Airworthiness Directives; Bombardier Model DHC-8-400 Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Notice of proposed rulemaking (NPRM).

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 repetitive inspections for cracks of the first fuel access panel outboard of the nacelle on the left- and right-hand wings, and related investigative/corrective actions if necessary. This proposed AD also would require eventual replacement of each access panel with a new access panel having a new part number. The replacement would terminate the repetitive inspection requirements. This proposed AD results from reports of cracks of the fuel access panels. We are proposing this AD to detect and correct cracked fuel access panels, which could lead to arcing and ignition of fuel vapor during a lightning strike, and result in fuel tank explosions and consequent loss of the airplane.

DATES:

We must receive comments on this proposed AD by May 11, 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: (202) 493-2251.
• 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, New York Aircraft Certification Office, FAA, 1600 Stewart Avenue, suite 410, Westbury, New York 11590; telephone (516) 228-7325; fax (516) 794-5531.

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-2006-24365; Directorate Identifier 2006-NM-022-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 (800) 647-5227) 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 there have been a number of reports of cracks of the first fuel access panel outboard of the nacelle. Operators found the cracks, some up to 4 inches long, during routine checks. Investigation showed that certain fuel access panels were manufactured with seal grooves that have sharp corner radii. This condition, if not corrected, could lead to arcing and ignition of fuel vapor during a lightning strike, and result in fuel tank explosions and consequent loss of the airplane.

Relevant Service Information

Bombardier has issued Service Bulletin 84-57-13, dated August 17, 2005. The service bulletin describes procedures for an ultrasonic inspection for cracks of the first fuel access panel outboard of the nacelle on the left- and right-hand wings, and doing the following related investigative and corrective actions, as applicable, before further flight after the inspection:

1. If there is no crack, the service bulletin describes procedures for an ultrasonic inspection to see if there is a radius in the seal groove, and the service bulletin describes procedures for one of the following actions, as applicable:

• If there is a radius in all locations inspected, doing a detailed visual inspection for cracks of the external surface of the panel, and repeating the detailed visual inspection thereafter at intervals not to exceed 1,200 flight hours.
• If a radius is not present in all locations, repeating the ultrasonic inspection for cracks thereafter at intervals not to exceed 1,200 flight hours.
• If any crack is found during any inspection, replacing the panel in accordance with paragraph 2 or 3 below, as applicable.

2. If there is a crack or cracks, and all cracks are inside certain limits specified in the service bulletin, the service bulletin describes procedures for doing one of the following actions: Doing a temporary repair of the crack, and, within 1,000 flight hours after the temporary repair, replacing the cracked access panel with a new panel having one of two new part numbers (P/N) as identified in the service bulletin; or replacing the cracked panel with a new panel having the same P/N that has had an ultrasonic inspection to determine that it has no crack, and doing the ultrasonic inspection and applicable repetitive inspection as described in paragraph 1 above.

3. If there is a crack or cracks, and any crack is outside certain limits specified in the service bulletin, the service bulletin describes procedures for installing a new access panel having a new P/N before further flight.

The service bulletin states that replacing the fuel access panel with a new panel that has a new P/N is terminating action for the repetitive inspections for the replaced fuel access panel; replacing both fuel access panels terminates all repetitive inspections specified in the service bulletin. The service bulletin specifies that both access panels be replaced within 6,000 flight hours after doing the initial ultrasonic inspection.

The service bulletin also describes procedures for reporting the results of the ultrasonic inspections to the manufacturer.

Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.

The service bulletin refers to Bombardier Repair Drawing (RD) 8/4-57-451, dated February 2005, as an additional source of service information for doing the temporary repair.

TCCA mandated the service information and issued Canadian airworthiness directive CF-2005-37, dated October 11, 2005, to ensure the continued airworthiness of these airplanes in Canada.

FAA's Determination and Requirements of the Proposed AD

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. We have examined 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 the service information described previously.

Clarification of Inspection Terminology

In this proposed AD, the “detailed visual inspection” specified in the Canadian airworthiness directive and the service bulletin is referred to as a “detailed inspection” in the proposed AD. We have included the definition for a detailed inspection in a note in the proposed AD.

Costs of Compliance

The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

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.