01-28797. Airworthiness Directives; Bombardier Model DHC-8-400 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 certain Bombardier Model DHC-8-400 series airplanes. This proposal would require two actions—a modification and a replacement—affecting the fuel tanks in the wings. All affected airplanes would require modification of the clearance of the fuel tank vent lines to the left and the right wing fuel tanks. Some affected airplanes would also require replacement of three existing fuel probes from the center fuel tank on the left and right wings with new production fuel probes. This action is prompted by mandatory continuing airworthiness information from a foreign airworthiness authority. This action is necessary to prevent inadequate clearance between the fuel tank vent lines and the adjacent rib structures of the wings or failure of certain temporary, reworked fuel probes in the center fuel tanks in the wings. Either condition could compromise the airplane's lightning protection system, possibly resulting in a fire or explosion if the airplane were hit by lightning. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by December 19, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket Number 2001-NM-140-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. Comments may be submitted via fax to [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2001-NM-140-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

The service information referenced in the proposed rule may be obtained from Bombardier, Inc., Bombardier Regional Aircraft Division, 123 Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, New York Aircraft Certification Office, 10 Fifth Street, Third Floor, Valley Stream, New York.

FOR FURTHER INFORMATION CONTACT:

James Delisio, Aerospace Engineer, ANE-171, FAA, New York Aircraft Certification Office, 10 Fifth Street, Third Floor, Valley Stream, New York 11581; telephone [phone]; fax [phone].

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 action may be changed in light of the comments received.

Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

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 action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2001-NM-140-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. 2001-NM-140-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

Transport Canada Civil Aviation (TCCA), which is the airworthiness authority for Canada, notified the FAA that an unsafe condition may exist on certain Bombardier Model DHC-8-400 series airplanes. TCCA advises that two problems have been identified with the wing fuel tanks which, if not corrected, could compromise the lightning protection of the airplanes. The first problem is a possible lack of clearance between the fuel tank vent lines and the adjacent wing rib structures. The second is possible failure of temporary, re-worked fuel probes in the wing center fuel tanks. Either condition, if not corrected, could compromise the airplane's lightning protection system, possibly resulting in a fire or explosion if the airplane were hit by lightning.

Explanation of Relevant Service Information

Bombardier has issued Alert Service Bulletin A84-28-02, dated February 7, 2001, which describes procedures for modification of the fuel tank vent lines by adding Teflon tubing and band clamps to insulate and separate the fuel tank vent lines from the adjacent wing rib structures. Bombardier has also issued Service Bulletin 84-28-01, Revision ‘A’, dated February 8, 2001, which describes procedures for replacement of existing fuel probes numbers 1, 2, and 5 with new production fuel probes. The existing fuel probes were previously reworked as a temporary solution to potential inadequate clearance between the fuel probes and the structure of the center fuel tanks in the wings. Accomplishment of the actions specified in the service bulletins is intended to adequately address the identified unsafe condition. TCCA classified these service bulletins as mandatory and issued Canadian airworthiness directive CF-2001-14, dated March 21, 2001, in order to assure the continued airworthiness of these airplanes in Canada.

FAA's Conclusions

This airplane model is manufactured in Canada 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, TCCA has kept the FAA informed of the situation described above. The FAA has examined the findings of TCCA, 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 accomplishment of the actions specified in the service bulletins described previously.

Cost Impact

There are approximately 32 airplanes of the affected design in the worldwide fleet. The FAA estimates that 15 airplanes of U.S. registry would be affected by the proposed AD with 13 airplanes affected by the proposed modification of the clearance of the fuel tank vent line and 7 airplanes affected by the proposed replacement of the numbers 1, 2, and 5 fuel probes.

It would take approximately 12 work hours to accomplish the proposed modification of the clearance of the fuel tank vent line, at an average labor rate of $60 per work hour. Required parts would cost approximately $440 per airplane. Based on these figures, the cost impact of the proposed modification on U.S. operators is estimated to be $15,080, or $1,160 per airplane.

It would take approximately 2 work hours to accomplish the proposed replacement of fuel probes numbers 1, 2, and 5, at an average labor rate of $60 per work hour. The required parts would be provided by the manufacturer at no cost to the operators. Based on these figures, the cost impact of the proposed replacement on U.S. operators is estimated to be $840, or $120 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, and that no operator would accomplish those actions in the future if this proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

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.

§ 39.13

[Amended]

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

Bombardier, Inc. (Formerly de Havilland, Inc.): Docket 2001-NM-140-AD.

Applicability: Model DHC-8-400 series airplanes; certificated in any category; serial numbers 4005, 4006, 4008 through 4010 inclusive, 4012 through 4015 inclusive, and 4018 through 4040 inclusive.

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 (c) 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 inadequate clearance between the fuel tank vent line and the adjacent rib structures of the wings or failure of certain temporary, reworked fuel probes in the center fuel tanks in the wings, either of which could compromise the airplane's lightning protection system, possibly resulting in a fire or explosion if the airplane were hit by lightning, accomplish the following:

Modification of Clearance of Fuel Tank Vent Lines

(a) For airplanes having serial numbers 4005, 4006, 4008 through 4010 inclusive, 4012 through 4015 inclusive, and 4018 through 4040 inclusive: Within 120 days after the effective date of this AD, modify the clearance of the fuel tank vent lines to the left and the right wing fuel tanks by wrapping 1 piece of Teflon tube around the vent line at each of 10 stations (2 pieces at station 191.200) and securing it with a clamping band (2 clamping bands at station 191.200), in accordance with the Accomplishment Instructions (including Table 1) and Figure 1 of Bombardier Alert Service Bulletin A84-28-02, dated February 7, 2001.

Replacement of Fuel Probes Numbers 1, 2, and 5

(b) For airplanes having serial numbers 4006, 4008, 4012 through 4015 inclusive, and 4018 through 4027 inclusive: Prior to the accumulation of 4,000 flight hours after the effective date of this AD, or within 120 days after the effective date of this AD, whichever occurs later: Replace existing fuel probes numbers 1, 2, and 5 from the center fuel tank on the left and the right wings with new production fuel probes, in accordance with Bombardier Service Bulletin 84-28-01, Revision “A,” dated February 8, 2001.

Alternative Methods of Compliance

(c) 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, New York Aircraft Certification Office (ACO), FAA. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, New York ACO.

Note 2:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the New York ACO.

Special Flight Permits

(d) 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.

Note 3:

The subject of this AD is addressed in Canadian airworthiness directive CF-2001-14, dated March 21, 2001.

Issued in Renton, Washington, on November 9, 2001.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.