# AD 96-09-07: Abex Electro-Hydraulic Servo Valves - Type: Airworthiness directive - Status: Current - Products: Boeing 757-200 Series, 757-200CB Series, 757-200PF Series and 757-300 Series - Effective: May 10, 1996 - Published: April 25, 1996, 61 FR 18238–18242 - Issued as: Final rule; request for comments - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Large airplane - Amendment: 39-9581 - Docket: 96-NM-75-AD - Registered aircraft: 270 may be affected, by airframe or engine model (OpenAirDocs) - Official PDF: https://openairdocs.org/files/sha256/ac/e1/ace11cd2998b34fc31044dae74024d8a5b9ae03b5f3d493f4fefc00e4f8f142c (from https://www.govinfo.gov/content/pkg/FR-1996-04-25/pdf/96-10209.pdf) - Federal Register: https://www.federalregister.gov/documents/1996/04/25/96-10209/airworthiness-directives-boeing-model-757-series-airplanes-equipped-with-moog-spoiler-actuators - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/01A631E3AA452B2D8625697B00450B5A.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/96-09-07 ## Summary This amendment supersedes an existing airworthiness directive (AD) that is applicable to Boeing Model 757 series airplanes equipped with certain Abex spoiler actuator electro-hydraulic servo valves (EHSV) installed in certain spoiler actuators. The existing AD currently 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. That amendment was prompted by reports that a bias spring in the EHSV of certain spoiler actuators was found to be incorrectly installed. The actions specified by that 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. This amendment adds additional suspect EHSV's that require inspection; it also corrects the actuator manufacturer's name and corrects the serial number of one EHSV. ## The airworthiness directive 96-09-07 BOEING: Amendment 39-9581. Docket 96-NM-75-AD. Supersedes AD 96-06-01, Amendment 39-9537. Applicability: Model 757 airplanes, certificated in any category, that are equipped with Moog 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 EHSV Serial Number Abex Order No.* Shipment Date* AH-0001 C716657 08 November 1991 AH-0002 C716657 08 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 1989 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 1989 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 559 C728290 05 September 1994 563 C724224 14 September 1993 579 C724176 14 September 1993 595 C727735 24 January 1994 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 909 C724877 29 November 1993 912 C727977 04 August 1994 991 C713602 10 December 1990 998 C731477 04 September 1995 1022 C708905 13 November 1989 1023 C708905 13 November 1989 1072 C709166 14 November 1989 1148 C730192 13 March 1995 1175 C723278 05 August 19931227 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 Abex 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 thathave 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 Moog 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 spoileractuator 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 May 10, 1996. ## Rule preamble ### Supplementary information On March 5, 1996, the FAA issued AD 96-06-01, amendment 39-9537 (61 FR 9607, March 11, 1996), which is applicable to Boeing Model 757 series airplanes equipped with certain electro hydraulic servo valves (EHSV) installed in certain spoiler actuators. That AD requires a one-time inspection of the EHSV on the spoiler actuator to determine if a suspect valve is incorrectly installed; if so, the EHSV must be replaced. That action was prompted by reports that a bias spring in the EHSV of certain spoiler actuators was found to be incorrectly installed. 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 airplaneis 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. The actions required by AD 96-06-01 are intended to prevent the occurrence of such a control upset. New Data Since Issuance of AD 96-06-01 Since the issuance of that AD, the manufacturer has provided the FAA with data indicating that additional suspect EHSV's may be installed on the affected airplanes. These suspect EHSV's have serial numbers of 595, 563, and 909. If any of these EHSV's are installed on an airplane, there is the potential for the occurrence of the same unsafe condition that was addressed by AD 96-06-01. Explanation of New AD Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of this same type design, this AD supersedes AD 96-06-01 to require 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 AD requires the inspection for and removal of three additional suspect EHSV's. Additionally, action is taken throughout this AD to specify the correct names of the manufacturers of the spoiler actuator and the EHSV. The subject spoiler actuators are manufactured by Moog; the subject EHSV's are manufactured by Abex. Table 1 of this AD has been corrected to indicate that the order numbers are "Abex" order numbers, rather than "Boeing" order numbers. Due to a typographical error, EHSV serial number "559" was incorrectly listed in Table 1 of AD 96-06-01 as serial number "569." This AD corrects that error. Cost Impact According to the records of the EHSV manufacturer, all of the affected EHSV's were shipped to be installed on Model 757 series airplanes that currently are operated by non-U.S. operators under foreign registry. None of the Model 757 series airplanes affected by this action are onthe U.S. Register; 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: 1. any of the subject airplanes are imported and placed on the U.S. Register in the future; or 2. any one of the suspect EHSV's is installed on a U.S.-registered airplane in the future. Should an affected airplane be 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. Conclusion 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 96-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. 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: 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 removing amendment 39-9537 (61 FR 9607, March 11, 1996), and by adding a new airworthiness directive (AD), amendment 39-9581, to read as follows: ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS A2NM](https://openairdocs.org/tcds/A2NM): The Boeing Company; names 4 of 4 models: 757-200CB Series, 757-200PF Series, 757-300 Series, 757-200 Series ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 270 (270 by airframe model, 0 by engine model) - Makers: Boeing 270 Models with the most aircraft: - [Boeing 757-232](https://openairdocs.org/model/boeing-757-232): 63 aircraft (airframe model) - [Boeing 757-224](https://openairdocs.org/model/boeing-757-224): 40 aircraft (airframe model) - [Boeing 757-222](https://openairdocs.org/model/boeing-757-222): 38 aircraft (airframe model) - [Boeing 757-223](https://openairdocs.org/model/boeing-757-223): 23 aircraft (airframe model) - [Boeing 757-236](https://openairdocs.org/model/boeing-757-236): 20 aircraft (airframe model) - [Boeing 757-251](https://openairdocs.org/model/boeing-757-251): 18 aircraft (airframe model) - [Boeing 757-351](https://openairdocs.org/model/boeing-757-351): 16 aircraft (airframe model) - [Boeing 757-231](https://openairdocs.org/model/boeing-757-231): 13 aircraft (airframe model) - [Boeing 757-324](https://openairdocs.org/model/boeing-757-324): 9 aircraft (airframe model) - [Boeing 757-200 SERIES](https://openairdocs.org/model/boeing-757-200-series): 7 aircraft (airframe model) - [Boeing 757-204](https://openairdocs.org/model/boeing-757-204): 6 aircraft (airframe model) - [Boeing 757-225](https://openairdocs.org/model/boeing-757-225): 5 aircraft (airframe model) - [Boeing 757-230](https://openairdocs.org/model/boeing-757-230): 4 aircraft (airframe model) - [Boeing 757-258](https://openairdocs.org/model/boeing-757-258): 3 aircraft (airframe model) - [Boeing 757-256](https://openairdocs.org/model/boeing-757-256): 3 aircraft (airframe model) - [Boeing 757-260PF](https://openairdocs.org/model/boeing-757-260pf): 2 aircraft (airframe model) All 16 models: https://openairdocs.org/ad/96-09-07/models.md Every aircraft: https://openairdocs.org/ad/96-09-07/aircraft.md 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.