[Federal Register Volume 59, Number 131 (Monday, July 11, 1994)] [Unknown Section] [Page 0] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 94-16405] [[Page Unknown]] [Federal Register: July 11, 1994] ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION 14 CFR Part 39 [Docket No. 94-NM-75-AD; Amendment 39-8967; AD 94-14-19] Airworthiness Directives; de Havilland Model DHC-7 Series Airplanes AGENCY: Federal Aviation Administration, DOT. ACTION: Final rule; request for comments. ----------------------------------------------------------------------- SUMMARY: This amendment adopts a new airworthiness directive (AD) that is applicable to certain de Havilland Model DHC-7 series airplanes. This action requires repetitive inspections of the hydraulic selector valve to determine the rate of leakage of hydraulic fluid, and replacement of certain valves with serviceable valves, if necessary. This AD also provides an optional terminating action for the repetitive inspections. This amendment is prompted by a report of pilot valve leakage of hydraulic fluid in a landing gear selector valve on a Model DHC-7 series airplane. The actions specified in this AD are intended to prevent inadvertent retraction of the landing gear in the event of a low voltage condition at the selector valve down solenoid. DATES: Effective July 26, 1994. The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of July 26, 1994. Comments for inclusion in the Rules Docket must be received on or before September 9, 1994. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 94-NM-75-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. The service information referenced in this AD may be obtained from de Havilland, Inc., 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, Engine and Propeller Directorate, New York Aircraft Certification Office, 181 South Franklin Avenue, room 202, Valley Stream, New York; or at the Office of the Federal Register, 800 North Capitol Street NW., suite 700, Washington, DC. FOR FURTHER INFORMATION CONTACT: Danko Kramar, Aerospace Engineer, Systems and Equipment Branch, ANE-173, FAA, Engine and Propeller Directorate, New York Aircraft Certification Office, 181 South Franklin Avenue, Room 202, Valley Stream, New York 11581; telephone (516) 791- 6428; fax (516) 791-9024. SUPPLEMENTARY INFORMATION: Transport Canada Aviation, which is the airworthiness authority for Canada, recently notified the FAA that an unsafe condition may exist on certain de Havilland Model DHC-7 series airplanes. Transport Canada Aviation advises that it has received a report of pilot valve leakage of hydraulic fluid in a landing gear selector valve on a Model DHC-7 series airplane. The cause of this leakage has been attributed to a faulty seal. Such leakage, if combined with a low voltage condition at the selector valve down solenoid, could result in inadvertent retraction of the landing gear. De Havilland, Inc., has issued Alert Service Bulletin S.B. A7-32- 97, dated November 10, 1992, that describes procedures for repetitive inspections of the hydraulic selector valve to determine the rate of leakage of hydraulic fluid, and replacement of certain valves with serviceable valves, if necessary. Transport Canada Aviation classified this service bulletin as mandatory and issued Canadian Airworthiness Directive CF-94-04, dated March 16, 1994, in order to assure the continued airworthiness of these airplanes in Canada. De Havilland, Inc., also has developed a valve (Modification 7/ 2516) that incorporates several improvements to minimize pilot valve leakage. This valve is equipped with an improved spring that keeps the valve firmly seated. The improved valve incorporates a reduced rate of opening and further restricts the orifice leading to the landing gear actuators. Replacement of certain valves with these improved valves will minimize the possibility of inadvertent landing gear retraction. 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, Transport Canada Aviation has kept the FAA informed of the situation described above. The FAA has examined the findings of Transport Canada Aviation, 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. 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 inadvertent retraction of the landing gear in the event of a low voltage condition at the selector valve down solenoid. This AD requires repetitive inspections of the hydraulic selector valve to determine the rate of leakage of hydraulic fluid, and replacement of certain valves with serviceable valves, if necessary. This AD also provides an optional terminating action for the repetitive inspections. The actions are required to be accomplished in accordance with the alert service bulletin described previously. The FAA is considering the issuance of parallel rulemaking action to address the same unsafe condition on Model DHC-8-100 series airplanes. 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 notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 94-NM-75-AD.'' The postcard will be date stamped and returned to the commenter. 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. The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and 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 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding the following new airworthiness directive: 94-14-19 de Havilland, Inc.: Amendment 39-8967. Docket 94-NM-75-AD. Applicability: Model DHC-7 series airplanes; serial numbers 003 through 110 inclusive; equipped with landing gear selector valve, part number 57420 or 57420-3; certificated in any category. Compliance: Required as indicated, unless accomplished previously. To prevent inadvertent landing gear retraction due to pilot valve leakage, accomplish the following: (a) Within 300 hours time-in-service after the effective date of this AD, inspect the hydraulic selector valve to determine the rate of leakage of hydraulic fluid, in accordance with the Accomplishment Instructions of de Havilland Alert Service Bulletin S.B. A7-32-97, dated November 10, 1992. (1) If the rate of leakage is 100 cubic centimeters (cc) per minute or less: Repeat the inspection required by paragraph (a) of this AD thereafter at intervals not to exceed 5,400 hours time-in- service. (2) If the rate of leakage is more than 100 cc per minute, but less than 1,000 cc per minute: Within 300 hours time-in-service, replace the hydraulic selector valve with a serviceable valve in accordance with the alert service bulletin. Thereafter, repeat the inspection required by paragraph (a) of this AD at intervals not to exceed 5,400 hours time-in-service. (3) If the rate of leakage is 1,000 cc or more per minute, but less than 1,500 cc per minute: Within 50 hours time-in-service, replace the hydraulic selector valve with a serviceable valve in accordance with the alert service bulletin. Thereafter, repeat the inspection required by paragraph (a) of this AD at intervals not to exceed 5,400 hours time-in-service. (4) If the rate of leakage is 1,500 cc or more per minute: Prior to further flight, replace the hydraulic selector valve with a serviceable valve in accordance with the alert service bulletin. Thereafter, repeat the inspection required by paragraph (a) of this AD at intervals not to exceed 5,400 hours time-in-service. (b) Replacement of the hydraulic selector valve, part number 57420 or 57420-3, with an improved valve (Modification 7/2516), part number 57420-5, constitutes terminating action for the requirements of 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: 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 inspections and replacement shall be done in accordance with de Havilland Alert Service Bulletin S.B. A7-32-97, dated November 10, 1992. 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 de Havilland, Inc., 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, 181 South Franklin Avenue, room 202, Valley Stream, New York; or at the Office of the Federal Register, 800 North Capitol Street NW., suite 700, Washington, DC. (f) This amendment becomes effective on July 26, 1994. Issued in Renton, Washington, on June 30, 1994. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 94-16405 Filed 7-8-94; 8:45 am] BILLING CODE 4910-13-U