AD 98-11-21

This amendment adopts a new airworthiness directive (AD), applicable to certain de Havilland Model DHC-8-102, -103, and -301 series airplanes, that requires a one-time inspection for wear and breakage of wire segments of the individual lighting units of the ceiling and sidewall lights, and replacement of any damaged wiring. This amendment also requires installation of teflon spiral wrap on the wiring of the ceiling and sidewall lights. This amendment is prompted by reports of chafing found on the electrical wiring of the cabin ceiling lighting system. The actions specified by this AD are intended to prevent the possibility of a fire on an airplane due to such chafing and consequent short circuiting, overheating, and smoking of the wires on the aircraft structure.

Final rule

98-11-21 DE HAVILLAND, INC.: Amendment 39-10546. Docket 96-NM-58-AD.

Applicability: Model DHC-8-102, -103, and -301 series airplanes; serial numbers 002 though 010 inclusive, 012 through 201 inclusive, 203 through 209 inclusive, 211 through 215 inclusive, 217 through 220 inclusive, 222, and 223; on which de Havilland Modification 8/1114 or 8/1110 (reference de Havilland Service Bulletin S.B. 8-33-35) has not been accomplished; 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 (b) 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 the possibility of a fire on an airplane due to chafing of the electrical wiring of the cabin ceiling lighting system, accomplish the following:

(a) Within 1,000 hours time-in-service or 6 months after the effective date of this AD, whichever occurs first: Accomplish the requirements of paragraphs (a)(1) and (a)(2) of this AD in accordance with de Havilland Service Bulletin S.B. 8-33-35, dated September 1, 1995.

(1) Perform a one-time inspection for wear and breakage of wire segments of the individual lighting units of the ceiling and sidewall lights. Prior to further flight, replace any damaged wiring.

(2) Install teflon spiral wrap on the wiring of the ceilingand sidewall lights (Modification 8/2158).

(b) 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.

(c) 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.

(d) The actions shall be done in accordance with de Havilland Service Bulletin S.B. 8-33-35, dated September 1, 1995. 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 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, Engine and Propeller Directorate, New York Aircraft Certification Office, 10 Fifth Street, Third Floor, Valley Stream, New York; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

NOTE 3: The subject of this AD is addressed in Canadian airworthiness directive CF-95-18, dated December 15, 1995.

(e) This amendment becomes effective on July 6, 1998.

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-8-102, -103, and -301 series airplanes was published in the Federal Register on September 13, 1996 (61 FR 48437). That action proposed to require a one-time inspection for wear and breakage of wire segments of the individual lighting units of the ceiling and sidewall lights, and replacement of any damaged wiring. That action also proposed to require installation of teflon spiral wrap on the wiring of the ceiling and sidewall lights.

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

One commenter, an aerospace lighting manufacturer, requests that the proposed rule be revised to require, as a first step, an initial inspection of the entire cabin lighting system, and repetitive inspections of the entire cabin lighting system after a fixed number of flight hours after a trigger event such as any lighting component failure. The commenter contends that, despite initial inspections and installation of secondary insulation, cases of fire or smoke caused by arcing from fluorescent lighting high voltage wiring have continued in other airplane models. Further, the commenter notes that an existing AD [AD 95-08-04, amendment 39-9193, (60 FR 19348, April 18, 1995)] was issued for a similar electrical arcing problem of the fluorescent lighting system connector and requires an inspection and modification of some connectors. However, the commenter asserts that the requirement for repetitive inspections is not the total answer in preventing cases of fire or smoke due to arcing from fluorescent lighting high voltage wiring. An additional step would be to require certain protection circuitry for the fluorescent lighting systems that would provide forterminating action of the repetitive inspections. The commenter suggests that, since certain protection circuitry for fluorescent lighting components has been approved by the FAA, is in use on several different airplanes, and has had no negative in-service reports, the FAA should consider requiring installation of such protection circuitry as a terminating action for the requirements of the proposed rule.

The FAA does not concur that installation of protection circuitry should be required in this case. The FAA finds that, based on information provided by the airplane manufacturer, installation of the Teflon spiral wrap will provide an adequate level of safety. No change to the final rule is necessary. However, the FAA may approve a request for an alternative method of compliance under the provisions of paragraph (b) of this final rule if data are submitted to substantiate that an equivalent level of safety would provided.

In regard to the commenter s reference to AD 95-08-04, the FAA acknowledges that the unsafe condition of both AD s are similar (possibility of a fire on an airplane). However, the FAA has determined that the causes of the unsafe condition are not the same. The earlier existing AD addresses a component failure in the high voltage circuitry of the lighting system as the cause of the unsafe condition; this AD addresses chafed wires in the 28VdC supply side of the lighting system as the cause of the unsafe condition. Therefore, the FAA finds that it is logical and practical that the actions required to correct the unsafe condition are not necessarily identical to each other.

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 73 de Havilland Model DHC-8-102, -103, and 301 series airplanes of U.S. registry will be affected by this proposed AD, that itwill take approximately 30 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $250 per airplane. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $149,650, or $2,050 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 among the 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 U.S.C. 106(g), 40113, 44701.

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