E6-1684. Airworthiness Directives; Bombardier Model DHC-8-400 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking.

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Bombardier Model DHC-8-400 series airplanes. This proposed AD would require replacing all domed anchor nuts at all attachment locations of the upper fuel access panels of the center wing in the wet bay location with new nuts. This proposed AD results from reported cases of corroded dome anchor nuts at the attachment locations of the upper surface of the fuel access panel of the center wing. We are proposing this AD to prevent corrosion or perforation of domed anchor nuts, which could result in arcing and ignition of fuel vapor in the center wing fuel tank during a lightning strike and consequent explosion of the fuel tank.

DATES:

We must receive comments on this proposed AD by March 10, 2006.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

• DOT Docket Web site: Go to http: //dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., Nassif Building, room PL-401, Washington, DC 20590.
• Fax: [phone].
• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Contact Bombardier, Inc., Bombardier Regional Aircraft Division, 123 Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada, for service information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT:

George Duckett, Aerospace Engineer, Airframe and Propulsion Branch, ANE-171, FAA, New York Aircraft Certification Office, 1600 Stewart Avenue, suite 410, Westbury, New York 11590; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed in the ADDRESSES section. Include the docket number “FAA-2006-23798; Directorate Identifier 2005-NM-162-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov.

Examining the Docket

You may examine the AD docket on the Internet at http://dms.dot.gov,, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone [phone]) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the Docket Management System receives them.

Discussion

Transport Canada Civil Aviation (TCCA), which is the airworthiness authority for Canada, notified us that an unsafe condition may exist on certain Bombardier Model DHC-8-400 series airplanes. TCCA advises that, during “2C” checks, there have been a number of reported cases of corrosion of dome anchor nuts at the attachment locations of the upper surface of the fuel access panel of the center wing. In some cases, the dome anchor nuts were severely corroded and perforated. This condition, if not corrected, could result in arcing and ignition of fuel vapor in the center wing fuel tank during a lightning strike and consequent explosion of the fuel tank.

Relevant Service Information

Bombardier has issued Service Bulletin 84-57-10, Revision “A,” dated March 14, 2005. The service bulletin describes procedures for replacing all domed anchor nuts at all attachment locations of the upper fuel access panels of the center wing in the wet bay location with new, corrosion-resistant anchor nuts. Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.

The TCCA mandated the service information described previously, or Bombardier Service Bulletin 84-57-11, dated February 25, 2004, or Revision “A,” dated March 9, 2004; and Bombardier Service Bulletin 84-57-12, dated March 11, 2005. The TCCA also issued Canadian airworthiness directive CF-2005-08R1, issued August 10, 2005, to ensure the continued airworthiness of these airplanes in Canada.

FAA's Determination and Requirements of the Proposed AD

These airplane models are manufactured in Canada and are type certificated for operation in the United States under the provisions of § 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the TCCA has kept the FAA informed of the situation described above. We have examined the TCCA's findings, evaluated all pertinent information, and determined that we need to issue an AD for airplanes of this type design that are certificated for operation in the United States.

Therefore, we are proposing this AD, which would require accomplishing the actions specified in Bombardier Service Bulletin 84-57-10, Revision “A,” dated March 14, 2005.

Differences Between the Proposed AD and the Canadian Airworthiness Directive

Instead of doing the replacement specified in Bombardier Service Bulletin 84-57-10, Revision “A,” dated March 14, 2005, Canadian airworthiness directive mandates the inspections, installation, and corrective actions if necessary specified in Bombardier Service Bulletin 84-57-11, dated February 25, 2004, or Revision “A,” dated March 9, 2004; and Bombardier Service Bulletin 84-57-12, dated March 11, 2005. The TCCA allows those actions because of the limited availability of new, corrosion-resistant anchor nuts.

Since issuance of the Canadian airworthiness directive, the TCCA has advised us that corrosion-resistant anchor nuts are now available. Therefore, this proposed AD would require only the replacement specified in Bombardier Service Bulletin 84-57-10. In addition, the Canadian airworthiness directive requires the replacement within 9 months after April 27, 2005 (the effective date of the Canadian airworthiness directive). However, this proposed AD would require the replacement within 3 months after the effective date of the AD. Deterioration of anchor nuts over time can cause the anchor nuts to become perforated, which could result in a potential source of ignition in a fuel tank and consequent fire or explosion. Therefore, we have determined that a compliance time of 3 months after the effective date of this AD is the maximum time allowable for all affected airplanes to continue to operate without compromising safety. TCCA agrees with our decision to mandate that replacement and to shorten the compliance time, which will align closer to their compliance date. Bombardier has been contacted, and they can support the part requirements.

Costs of Compliance

This proposed AD would affect about 20 airplanes of U.S. registry. The proposed actions would take about 62 work hours per airplane, at an average labor rate of $65 per work hour. Required parts would cost about $300 per airplane. Based on these figures, the estimated cost of the proposed AD for U.S. operators is $86,600, or $4,330 per airplane.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, section 44701, “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD 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.

For the reasons discussed above, I certify that the 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. 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.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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. The Federal Aviation Administration (FAA) amends § 39.13 by adding the following new airworthiness directive (AD):

Bombardier, Inc. (Formerly de Havilland, Inc.): Docket No. FAA-2006-23798; Directorate Identifier 2005-NM-162-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by March 10, 2006.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Bombardier Model DHC-8-400 series airplanes, certificated in any category; serial numbers 4001, and 4003 through 4115 inclusive.

Unsafe Condition

(d) This AD results from reported cases of corroded dome anchor nuts at the attachment locations of the upper surface of the fuel access panel of the center wing. We are issuing this AD to prevent corrosion or perforation of domed anchor nuts, which could result in arcing and ignition of fuel vapor in the center wing fuel tank during a lightning strike and consequent explosion of the fuel tank.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Replacement With Corrosion Resistant Anchor Nuts

(f) At the applicable time in Table 1 of this AD, replace all domed anchor nuts at all attachment locations of the upper fuel access panels of the center wing in the wet bay location with new, corrosion-resistant anchor nuts. Do all the actions in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 84-57-10, Revision ‘A,’ dated March 14, 2005.

Table 1.—Compliance Time

For airplanes having serial number(s)	On which the inspection(s) specified in	Do the replacement
(1) 4108 through 4115 inclusive	None	Within 48 months after the date of issuance of the original standard Canadian airworthiness certificate or the date of issuance of the original Canadian export certificate of airworthiness, or within 2 months after the effective date of this AD, whichever occurs later.
(2) 4001, and 4003 through 4107 inclusive	Bombardier Service Bulletin 84-57-11, dated February 25, 2005; or Revision ‘A,’ dated March 9, 2005; have been done before the effective date of this AD	Within 24 months after those inspections, or within 2 months after the effective date of this AD, whichever occurs later.
	Bombardier Service Bulletin 84-57-12, dated March 11, 2005, has been done before the effective date of this AD	Within 48 months after that inspection, or within 2 months after the effective date of this AD, whichever occurs later.
	Bombardier Service Bulletin 84-57-11, dated February 25, 2005, or Revision ‘A,’ dated March 9, 2005; or Bombardier Service Bulletin 84-57-12, dated March 11, 2005; has not been done before the effective date of this AD	Within 3 months after the effective date of this AD.

Alternative Methods of Compliance (AMOCs)

(g)(1) The Manager, New York Aircraft Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

(2) Before using any AMOC approved in accordance with § 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office.

Related Information

(h) Canadian airworthiness directive CF-2005-08R1, issued August 10, 2005, also addresses the subject of this AD.

Issued in Renton, Washington, on January 26, 2006.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.