tank ribs on each wing, and repair, if necessary; and

3. modification of top-hat stringers in each outer wing tank.

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
All commenters supported the proposal.

Request Not to Reference New Service Information
Although all of the commenters support the proposal, they have concerns about the recommended compliance times that are specified in a recent revision to Fokker Service Bulletin SBF100-57-030. The original issue of the service bulletin was referenced in the proposal as the appropriate source of service information related to the proposed inspection. The commenters point out that Revision 1 of that service bulletin, which was released on September 27, 1995, now recommends that the inspection be performed within a shorter time period than that recommended in the original issue of the service bulletin. The commenters state that, if the FAA were to reduce the compliance period of the proposed AD as recommended in Revision 1, then they would be faced with scheduling problems and/or increased costs resulting from airplane downtime and labor.

The commenters further point out that Fokker's reason for recommending the more restrictive compliance time specified in Revision 1, is that further analyses could not completely exclude the possibility of static electricity build-up during refueling. The commenters consider this reason to be highly improbable and maintain that it does not constitute adequate justification for the reduced compliance time.

For these reasons, the commenters assert that, if the FAA were to issue a supplemental proposed rule to propose reducing the compliance to correlate with the recommendations of Revision 1 of the service bulletin, they would oppose adoption of the AD.

The FAA responds to these commenters' concern by stating that it does not consider reducing the compliance time of this AD to correlate with the revised service bulletin to be warranted. The FAA has based the compliance time requirements of this AD in consideration of the safety implications, the average utilization rate of the affected fleet, the practical aspects of an orderly inspection of the fleet during regular maintenance periods, and the availability of required modification parts. In addition, theFAA has worked in consultation with the airworthiness authorities of the Netherlands and with Fokker to develop the compliance time. The FAA has determined that the compliance time requirements, as specified in the proposal and in this final rule, are acceptable to correct the unsafe condition in a timely manner.

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 58 airplanes of U.S. registry will be affected by this AD, that it will take approximately 85 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $295,800, or $5,100 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 USC 106(g), 40113, 44701.

39.13 - [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: