AD 98-05-09

This amendment adopts a new airworthiness directive (AD), applicable to all IAI, Ltd., Model 1121, 1121A, 1121B, 1123, 1124, and 1124A series airplanes, that requires repetitive inspections of the trim actuator of the horizontal stabilizer to verify jackscrew integrity and to detect excessive wear of the tie rod, and replacement of the actuator or tie rod, if necessary. This amendment is prompted by issuance of mandatory continued airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to ensure that the trim actuator of the horizontal stabilizer operates properly; failure of the actuator to operate properly could result in reduced controllability of the airplane.

Final rule.

98-05-09 ISRAEL AIRCRAFT INDUSTRIES (IAI), LTD.: Amendment 39-10370. Docket 97-NM-166-AD.

Applicability: All Model 1121, 1121A, 1121B, 1123, 1124, and 1124A 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 (e) 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, unlessaccomplished previously.

To ensure that the trim actuator of the horizontal stabilizer operates properly, accomplish the following:

(a) Perform an inspection of the trim actuator of the horizontal stabilizer to verify jackscrew integrity and to detect excessive wear of the tie rod, in accordance with Commodore Jet Service Bulletin SB 1121-27-023, dated August 14, 1996, or Revision 1, dated May 28, 1997 (for Model 1121, 1121A, and 1121B series airplanes); Westwind Service Bulletin SB 1123-27-046, dated August 14, 1996, or Revision 1, dated May 28, 1997 (for Model 1123 series airplanes); or Westwind Service Bulletin 1124-27-133, dated August 14, 1996, or Revision 1, dated May 28, 1997 (for Model 1124 and 1124A series airplanes), as applicable; at the time specified in paragraph (a)(1) or (a)(2) of this AD, as applicable.

(1) For airplanes that have accumulated 6,000 or more total flight cycles, or on which the horizontal trim actuator has accumulated 2,000 or more flight cycles as of the effective date of this AD: Inspect within 50 flight hours after the effective date of this AD. Repeat the inspection thereafter at intervals not to exceed 300 flight hours (for Model 1121, 1121A, 1121B, and 1123 series airplanes); or 400 flight hours (for Model 1124 and 1124A series airplanes); as applicable.

(2) For airplanes that have accumulated less than 6,000 total flight cycles, and on which the horizontal trim actuator has accumulated less than 2,000 total flight cycles as of the effective date of this AD: Inspect at the times specified in paragraph (a)(2)(i) or (a)(2)(ii) of this AD, as applicable.

(i) For Model 1121, 1121A, 1121B, and 1123 series airplanes: Inspect within 300 flight hours after the effective date of this AD. Repeat the inspection thereafter at intervals not to exceed 300 flight hours.

(ii) For Model 1124 and 1124A series airplanes: Inspect within 400 flight hours after the effective date of this AD. Repeat the inspection thereafter at intervals not to exceed 400 flight hours.

(b) If any discrepancy is found during any inspection required by paragraph (a) of this AD, prior to further flight, replace the actuator or tie rod, as applicable, in accordance with Commodore Jet Service Bulletin SB 1121-27-023, dated August 14, 1996, or Revision 1, dated May 28, 1997 (for Model 1121, 1121A, and 1121B series airplanes); Westwind Service Bulletin SB 1123-27-046, dated August 14, 1996, or Revision 1, dated May 28, 1997 (for Model 1123 series airplanes); or Westwind Service Bulletin 1124-27-133, dated August 14, 1996, or Revision 1, dated May 28, 1997 (for Model 1124 and 1124A series airplanes); as applicable.

(c) As of the effective date of this AD, no horizontal stabilizer trim actuator shall be installed on any airplane unless that trim actuator has been inspected in accordance with the requirements of paragraph (a) of this AD.

(d) Replacement of the trim actuator of the horizontal stabilizer with a modified trim actuator with modified jackscrew assemblies in accordance with Commodore Jet Service Bulletin SB 1121-27-025, dated December 22, 1997 (for Model 1121, 1121A, and 1121B series airplanes); Westwind Service Bulletin SB 1123-27-047, dated September 1, 1997 (for Model 1123 series airplanes); or Westwind Service Bulletin 1124-27-136, dated September 1, 1997 (for Model 1124 and 1124A series airplanes), as applicable; constitutes terminating action for the requirements of this AD.

(e) 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, International Branch, ANM-116, 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, International Branch, ANM-116.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.

(f) 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.

(g) The actions shall be done in accordance with the following service bulletins, which contain the specified effective pages:

Service Bulletin Referenced and Date
Page Number Shown on Page
Revision Level Shown on Page
Date
Shown on Page

Westwind
SB 1124-27-133,
August 14, 1996
1-6
Original
August 14, 1996

Westwind
SB 1124-27-133,
Revision 1,
May 28, 1997
1-4

5, 6
1

Original
May 28, 1997

August 14, 1996

Westwind
SB 1123-27-046,
August 14, 1996
1-6
Original
August 14, 1996

Westwind
SB 1124-27-046,
Revision 1,
May 28, 1997
1-4

5, 6
1

Original
May 28, 1997

August 14, 1996

Westwind
SB 1124-27-136,
September 1, 1997
1-3
Original
September 1, 1997

Westwind
SB 1123-27-047,
September 1, 1997
1-3
Original
September 1, 1997

Commodore Jet
SB 1121-27-025,
December 22, 1997
1-3
Original
December 22, 1997

Commodore Jet
SB 1121-27-023,
August 14, 1996
1-6
Original
August 14, 1996

Commodore Jet
SB 1121-27-023,
Revision 1,
May 28, 1997
1-4

5, 6
1

Original
May 28, 1997

August 14, 1996

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 Galaxy Aerospace Corporation, One Galaxy Way, Fort Worth Alliance Airport, Fort Worth, Texas 76177. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

NOTE 3: The subject of this AD is addressed in Israeli airworthiness directive 96-92, dated September 1, 1996.

(h) This amendment becomes effective on April 10, 1998.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to all IAI, Ltd., Model 1121, 1121A, 1121B, 1123, 1124, and 1124A series airplanes was published in the Federal Register on August 11, 1997 (62 FR 42952). That action proposed to require repetitive inspections of the trim actuator of the horizontal stabilizer to verify jackscrew integrity and to detect excessive wear of the tie rod, and replacement of the actuator or tie rod, if necessary.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Requests to Mandate Modifications
One commenter requests that the FAA not issue this AD, but instead issue an AD to require replacement of the trim actuator of the horizontal stabilizer. This commenter notes that a modification to the jackscrew threads has been identified, which will reduce stress concentration at the thread root and would eliminate the need to conduct the inspections of the jackscrews. The commenter further notes that, since the issuance of the proposed rule, Galaxy Aerospace Corporation has issued Westwind Service Bulletins SB 1123-27-047 (for Model 1123 series airplanes) and SB 1124-27-136 (for Model 1124 and 1124A series airplanes), both dated September 1, 1997. The commenter also notes that Galaxy Aerospace Corporation is scheduled to issue Commodore Jet Service Bulletin SB 1121-27-025 (for Model 1121, 1121A, and 1121B series airplanes) in December 1997. These three service bulletins describe procedures for replacement of the trim actuators of the horizontal stabilizer with modified trim actuators containing jackscrews with modified threads. The commenter considers that accomplishment of these service bulletins provides a more effective means to resolve the safety of flight issues.

The FAA concurs partially with the commenter s request. Since the issuance of the proposed rule, Galaxy Aerospace Corporation has issued Service Bulletin SB 1121-27-025, dated December 22, 1997. The FAA agrees that replacement of the trim actuator of the horizontal stabilizer with a modified trim actuator in accordance with the procedures described in the three service bulletins referenced previously provides a more effective means to prevent failure of the trim actuator jackscrews and would eliminate the need for the repetitive inspections required by this AD. Therefore, the final rule has been revised to include the replacement of the trim actuator as an optional terminating action.

However, the FAA does not agree that this AD, which would require inspections, should be withdrawn. Rather, the FAA considers that, consistent with the actions taken by the Civil Aviation Administration of Israel (CAAI), and due to the urgency of the problem, the inspections must be performed as an interim action to ensure safe operation. Although the replacement of the trim actuator is provided as an optional terminating action in this final rule, the FAA is considering further rulemaking to require replacement of the trim actuator on all affected airplanes. The FAA notes that Israeli airworthiness directive 27-97-09-02 was issued on September 4, 1997. That airworthiness directive requires replacement of the trim actuator with a modified trim actuator in accordance with the service bulletins defined above, and specifies that the replacement of the trim actuator is terminating action for the repetitive inspections required by Israeli airworthiness directive 96-92 dated September 1, 1996, which is the Israeli airworthiness directive addressed by this AD.

Request to Not Mandate Modifications
One commenter supports the requirement of the proposed AD to perform repetitive inspections of the jack screws and tie rods of the trim actuator of the horizontal stabilizer. However, this commenter (and several others) object to any plans to mandate replacement of the trim actuators. The commenter notes that it is only aware of one cracked eye bolt that was found during inspections of the trim actuators. The commenter also notes that some of the modified trim actuators were obtained from non-operable aircraft in salvage yards, and that it believes that the trim actuator could be rebuilt to meet the specifications for much less cost than the price quoted in the service bulletins. The commenter considers that the replacement of the trim actuators is driven by money issues and not safety issues. Other commenters consider the replacement too costly. Another commenter notes that both broken jack screws were found on airplanes operated by the same flight department, and that this may not be a fleet-wide problem.

The FAA points out that this AD does not mandate replacement of the trim actuators of the horizontal stabilizer, but rather now provides for optional terminating action to replace thetrim actuators. However, as stated above, the FAA is considering further rulemaking to require replacement of the trim actuators on all affected airplanes. The FAA will consider the remarks submitted by these commenters, and will determine whether other options are available to address the identified unsafe conditions. In addition, under the provisions of paragraph (e) of this final rule, the FAA may approve requests for approval of an alternative method of compliance for the requirements of this AD, if data are submitted to substantiate that accomplishment of such actions would provide an acceptable level of safety.

Request to Include Later Revisions of the Service Information
One commenter requests that the AD be revised to include an option to inspect the jackscrews of the trim actuator in accordance with Revision 1 of the service bulletins referenced in the proposed AD. The commenter notes that the service bulletins referenced in the proposed AD have been revised to permit use of alternative sealants during reassembly following inspection.

The FAA concurs with the commenter s request, and has revised this final rule to include an option to comply with Revision 1 of the service bulletins.

Request to Change Name and Address of Service Information Source
One commenter requests that the AD be revised to change the name and address where service information can be obtained. The commenter notes that Astra Jet Corporation no longer provides support for these aircraft, and that all references to Astra Jet Corporation should be changed to "Galaxy Aerospace Corporation." The commenter further notes that, effective October 13, 1997, the new address for customer service and product support for IAI products is: Galaxy Aerospace Corporation, One Galaxy Way, Fort Worth Alliance Airport, Fort Worth, Texas 76177. The FAA concurs, and has revised this final rule accordingly.

Conclusion
After careful review of the available data, including the commentsnoted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

Cost Impact
The FAA estimates that 292 airplanes of U.S. registry will be affected by this AD, that it will take approximately 4 work hours per airplane to accomplish the required inspection, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the inspection required by this AD on U.S. operators is estimated to be $70,080, or $240 per airplane.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.

Should an operator elect to accomplish the optional terminating action rather than continue the repetitive inspections, it would take approximately 4 work hours per airplane to accomplish the replacement, at an average labor rate of $60 per work hour. Required parts would cost approximately $44,350 per airplane. Based on these figures, the cost impact of this optional terminating action is estimated to be $44,590 per airplane.

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.

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, 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. 106(g), 40113, 44701.

39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: