# AD 98-16-17: Secondary Horizontal Stabilizer Trim Actuator - Type: Airworthiness directive - Status: Historical - Products: Cessna Aircraft Company, The 750 - Effective: August 24, 1998 - Published: August 7, 1998, 63 FR 42206–42208 - Issued as: Final rule; request for comments - Superseded by: [AD 98-16-17 R1](https://openairdocs.org/ad/98-16-17-R1) - Product type: Aircraft, Large airplane - Amendment: 39-10693 - Docket: 98-NM-208-AD - Registered aircraft: 288 may be affected, by airframe or engine model (OpenAirDocs) - Official PDF: https://openairdocs.org/files/sha256/5a/bc/5abc4b025cd2e4008bb11a288703291bc18c185c2cd8fb15171ee2a44e64ad38 (from https://www.govinfo.gov/content/pkg/FR-1998-08-07/pdf/98-20836.pdf) - Federal Register: https://www.federalregister.gov/documents/1998/08/07/98-20836/airworthiness-directives-cessna-model-750-citation-x-series-airplanes - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/04F105BF0732702D86256A1F0066BC48.0001 - DRS record last changed: August 7, 2025 - Page: https://openairdocs.org/ad/98-16-17 ## Summary This amendment adopts a new airworthiness directive (AD) that is applicable to all Cessna Model 750 Citation X series airplanes. This action requires repetitive in-flight functional tests to verify proper operation of the secondary horizontal stabilizer pitch trim system, and repair, if necessary. This amendment is prompted by reports of simultaneous failures of the primary and secondary horizontal stabilizer pitch trim system during flight, due to internal water contamination and corrosion damage in the system actuator. The actions specified in this AD are intended to detect and correct such contamination and damage, which could result in simultaneous failure of both primary and secondary pitch trim systems, and consequent reduced controllability of the airplane. ## The airworthiness directive 98-16-17 CESSNA AIRCRAFT COMPANY: Amendment 39-10693. Docket 98-NM-208-AD. Applicability: All Model 750 Citation X series airplanes, certificated in any category. 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 detectand correct internal water contamination and corrosion damage of the secondary horizontal stabilizer trim actuator, which could result in simultaneous failure of both primary and secondary pitch trim systems, and consequent reduced controllability of the airplane, accomplish the following: (a) Within 10 days after the effective date of this AD, perform an in-flight functional test to verify proper operation of the secondary horizontal stabilizer pitch trim system, in accordance with Cessna Alert Service Bulletin ASB750-27-22, dated July 2, 1998. (1) If the secondary trim system does not fail during the in-flight functional test, repeat the action thereafter at intervals not to exceed 30 days. (2) If the secondary trim system fails during the in-flight functional test, prior to next flight, inspect the actuator components and clutch assemblies for evidence of internal water contamination or corrosion damage in accordance with the alert service bulletin. If any evidence of internal water contamination or corrosion damage is detected, prior to further flight, repair in accordance with the alert service bulletin. Repeat the in-flight functional test thereafter at intervals not to exceed 30 days. (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, Wichita Aircraft Certification Office (ACO), FAA, Small 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, Wichita ACO. NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Wichita 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 therequirements of this AD can be accomplished. (d) The actions shall be done in accordance with Cessna Alert Service Bulletin ASB750-27-22, dated July 2, 1998. 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 Cessna Aircraft Co., P.O. Box 7706, Wichita, Kansas 67277. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Small Airplane Directorate, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. (e) This amendment becomes effective on August 24, 1998. ## Rule preamble ### Supplementary information The FAA recently received reports of simultaneous primary and secondary horizontal stabilizer pitch trim system failures during flight on Cessna Model 750 Citation X series airplanes. Inspection of the horizontal stabilizer pitch trim actuators utilized for both primary and secondary pitch trim has revealed evidence of internal water contamination and corrosion damage. This condition may be caused by water being ingested into the actuator due to condensation during airplane descent from high altitude into a warm, humid environment. Subsequent testing by the manufacturer has verified that the trapped water may freeze in the actuator mechanism and disable actuation of both primary and secondary trim. It has been determined that the actuator case seal, as applied to some actuators, may be ineffective at preventing internal water contamination and corrosion damage. Such contamination and damage, if not corrected, could result in simultaneous failure of bothprimary and secondary trim system, and consequent reduced controllability of the airplane. Explanation of Relevant Service Information The FAA has reviewed and approved Cessna Alert Service Bulletin ASB750-27-22, dated July 2, 1998, which describes procedures for repetitive in-flight functional tests to verify proper operation of the secondary horizontal stabilizer pitch trim system. (Such functional testing of the primary horizontal stabilizer pitch trim system is currently addressed in the FAA-approved Airplane Flight Manual and FAA-approved maintenance procedures for these airplanes.) For airplanes on which the functional test fails, the alert service bulletin also describes procedures for inspection of the actuator components and clutch assemblies for evidence of internal water contamination in the system actuator and corrosion damage; and repair, if necessary. Explanation of the Requirements of the Rule 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 failure of both primary and secondary pitch trim systems due to internal water contamination and corrosion damage in the system actuator, which could result in reduced controllability of the airplane. This AD requires accomplishment of the actions specified in the alert service bulletin described previously. Interim Action This is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking. 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 notpreceded 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, inthe 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 98-NM-208-AD." The postcard will be date stamped and returned to the commenter. 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. The FAA has determined that this regulationis 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 to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFRpart 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: ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS T00007WI](https://openairdocs.org/tcds/T00007WI): Textron Aviation Inc.; names 1 of 1 models: 750 ## 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: 288 (288 by airframe model, 0 by engine model) - Makers: Cessna 273, Textron 15 Models with the most aircraft: - [Cessna 750](https://openairdocs.org/model/cessna-750): 273 aircraft (airframe model) - [Textron 750](https://openairdocs.org/model/textron-750): 15 aircraft (airframe model) All 3 models: https://openairdocs.org/ad/98-16-17/models.md Every aircraft: https://openairdocs.org/ad/98-16-17/aircraft.md ## Related documents - [AD 98-16-17 R1](https://openairdocs.org/ad/98-16-17-R1): Secondary horizontal stabilizer · Textron 750. Effective Oct 23, 2003. Supersedes this AD 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.