AD 2000-01-07

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Bombardier Model DHC-8-100, -200, and -300 series airplanes. This action requires the removal and testing of sections of bonded skin from the upper and lower skin panels of the horizontal stabilizer, repair of those areas, and follow-on corrective actions, if necessary. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified in this AD are intended to prevent reduced strength capability and consequent failure of the horizontal stabilizer, which could result in loss of controllability of the airplane.

Final rule; request for comments

2000-01-07 BOMBARDIER, INC. (Formerly de Havilland, Inc.): Amendment 39-11504. Docket 99-NM-357-AD.

Applicability: Model DHC-8-100, -200, and -300 series airplanes, certificated in any category; equipped with Canadian Aviation Products (CAP) horizontal stabilizers having serial numbers CAP 003 through CAP 050 inclusive.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been 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 (d) 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 reduced strength capability of the horizontal stabilizer and consequent failure of the horizontal stabilizer, which could result in loss of controllability of the airplane, accomplish the following:

Removal of Skin Sections
(a) Within 2 months after the effective date of this AD, accomplish the requirements of paragraphs (a)(1), (a)(2), and (a)(3) of this AD.

(1) Remove sections of bonded skin (test coupons) from the upper panel P/N 85510026, and the lower skin panel P/N 85510025, of the horizontal stabilizer port and starboard side, at stations Yh77.50-90.90 between stringer number 6 and the rear spar, in accordance with a method approved by the Manager, FAA, Engine and Propeller Directorate, New York Aircraft Certification Office (ACO); and

(2) Mark and send for testing the removed sections of bonded skin to the attention of M. Elliott X3177 or M. Clark X3092, Bombardier Aerospace Mailroom (A.O.G.), 123 Garratt Boulevard, Downsview, Ontario, Canada, M3K-1Y5; and

(3) Repair the areas where the sections of bonded skin were removed, in accordance with a method approved by the Manager, FAA, Engine and Propeller Directorate, New York Aircraft Certification Office (ACO). After the repair, the airplane may be returned to service while awaiting test results.

NOTE 2: The Manager, FAA, Engine and Propeller Directorate, New York ACO, has approved Bombardier Repair Drawing RD8-55-669, Issue 3, dated March 17, 1999, as an acceptable method for accomplishing the actions required by paragraph (a) of this AD. Operators should note that the repair drawing recommends a one-time ultrasonic inspection to detect disbonding on the stringers and doublers of the horizontal stabilizer. However, the approved method of compliance does not require the ultrasonic inspection.

Corrective Actions
(b) Within 30 days following the removal of the sections of bonded skin (test coupons) from the upper and lower skin panels of the horizontal stabilizer, determine the test results and accomplish paragraph (b)(1) or (b)(2) of this AD, as applicable.

(1) For airplanes on which all sections of bonded skin (test coupons) pass the test required by this AD, no further action is required by this AD.

(2) For airplanes on which any section of bonded skin (test coupon) fails the test, prior to further flight, either replace the horizontal stabilizer with a new horizontal stabilizer in accordance with Bombardier Service Bulletin S.B. 8-55-24, dated February 26, 1998, or repair in accordance with a method approved by the Manager, New York ACO.

(c) Model DHC-8-100, -200, and -300 series airplanes, equipped with Canadian Aviation Products (CAP) horizontal stabilizers having serial numbers CAP 003 through CAP 050 inclusive: Passing the test on all sections of bonded skin constitutesterminating action for the repetitive inspections required by AD 98-24-18, amendment 39-10903. Accomplishment of either the replacement or an approved repair, as required by paragraph (b)(2) of this AD, on any airplane on which any section of bonded skin fails the test also constitutes terminating action for the repetitive inspections required by AD 98-24-18, amendment 39-10903.

NOTE 3: Following accomplishment of the requirements of this AD, the horizontal stabilizer remains subject to the normal bonding integrity inspection program, which is performed in accordance with de Havilland Product Support Manual (PSM) 1-8-7.

Alternative Methods of Compliance
(d) 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 ACO. 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 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the New York ACO.

Special Flight Permits
(e) 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.

Incorporation by Reference
(f) Except as provided by paragraphs (a)(1) and (a)(3) of this AD, the actions shall be done in accordance with Bombardier Service Bulletin S.B. 8-55-24, dated February 26, 1998, as applicable. 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, 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 5: The subject of this AD is addressed in Canadian airworthiness directive CF-99-15R1, dated December 6, 1999.

(g) This amendment becomes effective on January 27, 2000.

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-8-100, -200, and -300 series airplanes. TCCA advises that it received results of previous inspections to detect disbonding of the upper and lower skin panels of the horizontal stabilizer. Results of these inspections indicate that certain doublers and stringers were disbonded from their skin panels. The subject doublers and stringers are installed on the upper and lower skin panels of the horizontal stabilizer at stations Yh6.15-139.00 between the front spar and rear spar. The cause of such disbonding has been attributed to an improper bonding process of the skin panels of the doublers and stringers during manufacturing. This condition, if not corrected, could result in reduced strength capability and consequent failure of horizontal stabilizer, which could further result in loss of controllability of the airplane.

TCCA has recommended further testing on sample coupons of the sections of skin panels to determine the bonding integrity of the skin panels. A destructive peel test would be conducted on the removed sections of bonded skin (test coupons) by the manufacturer. This type of testing would determine how much force is necessary in order to separate the bonded layers of the skin panel.

Explanation of Relevant Service Information
The manufacturer has issued Bombardier Service Bulletin S.B. 8-55-24, dated February 26, 1998, which describes procedures for replacement of the horizontal stabilizer with a new horizontal stabilizer.

Accomplishment of the test on the sample coupons and, if necessary, accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition. TCCA approved this service bulletin and issued Canadian airworthiness directive CF-99-15R1, dated December 6, 1999, inorder to assure the continued airworthiness of these airplanes in Canada.

Related Rulemaking
On November 16, 1998, the FAA issued AD 98-24-18, amendment 39-10903 (63 FR 64609, November 23, 1998), applicable to certain Bombardier Model DHC-8-100 and -300 series airplanes equipped with Canadian Aviation Products (CAP) horizontal stabilizers having serial numbers 003 through 214, that requires repetitive ultrasonic inspections to detect disbonding of the upper and lower skin panels of the horizontal stabilizer, and repair, if necessary.

Based on the information provided by TCCA, the FAA has determined that an additional disbonding test of the skin panels is needed on airplanes equipped with CAP horizontal stabilizers having serial numbers 003 through 050, the repetitive ultrasonic inspections required by AD 98-24-18 may not be adequate to detect disbonding of the upper and lower skin panels of the horizontal stabilizer, and, therefore, may not be providing an adequate level of safety for the transport airplane fleet. This AD affects the requirements of that AD. For certain airplanes, the corrective actions of this AD eliminate the need for the repetitive inspections required by AD 98-24-18.

FAA's Conclusions
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. The FAA has 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 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, this AD is being issued to prevent reduced strength capability of the horizontal stabilizer and consequent failure of the horizontal stabilizer, which could result in loss of controllability of the airplane. This AD requires removal and testing of the sections of bonded skin from the upper and lower skin panels of the horizontal stabilizer, repair of those areas, and follow-on corrective actions, if necessary. Certain actions (removal and repair) are required to be accomplished in accordance with a method approved by the Manager, FAA, Engine and Propeller Directorate, New York Aircraft Certification Office (ACO). Other actions (replacement) are required to be accomplished in accordance with the service bulletin described previously.

Determination of Rule's Effective Date
Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Comments Invited
Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this 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 under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 99-NM-357-AD." The postcard will be date stamped and returned to the commenter.

Regulatory Impact
The regulations adopted herein 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. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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 tothe 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: