Airworthiness Directives; Fokker Model F.28 Mark 0070 and 0100 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Fokker Model F.28 Mark 0070 and 0100 series airplanes. This proposal would require installation of new, improved bonding jumpers on the horizontal stabilizer. This proposal is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by the proposed AD are intended to ensure adequate electrical bonding between the horizontal and vertical stabilizers. Inadequate electrical bonding, in the event of a lightning strike, could cause electrical arcing, and result in damage to the hydraulic lines and consequent failure of the hydraulic systems.

DATES:

Comments must be received by March 6, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-369-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 Services B.V., P.O. Box 231, 2150 AE Nieuw-Vennep, the Netherlands. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

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:

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 99-NM-369-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-114, Attention: Rules Docket No. 99-NM-369-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The Rijksluchtvaartdienst (RLD), which is the airworthiness authority for the Netherlands, notified the FAA that an unsafe condition may exist on all Fokker Model F.28 Mark 0070 and 0100 series airplanes. The RLD advises that in February 1988, during a routine scheduled flight, a Fokker Model F.28 Mark 0100 series airplane was struck by lightning. The report indicated that the No. 2 hydraulic system's “Low Quantity Warning” occurred; shortly thereafter, the same warning occurred on the No. 1 hydraulic system. Although only the hydraulic accumulator-driven systems remained available after the “Total Hydraulic Failure” procedure was accomplished, the flight crew was able to land the airplane safely. Investigation revealed that the lightning current penetrated the vertical stabilizer and bonding jumper of the horizontal stabilizer.

Bonding Jumper Design

At present, on Fokker Model F.28 Mark 0070 and 0100 series airplanes, only a single bonding jumper is installed between the vertical and horizontal stabilizer on the left-hand side. (Currently, no bonding jumper is installed on the right-hand side.) Reports indicate that a bonding jumper had melted, although it is unclear whether this was due to the lightning strike event preceding the hydraulic systems failure, or due to an earlier event. In either case, because the bonding jumper failed, the electrical arcing that resulted from the lightning strike damaged the hydraulic lines.

Further investigation revealed that the existing bonding jumper installation is not adequate to meet certain requirements, and the RLD advises that it is necessary to improve the electrical bonding of the horizontal stabilizer. Inadequate electrical bonding between the horizontal and vertical stabilizers, in the event of a lightning strike, could cause electrical arcing, and result in damage to the hydraulic lines and consequent failure of the hydraulic systems.

Explanation of Relevant Service Information

Fokker has issued Service Bulletin SBF100-23-032, dated September 22, 1999, which describes procedures for installing new, improved bonding jumpers on the horizontal stabilizer. On the left-hand side of the horizontal stabilizer, installation procedures include removing the existing bonding jumper of the horizontal stabilizer torsion box and replacing it with a new, improved bonding jumper; removing and discarding the existing fasteners; and ensuring that the fastener holes are in proper condition. On the right-hand side of the horizontal stabilizer, installation procedures include drilling new fastener holes in the horizontal stabilizer hinge fitting and in the lower skin of the horizontal stabilizer torsion box; deburring all drilled holes; and installing a new, improved bonding jumper. The Fokker service bulletin references Fokker 70/100 Aircraft Maintenance Manual (AMM), Chapter 20-13-05, as an additional source of service information to accomplish the installation of the new bonding jumpers.

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 1999-128(A), dated October 29, 1999, 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 the accomplishment of the actions specified in accordance with the service bulletin described previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletin

Operators should note that, although the service bulletin recommends a compliance time of 24 months for accomplishment of the actions specified in the service bulletin, the RLD has mandated a compliance time of 18 months. The FAA concurs with the RLD and has determined that an 18-month compliance time would have a limited impact on the operators while ensuring the continued safety of the fleet. In determining the proposed compliance time, the FAA considered the safety implications, average utilization rate of the affected fleet, and availability of required modification parts. In light of this, the FAA considers that the proposed compliance time of 18 months is appropriate.

Cost Impact

The FAA estimates that 129 Fokker Model F.28 Mark 0070 and 0100 series airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 2 work hours per airplane to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Required parts would cost approximately $69 per airplane. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $24,381, or $189 per airplane.

The 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 a substantial direct effect 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, it is determined that this proposal would not have federalism implications under Executive Order 13132.

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.