# AD 96-06-01: Airworthiness Directives; Boeing Model 757 Series Airplanes Equipped With Abex Spoiler Actuators - Type: Airworthiness directive - Effective: March 26, 1996 - Published: March 11, 1996, 61 FR 9607–9611 - Issued as: Final rule; request for comments - Superseded by: Nothing supersedes this AD - Amendment: 39-9537 - Docket: 95-NM-277-AD - Official PDF: https://openairdocs.org/files/sha256/41/b8/41b889a873cf6ed8e63367ecafd41e1a938647654e67173b2a9edd0582007fd1 (from https://www.govinfo.gov/content/pkg/FR-1996-03-11/pdf/96-5689.pdf) - Federal Register: https://www.federalregister.gov/documents/1996/03/11/96-5689/airworthiness-directives-boeing-model-757-series-airplanes-equipped-with-abex-spoiler-actuators - Page: https://openairdocs.org/ad/96-06-01 ## Summary This amendment adopts a new airworthiness directive (AD), applicable to Boeing Model 757 series airplanes that are equipped with certain Abex spoiler actuator electro-hydraulic servo valves (EHSV) installed in Abex spoiler actuators. This action requires a one-time inspection of the spoiler actuator to determine if a suspect EHSV is incorrectly installed, and replacement of the EHSV, if necessary. This amendment is prompted by reports that a bias spring in the Abex EHSV of certain Abex spoiler actuators has been found to be incorrectly installed. The actions specified in this AD are intended to prevent a significant control upset of the airplane as a result of problems associated with an incorrectly installed EHSV in the spoiler actuator assembly. ## The airworthiness directive ### PART 39--AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 USC 106(g), 40113, 44701. ### Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding the following new airworthiness directive: 96-06-01 Boeing: Amendment 39-9537. Docket 95-NM-277-AD. Applicability: Model 757 airplanes, certificated in any category, that are equipped with Abex spoiler actuators having Abex electro-hydraulic servo valves (EHSV), part number 72196, with the serial numbers listed in Table 1 of this AD: Table 1 ------------------------------------------------------------------------ Boeing order EHSV serial No. No.*- Shipment date* ------------------------------------------------------------------------ AH-0001...................... C716657........ 8 November 1991. AH-0002...................... C716657........ 8 November 1991. AH-0003...................... C727995........ 25 August 1994. AH-0004...................... C727995........ 25 August 1994. AH-0005...................... C727995........ 25 August 1995. AH-0006...................... C727995........ 25 August 1995. AH-0007...................... C727995........ 25 August 1995. 13........................... C731181........ 12 June 1995. 49........................... C730878........ 01 June 1995. 61........................... C727955........ 13 September 1994. 131.......................... C708905........ 13 November 89. 233.......................... C727730........ 17 June 1994. 241.......................... C731540........ 13 September 1995. 260.......................... C727955........ 13 September 1994. 279.......................... C728298........ 02 September 1994. 275.......................... C727880........ 24 June 1994. 308.......................... C725421........ 01 December 1993. 329.......................... C727711........ 17 June 1994. 347.......................... C727518........ 14 June 1994. 401.......................... C728298........ 05 September 1994. 407.......................... C727730........ 17 June 1994. 427.......................... C731181........ 03 July 1995. 450.......................... C731181........ 03 July 1995. 445.......................... C706627........ 22 February 89. 457.......................... C731663........ 12 September 1995. 456.......................... C728887........ 28 November 1994. 463.......................... C731435........ 21 August 1995. 484.......................... C727748........ 22 June 1994. 515.......................... C727745........ 24 June 1994. 569.......................... C728290........ 05 September 1994. 579.......................... C724176........ 14 September 1993. 611.......................... C727955........ 14 September 1994. 607.......................... C727997........ 20 July 1994. 647.......................... C728459........ 10 October 1994. 726.......................... C731096........ 04 September 1995. 725.......................... C729525........ 19 December 1994. 819.......................... C728135........ 03 August 1994. 890.......................... C726803........ 06 April 1994. 874.......................... C730890........ 26 April 1995. 912.......................... C727977........ 04 August 1994. 991.......................... C713602........ 10 December 90. 998.......................... C731477........ 4 September 1995. 1022......................... C708905........ 13 November 89. 1023......................... C708905........ 13 November 89. 1072......................... C709166........ 14 November 89. 1148......................... C730192........ 13 March 1995. 1175......................... C723278........ 05 August 1993. 1227......................... C728303........ 31 August 1994. 1283......................... C731833........ 04 September 1995. 1487......................... C728549........ 04 October 1994. 1655......................... C728442........ 28 November 1994. 1780......................... C726757........ 06 April 1994. 1807......................... C728669........ 29 September 1994. 1862......................... C727625........ 17 June 1994. 1929......................... C727977........ 04 August 1994. 1986Z........................ C727730........ 17 June 1994. 2017Z........................ C725411........ 24 November 1993. 2034......................... C727730........ 17 June 1994. 2073......................... C731272........ 12 September 1995. 2125......................... C725713........ 12 January 1994. 2220......................... C729735........ 29 March 1995. 2334......................... C727730........ 17 June 1994. 2348......................... C727730........ 17 June 1994. 2426......................... C731623........ 12 July 1995. ------------------------------------------------------------------------ *The Boeing Order Number and Shipment Date are included in this listing to enable operators to review their records in order to determine if a suspect EHSV has been ordered, and if, or where, it has been installed on an airplane. 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 (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 a significant control upset of the airplane due to problems associated with incorrectly assembled Abex electro- hydraulic servo valves (EHSV) on certain Abex spoiler actuators, accomplish the following: (a) Within 6 months after the effective date of this AD, perform the following procedure: (1) While the airplane is on the ground, extend the flaps to 40 degrees. and visually inspect the spoiler actuator EHSV assembly to determine the location of the second stage bias spring end cap assembly. (2) If the second stage bias spring cap assembly is on the aft or lower side of the EHSV assembly, prior to further flight, replace the EHSV, having Abex part number 72196, with a serviceable unit in accordance with the airplane maintenance manual. Note 2: To be correctly positioned, the second stage bias spring cap assembly should be on the upper or forward side of the EHSV assembly. Appendix 1 of this AD provides a visual representation of the correct positioning of the EHSV assembly. (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, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO. Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle 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) This amendment becomes effective on March 26, 1996. BILLING CODE 4910-13-U Appendix 1 [GRAPHIC] [TIFF OMITTED] TR11MR96.004 BILLING CODE 4910-13-C Issued in Renton, Washington, on March 5, 1996. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. ## Rule preamble ### Dates Effective March 26, 1996. Comments for inclusion in the Rules Docket must be received on or before May 10, 1996. ### Addresses Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 95-NM-277-AD, 1601 Lind Avenue SW., Renton, Washington 98055-4056. Information concerning this AD action may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington. ### For further information contact Don Eiford, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, Washington; telephone (206) 227-2788; fax (206) 227-1181. ### Supplementary information The FAA has received reports that a bias spring in the Abex electro-hydraulic servo valve (EHSV) in certain Abex spoiler actuators that are installed on certain Boeing Model 757 series airplanes has been found to be incorrectly installed. One operator received three valves on which the bias spring was installed on the wrong side of the EHSV second stage spool. Investigation revealed that the valves had been assembled incorrectly during repair at a non-U.S. repair facility. The subject EHSV's are Abex P/N 72196, Boeing Specification S251N116-1, Model 410-1870. If the jet pipe in the first stage of the EHSV is plugged, or if the differential pressure between the extend and retract ports pressurized by the jet pipe is inadequate, an incorrectly installed bias spring on the second stage spool would cause the spoiler to be driven into the ``deploy'' position. Such inadvertent spoiler deployment would result in the airplane experiencing a rolling moment. If the airplane is already banked or is at a low altitude, or if the crew does not respond rapidly enough to control the uncommanded roll, a significant control upset of the airplane could result. Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design, this AD is being issued to prevent the occurrence of a significant control upset of the airplane due to problems associated with suspect EHSV's in the spoiler actuator. This AD requires a one-time inspection of the Abex EHSV on the spoiler actuator to determine if a suspect valve is incorrectly installed; if so, the EHSV must be replaced. None of the Model 757 series airplanes affected by this action are on the U.S. Register. All airplanes included in the applicability of this rule currently are operated by non-U.S. operators under foreign registry; therefore, they are not directly affected by this AD action. However, the FAA considers that this rule is necessary to ensure that the unsafe condition is addressed in the event that any of these subject airplanes are imported and placed on the U.S. Register in the future. Should an affected airplane be imported and placed on the U.S. Register in the future, it would require approximately 1 work hour to accomplish the required actions, at an average labor charge of $60 per work hour. Based on these figures, the cost impact of this AD would be $60 per airplane. Since this AD action does not affect any airplane that is currently on the U.S. register, it has no adverse economic impact and imposes no additional burden on any person. Therefore, notice and public procedures hereon are unnecessary and the amendment may be made effective in less than 30 days after publication in the Federal Register. ### Comments Invited Although this action is in the form of a final rule and was not preceded by notice and 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 95-NM-277-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. 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, 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: No proposed rule in this release led to it. Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.