AD 2004-21-06

This AD becomes effective on December 6, 2004.

As of December 6, 2004, the Director of the Federal Register approved the incorporation by reference of certain publications listed in the regulation.

You may get the service information identified in this AD from Bombardier Commercial Service Center, Plant 9, C.P. 6087 Succurale Centre-ville, Montreal QC H3C 3G9, Canada.

You may view the AD docket at FAA, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 2004-CE-02-AD, 901 Locust, Room 506, Kansas City, Missouri 64106. Office hours are 8 a.m. to 4 p.m., Monday through Friday, except Federal holidays.

Mazdak Hobbi, Aerospace Engineer, New York Aircraft Certification Office (ACO), FAA, 1600 Stewart Avenue, Suite 410, Westbury, New York 11590; telephone: (516) 228-7330; facsimile: (516) 794-5531.

What events have caused this AD? Transport Canada, which is the airworthiness authority for Canada, recently notified FAA that an unsafe condition may exist on all deHavilland DHC-2 Mk. I and DHC-2 Mk. II airplanes and all Bombardier (Otter) DHC-3 airplanes powered by radial engines. Transport Canada reports that a DHC-3 airplane lost both ignition systems during flight.

The lockwire hole in the connector plug on the firewall broke and the plug vibrated loose. Both magnetos then grounded through a spring-loaded center pin in the plug (a maintenance safety feature).

The DHC-2 Mk. I and DHC-2 Mk. II airplanes have a similar ignition system.

What is the potential impact if FAA took no action? If not detected and corrected, failure of the lockwire hole could result in engine failure. This failure could lead to a forced landing of the airplane.

Has FAA taken any action to this point? We issued a proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to all deHavilland Inc. Models DHC-2 Mk. I and DHC-2 Mk. II airplanes, and all Bombardier Inc. (Otter) DHC-3 airplanes powered by radial engines of the same type. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on April 12, 2004 (69 FR19132). The NPRM proposed to require you to visually inspect the firewall connector plugs for proper lockwire security and replace or modify as appropriate.

Comment Issue No. 1: Incorporate Revision “B” of the Applicable Service Bulletins

What is the commenter's concern? The manufacturer has revised the applicable service bulletins to clarify the information presented in the Description and in the Accomplishment Instructions.

The revisions delete the requirement to remove the upholstery in order to perform the visual inspections and delete the requirement to inspect the receptacle. The receptacle is attached with four self-locking nuts. Lockwire is not used to secure these nuts.

The manufacturer wants the revised service bulletins incorporated into the final rule AD action.

What is FAA's response to the concern? We concur with the commenter and will make these changes in the final rule AD action.

Comment Issue No. 2: Update the Manufacturer's Address

What is the commenter's concern? The manufacturer has provided an updated address and wants it incorporated into the final rule AD action.

What is FAA's response to the concern? We concur with the commenter and will make these changes in the final rule AD action.

What is FAA's final determination on this issue? We have carefully reviewed the available data and determined that air safety and the public interest require adopting the AD as proposed except for the changes discussed above and minor editorial corrections. We have determined that these changes and minor corrections:

• Are consistent with the intent that was proposed in the NPRM for correcting the unsafe condition; and

• Do not add any additional burden upon the public than was already proposed in the NPRM.

How does the revision to 14 CFR part 39 affect this AD? On July 10, 2002, the FAA published a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs the FAA's AD system. This regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance. This material previously was included in each individual AD. Since this material is included in 14 CFR part 39, we will not include it in future AD actions.

How many airplanes does this AD impact? We estimate that this AD affects 242 airplanes in the U.S. registry.

What is the cost impact of this AD on owners/operators of the affected airplanes? We estimate the following costs to accomplish the inspection(s):

We estimate the following costs to accomplish any necessary replacements that will be required based on the results of the inspection(s). We have no way of determining the number of airplanes that may need these replacements:

Will this AD impact various entities? We have determined that this AD will not have federalism implications under Executive Order 13132. This AD will 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.

Will this AD involve a significant rule or regulatory action? For the reasons discussed above, I certify that this AD:

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 summary of the costs to comply with this AD and placed it in the AD Docket. You may get a copy of this summary by sending a request to us at the address listed under ADDRESSES. Include “AD Docket No. 2004-CE-02-AD” in your request.

Accordingly, under the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

1. The authority citation for part 39 continues to read as follows:

2. FAA amends § 39.13 by adding a new AD to read as follows: