03-25588. Airworthiness Directives; Bombardier Model DHC-8-400, -401, and -402 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, -401, and -402 airplanes. This proposal would require a one-time inspection of the forward engine mount assemblies on the left and right engine nacelles for installation of pre-production engine mount assemblies, and follow-on corrective actions if necessary. This action is necessary to prevent failure of the forward engine mount, which could result in reduced structural integrity of the nacelle and engine support structure. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by November 10, 2003.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2002-NM-78-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 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. 2002-NM-78-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 or 2000 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:

Douglas G. Wagner, Aerospace Engineer, Systems and Flight Test Branch, ANE-172, 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 2002-NM-78-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. 2002-NM-78-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, -401, and -402 airplanes. TCCA advises that the manufacturer of the forward engine mount assembly has indicated that an unapproved pre-production engine mount assembly was found installed in place of a production engine mount assembly. Pre-production engine mount assemblies are more susceptible to fatigue cracking than production engine mount assemblies. In addition, there is a possibility that pre-production assemblies having part number (P/N) 96042-07 are incorrectly marked with P/N 96042-09, which is the P/N on the production assemblies. Operation with pre-production engine mount assemblies could result in failure of the forward engine mount, and consequent reduced structural integrity of the nacelle and engine support structure.

Explanation of Relevant Service Information

Bombardier has issued Alert Service Bulletin A84-71-06, Revision “A,” dated December 5, 2001, which describes procedures for a visual inspection to determine the P/N and configuration of the forward engine mount assemblies on the left and right engine nacelles. If the inspection shows that any pre-production engine mount assembly is installed, the service bulletin describes procedures for follow-on corrective actions for that assembly. Those actions include repetitive detailed visual inspections of each assembly for cracking at intervals of 250 flight cycles, and replacement of the pre-production engine mount assembly with a production engine mount assembly before further flight if cracking is found. If no cracking is found, the service bulletin specifies that the pre-production engine mount assembly may remain in service for up to 1,000 flight cycles after the initial inspection, and then reworked or replaced with a production engine mount assembly. If both engine mounts on the same nacelle have the pre-production configuration, the service bulletin specifies that one pre-production engine mount assembly must be replaced with a production engine mount assembly before further flight. The service bulletin also includes a repair letter issued by the engine manufacturer which contains rework procedures for the pre-production engine mount assembly. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.

TCCA classified this service bulletin as mandatory and issued Canadian airworthiness directive CF-2002-07, dated January 21, 2002, to ensure the continued airworthiness of these airplanes in Canada.

FAA's Conclusions

These airplane models are manufactured in Canada and are 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 us informed of the situation described above. We have 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 bulletin described previously, except as discussed below.

Differences Between Canadian Airworthiness Directive, Service Bulletin, and Proposed Rule

The service bulletin and Canadian airworthiness directive specify a visual inspection to determine the P/N and configuration of the forward engine mount assemblies, but this proposed rule would require a general visual inspection. A note has been added to the proposed rule to define that inspection.

The service bulletin and Canadian airworthiness directive also specify a detailed visual inspection for cracking if a pre-production engine mount is installed, but this proposed rule would require a detailed inspection. A note has been added to the proposed rule to define that inspection.

Cost Impact

We estimate that 11 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 inspection, and that the average labor rate is $65 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $1,430, or $130 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. 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 2002-NM-78-AD.

Applicability: Model DHC-8-400, -401, and -402 airplanes; serial numbers 4005, 4006, 4008 through 4016 inclusive, 4018 through 4051 inclusive, and 4053; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of the forward engine mount, which could result in reduced structural integrity of the nacelle and engine support structure, accomplish the following:

Inspection

(a) Within 100 flight cycles after the effective date of this AD: Do a general visual inspection of the forward engine mount assemblies on the left and right engine nacelles for installation of pre-production assemblies (determine the part number and configuration for each assembly), per the Accomplishment Instructions of Bombardier Alert Service Bulletin A84-71-06, Revision “A,” dated December 5, 2001. If no pre-production engine mount assembly is installed, no further action is required by this AD.

Note 1:

For the purposes of this AD, a general visual inspection is defined as: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to enhance visual access to all exposed surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

Follow-On Corrective Actions

(b) If any pre-production engine mount assembly is installed, do all the applicable follow-on corrective actions (including repetitive detailed inspections for cracking, and rework or replacement of the pre-production engine mount assembly, if necessary) per all the actions specified in the Accomplishment Instructions of the service bulletin, at the applicable times specified in Paragraph I., Part D., “Compliance,” of the service bulletin. Any replacement due to cracking must be done before further flight.

Note 2:

For the purposes of this AD, a detailed inspection is defined as: “An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”

Optional Terminating Action for Follow-On Repetitive Inspections

(c) Installation of production engine mount assemblies on all four forward engine mounts ends the repetitive inspection requirements of paragraph (b) of this AD.

Part Installation

(d) As of the effective date of this AD, no person may install an engine mount assembly having a pre-production configuration and/or part number 96042-07 on any airplane, unless the assembly has been reworked per Part B of the Accomplishment Instructions of Bombardier Alert Service Bulletin A84-71-06, Revision “A,” dated December 5, 2001.

Alternative Methods of Compliance

(e) In accordance with 14 CFR 39.19, the Manager, New York Aircraft Certification Office, FAA, is authorized to approve alternative methods of compliance for this AD.

Note 3:

The subject of this AD is addressed in Canadian airworthiness directive CF-2002-07, dated January 21, 2002.

Issued in Renton, Washington, on October 3, 2003.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.