AD 96-11-06

This amendment adopts a new airworthiness directive (AD), applicable to certain de Havilland Model DHC-7 series airplanes, that requires modification of the emergency lights circuitry. This amendment is prompted by reports of the emergency lights turning on inadvertently due to voltage spikes from other equipment; and reports that the existing emergency light switch arrangement allows the flight compartment and flight attendant's panel switches to override each other. The actions specified by this AD are intended to prevent such failures of the emergency light systems, which could prevent the use of the emergency lights in the event of an emergency.

Final rule

96-11-06 DE HAVILLAND, INC.: Amendment 39-9631. Docket 95-NM-110-AD.
Applicability: Model DHC-7 series airplanes, serial numbers 3 through 27 inclusive, on which de Havilland Modification No. 7/1697 has not been installed; certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise 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 failure of the emergency lighting system due to voltage spikes from other equipment or due to inadvertent override of the emergency lighting switches, accomplish the following:

(a) Within 6 months after the effective date of this AD, modify the emergency lights circuitry by accomplishing de Havilland Modification No. 7/1697 (Emergency Lights- Revised Switching Logic), in accordance with the Accomplishment Instructions of de Havilland Service Bulletin No. 7-33-7, dated October 17, 1980.

(b) As of the effective date of this AD, no person shall install an emergency light switch, part number MS24659-21A, on any airplane subject to this AD.

(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, Engine and Propeller Directorate. 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.

(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.

(e) The modification shall be done in accordance with de Havilland Service Bulletin No. 7-33-7, dated October 17, 1980. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Bombardier, Inc., Bombardier Regional Aircraft Division, Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, New York Aircraft Certification Office, Engine and Propeller Directorate, 10 Fifth Street, Third Floor, , Valley Stream, New York 11581; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(f) This amendment becomes effective on June 28, 1996.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain de Havilland Model DHC-7 series airplanes was published in the Federal Register on January 9, 1996 (61 FR 636). That action proposed to require modification of the emergency lights circuitry.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Support for the Proposal
Two commenters support the proposed rule.

Request to Include an Additional Modification Requirement
One commenter requests that proposed rule be revised to include a requirement to install Modification 7/2622. This modification is described in de Havilland Service Bulletin 7-33-23 and also affects the emergency lighting system. The commenter mentions that this modification is mandated by Canadian airworthiness directive CF 95-03. The commenter states that, by including a requirement in the proposal to install Modification 7/2622, safety would be enhanced and unnecessary requests for alternate means of compliance would be avoided.

The FAA does not concur with the commenter's request to revise this AD action to require installation of Modification 7/2622. The FAA finds that, although the unsafe condition that prompted the Transport Canada airworthiness action to mandate that modification concerns the failure of the emergency lighting systems, the cause of that failure is different from the causes of failure addressed in this AD. Additionally, the modification affects some airplanes other than those identified in the applicability of this AD.

However, the FAA is considering separate rulemaking action to address the installation of Modification 7/2622 on applicable airplanes.

Conclusion
After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

Cost Impact
The FAA estimates that 14 airplanes of U.S. registry will be affected by this AD, that it will take approximately 8 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will be provided at no cost to the operators. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $6,720, or $480 per airplane.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.

Regulatory Impact
The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities amongthe various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under 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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to 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:

PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 USC 106(g), 40113, 44701.

39.13 - [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: